Need some help with a conversion

11 views
Skip to first unread message

z0ck

unread,
May 23, 2001, 2:32:23 PM5/23/01
to
I have an 85 GMC Suburban 4x4 with a sick Gas 350. I want to convert it
over to diesel/electric. I recently bought a house that had most of an
80-something Isuzu pup in the back yard, to include a functioning 4-cyl
diesel engine.

My current thought is to have that diesel engine rebuilt and loaded up with
with either several Delco-type 200 amp Alternators or perhaps a single large
generator of similar output. Which would be better? I'm also planning on
using either a single large motor directly connected to the Trans (updated
4L80E w/ shift control box) or several smaller motors totalling the same
output driving a flywheel (via a clutching system) which is conected
directly to the trans. Given that I will be using electric motors, rather
than a gas engine, I cannot see a need for a stall converter.

I think I'd like to use a smart electronic speed control system that can
figure out the difference between accelerating (or climbing a hill) and flat
highway cruising. With such a system, I could instruct it to use fewer
motors (assuming a multi-motor setup) for flat highway use, thus extending
range.

The target is to build a power system which can develop a maximum of 500+
lb-ft of torque and can comfortable cruise the highways with a loaded car
trailer attached.

Questions are:

1) Would I achieve better efficiency with several small alternators or a
single, larger unit?

2) Same question: Would I achieve better efficiency with several small
motors or a single larger?

3) Am I wrong about the Stall converter?

4) How can I determine the amount of power I will have to provide in order
to generate a specific amount of torque?

5) Is it possible to charge batteries from multiple sources with varying
(sometimes radically) voltages (i.e. alternator(s) and solar panels)?

6) Will the output from 5 identical motors add up in a linear fashion (i.e.
five 100hp motors provide the same power as a single 500h.p. motor)?

7) Assuming a multi-motor setup, is there an efficient way to predict
mechanical losses induced by additional equipment, like clutches and such?

If you think I'm way off with this, please let me know.

TIA!


ALFRED B

unread,
May 23, 2001, 3:13:10 PM5/23/01
to
I'd say rebuild the gasser. I'm no expert on those 58 horsepower non-turbo
Isuzu diesels, but the parts alone for it are nearly non-existent now. Just
keeping that engine alive may be a chore.

Of course, I was just thinking that you wanted to get the Suburban working
for relatively cheap.

I see a patent coming, I think.


Mark Kinsler

unread,
May 23, 2001, 3:42:08 PM5/23/01
to
>I have an 85 GMC Suburban 4x4 with a sick Gas 350. I want to convert it
>over to diesel/electric. I recently bought a house that had most of an
>80-something Isuzu pup in the back yard, to include a functioning 4-cyl
>diesel engine.

It might pay to look at the overall scheme: would this truck perform
adequately if the four-cylinder diesel was installed in place of the
existing V-8? The electric part of the system is just a replacement
for the transmission. The power to drive the truck comes from the
engine.


>My current thought is to have that diesel engine rebuilt and loaded up with
>with either several Delco-type 200 amp Alternators or perhaps a single large
>generator of similar output. Which would be better? I'm also planning on
>using either a single large motor directly connected to the Trans (updated
>4L80E w/ shift control box) or several smaller motors totalling the same
>output driving a flywheel (via a clutching system) which is conected
>directly to the trans. Given that I will be using electric motors, rather
>than a gas engine, I cannot see a need for a stall converter.

I wonder where you're planning to put all of this equipment. The
diesel isn't much smaller than the original engine, you want to keep
the transmission, and you're adding several motors and a big
generator. You'll be paying a considerable weight penalty, too.

>I think I'd like to use a smart electronic speed control system that can
>figure out the difference between accelerating (or climbing a hill) and flat
>highway cruising. With such a system, I could instruct it to use fewer
>motors (assuming a multi-motor setup) for flat highway use, thus extending
>range.

Your biggest electrical problem will be the design of the speed
control switching devices. In a motor vehicle, these take quite a
beating, what with braking transients and such.

>The target is to build a power system which can develop a maximum of 500+
>lb-ft of torque and can comfortable cruise the highways with a loaded car
>trailer attached.

Yee hah. You're gonna do this with an Isuzu diesel engine?

>Questions are:
>
>1) Would I achieve better efficiency with several small alternators or a
>single, larger unit?

Generally a larger machine is a more efficient machine: fewer design
compromises (and cost compromises) have to be made in the design. An
automotive alternator is meant to charge a car-starting battery and
run auto accessories. It's not really rated for traction work.

>2) Same question: Would I achieve better efficiency with several small
>motors or a single larger?

Depends on the sort of motor: brush or brushless DC, induction, or
whatever. Again, smaller motors tend to be less efficient than bigger
ones, but I don't think that this would be a major issue.

>3) Am I wrong about the Stall converter?

I don't know what a stall converter is.

>4) How can I determine the amount of power I will have to provide in order
>to generate a specific amount of torque?

Power= torque x angular velocity. Angular velocity is rpm divided by
2 x pi x 60, I think. (I oughta know: I just taught this in my
physics class last night, but I'm never sure if I have formulas right
when I type them on the computer.)

>5) Is it possible to charge batteries from multiple sources with varying
>(sometimes radically) voltages (i.e. alternator(s) and solar panels)?

With some penalty for power loss in the conversion process, yes. The
device to be investigated is known as a "dc-to-dc converter."

>6) Will the output from 5 identical motors add up in a linear fashion (i.e.
>five 100hp motors provide the same power as a single 500h.p. motor)?

Theoretically, but it's important to know that motor power rating is
not a particularly simple matter. I hope you're aware that your
truck, when new, would have found it quite a challenge to transport a
100 horsepower electric motor. I have no idea what a 500 hp motor
would weigh because I don't recall ever having seen one that large.

>7) Assuming a multi-motor setup, is there an efficient way to predict
>mechanical losses induced by additional equipment, like clutches and such?

I don't know. There are an awful lot of variables.

>If you think I'm way off with this, please let me know.

I'm afraid I do. I think you'll agree if you take a look at some real
electric vehicles and multi-horsepower motors. Electric motors are
really practical only for railroad equipment, where the weight penalty
is offset by the lack of rolling friction. They are quite heavy for
the power which they deliver. Generators are similarly weighty items.


I think that, as you learn about the engineering and construction of
existing transportation equipment, you'll get an appreciation of the
original setup in your old truck. Notice that there are no
diesel-electric road vehicles in use: conventional transmissions are
better in many ways than electric drives.

It's an exceptionally interesting problem, however, and I think you
should continue to study and work on a solution. Let us know how it
goes.

Mark Kinsler
512 E Mulberry St Lancaster Ohio USA 740.687.6368
http://www.frognet.net/~kinsler

Mark Daniels

unread,
May 23, 2001, 4:06:31 PM5/23/01
to
In article <3b0c0aa7...@news.earthlink.net>, Mark Kinsler
<kin...@frognet.net> writes

They certainly can be, but this is by no means always the case. An
example of a large(ish) electric motor is one I installed over in PA
somewhere last year. Rated output 192 kW at 1790 rpm continuous, 500 kW
for 60 seconds and it weighed in at 813 kg. I don't necessarily agree
that they are only suitable for rail applications, either, but you do
have a point.


>
>
>I think that, as you learn about the engineering and construction of
>existing transportation equipment, you'll get an appreciation of the
>original setup in your old truck. Notice that there are no
>diesel-electric road vehicles in use: conventional transmissions are
>better in many ways than electric drives.

Each has its own set of advantages and disadvantages. A diesel-electric
setup is inherently stronger than a diesel-gearbox setup. All the drive
is through magnetic coupling, with none of the contact stresses
prevalent in a mechanical gear system. I won't list the benefits of
gearboxes, here.

I think the best example I can give of a diesel-electric setup in a non-
rail transportation system is the Terex Titan open cast mining truck and
its cousins. 3300 bhp at 900 rpm from a large 24(?) cylinder diesel
coupled to an equally large alternator driving multi-pole hub motors
which are in turn directly coupled to the massive (12 ft dia) wheels.
The engine capacity is either 127 or 169 litres. Gallons per mile, I
think is how they quote the fuel consumption.


>
>It's an exceptionally interesting problem, however, and I think you
>should continue to study and work on a solution. Let us know how it
>goes.

Having said all that, I do agree with your general comments, Mark.


>
>Mark Kinsler
>512 E Mulberry St Lancaster Ohio USA 740.687.6368
>http://www.frognet.net/~kinsler

--
Mark Daniels

Stephen H. Westin

unread,
May 23, 2001, 4:50:28 PM5/23/01
to
kin...@frognet.net (Mark Kinsler) writes:

> >I have an 85 GMC Suburban 4x4 with a sick Gas 350. I want to convert it
> >over to diesel/electric. I recently bought a house that had most of an
> >80-something Isuzu pup in the back yard, to include a functioning 4-cyl
> >diesel engine.
>
> It might pay to look at the overall scheme: would this truck perform
> adequately if the four-cylinder diesel was installed in place of the
> existing V-8? The electric part of the system is just a replacement
> for the transmission. The power to drive the truck comes from the
> engine.

Well I think the thing that's missing here is a battery; the mean
power demand could probably be dealt with by the small Diesel, but the
peak demand can't. That's why hybrid vehicles use storage batteries:
to provide extra oomph when needed, while letting the engine deal with
the mean demand.

I once asked an electrical engineer friend (specialist in electrical
machines) about a railroad-like electric transmission with no
storage. His guess was that a Diesel-electric locomotive probably
achieves drivetrain efficiency in the low 90% range at cruise: not
bad. But efficiency during startup would be much lower. Since a
freight train mainly runs in a steady-state mode, this works
nicely. For a passenger vehicle, it stinks: most of the time is spent
accelerating or decelerating, and drivers demand acceleration better
than what is strictly necessary.

Another point that is often ignored is that an electric motor doesn't
function at top efficiency across a wide range of speeds; either you
need a conventional transmission or you need to alter its electrical
characteristics as you shift from a low-speed, high-torque (high
current) mode to a high-speed, high-power (high voltage) cruising
mode. Ford's Ecostar electric vehicle from the '80s used a 5-step
electromechanical contactor to achieve this.

I guess there are two points here: that there's no free lunch, and
that it is a lot more complicated than it looks.

Trying this as a backyard conversion probably won't work, especially
with trying to integrate with an existing automatic transmission.

<snip>

--
-Stephen H. Westin
Any information or opinions in this message are mine: they do not
represent the position of Cornell University or any of its sponsors.

z0ck

unread,
May 23, 2001, 4:59:53 PM5/23/01
to
So far I have a lot of thought in this project, along with a significant
amount of time invested in crawling around under the hood with a tape
measure.

The 4-cyl diesel is SIGNIFICANTLY smaller than the gas 350 currently in the
truck. I guess my thought was to replace the motive force of the truck (the
engine), rather than the machinery that connects it to the road (the
transmission). My need here, is not for horsepower but for torque and
reduced emissions. As I recall from my days of electric R/C racing, torque
is merely a matter of the relative strength of the magnets in the motor can
and the number of coils on the armature.

I am currently convinced, perhaps wrongly so, that I can get the power I
need out of that engine. All I need it to do is generate enough electricity
to keep my battery farm charged. In order to keep things as simple as
possible, I had thought to use the existing transmission. This would
insulate the drive motor(s), and thus the Speed Control, from the transient
loads presented by braking. In this configuration, I would eliminate the
possibility of using regenerative braking (I think).

I don't mind paying the weight penalty, although I admit that I have not yet
worked out exactly how much of a penalty that will be.

Up to this point, I had simply assumed that there were no diesel/electric
cars (or trucks) simply because of the expense involved. However, Toyota is
mass-producing their Prius, which is Gas/Electric hybrid.

As far as having enough space goes, I've been thinking to remove the
transmissions bell housing, since it will no longer be needed. This will
free up a modicum of space under the hood. The motor(s) could then be
mounted to face aft. The engine can lay on its side, but I'll have to make
some modifications to the oiling system to make that work properly. Perhaps
I should also look into purchasing a more modern diesel engine of similar
physical size but with more power. Additionally, because of the way I use
the truck, I am planning to build a housing for batteries where the 2nd row
bench seat currently is. This should allow for decent weight balance and
still have plenty of space for the number of batteries I'll surely need.

Actually, if I just wanted to get it up and running for the least possible
dollars, I'd probably just rebuild the existing 350 or install a slightly
modified version thereof. Really, I want to have an SUV that does not suck
down as much fuel or emit as many pollutants as normal SUVs.


Mark Kinsler <kin...@frognet.net> wrote in message
news:3b0c0aa7...@news.earthlink.net...
<SNIP stuff I wrote>


> It might pay to look at the overall scheme: would this truck perform
> adequately if the four-cylinder diesel was installed in place of the
> existing V-8? The electric part of the system is just a replacement
> for the transmission. The power to drive the truck comes from the
> engine.
>
>

<SNIP stuff I wrote> >


> I wonder where you're planning to put all of this equipment. The
> diesel isn't much smaller than the original engine, you want to keep
> the transmission, and you're adding several motors and a big
> generator. You'll be paying a considerable weight penalty, too.
>

<SNIP stuff I wrote>


>
> Your biggest electrical problem will be the design of the speed
> control switching devices. In a motor vehicle, these take quite a
> beating, what with braking transients and such.
>

<SNIP stuff I wrote>


>
> Yee hah. You're gonna do this with an Isuzu diesel engine?
>

<SNIP stuff I wrote>


>
> Generally a larger machine is a more efficient machine: fewer design
> compromises (and cost compromises) have to be made in the design. An
> automotive alternator is meant to charge a car-starting battery and
> run auto accessories. It's not really rated for traction work.
>

<SNIP stuff I wrote>


>
> Depends on the sort of motor: brush or brushless DC, induction, or
> whatever. Again, smaller motors tend to be less efficient than bigger
> ones, but I don't think that this would be a major issue.
>

<SNIP stuff I wrote>


>
> I don't know what a stall converter is.
>

<SNIP stuff I wrote>


>
> Power= torque x angular velocity. Angular velocity is rpm divided by
> 2 x pi x 60, I think. (I oughta know: I just taught this in my
> physics class last night, but I'm never sure if I have formulas right
> when I type them on the computer.)
>

<SNIP stuff I wrote>


>
> With some penalty for power loss in the conversion process, yes. The
> device to be investigated is known as a "dc-to-dc converter."
>

<SNIP stuff I wrote>


>
> Theoretically, but it's important to know that motor power rating is
> not a particularly simple matter. I hope you're aware that your
> truck, when new, would have found it quite a challenge to transport a
> 100 horsepower electric motor. I have no idea what a 500 hp motor
> would weigh because I don't recall ever having seen one that large.
>

<SNIP stuff I wrote>


>
> I don't know. There are an awful lot of variables.
>

<SNIP stuff I wrote> .

Kevin Mouton

unread,
May 23, 2001, 6:00:18 PM5/23/01
to

I was involved in a similar project once. Converted a Ford Escort to
electric using a 60 HP (if memory serves me right) electric fork lift
motor to drive a standard transmission. Originally planned to add a
small gas engine and generator to charge the batteries. Turned out that
once the necessary batteries to give decent performance were installed,
the generator and gas engine would have far exceeded the amount of
weight the vehicle suspension could handle. So, what we wound up with
was an electric powered Escort that could accelerate to 90 mph in 24
seconds and had a cruising range of about 100 miles at 50 mph with all
twelve batteries fully charged. Overall, not very efficient and very
expensive to maintain (it ate batteries for lunch). I believe as others
have said, the overall picture of powering a large truck with a small
diesel is not a good idea even if you convert the engine output to
electrical energy in the process. A large battery bank may offer the
solution to satisfactory acceleration, but the battery weight along with
the generator, and their expense makes the whole idea a bit counter
productive. However, it might be a nice (although expensive) hobby that
could keep you busy for the next 5 or 10 years.

p.s. BTW, don't forget that you will also need an electric vacuum pump
and reservoir to operate the brake booster and heater vent controls. Air
conditioning is out of the question. If you keep the Automatic
transmission you will need the torque converter (it won't work with out
it) and a small radiator to cool the fluid.
--
WARNING:
Return address may contain antispam. Take out the garbage to reply.
* * * * * * * * * * * * * * * * * * * * * * * * * * * *
Kevin Mouton ..... Automotive Technology Instructor

"If women don't find you handsome, they should at least find you handy"
Red Green

BJC

unread,
May 23, 2001, 8:08:20 PM5/23/01
to
Better yet pour oil and grease all over your self, roll around in the dirt,
bang your knuckle on the door step, stay up late and tear up $50 bills until
the ideal goes away.
z0ck wrote in message ...

Clyde Manning

unread,
May 23, 2001, 8:03:56 PM5/23/01
to
What about the hybrids from Toyota and Honda. AIUI they use gasoline
motors to drive a generator which charges the batteries used to drive
motors at each wheel. The Toyota looks similar to my Camry. I don't
know the BHP rating or have any acceleration numbers. Living in
Colorado, it would have to have good hill climbing power.

--
邢 唷��

Robert

unread,
May 24, 2001, 12:19:46 AM5/24/01
to
Hahaha, rude as it sounds that at least in my opinion is pretty good advice.
Sounds like the kind of project that could chew through thousands of dollars
without ever getting the desired results, or even being drivable for that
matter.
Bob
"BJC" <oakie...@hotmail.com> wrote in message
news:UhYO6.4435$CQ4.5...@paloalto-snr1.gtei.net...

Robert Hancock

unread,
May 24, 2001, 12:43:55 AM5/24/01
to
No, the Prius and Insight both just have a motor/generator attached to the
engine through some sort of special gearbox and that can either assist the
engine or absorb power from it (for battery charging or regenerative
braking). Other than that, I don't think the mechanical drivetrain is much
different than other FWDs.

When high power is demanded, both the gas engine and electric motor would be
pushing the vehicle.

--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from hanc...@nospamhome.com
Home Page: http://roberthancock.netfirms.com/


"Clyde Manning" <clyde_...@storagetek.com> wrote in message
news:3B0C4FEC...@storagetek.com...

William L. Bahn

unread,
May 24, 2001, 10:33:08 AM5/24/01
to
When all is said and done, you are trying to drive a large SUV pulling a
loaded car trailer at highway speeds with a small four cylinder diesel
engine. Ain't gonna happen.

z0ck wrote in message ...

Stephen H. Westin

unread,
May 24, 2001, 11:38:48 AM5/24/01
to
"William L. Bahn" <wb...@q.nospam.west.net> writes:

> When all is said and done, you are trying to drive a large SUV pulling a
> loaded car trailer at highway speeds with a small four cylinder diesel
> engine. Ain't gonna happen.

Actually, it's hard to think of a passenger vehicle that would need
50HP for steady-state highway cruising; typical passenger cars are
under 20HP. Perhaps a Suburban with a trailer. Anyway, it's quite
conceivable that a small Diesel would do this nicely. A battery would
be used to supply burst requirements, such as passing and climbing
hills.

But it's a complicated undertaking.

Alex Shirley

unread,
May 24, 2001, 11:49:59 AM5/24/01
to
> My need here, is not for horsepower but for torque and
> reduced emissions.

What do you need all this torque for? Power (Work Done/Time) is what is
important. Torque is simply a matter of gearing.

Emissions are linked to engine/drivetrain efficiency and the amount of work
they have to do. You'll be increasing the weight of the vehicle (batteries
and other equipment are pretty heavy), so the amount of work required of the
engine/drivetrain will increase. You'll probably also be reducing the
efficiency of the engine/drivetrain - sure, the diesel itself will be pretty
efficient, but all the stages of power generation and storage and use will
reduce the overall efficiency. You will also not be saving any of the
braking energy. Therefore you can't expect the emissions to decrease.

Current hybrid vehicles get their increased efficiency (over a car of
similar performance) in three ways. Firstly, a much smaller engine is used.
Secondly, this engine is operated at high load (which is more efficient)
charging the batteries as well as driving the car. Thirdly, some of the
energy normally wasted through braking is saved, again going to the
batteries. Then the electric motor can raise the performance (to the level
of the car with which you are comparing the hybrid) when required. Actually,
come to think of it, some current hybrids run on electric most of the time
and only use the engine when extra acceleration or battery charging is
required, but these benefit in the same 3 ways - small engine run at high
load and braking energy saved.

Your car may actually fall into this second category (apart from saving the
braking energy), but you only get out what you put in - inserting all of the
electric stuff is not going to magically increase the potential of your
little diesel engine. Your SUV could be made to run at an acceptable speed
if the electric motors were powerful enough, but you'd need to keep stopping
to recharge the bateries. I would think it takes more than 80bhp to drive a
large SUV with trailer at highway speeds.

Please note that I haven't done any calculations, so your idea might just
work. What you need to know is whether...
a) Power of diesel engine > Power required to push SUV/trailer at acceptable
speed + Total power losses
b) Power of diesel engine > Power required to accelerate SUV/trailer at
acceptable rate + Total power losses

If the answer to both is yes, it will work
If (a) is yes but (b) is no, it will work, but while accelerating you will
be using more electrical energy than you are generating - could be a bummer
up a long hill!
If the answer to (a) is no, it will not work.

Alex.


z0ck

unread,
May 24, 2001, 12:55:39 PM5/24/01
to
Ok...how's this for a major project revision...

What if I use a larger diesel engine/generator combo mounted in the existing
engines position. It could be installed in a fashion such that the
generator would ride where the transmission is. Removing the existing
transmission, transfer case, driveshafts and all the associated plumbing
should free up several hundred pounds. Mount up electric motors to each
axle. A simple switching system could switch me from 2wd to 4wd, but I
would not have the low ranges gears that the transfer case gives me. In
that case, I would get back the regenerative braking capability, but there
would be little or no assistance from a gearbox in terms of torque
multiplication. I would, therefore, be reliant upon whatever motor(s) I
installed to be powerful enough to handle the eventualities of
hill-climbing, etc., since there would be NO downshifting. Perhaps a
dual-range axle would resolve that, or simply retaining the existing
transfer case.


Alex Shirley <ce...@LOOSETHESPAM-bath.ac.uk> wrote in message
news:GDuJz...@bath.ac.uk...

Mark Kinsler

unread,
May 25, 2001, 12:23:23 AM5/25/01
to
> My need here, is not for horsepower but for torque and
>reduced emissions. As I recall from my days of electric R/C racing, torque
>is merely a matter of the relative strength of the magnets in the motor can
>and the number of coils on the armature.

But it's the horsepower that moves the truck. In electric R/C cars,
the power comes from batteries that are presumably recharged from the
power company's lines and are required to supply energy for only a
very short time. Your power was coming from your power company in
your R/C cars, but in your truck, you'll have to produce it yourself.


>I am currently convinced, perhaps wrongly so, that I can get the power I
>need out of that engine. All I need it to do is generate enough electricity
>to keep my battery farm charged.

The power from the generator comes from the engine. If the motors
pull energy from the batteries faster than the generator can re-supply
it, the machine will stop after a while.

> In order to keep things as simple as
>possible, I had thought to use the existing transmission. This would
>insulate the drive motor(s), and thus the Speed Control, from the transient
>loads presented by braking. In this configuration, I would eliminate the
>possibility of using regenerative braking (I think).

One of the few advantages of electric drive is that it can eliminate
the transmission. The idea is that a series-wound DC motor, unlike a
gasoline engine, produces its highest torque when it's stalled, as
when it's first getting the vehicle underway. That's why you don't
need a transmission on a train or streetcar.

>I don't mind paying the weight penalty, although I admit that I have not yet
>worked out exactly how much of a penalty that will be.
>Up to this point, I had simply assumed that there were no diesel/electric
>cars (or trucks) simply because of the expense involved. However, Toyota is
>mass-producing their Prius, which is Gas/Electric hybrid.

It's a gas-powered car with an electric assist for cheaper
acceleration. Works well enough, though the cost is quite high and
the gas mileage isn't vastly better than my much simpler
three-cylinder Geo Metro.

>As far as having enough space goes, I've been thinking to remove the
>transmissions bell housing, since it will no longer be needed.

Where will you put the torque converter, which lives inside the bell
housing? The torque converter constitutes the majority of the
transmission.

>This will
>free up a modicum of space under the hood. The motor(s) could then be
>mounted to face aft. The engine can lay on its side, but I'll have to make
>some modifications to the oiling system to make that work properly. Perhaps
>I should also look into purchasing a more modern diesel engine of similar
>physical size but with more power. Additionally, because of the way I use
>the truck, I am planning to build a housing for batteries where the 2nd row
>bench seat currently is. This should allow for decent weight balance and
>still have plenty of space for the number of batteries I'll surely need.
>
>Actually, if I just wanted to get it up and running for the least possible
>dollars, I'd probably just rebuild the existing 350 or install a slightly
>modified version thereof. Really, I want to have an SUV that does not suck
>down as much fuel or emit as many pollutants as normal SUVs.

I'd put in a diesel that'll do the job. Good luck with it.

Michael Groszek

unread,
May 25, 2001, 7:19:48 AM5/25/01
to
How many is several alternators? 5 or so? 5 x 12V x 200A = 12kW = 15.7hp.
Someone mentioned that most passenger cars take 20 hp when cruising. These are
much lighter cars (will be once you're finished putting in motors, alternators
and batteries) and have a much lower coefficient of drag than a SUV. Your car
would probably take a lot more than this while cruising let alone accelerating.
You'd probably need at least 10 alternators and that's before acceleration is
taken into account. Assume that everything is perfect e.g no drivetrain or
conversion losses (nowhere near real life), constant power (impossible as that
means infinite torque at 0 rpm) and no air friction. 58 hp = 44.3 kW Assume
your vehicle will weigh 2500kg after conversion with trailer. Kinetic energy at
27.8 m/s (100km/h 62mph) is 966 kJ. Time required for engine to generate that
much energy is 23.5s which is reasonable but the assumptions in this example are
absolutely ridiculous. At highway speeds with the trailer your SUV will easily
use 50hp out of 58hp before drivetrain losses are taken into account. Notice
that when manufacturers make hybrid cars with approximately the same power as
your engine (Insight has 50 or 60hp doesn't it?) they are under 1000 kg, have a
good areodynamic profile, employ extensive frictional loss reduction technology,
have high tech motors, batteries and generators, use sophisticated drivetrain
management and aren't expected to tow large loads. Then there's the fact that
all this will have to be properly engineered (not hit and miss) to get an
engineers approval before it is roadworthy. Do not expect to be roadworthy if
you use such ridiculously simple approaches to the problem as I just did. I
wouldn't even design a R/C toy with such assumptions.

Werehatrack [Russ Ault]

unread,
May 25, 2001, 9:40:18 AM5/25/01
to
"z0ck" <z0...@hotmail.com> wrote:

>
>If you think I'm way off with this, please let me know.

The Really Short Version:

An engineer with *many* years of experience in electric drivetrain
design might be able to make this conversion work if the budget were
large enough, say in the $150K-$500K range, since he'd already know
where to get the components that would make it functional, and how to
make the *many* adaptations that would be required along the way.
And, if he had such a budget of his own money, I strongly suspect that
he'd look the situation over carefully, and not spend a penny more
than it took to get the Isuzu hauled off to the junkyard, after which
he'd spend a modest sum acquiring a reasonably new conventionally
powered vehicle which would do what he really needed.

--

My email address is spamblocked. Remove SnowFromDriveway to reply

William L. Bahn

unread,
May 25, 2001, 9:49:56 AM5/25/01
to
My point is that he is NOT working with a typical passenger vehicle - his
goal was specifically for a large SUV pulling a loaded car trailer.

How much margin could he possibly have? Hybrid vehicles need to have an
engine with a pretty reasonable margin so that the margin can be used to
recharge the batteries between peaks. If his margin is so low that the
diesel has to be operating most of the time just to satisfy present output
requirements, the batteries are not going to be able to be fully charged
except for very rare and short duration peak needs. How much of even a minor
grade would it take before the diesel was overtaxed? How much reserve would
the batteries provide under those conditions?

Stephen H. Westin wrote in message ...

Alex Shirley

unread,
May 25, 2001, 12:39:17 PM5/25/01
to
Using a bigger engine would certainly help.

Replacing the gearbox and centre diff with a generator and putting a motor
on each axle would certainly make for a simpler, lighter, more efficient
setup. Of course, it would be even better if you could do away with the
transmission altogether and put a motor on each wheel, but you'd need
independent suspension for that. Come to think of it, I suppose a compromise
would be to mount the two motors in the axle, in place of the diff. However,
there are still some major drawbacks...

With a fixed gear ratio, you'd either need massive (therefore inefficient)
motors, or you'd have to put up with mediocre performance - see the British
milk float for an example!

I don't think the switching (varying from drive to braking) is as easy as
you imagine - the power control systems are, I believe, one of the most
critical parts of the process. Motor manufacturers have spent millions
developing them.

You'd probably spend the rest of your life getting it to work, but then
again, perhaps you're rich and retired and need a hobby :-)

Well, good luck with it anyway! If I were you, I'd simply replace the engine
with a decent turbo-diesel.

Alex.

PS - I'm researching reformers that generate hydrogen for my PhD, so if you
wait a few years you'll be able to generate the electricity you need with a
fuel cell :-)


z0ck

unread,
May 25, 2001, 1:24:09 PM5/25/01
to
Ok...how's this for a major project revision...

What if I use a larger diesel engine/generator combo mounted in the existing
engines position. It could be installed in a fashion such that the
generator would ride where the transmission is. Removing the existing
transmission, transfer case, driveshafts and all the associated plumbing
should free up several hundred pounds. Mount up electric motors to each
axle. A simple switching system could switch me from 2wd to 4wd, but I
would not have the low ranges gears that the transfer case gives me. In
that case, I would get back the regenerative braking capability, but there
would be little or no assistance from a gearbox in terms of torque
multiplication. I would, therefore, be reliant upon whatever motor(s) I
installed to be powerful enough to handle the eventualities of
hill-climbing, etc., since there would be NO downshifting. Perhaps a
dual-range axle would resolve that, or simply retaining the existing
transfer case.

Mark Kinsler <kin...@frognet.net> wrote in message
news:3b0dda03...@news.earthlink.net...

Mark Kinsler

unread,
May 25, 2001, 5:54:18 PM5/25/01
to
>Ok...how's this for a major project revision...
>
>What if I use a larger diesel engine/generator combo mounted in the existing
>engines position. It could be installed in a fashion such that the
>generator would ride where the transmission is. Removing the existing
>transmission, transfer case, driveshafts and all the associated plumbing
>should free up several hundred pounds.

That's what an adequate generator would weigh, but I urge you to apply
some real numbers to the project. Assume that
one horspower=746 watts. That means that a generator that'll handle
the minimum 100 hp you need will have to have a capacity of 74600 W,
and a 75 kW generator is no joke.

>Mount up electric motors to each
>axle.

Good luck doing that. Where would they go, and what would they weigh?

> A simple switching system could switch me from 2wd to 4wd, but I
>would not have the low ranges gears that the transfer case gives me.

And the switching system wouldn't be so simple. You'd be working with
rather high steady-state currents and some real impressive voltage and
current transients.

>In that case, I would get back the regenerative braking capability, but there
>would be little or no assistance from a gearbox in terms of torque
>multiplication. I would, therefore, be reliant upon whatever motor(s) I
>installed to be powerful enough to handle the eventualities of
>hill-climbing, etc., since there would be NO downshifting. Perhaps a
>dual-range axle would resolve that, or simply retaining the existing
>transfer case.

Proper motors would help, but you've got some real impressive issues
to learn about here. For example, the full voltage can't be applied
to a stalled motor, or it'll burn out. And the motor will be stalled
whenever you're at a traffic light. That means that you'll need
either a switching power supply or one of those giant resistors (about
the size of a steam radiator) that they mount on subway cars.

If you want to horse around with alternative transmissions, consider
having the motor drive a hydraulic pump. Put hydraulic motors at each
wheel. There is no magic in an electric drive: it's just a
transmission like any other.

M Kinsler

z0ck

unread,
May 25, 2001, 6:30:54 PM5/25/01
to
I suppose, then, that I have some misconceptions of scale.

My thoughts went something along these lines. There are, essentially, 2
ways to build a car. The first is to build it with a power system that
develops high horsepower and spins at (relatively) high RPM. You then use
relatively short gearing, say high 3.x or low 4.x ratios, so that the
vehicle has sufficient torque to accelerate at an acceptable rate. The
other way is to use a power system that develops high torque but spins at
(again, relatively) low RPM. In this case, you use much taller gearing,
probably something in the mid to low 2.x range, to get acceptable top speed.

Since the torque provided by an electric motor is really a function of the
relative strength of the magnets in the can and the number of coils on the
armature, it seems to me that a motor might produce low HP, due to its low
RPM, but would still be sufficient to the task, given appropriate gearing,
because of its, theoretical, high torque. In a scenario like this, a power
source providing sufficient torque does not have to spin particularly fast,
since I can add a gearbox (or appropriately geared differential, as the case
may be) behind it to step up the rotational speed. Since horsepower is a
function of Torque over Time, it seems to me that an electric motor
producing X Torque would produce a disproportionately low (at least as
compared to an Internal Combustion Engine) Y horsepower rating due to its
much lower speed.

Oh, Almost forgot. I need to correct myself. In my previous post, I
mentioned a "simple switching system". What I meant by that was the simple
ability to connect or disconnect a particular motor to/from power regardless
of throttle position. Does that make any more sense?

So lets get down to the nuts and bolts of the thing. Given the high-dnesity
magnets that modern metallurgy is capable of producing, how large would a
motor have to be to produce (just a number for the sake of argument)
say...300lb-ft? Given a motor of that physical size, how would one go about
determining its maximum RPM before it ate itself, and how much torque would
it be producing at that speed? How much power required to drive that motor
to 3/4 of its "redline"?

Of course, as I sit here thinking about it some more, It seems that the
speed of a motor is dependent entirely upon available power regardless of
load, assuming that the load does not exceed the stalled motor's ability to
turn (torque limit). I suppose that if that is, in fact, the case, then I
should take the advice and just forget it.


Mark Kinsler <kin...@frognet.net> wrote in message

news:3b0ed0b9...@news.earthlink.net...

Mike Graham

unread,
May 25, 2001, 6:58:27 PM5/25/01
to
Mark Kinsler <kin...@frognet.net> wrote:

>That's what an adequate generator would weigh, but I urge you to apply
>some real numbers to the project. Assume that
>one horspower=746 watts. That means that a generator that'll handle
>the minimum 100 hp you need will have to have a capacity of 74600 W,
>and a 75 kW generator is no joke.

I'm jumping in here late, but why does he need a 100 hp generator? With a
few batteries you can have 100hp peak with a generator supplying only the
'average' usage, say 20 hp with a 15 kW generator. Still not a tiny
generator, but getting realistic. Run high voltage to keep the current
down, and it could be doable.

--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Mike Graham | Steel-fitter and CWB-certified weldor
mike at metalmangler dot com | Raiser of horses
<http://www.metalmangler.com> | Tester of limits (esp. patience)
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=


Mike Graham

unread,
May 25, 2001, 6:58:27 PM5/25/01
to
z0ck <z0...@hotmail.com> wrote:

>relative strength of the magnets in the can and the number of coils on the
>armature, it seems to me that a motor might produce low HP, due to its low
>RPM, but would still be sufficient to the task, given appropriate gearing,
>because of its, theoretical, high torque.

Low RPMs = high horsepower. Not the reverse.

z0ck

unread,
May 25, 2001, 7:43:50 PM5/25/01
to
I beg to differ only because of what I can observe. That is, all the
engines I know of that produce HUGE amounts of torque (i.e. large diesel
engines, etc.) turn at relatively low RPM. On the other hand, every engine
I know of that produces high horsepower spins really fast. As a point of
reference, when was the last time you saw say... a Kenworth running down the
highway are 12000RPM? What about an F1 car at Nurburg?


Mike Graham <metalm...@metalmangler.com> wrote in message
news:slrn9gtp30.kh...@localhost.localdomain...

Mike Graham

unread,
May 25, 2001, 8:37:19 PM5/25/01
to
z0ck <z0...@hotmail.com> wrote:

>I beg to differ only because of what I can observe.

Sorry, I had my head up my ass. Low RPMs = high torque given static
horsepower.

Mark Kinsler

unread,
May 26, 2001, 11:00:56 AM5/26/01
to
>Mark Kinsler <kin...@frognet.net> wrote:
>
>>That's what an adequate generator would weigh, but I urge you to apply
>>some real numbers to the project. Assume that
>>one horspower=746 watts. That means that a generator that'll handle
>>the minimum 100 hp you need will have to have a capacity of 74600 W,
>>and a 75 kW generator is no joke.
>
> I'm jumping in here late, but why does he need a 100 hp generator? With a
>few batteries you can have 100hp peak with a generator supplying only the
>'average' usage, say 20 hp with a 15 kW generator. Still not a tiny
>generator, but getting realistic. Run high voltage to keep the current
>down, and it could be doable.

He wants to move an SUV with a large trailer. I guessed that 100 HP
would be about what he'd need since that's the rating of the engine in
my Econoline van. The engine in the Honda hybrid vehicle is about the
same one that's in my Geo Metro, and that's rated at 50 HP.

For what it's worth, power is the rate of energy conversion. In
rectilinear motion, it's force x distance / time. In rotary motion,
which is what we're considering here, it's torque x angular
velocity/time, which translates most readily to
torque x rpm / time. The original poster is basing his design on the
assumption that power = torque / time, which is incorrect. A stalled
motor can develop a great deal of torque, but so can a brick sitting
on the end of a wrench. There's no energy transferred, and thus no
power.

Thus the strength of the magnets might affect the stall torque of the
motor, but this won't really help you move a load along the road.

I don't think, however, that the original poster should "just forget
the whole thing." He _certainly_ should not do so on solely on the
basis of the opinions of others: he should convince himself that it
either will or will not work, and there's a reasonable chance that he
will develop an interest in mechanical engineering that far too few
people share. There's also a splendid possibility that he may figure
out something that has escaped the rest of us.

William L. Bahn

unread,
May 26, 2001, 1:05:33 PM5/26/01
to
power = torque * angular velocity.


Mike Graham wrote in message ...

Mike Graham

unread,
May 26, 2001, 4:27:05 PM5/26/01
to
Mark Kinsler <kin...@frognet.net> wrote:

>He wants to move an SUV with a large trailer. I guessed that 100 HP
>would be about what he'd need since that's the rating of the engine in
>my Econoline van. The engine in the Honda hybrid vehicle is about the
>same one that's in my Geo Metro, and that's rated at 50 HP.

Yeah, but how *often* does he need the full 100HP? To accelerate up a
hill, maybe, but on average? I mean, you're not redlining your econoline
all the time, are you? If your *average* requirement is 20HP, then that's
all you need to supply (within reason). The engine in your Geo Metro may
well be rated at 50HP, but even if the engine in the Honda hybrid has the
same displacement and the same number of cylinders etc. it might be horribly
detuned for economy and putting out far less than your Metro.
Let's look at the amount of power you're talking about: you're talking
about 100HP in a vehicle, so that's exactly 75KW for us metric types 8-).
Let's use 5000lb (2268kg) for the combined weight of the vehicle and trailer
(explorer with 3000lb trailer or navigator with 2000lb trailer, sorta).
Okay, so 75KW = 75KJ/s

Let's look at driving up a hill.
A round number that is useful for defining the resistance of movement of
a biggish car is 1000N. We'll use 1500 for an SUV with a trailer. Add on
the mass (2268kg) and you get an overhead of 3768N. A hill of 10 degrees
would increase the overhead to mg sin(10) = 3859 plus the 1500 overhead
equals a total of 5359N. Say you're driving 80km/h up this hill (50mph)
that would be 22m/s so:

p=Fv
= 5359 * 22 = 118 KW = 157 horsepower. That's a lot. Your econoline
wouldn't have a prayer, apparently. However, let's look at flat cruising:

Same arrangement cruising at 50mph on a flat road:

p=Fv
=3768 * 22 = 83 KW = 110 HP.

Hmmm.. I'm doing a good job of killing my argument, eh? 8-) Alright,
then, let's look as a 'control' at the requirements for moving your Geo
Metro. Call it 650kg (1430-ish lbs). Add on 700N for resistance to motion
(reasonably streamlined, and a light vehicle... conservative estimate) and
on the flat you need:

p=Fv
= 1350 * 22 = 30KW = 40 HP reaching the wheels.

To cruise up a hill as above you'd need
p=Fv
= 1808 * 22 = 40KW = 53 HP reaching the wheels. So, given standard
manufacturing lies etc, this would indicate that your metro would have a
hard time maintaining 80km/h (50mph) on a 10 degree slope, and the maximum
attainable speed on the flat would be:

p=Fv
37KW = 1350 * v
v = 37KW / 1350
v = 27.4 m/s = 100km/h = 60mph.

Sound about right? If so, the calculations should be reasonably
trustworthy, and we can figure out how much horsepower is required for this
application.

Mike Graham

unread,
May 26, 2001, 8:25:10 PM5/26/01
to
Mike Graham <metalm...@metalmangler.com> wrote:

> Same arrangement cruising at 50mph on a flat road:
>
> p=Fv
> =3768 * 22 = 83 KW = 110 HP.

Doh! You don't need the weight of the vehicle in there for flat cruising,
just the resistance to travel.

p=Fv
= 1500 * 22 = 33 KW = 44 horsepower. That sounds more like it.

Similarly:

> p=Fv
> 37KW = 700 * v
> v = 37KW / 700
> v = 53m/s = 190km/h = 118mph.

So if your engine can get a true 50 horsepower to the wheels then it
should be able to hit 118mph on flat ground without a headwind. Not bad for
a metro. 8-)

So, given these modifications to my equations, my original point has been
partially resurrected. 8-) The big huge SUV with trailer in tow only needs
44 horsepower at the wheels to cruise at 50mph on the flats, so you need to
figure out what percentage of the time it would be on hills and drawing more
than 50 horses. If you have enough battery storage then a 50hp motor should
be sufficient to generate power for the vehicle given, of course, 100%
efficiency in the generator, motors, etc. 8-)

Mark Kinsler

unread,
May 27, 2001, 10:43:02 AM5/27/01
to
>power = torque * angular velocity.

Sure is. I _thought_ I had that wrong, but God forbid I should get up
and look it up in my own notes. I was thinking of
power=torque x angle / time.

I was thinking about the original poster's initial reasoning, which
derives from his experience with remote-control model cars. It's
clear that his work there confirmed that stronger motor field magnets
improved the performance of the model, but I don't understand the
reason why. Was the motor's overall efficiency improved, or just its
performance under the rather severe restrictions imposed by a
high-impedance power supply (those batteries can't be that good) and
rather imperfect gearing?

On another point, I agree with Mr Graham's analysis. The Geo Metro's
overall mass is just about 1000 kg with driver and all his junk, and I
think we calculated that most of the engine's power went to overcome
friction of various sorts. The difficulty I have with the discussion
is that we don't really have good ways to store energy. They're
either chemically unstable (sodium-sulfur batteries and fuel cells)
and/or expensive (fuel cells, flywheels, motor/generator setups)
and/or heavy (batteries, hydraulic accumulators, flywheels), or
dangerous (any of the above.)

And without some sort of energy storage capacity, you cannot "average
out" the power demand of a road vehicle. The engine must be sized to
satisfy the peak load, which is precisely the case in both electric
power work and transportation. It would be great if we could, but we
haven't mastered the technology sufficiently just yet.

I think someone figured out that the most efficient energy storage
system would involve mechanical springs, a la rubber-powered model
airplanes. I rather like the idea.

Mike Graham

unread,
May 27, 2001, 12:59:32 PM5/27/01
to
Mark Kinsler <kin...@frognet.net> wrote:

>I think someone figured out that the most efficient energy storage
>system would involve mechanical springs, a la rubber-powered model
>airplanes. I rather like the idea.

8-)

Sam Mayberry

unread,
May 26, 2001, 8:35:40 AM5/26/01
to
i agree that the project, as i understand it, is impractical, i've used the
ploy of connecting the armatures of the motor and generator together and
just controlling the field of the generator.
(i may not have seen the whole original question....)
sam


"Mark Kinsler" <kin...@frognet.net> wrote in message

news:3b0ed0b9...@news.earthlink.net...

Mark Olson

unread,
May 24, 2001, 8:11:53 AM5/24/01
to
Robert Hancock wrote:
>
> No, the Prius and Insight both just have a motor/generator attached to the
> engine through some sort of special gearbox and that can either assist the
> engine or absorb power from it (for battery charging or regenerative
> braking). Other than that, I don't think the mechanical drivetrain is much
> different than other FWDs.
>
> When high power is demanded, both the gas engine and electric motor would be
> pushing the vehicle.

A fairly good discussion of the Prius' system is at:

http://www.autofieldguide.com/articles/129805.html

An excerpt:

...

Toyota engineers have come up with a different arrangement from a
strict parallel or series approach. Rather, their system, designated
the Toyota Hybrid System (THS), is a melding of the two. There is a
gasoline engine and a motor. The motor or the engine can power the
car at low speeds, which is like a parallel system. Additionally,
there is a connection whereby the gasoline engine sends power to
a generator, which then can be used by the motor, which makes the
arrangement like a series hybrid.

And there's even another option, which is that both the motor and the
engine are used at the same time, thereby providing more oomph. That
is, when the engine- an in-line, four-cylinder, DOC, 1.5-liter engine-
is used alone, the top speed is 88 mph. When the 30-kW permanent magnet
motor is added to the mix, the top speed is cranked up to 100 mph.

Splitting the Power

Key to the THS is a power split device that's in the transmission. This
is based on a planetary gear system (including a sun gear, ring gear,
and planetary carrier with pinion gears). David W. Hermance, general
manager, Powertrain, Toyota Technical Center USA (Gardena, CA),
speaking of the transmission, says that compared to a conventional
transmission, the Prius arrangement is "mechanically simpler." For
example, there are no valve bodies or solenoids to make. He admits
that it is more expensive to producefor now. One can only imagine
that when the Toyota Production System comes into play in earnest,
the consequent efficiencies will help make the economies a whole
lot better.

...

Michael Groszek

unread,
May 29, 2001, 8:37:01 AM5/29/01
to
Sorry but you just stuffed up basic physics and car knowledge. Power = Force x
Velocity. Which can be rewritten as Power = Torque x Angular velocity. It
follows that for a certain torque you need high angular velocity (revs) to get
high power.

Michael Groszek

unread,
May 29, 2001, 8:38:00 AM5/29/01
to
Whoops. I should finish reading the thread before I reply.

Michael Groszek

unread,
May 29, 2001, 8:44:48 AM5/29/01
to
I hope you realise that drag increases with the square of the velocity and
aerodynamic drag is the main factor at high speed. Hence the Geo will not be
reaching 118mph

Michael Groszek

unread,
May 29, 2001, 8:59:22 AM5/29/01
to
Another misconception that you seem to have it that you can have either power or
torque. You need a ceratin amount of power no matter what. Torque is
meaningless. Force pushing on the road is what you want. Even if you have 1 Nm
of torque you can produce a force large enough to move a truck if you gear down
enough (assuming the speed reduction system didn't use it all up in the
reduction). If you don't take gearbox losses into account then you could drive
anything with any engine as long as it has the right power output.
In my opinion it is quite foolish to take on a full scale project with the
knowledge that you have. Start off on something smaller like a R/C car or
something if you are simply inventing and not engineering (if you were
engineering this project you wouldn't come to these newsgroups for help)

z0ck

unread,
May 29, 2001, 2:02:11 PM5/29/01
to
Well, as I said, I'm not an engineer, just a guy with an idea.

I suppose it had occured to me that Horsepower is a function of Torque/Time.
If this is the case, then you are absolutely right. By virtue of haveing
one, you automatically have the other. What you DO have a choice about,
though, is the way in which you go about determining your priorities for the
build. As I said before, engines intended to pull heavy loads (Semi Trucks,
Ships and heavy equipment) tend to develop high torque at low RPM, and use a
set of gears to provide both torque multiplication and stepup in output
speed. If you look at the Torque and HP ratings of some
"Middle-of-the-road" street cars, you will find that these ratings are
generally fairly close to each other in terms of maximum output, but not
necessarily in RPM range (ex. off the top of my head is 92 Taurus SHO.
200lb-ft@2000RPM, 220hp@5500. Now that I've written it, I can't seem to
recall the exact RPM in the specs). As the vehicle gets more specialized,
either for hauling lumber or hauling butt, you find that the HP and Torque
numbers get further and further away from each other (check the HP and
Torque ratings on a PowerStroke powered Ford F-350 and a Mustang Cobra).

What these simple observations imply to me is that it is not only possible,
but desirable to separate the ideas of peak torque and hp production with
the design philosophy of the vehicle kept firmly in mind. Yes, you could
swap the engines between the Cobra and Pickup and, theoretically, still do
the same job, albeit with significantly altered gearboxes. It would,
however, be significantly less efficient to do this (to say nothing of being
unnecessarily hard on both engines). Since it is, obviouly, possible to use
gears to either speed up or slow down output speed, the net effect is that
you either multiply available torque (slow down output) at the expense of
maximum HP or sacrifice max torque in favor of increased HP (speed up
output). If this is the case, does it not stand to reason that an electric
motor with sifficient field-strength could provide all the required motive
force at low RPM (and therefore low HP) given correct gearing?


Michael Groszek <mi...@dingoblue.net.au> wrote in message
news:3B139D2A...@dingoblue.net.au...


> Another misconception that you seem to have it that you can have either
power or
> torque. You need a ceratin amount of power no matter what. Torque is
> meaningless. Force pushing on the road is what you want. Even if you have
1 Nm
> of torque you can produce a force large enough to move a truck if you gear
down
> enough (assuming the speed reduction system didn't use it all up in the
> reduction). If you don't take gearbox losses into account then you could
drive
> anything with any engine as long as it has the right power output.
> In my opinion it is quite foolish to take on a full scale project with the
> knowledge that you have. Start off on something smaller like a R/C car or
> something if you are simply inventing and not engineering (if you were
> engineering this project you wouldn't come to these newsgroups for help)
>

<SNIP a lot of other commentary>


Mike Graham

unread,
May 29, 2001, 6:13:21 PM5/29/01
to
Michael Groszek <mi...@dingoblue.net.au> wrote:

>I hope you realise that drag increases with the square of the velocity and
>aerodynamic drag is the main factor at high speed. Hence the Geo will not be
>reaching 118mph

I was trying to keep it simple and figure out if the calculations were
reasonable for rule-of-thumb use, and I think they were okay. Not great,
but okay.

Alex Shirley

unread,
May 29, 2001, 8:12:41 PM5/29/01
to
> Since it is, obviouly, possible to use
> gears to either speed up or slow down output speed, the net effect is that
> you either multiply available torque (slow down output) at the expense of
> maximum HP or sacrifice max torque in favor of increased HP (speed up
> output).

Forgive me if I have misread or misunderstood your post, but you don't quite
seem to have grasped the concept of what torque and power are, or why
engines have been given certain characteristics for certain applications.
Gearing does not affect the power (except through frictional losses which do
not depend on ratio) which is transmitted to the road. Gearing only affects
the torque. The purpose of using gears it to keep the motor turning at the
rate required to produce sufficient power.

Also, the gap you mentioned between the revs at which max torque and max
power are developed is dependant on how flat the torque curve is. In
general, a flat torque curve (torque doesn't change much over a large band
of revs) is good - you can have larger gaps between gear ratios and the car
is more relaxed to drive.

A highly tuned engine has a peak in the torque curve at high revs. These
engines are used where high performance and light weight are more important
than low-rev flexibility and where maximum performance is not going to be
required much of the time - ie sports cars.

A "middle of the road" engine will have a flat torque curve. Flexibility,
ease of use and reduced wear are the paybacks for reducing the power and
performance.

A "working" engine is of large capacity and has a peak in the torque curve
at low revs. The torque drops off rapidly as revs rise, so high specific
power output is imposible. However, these engines are used in applications
where weight is not as important as durability and the ability to work hard.
The power is regained by increasing the capacity.

> If this is the case, does it not stand to reason that an electric
> motor with sifficient field-strength could provide all the required motive
> force at low RPM (and therefore low HP) given correct gearing?

If the motor has a sufficient POWER output and is correctly geared, I can't
see a problem, but I'm no expert on electric motors.

Alex.


Ray L

unread,
May 29, 2001, 9:14:07 PM5/29/01
to

Stephen H. Westin <westin*nos...@graphics.cornell.edu> wrote in message
news:uofsio...@graphics.cornell.edu...

> Actually, it's hard to think of a passenger vehicle that would need
> 50HP for steady-state highway cruising; typical passenger cars are
> under 20HP. Perhaps a Suburban with a trailer. Anyway, it's

20 HP is fine for doing 65 on a
nice day, but to sustain 85 mph against a
headwind across southern Texas, it takes
a lot more.

A station wagon going at 110 mph needs
about 130 HP just to overcome wind
resistance.

Mark Kinsler

unread,
May 29, 2001, 10:52:47 PM5/29/01
to

>What these simple observations imply to me is that it is not only possible,
>but desirable to separate the ideas of peak torque and hp production with
>the design philosophy of the vehicle kept firmly in mind. Yes, you could
>swap the engines between the Cobra and Pickup and, theoretically, still do
>the same job, albeit with significantly altered gearboxes. It would,
>however, be significantly less efficient to do this (to say nothing of being
>unnecessarily hard on both engines). Since it is, obviouly, possible to use
>gears to either speed up or slow down output speed, the net effect is that
>you either multiply available torque (slow down output) at the expense of
>maximum HP or sacrifice max torque in favor of increased HP (speed up
>output). If this is the case, does it not stand to reason that an electric
>motor with sifficient field-strength could provide all the required motive
>force at low RPM (and therefore low HP) given correct gearing?

You don't have it quite right just yet. Energy is transferred from
the gas tank to the tires by the engine. Energy equals force times
distance, and you use the force to overcome friction. If you want to
faster, you'll have to transfer the energy from the gas to the tires
at a faster rate. This is power, the rate of energy transfer, and it
requires a bigger engine to transfer power at a faster rate. As
others have said, power is force x distance / time, which is equal to
force times speed. In rotary motion, power equals rotary force
multiplied by the rate of rotation of the wheels. Rotary force is the
same as torque.

The torque specification of an engine gives us an idea of how the
reduction gearing must be designed, but it is _not_ equivalent to
power, nor is it closely related.

Michael Groszek

unread,
May 30, 2001, 12:21:29 AM5/30/01
to
Man I must have been tired last night (2 am or so with 9 am start). Where did I
pull 118 mph? Must have been your power figure for cruising up the hill. There's
a four fold drag difference at 120 compared to 60 like you said and that means
an 8 fold power difference. That's why I saw your calculations as crazy!

z0ck

unread,
May 30, 2001, 11:12:40 AM5/30/01
to
Well, I have simply decided that I lack the background knowledge that would
be required to build something like a Diesel/Electric powered Suburban. In
the mean time, the poor truck's health has deteriorated significantly, and
is in dire need of surgery now. Therefore, I have just placed an order with
my local Chevy dealer for a 6.6L Duramax Turbo Diesel (option code LB7 on
the Sierra line, for those interested) and Allison Transmission. You guys
do NOT want to know what I spent for these items. Anyway, I am told that I
can expect delivery in a couple of weeks, whereupon I will install them in
my good ol' truck and power them with BioDiesel. Thank you for your time.


Mark Kinsler <kin...@frognet.net> wrote in message

news:3b145cc6...@news.earthlink.net...

Stephen H. Westin

unread,
May 30, 2001, 11:22:07 AM5/30/01
to
"z0ck" <z0...@hotmail.com> writes:

> Well, I have simply decided that I lack the background knowledge that would
> be required to build something like a Diesel/Electric powered Suburban. In
> the mean time, the poor truck's health has deteriorated significantly, and
> is in dire need of surgery now. Therefore, I have just placed an order with
> my local Chevy dealer for a 6.6L Duramax Turbo Diesel (option code LB7 on
> the Sierra line, for those interested) and Allison Transmission. You guys
> do NOT want to know what I spent for these items. Anyway, I am told that I
> can expect delivery in a couple of weeks, whereupon I will install them in
> my good ol' truck and power them with BioDiesel. Thank you for your time.

Actually, this is a lot cheaper and will work better than a hybrid
conversion. You'll improve your fuel economy and reduce emissions. A
hybrid might be a fascinating project, but expensive and involved, and
you wouldn't want to rely on it for transportation.

<snip>

--
-Stephen H. Westin
Any information or opinions in this message are mine: they do not
represent the position of Cornell University or any of its sponsors.

Nathan Nagel

unread,
May 30, 2001, 11:59:57 AM5/30/01
to
Sounds like a good combo for that vehicle, I've had some experience
driving prototypes with that engine/trans combination. Only gotcha I
can think of is do you have to pass emissions in your area? that could
be a big problem if you have swapped from gas to diesel. You may be
required to pass the gas standards for YOM or if you're really unlucky
and live in CA they may nix the whole swap altogether and you'll find
yourself with a great vehicle that you can't legally drive on the
street.

good luck,

nate

Nathan Nagel

unread,
May 30, 2001, 12:13:38 PM5/30/01
to
Ooh, just thought of something else. I assume you have vacuum operated
power brakes, you may have to convert to Hydroboost (yuck) or add a
vacuum pump. Make sure if you get a Hydroboost that you use a power
steering pump designed for use with one, becuase even the new GM
vehicles can be made to "run out" of hyd. pressure if you slam on the
brakes and turn the wheel hard at the same time. I'm sure this problem
would be much worse with a P/S pump not designed for the added load. I
hope for your sake that you do not have vacuum operated climate controls
as well, in which case you will be forced to rig a vacuum pump. I have
no idea if the Duramax has provisions for such a thing. A good thing to
do at this point would be to see if Helm has a manual for a newer C/K
(it feels odd to use the term C/K to refer to a truck, I'm more used to
it in a Studebaker context where it means something much more fun!) with
a Duramax so you at least can see how everything is intended to work
together, including climate controls etc. I think by the time you are
done with this you will be rather familiar with your local recycling
yard! Don't let me discourage you though, this is an ambitious project
but I think a lot more feasible than what you were proposing before.

A word of advice... if you decide to swap the rear axle for something
more suited to the diesel, stay away from the new locking diffs. They
are garbage and generally fail after a few hard launches. Go with
something older or aftermarket, or if you currently have a limited slip
rear stay with that and just have someone swap gears if necessary. (I
have no idea what rear end ratio you currently have and what is being
sold in new trucks with the Duramax. If they are close, you should be
OK.)

good luck

nate

(will babble more as I think of more stuff for you to consider <g>)

z0ck

unread,
May 30, 2001, 12:34:56 PM5/30/01
to
Well, I'm fortunate, in all of these regards.

It does have a vaccuum operated brake booster, but I intend to intall a
heavy-duty vaccuum pump to handle that. The gent I spoke to at the parts
counter said this has been done several times that he knows of and
recommended a pump to me. As far as the climate controls go, they are, or
at least USED to be, vaccuum operated. However, the previous owner chose
not to fix the controls when they dies years ago. Instead, he installled
electric heaters. Since I live in Washington, AC is a non-issue and all I
have to do is go down to the DMV and tell them that I am now Diesel powered,
not gas. Costs nothing to do. The previous owner also had the foresight to
expand the capacity of the fuel tank from its stock 37gallons to almost 45.
Range should be plenty good enough. :)

With the axles, I got exceptionally lucky. This truck was originally
ordered with the "Heavy Half" option package for towing and hauling. It has
what I believe to be the "Corporate 12-bolt" in the rear and Dana 44 (I
think?) up front. These will both be rebuilt with 3.73's and possibly
detroit lockers.

Ought to be interesting driving this big, old beatup looking suburban, with
those manly diesel sounds coming from the hood and an exhust pipe that
smells like donuts or french fries. :)


Nathan Nagel <njn...@worldnet.att.net> wrote in message
news:3B151CDC...@worldnet.att.net...

Nathan Nagel

unread,
May 30, 2001, 12:57:38 PM5/30/01
to
z0ck wrote:
>
> Well, I'm fortunate, in all of these regards.
>
> It does have a vaccuum operated brake booster, but I intend to intall a
> heavy-duty vaccuum pump to handle that. The gent I spoke to at the parts
> counter said this has been done several times that he knows of and
> recommended a pump to me. As far as the climate controls go, they are, or
> at least USED to be, vaccuum operated. However, the previous owner chose
> not to fix the controls when they dies years ago. Instead, he installled
> electric heaters. Since I live in Washington, AC is a non-issue and all I
> have to do is go down to the DMV and tell them that I am now Diesel powered,
> not gas. Costs nothing to do. The previous owner also had the foresight to
> expand the capacity of the fuel tank from its stock 37gallons to almost 45.
> Range should be plenty good enough. :)
>
> With the axles, I got exceptionally lucky. This truck was originally
> ordered with the "Heavy Half" option package for towing and hauling. It has
> what I believe to be the "Corporate 12-bolt" in the rear and Dana 44 (I
> think?) up front. These will both be rebuilt with 3.73's and possibly
> detroit lockers.
>
> Ought to be interesting driving this big, old beatup looking suburban, with
> those manly diesel sounds coming from the hood and an exhust pipe that
> smells like donuts or french fries. :)
>

Sounds like you got a handle on it then, I would look into resurrecting
the original HVAC system though since likely the Duramax will have a
serpentine belt drive and you'll have to install the A/C compressor
anyway. I am not so sure about putting a Detroit Locker in the front
axle (I did not realize we were talking about a 4WD) if you think you're
going to do some off roading you might want to look into an ARB air
locker or similar, but having it kick in while accelerating through a
snowy corner, say, could have some surprising yet not entirely good
results. I suppose messing with the axles is something that can be put
off until you get everything else sorted out unless your ratios turn out
to be completely unsuited for use with the diesel, I would probably
leave that for last. I do know that the 44 is a very stout axle and
that the 12 bolt is probably plenty sturdy as well. If you want to go
totally hard core you could probably find a 44 that will fit under the
rear as well. That is an *old* design (I have one under my '56
Studebaker) and very tough, although the 12 bolt probably has less power
loss, so I'd keep it unless you start having problems with it.

With all that said, you *did* make sure that your T-case will bolt up to
the Allison trans, didn't you? You may need to have some driveshafts
made, depending on whether or not the Allison is roughly the same length
as the THM350 you're removing, and/or the engine mounts are in the same
place and/or everything just coincidentally happens to bolt up so
everything fits just so (yeah, right.)

good luck

nate

Alex Shirley

unread,
May 30, 2001, 1:10:27 PM5/30/01
to
> is in dire need of surgery now. Therefore, I have just placed an order
with
> my local Chevy dealer for a 6.6L Duramax Turbo Diesel (option code LB7 on
> the Sierra line, for those interested) and Allison Transmission. You guys

6.6L - Holy c**p, you guys sure like your engines big in the States :)
Out of interest, what sort of power does that dish out?

Alex.


z0ck

unread,
May 30, 2001, 4:29:56 PM5/30/01
to
The trans is actually a 700R4 and so is slightly longer than the TH350, but
not quite as long as the allison (so I am told). The transfer case is
stock, so I think it is an NP205, and is in some need of a rebuild anyway.
My thought in this regard was that, since I'm already in for one hell of a
fabrication job, I might as well fabricate some new mounts and such for the
t-case.


Nathan Nagel <njn...@worldnet.att.net> wrote in message

news:3B15272B...@worldnet.att.net...

Nathan Nagel

unread,
May 30, 2001, 5:24:43 PM5/30/01
to
Either that or use a T-case meant to go with the Allison. I guess what
I was saying was that there can be a difference between 2WD and 4WD
versions of the same trans.

nate

Emanuel Brown

unread,
May 31, 2001, 2:07:16 PM5/31/01
to
On Wed, 30 May 2001 17:10:27 GMT, "Alex Shirley"
<ce...@LOOSETHESPAM-bath.ac.uk> wrote:
>6.6L - Holy c**p, you guys sure like your engines big in the States :)

Just a minute, buddy. My Rolls-Royce has a 6.23l engine, and where
are those made again? And the models a couple of years after mine went
up to 6.75l. We in the colonies came by it honest, I'd say.
Emanuel
"Everybody wants a normal life and a cool car;
most people settle for the car." Chris Titus
http://home.att.net/~epbrown01/1966-rolls.jpg
http://home.att.net/~epbrown01/1983-porsche.jpg

Alex Shirley

unread,
May 31, 2001, 2:56:48 PM5/31/01
to
> >6.6L - Holy c**p, you guys sure like your engines big in the States :)
>
> Just a minute, buddy. My Rolls-Royce has a 6.23l engine, and where
> are those made again? And the models a couple of years after mine went
> up to 6.75l. We in the colonies came by it honest, I'd say.
> Emanuel
> "Everybody wants a normal life and a cool car;
> most people settle for the car." Chris Titus
> http://home.att.net/~epbrown01/1966-rolls.jpg
> http://home.att.net/~epbrown01/1983-porsche.jpg

You've certainly got a couple of cool cars there.
I have to say though, a RR is hardly typical of a British car (and with fuel
at 90 pence per litre it's hardly surprising). I was kind of thinking of the
biggest "SUV" you can get over here, the Range Rover. This makes do with a
paltry 4.3 litres.

By the way, I have nothing against big engines, so long as someone else is
paying for the fuel :)

Alex.


Emanuel Brown

unread,
Jun 1, 2001, 3:23:45 AM6/1/01
to
On Thu, 31 May 2001 18:56:48 GMT, "Alex Shirley"
<ashi...@NOSPAMfreenet.co.uk> wrote:
>You've certainly got a couple of cool cars there.
>I have to say though, a RR is hardly typical of a British car (and with fuel
>at 90 pence per litre it's hardly surprising).

Wow, I thought all you guys drove over there were Rolls-Royces and
Jaguars - what a disappointment.
Seriously, thanks for the compliment on the cars. I should mention
I'm in danger of being excommunicated from the Rolls-Royce Owners
Club, as I'm having the car painted another color (probably black), so
I've only got it until the secret police come for me...
Emanuel :-)

Stephen H. Westin

unread,
Jun 1, 2001, 4:56:41 PM6/1/01
to
"Alex Shirley" <ce...@LOOSETHESPAM-bath.ac.uk> writes:

According to <http://www.gmpowertrain.com/>, that's 300HP @3100
rpm. Torque isn't bad: 520 lb-ft @1800.

Richard Perry

unread,
Jun 9, 2001, 10:13:25 PM6/9/01