8 vs 16 valves Engine
Hongbin Isaac Liu
can someone tell me how the 16 valve Engine works? what's the advantage
of it? My car is a 4 cylinder 8 valve engine, and the new models (Nissan
Sentra) all have 16 valves. Does this make the engine more efficient?
save more gas? Any comments would be appreciated.
'66 Mustang driver.
More things can and will fail in this engine.
the only REAL 16 V engine has 8 cylinders.
Richard
Cricket's Trucking Service
Brute force - Yea, that's the ticket!
Remember the Pinto 2.0L overhead cam engine? It is a Coventry built motor
that has been available with twin cams/16 valves for about 5 years. The same
engine, built to race specs, makes 100bhp or more than the 8 valve version.
Think about the possibilities of an old Pinto sedan with 245 bhp...... >:-)
Cricket
Jim Grunewald
There was a discussion of dual over head cams vs single over head
cams a while ago that touched on some of the issues of 8 vs 16 valves.
The real reason for 16 valves is breathing. Two small valves have
more area than one big one. This breathing increases efficency and
allows higher useful rpm. This is not a necessity for a street
engine as someone pointed out in the previous discussion. It *might*
be important with power vs emissions considerations and it *might*
be a factor for improvement later on if emission control regulations
get worse. One advantage right now is SEX. A 16 valve engine has the
aura of a performance engine that an 8 valve doesn't. It might also
work into racing plans as a means of advertising.
--
------------------------------------------------------------------------------
|Jim Grunewald Speaking | |
|only for himself. | DYSLEXICS OF THE WORLD, UNTIE! |
|7422...@compuserve.com | |
------------------------------------------------------------------------------
| We'er all BOZOs on this bus. -Firesign Theater |
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Jeff Scott
A 4valve/cyl engine works basically the same as a 2v/c engine. It just
has double the valve train. The engine is not necessarily more efficient,
and it isn't done to save gas. It is done to get a higher output out of the
engine.
Jeff Scott (jlscott@rchvmv3 or jeff_...@rchland.vnet.ibm.com)
Dept. 49D LAN/Rvx/Open Hardware Development
IBM Rochester, Minnesota
(507)253-1176
Ed Oriordan
>hon...@leland.Stanford.EDU (Hongbin Isaac Liu) writes:
>>can someone tell me how the 16 valve Engine works? what's the advantage
>>of it? My car is a 4 cylinder 8 valve engine, and the new models (Nissan
>>Sentra) all have 16 valves. Does this make the engine more efficient?
>>save more gas? Any comments would be appreciated.
>A 4valve/cyl engine works basically the same as a 2v/c engine. It just
>has double the valve train. The engine is not necessarily more efficient,
>and it isn't done to save gas. It is done to get a higher output out of the
>engine.
>Jeff Scott (jlscott@rchvmv3 or jeff_...@rchland.vnet.ibm.com)
Isn't that kind of the same thing? Higher output == more efficient. If
you can make more power from the same amount of gas the only way to do it
is to become more efficient.
4valve/cyl are more efficient in that it allows the combustion chamber to
be shaped into more of a hemispherical combustion chamber which is very
efficient at eliminating valve shrouding, which would allow higher mixture
velocities, which would allow better fuel atomization, which would inturn
create a better burn (more power) for a given amount of gas.
Another benifit of the hemispherical combustion chamber is that it allows
the maximum volume to minimum surface area in the combustion chamber.
Which makes the engine retain heat better and be more efficient. Also
there are less places for hot spots to form and cause preignition.
Ed O'
Andy Dingley
v078...@ubvms.cc.buffalo.edu " Cricket's Trucking Service" writes:
> Remember the Pinto 2.0L overhead cam engine?
Unfortunately.
> It is a Coventry built motor that has been available with twin cams
> /16 valves for about 5 years.
A 16 valve Pinto ? Do you mean "Coventry", the place near Birmingham in the
UK, or somewhere else ? The only 16 valve Pintos I've ever seen in the UK
have been the Piper Warrior conversion head (Don't even *ask* about the build
quality), and the Sierra Cosworth engine which isn't a Pinto by a *long* way.
> Think about the possibilities of an old Pinto sedan with 245 bhp...... >:-)
Nice, if "Cricket's Trucking Service" have tow-trucks 8-)
You can build 250hp into the Pinto engine without too much problem. Stopping
them kicking the rods through the side of the block is quite another
problem.
--
Andy Dingley Codesmiths of Newcastle din...@codesmth.demon.co.uk
richard welty
*4valve/cyl are more efficient in that it allows the combustion chamber to
*be shaped into more of a hemispherical combustion chamber which is very
*efficient at eliminating valve shrouding, which would allow higher mixture
*velocities, which would allow better fuel atomization, which would inturn
*create a better burn (more power) for a given amount of gas.
but 4 valves != hemi; 2 valve hemis date from the 1920s (or earlier)
and include famous racing motors from Alfa Romeo and Chrysler. the
trade offs are that 4 valve motors breath better at high revs but 2 valve
motors allow a more hemispherical shape for better combustion; these
days combustion chamber shapes are evolving away from the pure hemi in
a quest for better swirl, but that's an other story.
but please, never claim that a 4 valve is "more of a hemi".
cheers,
richard
--
richard welty we...@balltown.cma.com
518-393-7228, Infologic, 1400 Balltown Road, Niskayuna, New York
``Mario is slowing on the backstretch'' -- Tom Carnegie
Cricket's Trucking Service
Here in the U.S., the best stock-block, high flowing heads can push the
2.0L to about 205hp with 50mm side drafts. The twin cam head, which is from
the Sierra and has been available in the U.S. for about 3.5 years, will flow
enough air to run 245hp out of the box. Porting, etc, will push this
further. Of course, Esslinger's turbo kits are a nice touch... They've gotten
550 hp without any difficulty out of the Twin cam.
I do tow, but only on a trailer. My Suburban can't fit a lift and arm kit...
Cricket
(This comes from the Plymouth Cricket - Hillman Avenger - Which as of 1992 was
still being produced in Argentina by Volkswagon. It is called the VW1500)
Dave Williams
-> Remember the Pinto 2.0L overhead cam engine? It is a Coventry built
-> motor that has been available with twin cams/16 valves for about 5
-> years.
Hello?
The Pinto 2.0 was/is designed and built entirely in Germany. It is a
single overhead cam, two valve motor.
The Cosworth Sierra uses a German short block with a Cosworth head, but
the resulting powerplant is, for all practical purposes (and Ford's
parts books) an entirely different motor.
The relationship between the Pinto 2.0 and the Cosworth 2.0 is the same
as that of the 1600 Kent and the Cortina Twincam, or a plain old 429 and
a BOSS 429.
Green Eric L
In article <2jeb0q$j...@nntp2.Stanford.EDU>, hon...@leland.Stanford.EDU (Hongbin Isaac Liu) writes:
|> Hello everyone:
|> can someone tell me how the 16 valve Engine works? what's the advantage
|> of it? My car is a 4 cylinder 8 valve engine, and the new models (Nissan
|> Sentra) all have 16 valves. Does this make the engine more efficient?
The real reason for 16 valves is breathing. Two small valves have
more area than one big one. This breathing increases efficency and
allows higher useful rpm. This is not a necessity for a street
There's also the fact that each of two small valves is lighter than
one large valve of equal area. Thus at high RPM's the inertia of
the moving valves doesn't cause "valve float" as easily (the phenomenon
where the inertia of getting the valve changing direction overcomes the
ability of the valve spring to pull the valve back). Meaning lighter valve
springs, less wear/tear on the valve train for high-RPM engines. Meaning
that you can rev the engine higher with "reasonable" valve springs (i.e.,
valve springs that don't cause unacceptable wear).
For low-RPM engines, as you noted, there's little advantage. Except in
terms of advertising. My mother's Honda has a 16-valve engine. They
sold 8-valve engines of the same basic type during that model year.
The 16-valve engine revs 1500 RPM higher, produces its maximum
horsepower at redline (i.e., the power curve doesn't "drop" at high
end due to breathing constrictions), and has about 20 more horsepower
than the 8-valve engine. But really, it's no more useful for street
purposes than the 8-valve version of that engine... the average daily
driver is more interested in off-the-line torque and mid-range
horsepower than in winding the engine up to 6500 RPM. There is little
difference in those areas between the two engines. Unless you really
know how to row your gear lever to keep your revs up, you won't see a
whole lot of difference. But 16 valves was more "sporting", so since
my mother's car was a more "sporting" model, they of course had to fit
it with a 16 valve engine rather than the more prosaic 8-valve model.
Marketing dictated that, rather than practical concerns.
--
Eric Lee Green e...@usl.edu (318) 984-1820
P.O. Box 92191 Lafayette, LA 70509
shum...@eisner.decus.org
The improvement is in volumetric efficiency -- a head with 4 valves per
cylinder will allow more air/fuel mixture flow at all valve lifts, even
when the valves are only slightly open. In consequence, more power is
available from smaller, lighter engines, allowing manufacturers to build
lighter cars and offer reasonably good performance while meeting the
Federal fuel-economy mandates. A second advantage is that valves are
substantially less massive, allowing use of softer valve springs which
reduce cam lobe and follower wear and/or use of more radical cam profiles
with improved control of the valve's closing. A third advantage is that
the spark plug can be centrally located in the combustion chamber for
better flame propagation. For racing engine applications, at least,
in every case where the same bottom end has been used with 2-valve and
4-valve design heads, the available power has increased over the entire
RPM range and not just at the top end (for example the English Ford-based
1600cc Lotus twin-cam and Cosworth BD versions). The advantage holds
at larger displacements, as well -- the top Corvette V-8 is a four-valve
per cylinder design.
The downside is that there are more parts to fail, even if they are lower
stressed.
Desmond Chan
Objective opinion between the two is that you get a much larger
torque low down in an 8 valver than a 16 valver. In short, the 16 valver
needs to be revved more than an equivalent 8 valve at a certain
power-torque figure. Although the 16 valver will have a higher output,
driving both cars in a leisurely manner would make the 8 valver an
easier car to drive since the torque is more accessible down low.
-This doesn't say that a 16 valver is anything worse than an 8
valve. I myself own a 16 valver...
||
\/
--
=======================================================================
| chee...@tartarus.uwa.edu.au (Bee-Man) . JUST DO IT in PLANET REEBOK|
| ++++++++++++++++++SPEAK SOFTLY, BUT CARRY A BIG STICK++++++++++++++ |
=======================================================================
Milo
: hon...@leland.Stanford.EDU (Hongbin Isaac Liu) writes:
: >Hello everyone:
: >can someone tell me how the 16 valve Engine works? what's the advantage
: >of it? My car is a 4 cylinder 8 valve engine, and the new models (Nissan
: >Sentra) all have 16 valves. Does this make the engine more efficient?
: >save more gas? Any comments would be appreciated.
: Objective opinion between the two is that you get a much larger
: torque low down in an 8 valver than a 16 valver. In short, the 16 valver
: needs to be revved more than an equivalent 8 valve at a certain
: power-torque figure. Although the 16 valver will have a higher output,
: driving both cars in a leisurely manner would make the 8 valver an
: easier car to drive since the torque is more accessible down low.
I don't know about that. I have a Saturn with the 16 valve engine.
8-valve 1.9liter: 85hp@5000rpm 16-valve 1.9liter: 124hp@5600rpm
107ft-lb@2400rpm 122ft-lb@4800rpm
*********>118ft-lb@2400rpm
Low end torque is fairly good in this 16 valver.
--
You tell me whar a man gits his corn pone, en I'll tell you
what his 'pinions is.
--Mark Twain, Corn-Pone Opinions
mi...@netcom.com
Matt Liggett
Milo> : Objective opinion between the two is that you get a much
Milo> larger : torque low down in an 8 valver than a 16 valver. In
Milo> short, the 16 valver : needs to be revved more than an
Milo> equivalent 8 valve at a certain : power-torque
Milo> figure. Although the 16 valver will have a higher output, :
Milo> driving both cars in a leisurely manner would make the 8
Milo> valver an : easier car to drive since the torque is more
Milo> accessible down low.
Milo> I don't know about that. I have a Saturn with the 16 valve
Milo> engine.
[statistics deleted because my citing mechanism mangled them]
I think you're 16-valve engine has more differences between it and the
8-valve Saturn engine than just the valves (number, size, etc). For
one, I think it has a totally different head, and different
camshaft(s).
Corrections requested.
--
matt liggett '59 Austin Mini 850 (If only it ran...)
(mlig...@indiana.edu) '75 Suzuki GT250 (Mutant Chainsaw)
'79 Honda Civic 1200 (Rust Never Sleeps)
"Talk to me about Elvis." - The Dead Milkmen
Milo
: I think you're 16-valve engine has more differences between it and the
: 8-valve Saturn engine than just the valves (number, size, etc). For
: one, I think it has a totally different head, and different
: camshaft(s).
: Corrections requested.
You could be right. I didn't think of that.
Steven J Gallacher
> jls...@rchland.vnet.ibm.com (Jeff Scott) writes:
>
> >hon...@leland.Stanford.EDU (Hongbin Isaac Liu) writes:
> >>can someone tell me how the 16 valve Engine works? what's the advantage
> >>of it? My car is a 4 cylinder 8 valve engine, and the new models (Nissan
> >>Sentra) all have 16 valves. Does this make the engine more efficient?
> >>save more gas? Any comments would be appreciated.
> (Stuff deleted)
> there are less places for hot spots to form and cause preignition.
>
> Ed O'
The main advantage of 4v/cyl instead of 2v/cyl is the improved breathing of the engine at low engine speeds. Because more air can flow into the engine at lower speeds more torque is produced, thus giving better performance and ecconomy. The advantage can be best gained as the valve opens, as a far greater amount of air can flow. The advantages of 4v/cyl are lost at higher value lift.
A properly modified, and tuned 2v/cyl engine can produce more power than a coresponding 4v/cyl engine.
Steve.
--
\\\\//// | The person who remains calm in a crisis has already
|.||.| | thought of someone to blame it on...
/\ |
\____/ | email : s...@cs.bham.ac.uk
David J Heisterberg
Steven J Gallacher <s...@cs.bham.ac.uk> wrote:
>The main advantage of 4v/cyl instead of 2v/cyl is the improved breathing
>of the engine at low engine speeds. Because more air can flow into the
>engine at lower speeds more torque is produced, thus giving better
That's true, or at least it should be. But in the context of a modern,
small, commuter car, isn't this advantage obviated if the engine is
throttled at all? I have a dumpy Escort GT and accellerate at WOT at
every chance, but I notice most other drivers do not. Wouldn't this
great majority of the driving public be served just as well by a 2V
design? If you never use all the car you've got, you bought more car
than you need.
--
David J. Heisterberg Du kannst auf die Ruecke steigen!
Department of Chemistry -- C. G. Jung
The Ohio State University
Darin Ray Hamilton
: If you never use all the car you've got, you bought more car
: than you need.
Good quote!
I wholeheartedly agree!
That's why I need more than my '86 MR2 can offer.
It reaches _its_ limit well before I do.
Why buy a $300,000 car if you'll never _prove_ it'll do what it's meant
to do?
If I could afford a Ferrari 512TR, I could also afford to drive the #$%&
out of it!
...Darin
_______________________________________
Darin Ray Hamilton |
4th year MIS (BComm) |
University of Calgary, Alberta, CANADA |
e-mail: drha...@acs.ucalgary.ca |
shum...@eisner.decus.org
[snip]
> The main advantage of 4v/cyl instead of 2v/cyl is the improved breathing of
> the engine at low engine speeds. Because more air can flow into the engine
> at lower speeds more torque is produced, thus giving better performance and
> ecconomy. The advantage can be best gained as the valve opens, as a far
> greater amount of air can flow. The advantages of 4v/cyl are lost at higher
> value lift.
A four-valve design will allow more mixture flow at _all_ valve lifts.
Consider one example: The largest inlet valve that was fitted in the Lotus
Big-Valve Twin-Cam head was 1.625" diameter. At .450" lift, the area through
which air/fuel mixture could flow was about 2.29 square inches (circumference
of the valve x lift). The 1600 BDA engine is fit with two 1-1/8" diameter
valves, providing 3.18 square inches of flow area at .450" lift. That's about
39% higher flow area. At .100" lift, the areas are about .51 and .71 square
inches respectively -- also 39%.
> A properly modified, and tuned 2v/cyl engine can produce more power than
> a coresponding 4v/cyl engine.
I believe that this runs counter to current experience. For example, could
you list for me those Formula 1 engines which use 2v/cyl heads? Returning
to the Twin-Cam vs. BDA case, the last figures I saw for carbureted Big-Valve
Twin-Cam 1600cc engines were in the 200 peak bhp range with usable torque from
6800 to 9000 RPM. Carbureted 1600cc BDA (Formula Atlantic) engines (before the
change to Toyota engines in the U.S.), were delivering 225-230 peak bhp with
usable torque from 6500 to 9250 RPM.
Jeff Scott
>In article <2jnt0m$l...@percy.cs.bham.ac.uk>,
>Steven J Gallacher <s...@cs.bham.ac.uk> wrote:
>>The main advantage of 4v/cyl instead of 2v/cyl is the improved breathing
>>of the engine at low engine speeds. Because more air can flow into the
>>engine at lower speeds more torque is produced, thus giving better
>
>That's true, or at least it should be.
It isn't true, and it shouldn't be. Advantages of large valves/good flowing
heads is mostly on the top end. 4v/cyl cars have a better top end because
they flow better, and because the valves are more resistant to float.
> But in the context of a modern,
>small, commuter car, isn't this advantage obviated if the engine is
>throttled at all? I have a dumpy Escort GT and accellerate at WOT at
>every chance, but I notice most other drivers do not. Wouldn't this
>great majority of the driving public be served just as well by a 2V
>design? If you never use all the car you've got, you bought more car
>than you need.
Unless you are winding the car up high, you probably aren't getting a
whole lot more out of it than the 2V people either.
Jeff Scott (jlscott@rchvmv3 or jeff_...@rchland.vnet.ibm.com)
Stiliyan Kalitzin
...........
>That's why I need more than my '86 MR2 can offer.
>It reaches _its_ limit well before I do.
>
>Why buy a $300,000 car if you'll never _prove_ it'll do what it's meant
>to do?
>If I could afford a Ferrari 512TR, I could also afford to drive the #$%&
>out of it!
>
.............
You dont need a F 512TR to reach Your limit. Take a Kawazaki ZZR 1100 (costs < than VW Golf). Acually this
post is a question: Why is it that motorbyke engines have much higher power output per vollume than the
car ones? A figure of 110-140 bhp/l is not an exception. And these are normally aspirated engines! Obviously
this power comes from the high rpms - 11000 or more. But what makes it so difficult to implement these
designs in the sport cars?
Comments appreciated Stiv
Bob Rusk
> Milo> I don't know about that. I have a Saturn with the 16 valve
> Milo> engine.
>
>[statistics deleted because my citing mechanism mangled them]
>
>I think you're 16-valve engine has more differences between it and the
>8-valve Saturn engine than just the valves (number, size, etc). For
>one, I think it has a totally different head, and different
>camshaft(s).
I think you'll find that to be the case with many/most 16-valve versions
of 8-valve engines. You want the valves to be in different positions and
such.
--
Bob Rusk
rr...@ssd.csd.harris.com
My thoughts, probably not Harris'.
David J Heisterberg
Jeff Scott <jls...@rchland.vnet.ibm.com> wrote:
>It isn't true, and it shouldn't be. Advantages of large valves/good flowing
>heads is mostly on the top end. 4v/cyl cars have a better top end because
Well, the point is, if you're throttling the engine, who cares how well
the valve assembly breathes.
>Unless you are winding the car up high, you probably aren't getting a
>whole lot more out of it than the 2V people either.
No, but the regular Escort 1.9L engine just didn't have any oomph.
It's also a completely different engine. So the question is, and
here I'm echoing Ms. Lilly's thoughts, what's the point of 4V engines
on most cars? While Camarros and Mustangs have 2V push-rod designs,
my Escort has a 4V DOHC. Is the incremental cost of producing 4V
heads low enough that's it's really worthwhile to use them on low-
end commuters, given the small performance increase (and the value
of being able to badge them with 16V DOHC)? How might the performance
change if a good 2V head were used?
Jonathan Hacker 21420
>In article <1994Feb15.0...@rchland.ibm.com>,
>Jeff Scott <jls...@rchland.vnet.ibm.com> wrote:
>>It isn't true, and it shouldn't be. Advantages of large valves/good flowing
>>heads is mostly on the top end. 4v/cyl cars have a better top end because
>
>Well, the point is, if you're throttling the engine, who cares how well
>the valve assembly breathes.
>
>>Unless you are winding the car up high, you probably aren't getting a
>>whole lot more out of it than the 2V people either.
>
>No, but the regular Escort 1.9L engine just didn't have any oomph.
>It's also a completely different engine. So the question is, and
>here I'm echoing Ms. Lilly's thoughts, what's the point of 4V engines
>on most cars? While Camarros and Mustangs have 2V push-rod designs,
>my Escort has a 4V DOHC. Is the incremental cost of producing 4V
>heads low enough that's it's really worthwhile to use them on low-
>end commuters, given the small performance increase (and the value
>of being able to badge them with 16V DOHC)? How might the performance
>change if a good 2V head were used?
The 4V design allows more flexibility in the design of the
combustion chamber, which in turn can allow for higher
compression leading to better efficiency. That can be a
big plus for meeting the CAFE/emission requirements.
--
Jon Hacker | OS/2 2.1
Bellcore, Red Bank NJ | accept no substitutes
hac...@patagonia.bellcore.com |
Andy Dingley
s...@cs.bham.ac.uk "Steven J Gallacher" writes:
> The main advantage of 4v/cyl instead of 2v/cyl is the improved breathing of the
> engine at low engine speeds. Because more air can flow into the engine at
> lower speeds more torque is produced, thus giving better performance and
> ecconomy. The advantage can be best gained as the valve opens, as a far
> greater amount of air can flow. The advantages of 4v/cyl are lost at higher
> value lift.
>
> A properly modified, and tuned 2v/cyl engine can produce more power than a
> coresponding 4v/cyl engine.
Apart from having every instance of "2 valves" and "4 valves" transposed
incorrectly, that's not a bad summary of the situation.
.bham.ac.uk ? No wonder the Midlands has lost its car industry 8-(
--
Andy Dingley Codesmiths of Newcastle din...@codesmth.demon.co.uk
Klein bottle for sale. Apply within.
Jeff Scott
>>It isn't true, and it shouldn't be. Advantages of large valves/good flowing
>>heads is mostly on the top end. 4v/cyl cars have a better top end because
>
>Well, the point is, if you're throttling the engine, who cares how well
>the valve assembly breathes.
This can be seen as an advantage of the 4v/c technology. The _vast_majority_
of the time cars are not driven at full throttle, and at partial throttle 4v/c
cars can get the same mileage as a 2v/c car. But when the driver wants that
extra power, they can get it by running the car at higher rev's with full
throttle.
>>Unless you are winding the car up high, you probably aren't getting a
>>whole lot more out of it than the 2V people either.
>
>No, but the regular Escort 1.9L engine just didn't have any oomph.
>It's also a completely different engine. So the question is, and
>here I'm echoing Ms. Lilly's thoughts, what's the point of 4V engines
>on most cars? While Camarros and Mustangs have 2V push-rod designs,
>my Escort has a 4V DOHC. Is the incremental cost of producing 4V
>heads low enough that's it's really worthwhile to use them on low-
>end commuters, given the small performance increase (and the value
>of being able to badge them with 16V DOHC)? How might the performance
>change if a good 2V head were used?
You seem to have the false impression that the car companies are in
business to produce cars. Do you also think that IBM is in business to
build computers? All companies are in business to make a profit. If they
can sell more cars by having higher HP #'s, then they will find ways to
get higher HP #'s. Whether those numbers actually mean anything doesn't
matter. The value in the 4v/c engine is that they can produce these cars
that have higher peak HP, but yet still have good gas mileage (they also
have to satisfy Uncle Sam, aka CAFE requirements).
Don't misunderstand me, tho. The 4v/c engines are usually nicer engines
than their 2v/c counter-parts, and I am talking at all RPM's. But this
has to do with more than just the # of valves/cyl.
Jeff Scott (jlscott@rchvmv3 or jeff_...@rchland.vnet.ibm.com)
Dept. 49D LAN/RVX/Open Hardware Development
IBM Rochester, Minnesota
(507)253-1176
Chris BeHanna
:>You dont need a F 512TR to reach Your limit. Take a Kawazaki ZZR 1100
:>(costs < than VW Golf). Acually this post is a question: Why is it that
:>motorbyke engines have much higher power output per vollume than the
:>car ones? A figure of 110-140 bhp/l is not an exception. And these are
:>normally aspirated engines! Obviously this power comes from the high rpms -
:>11000 or more. But what makes it so difficult to implement these designs in
:>the sport cars?
As the proud owner of a ZZR1100 (or ZX-11 to us Yanks), let me give it
a shot:
1) Automobile emissions standards are stricter than motorcycle
emissions standards, so the autos are often restricted more,
as it is cheaper to build a low-power engine that runs cleanly
than a hipo engine that runs cleanly.
2) Automobiles are usually at least five times heavier than
motorcycles, so in the interest of making launches more
pleasant affairs, they're tuned for more low-end torque than
most motorcycles, at the expense of high-end power.
(Example: my 7.4L Buick makes 50bhp/L, but it puts out over
five hundred pound-feet of torque at just 2800rpm. This is a
tradeoff that I can live with--for now. :-)
3) Concomitant with such prodigious power output comes increased
maintenance requirements. The average driver doesn't want to
be bothered with a valve clearance check every 6000 miles, for
example, as I am with my ZZR.
These are all just WAGs, of course, but I hope they're at least in
the ballpark.
Note that you can take a normally aspirated car engine and pull
100bhp/L out of it, too, but you have to spend real money to do it.
--
Chris BeHanna DoD# 114 KotSTA Ed Green 1975 CB360T - Baby Bike
beh...@syl.nj.nec.com Fan Club #004 1991 ZX-11 - needs a name
kore ha en-ii-shi no iken dewa arimasen. 1973 RD350A
I was raised by a pack of wild corn dogs. 1987 EX500 - the RaceBike
Andy Dingley
jls...@rchland.vnet.ibm.com "Jeff Scott" writes:
> You seem to have the false impression that the car companies are in
> business to produce cars. Do you also think that IBM is in business to
> build computers? All companies are in business to make a profit.
Has anyone told IBM ? 8-)
Nigel Pearson
> Objective opinion between the two is that you get a much larger
>torque low down in an 8 valver than a 16 valver. In short, the 16 valver
>needs to be revved more than an equivalent 8 valve at a certain
>power-torque figure. Although the 16 valver will have a higher output,
>driving both cars in a leisurely manner would make the 8 valver an
>easier car to drive since the torque is more accessible down low.
>
There are reasons for this. Unless your engine's intake system is
seriously hi-tech, then there is a trade off between intake velocity and
total breathing capability (and thus max. power). It has to do with better
fuel atomisation and chamber swirl at higher intake velocities causing
higher torque.
Things like V-TEC and Variable Intake System (forget who used that)
allow small intake system area for low RPM, which effectively increases the
intake velocity as compared to a larger area. At high RPM, you open the
intake area up so that pumping losses are diminished.
Alan Ernest
>
>In article <2jfog6$5...@liberator.et.tudelft.nl>, ric...@duteinv.et.tudelft.nl ('66 Mustang driver.) writes...
[snip]
>Remember the Pinto 2.0L overhead cam engine? It is a Coventry built motor
>that has been available with twin cams/16 valves for about 5 years. The same
>engine, built to race specs, makes 100bhp or more than the 8 valve version.
>Think about the possibilities of an old Pinto sedan with 245 bhp...... >:-)
>
>
Pintos? Pintos were equiped with 2.0L engines until 1974, when they went
to 2.3L engines. Both the 2.0 and the 2.3 were single overhead cam, two
valve/cylinder engines. The main problem with the heads of both these
engines was the port design - even with massive massaging, the stock
heads wouldn't flow worth a damn. You can still get aftermarket heads for
these engines, which, with only two valves per cylinder will easily get the
engine up to 200hp. Considering the manner in which the stock valve train
actuated, I can't imagine trying to make a 16 valve head fit.
Anyway, stock rods are sufficient for such an application; all you really need
to do is swap out the rod bolts for hardened ones.
Alan
Cricket's Trucking Service
>to 2.3L engines. Both the 2.0 and the 2.3 were single overhead cam, two
>valve/cylinder engines. The main problem with the heads of both these
>engines was the port design - even with massive massaging, the stock
>heads wouldn't flow worth a damn. You can still get aftermarket heads for
>these engines, which, with only two valves per cylinder will easily get the
>engine up to 200hp. Considering the manner in which the stock valve train
>actuated, I can't imagine trying to make a 16 valve head fit.
>
>Anyway, stock rods are sufficient for such an application; all you really need
>to do is swap out the rod bolts for hardened ones.
>
>Alan
The Olds Pro series and the Sports 2000 series have a new offshoot
using the 2.0L and the 4 valve DOHC head. Besides, do you have to
keep with the same cam follower set-up with a new from ground up
head?
Cricket
acss...@acs.eku.edu
> hon...@leland.Stanford.EDU (Hongbin Isaac Liu) writes:
>
>>Hello everyone:
>>can someone tell me how the 16 valve Engine works? what's the advantage
>>of it? My car is a 4 cylinder 8 valve engine, and the new models (Nissan
>>Sentra) all have 16 valves. Does this make the engine more efficient?
>>save more gas? Any comments would be appreciated.
>
> Objective opinion between the two is that you get a much larger
> torque low down in an 8 valver than a 16 valver. In short, the 16 valver
> needs to be revved more than an equivalent 8 valve at a certain
> power-torque figure. Although the 16 valver will have a higher output,
> driving both cars in a leisurely manner would make the 8 valver an
> easier car to drive since the torque is more accessible down low.
Is this really true... if both engines are the same displacement. I
think that the extra valves just let the engine reach rpms that the
other engine can't. I don't think it's impossible to build a multi-valve
engine that is as strong or stronger at the bottom or middle as the
older designs. In doing so, you may sacrifice some power at the high end
though. This is no different than taking any old V8 out of a truck (low
end/mid range torque) and building it into to a high rpm (horsepower)
street engine. It's just the reverse.
Is this correct?
The only multi-valve engine I have ever owned was a 3.0 Supra. I thought
it was strong across the whole rpm band. It did *really* come on at
about 3600 rpms though. It felt like someone had just kicked you in the
rear.
dsc
acss...@acs.eku.edu
>>>>>> "Milo" == Milo <mi...@netcom.com> writes:
>
> Milo> : Objective opinion between the two is that you get a much
> Milo> larger : torque low down in an 8 valver than a 16 valver. In
> Milo> short, the 16 valver : needs to be revved more than an
> Milo> equivalent 8 valve at a certain : power-torque
> Milo> figure. Although the 16 valver will have a higher output, :
> Milo> driving both cars in a leisurely manner would make the 8
> Milo> valver an : easier car to drive since the torque is more
> Milo> accessible down low.
>
> Milo> I don't know about that. I have a Saturn with the 16 valve
> Milo> engine.
>
> [statistics deleted because my citing mechanism mangled them]
>
> I think you're 16-valve engine has more differences between it and the
> 8-valve Saturn engine than just the valves (number, size, etc). For
> one, I think it has a totally different head, and different
> camshaft(s).
>
> Corrections requested.
>
That could be. But my opinion is that if those changes are made
possible, practical, and/or necessary by the extra valves, then any
gains are indirectly attributable to the valve change.
Does anyone agree?
dsc
Jayant Mahto
> >torque low down in an 8 valver than a 16 valver. In short, the 16 valver
> >needs to be revved more than an equivalent 8 valve at a certain
> >power-torque figure. Although the 16 valver will have a higher output,
> >driving both cars in a leisurely manner would make the 8 valver an
> >easier car to drive since the torque is more accessible down low.
> >
>
> There are reasons for this. Unless your engine's intake system is
> seriously hi-tech, then there is a trade off between intake velocity and
> total breathing capability (and thus max. power). It has to do with better
> fuel atomisation and chamber swirl at higher intake velocities causing
> higher torque.
>
> Things like V-TEC and Variable Intake System (forget who used that)
> allow small intake system area for low RPM, which effectively increases the
> intake velocity as compared to a larger area. At high RPM, you open the
> intake area up so that pumping losses are diminished.
>
(Toyota Variable ...). Out of 4 valvaes only 2 open below 4500 RPM and above
this (red line at 7500) all 4 valves are open to breath.
-Jayant
Zippy the Pinhead
I can't answer that one; Ford and Olds have little in common.
Alan
Cricket's Trucking Service
>>>Alan
>>
>>The Olds Pro series and the Sports 2000 series have a new offshoot
>>using the 2.0L and the 4 valve DOHC head. Besides, do you have to
>>keep with the same cam follower set-up with a new from ground up
>>head?
>>
>
>I can't answer that one; Ford and Olds have little in common.
>
>Alan
I meant the racing series, not a combination Ford/Olds technology. The S2000
folks like their motor and wanted a combination that would be faster than the
Quad-4. They took the Ford production twin cam head, modified it for racing,
and started an off-shoot racing division.
Cricket
acss...@acs.eku.edu
> In article <1994Feb15.0...@rchland.ibm.com>,
> Jeff Scott <jls...@rchland.vnet.ibm.com> wrote:
>>It isn't true, and it shouldn't be. Advantages of large valves/good flowing
>>heads is mostly on the top end. 4v/cyl cars have a better top end because
I'm not sure it's that simple. I think it also helps low and mid
range... just not as noticably.
>
>>Unless you are winding the car up high, you probably aren't getting a
>>whole lot more out of it than the 2V people either.
>
> No, but the regular Escort 1.9L engine just didn't have any oomph.
> It's also a completely different engine. So the question is, and
> here I'm echoing Ms. Lilly's thoughts, what's the point of 4V engines
> on most cars? While Camarros and Mustangs have 2V push-rod designs,
> my Escort has a 4V DOHC. Is the incremental cost of producing 4V
> heads low enough that's it's really worthwhile to use them on low-
> end commuters, given the small performance increase (and the value
> of being able to badge them with 16V DOHC)? How might the performance
> change if a good 2V head were used?
> --
Ah... now you are hitting on something else entirely. Should the
expensive, high reving, high tech, multi-valve engines be standard bottom
of the line equipment? I think not... what does everyone think? Are they
worth having to some people... obvilusly, yes.
dsc
Bob Gilbert
>I think early generation non-supercharged MR2s have this. It is called T-VIS
>(Toyota Variable ...). Out of 4 valvaes only 2 open below 4500 RPM and above
>this (red line at 7500) all 4 valves are open to breath.
>
>-Jayant
I think not! This may have been done in some other engine, but not the
early MR2's.
-Bob
Brian Scott Haskett
>>>heads is mostly on the top end. 4v/cyl cars have a better top end because
>
>I'm not sure it's that simple. I think it also helps low and mid
>range... just not as noticably.
No, the original poster had it right. For low-end torque, you need some
resistance on both the intake and exhaust sides. A single plenum intake
will hurt your low-end power, as will open headers. This is a trade-off
that is also a crucial balancing act when building drag cars... though for
a drag car you almost always don't care about low-end, you just worry about
top-end, and gear it to get there fast.
>>>Unless you are winding the car up high, you probably aren't getting a
>>>whole lot more out of it than the 2V people either.
>> No, but the regular Escort 1.9L engine just didn't have any oomph.
>> It's also a completely different engine. So the question is, and
>> here I'm echoing Ms. Lilly's thoughts, what's the point of 4V engines
>> on most cars? While Camarros and Mustangs have 2V push-rod designs,
>> my Escort has a 4V DOHC. Is the incremental cost of producing 4V
>> heads low enough that's it's really worthwhile to use them on low-
>> end commuters, given the small performance increase (and the value
>> of being able to badge them with 16V DOHC)? How might the performance
>> change if a good 2V head were used?
>Ah... now you are hitting on something else entirely. Should the
>expensive, high reving, high tech, multi-valve engines be standard bottom
>of the line equipment? I think not... what does everyone think? Are they
>worth having to some people... obvilusly, yes.
Personally, I think that the reason that car manufacturers pay any attention
to the top-end is because you can say that the car has x amount of horsepower,
and the consumer isn't usually careful enough to notice that that horsepower
is made at 5400 RPM or something totally ridiculous like that. For normal,
everyday driving, torque is a much more dependable figure than horsepower.
Stop and go driving uses almost exclusively torque. It used to be that
horsepower was important for highway driving because on the highway the
RPM's would be pretty high, but now that overdrive transmissions are being
used, most drivers rarely get their RPM's over 3000 (especially if they
have an automatic transmission).
IMHO, horsepower figures for 4v/cyl engines are merely a marketing ploy...
The extra power developed by these engines is almost entirely in the top
of the tach, which for normal driving is never seen.
Peter Tong
>In article <2jqtku$9...@charm.magnus.acs.ohio-state.edu>, dhei...@magnus.acs.ohio-state.edu (David J Heisterberg) writes:
>> In article <1994Feb15.0...@rchland.ibm.com>,
>> Jeff Scott <jls...@rchland.vnet.ibm.com> wrote:
>>>It isn't true, and it shouldn't be. Advantages of large valves/good flowing
>>>heads is mostly on the top end. 4v/cyl cars have a better top end because
4v/c heads give the POTENTIAL for top end hp and even that depends on the
design. Ie if the intake ports are angled for as straight a shot into the
chambers as possible - and the same when it comes to the exhaust. The
potential is there but whether it attains that potential is the question.
There's some articles in the rec.autos.vw faq regarding different heads for
VW 1.8 (and now 2.0 litre) Golf/Rabbit engines - one of the 16V heads designed
for the VW block put out 200hp, whereas a similarly setup VW 16V head
attained maybe 75% of that. Supposedly the VW factory 16V heads pale
design wise in comparison with the Drake Engineering (offenhauser)
designed heads. I have noticed that most 16V motors that are pushing
about 75-80+ bhp have intake systems without U bends. For example the
BMW 325is and M3 heads. Those engines use a manifold that is practically
a straight shot in compared to say the new Neon engine which utilizes a
U bend intake manifold (most likely for packaging efficiency). On high
winding 16V type engines there are other factors that affect the torque
curve namely the rod length/stroke ratio changes the peak piston velocity
at midstroke. High ratio engines tend to develop a peakier torque curve and
vice versa for low ratio engines. I haven't begun even to think about intake/
exhaust manifold design.....
>I'm not sure it's that simple. I think it also helps low and mid
>range... just not as noticably.
As before usually a 4v/c loses moderately at low rpm up to say about
2.5-3k (but this is an arbitrary figure, and at wide open throttle only).
Since street vehicles are driven at part throttle most of the time the most
important thing is part throttle performance for day to day driving -
and in that 2v/c ends up being alot more responsive that most 4v/c.
>>>Unless you are winding the car up high, you probably aren't getting a
>>>whole lot more out of it than the 2V people either.
Again this depends on the specific engine design/ parts combination.
>>
>> No, but the regular Escort 1.9L engine just didn't have any oomph.
>> It's also a completely different engine. So the question is, and
>> here I'm echoing Ms. Lilly's thoughts, what's the point of 4V engines
>> on most cars? While Camarros and Mustangs have 2V push-rod designs,
>> my Escort has a 4V DOHC. Is the incremental cost of producing 4V
>> heads low enough that's it's really worthwhile to use them on low-
>> end commuters, given the small performance increase (and the value
>> of being able to badge them with 16V DOHC)? How might the performance
>> change if a good 2V head were used?
>
>dsc
Although the factory 1.8 litre 16V GTI heads compare favourably with
most any of the 16V heads out there - personally, I'd rather have a WELL
DESIGNED polished and ported two valve/cylinder head on my "warmed over"
(130hp) Rabbit than a mediocre (stock VW) 4v/c head. Torquewise I'd leave
a 16V for dead from a light, and at high rpm I'd outflow the stock
head as well.
If manufacturers designed their 2v/c heads right they'd be able to attain
the same hp but with more driveability. Unfortunately it seems that instead
of further developing 2v/cyl. heads, most manufacturers decide to just build
4v/c heads at a state of much lower tune but that still marginally outflow
2v/c heads.
>Ah... now you are hitting on something else entirely. Should the
>expensive, high reving, high tech, multi-valve engines be standard bottom
>of the line equipment? I think not... what does everyone think? Are they
>worth having to some people... obvilusly, yes.
>
Bottom of the line? No - just give most people a highly tuned 2v/c unit -
they'll appreciate the low end torque, and fuel economy better. So
comparing the same 4 cyl. blocks with identical displacement I'd choose an
8V motor over a 16V motor for driveability. However, with an increase in
displacement on the 16V to make the driveability issue a non issue then
perhaps I'd take the 16V compromising some fuel economy for better power.
I know this from experience - my VW Cabriolet is pushing about 125-130hp with
an Audi 2.0 block with a stock GTI 8V head. 0-60 comes in under 8 seconds.
40-60 times in 4.3 secs. Compression is 10.5:1 with a decked head and a knock
sensor ignition (even with a mild cam compression tests are around 205psi).
I average at least 35 mpg on the freeway at 70-75mph.
38-40 mpg going a steady 55mph. 30mpg going a constant 80-85 mph with the
convertible top down (this was across Wyoming and SD). Low and Midrange
torque on this thing is very good, and with decent top end.
I think you might be able to find a factory stock 16V combination of the same
displacement that matched my performance - perhaps something like the Sentra
SE-R (140hp 2.0 16V), but it still would fall quite short on the economy side.
And all I have done is utilize the best year stock parts on my VW 8V! - ie no
head porting or gas flowing. A gas flowed 8V head offers up another 10hp
with the same cam and another 20hp with a higher lift cam (top end power
would be up to 150hp).
Just tossing in my $0.02 worth!
I had to because I'm working on building a variable manifold intake manifold
as a project for my cabrio. Currently entering the design into Autocad.
Peter Tong
'82 2.0 8V VW Cabriolet (125-130hp & 2250lbs to drag around)
David Crooke
> Personally, I think that the reason that car manufacturers pay any attention
> to the top-end is because you can say that the car has x amount of horsepower,
> and the consumer isn't usually careful enough to notice that that horsepower
> is made at 5400 RPM or something totally ridiculous like that. For normal,
> everyday driving, torque is a much more dependable figure than horsepower.
> Stop and go driving uses almost exclusively torque. It used to be that
> horsepower was important for highway driving because on the highway the
> RPM's would be pretty high, but now that overdrive transmissions are being
> used, most drivers rarely get their RPM's over 3000 (especially if they
> have an automatic transmission).
5400 rpm may be ridiculous for an American big-block V8, but is perfectly normal
for most cars. I'd agree with you that torque makes the odds for motorway
driving - my car (Saab) isn't terribly quick off the lights, but it will beat a
small Ferrari 40-70 or 70-100, and steams up hills, due to its mid range torque
(177 lb.ft @ 3000rpm, not bad for under 2 litre, 4 cyl 8-valve :-)
Remember that : power = torque x revs
so while the torque increases up to about 3000-4000 rpm, and then drops off, the
peak power is much higher up the rev range, in a typical engine. The function of
a gearbox is to multiply the torque in order to accelerate quickly at low speeds.
Dave
--
David Crooke, Department of Computer Science, University of Edinburgh
Janet d...@ed.dcs : Internet d...@dcs.ed.ac.uk : IP talk d...@129.215.160.2
Work: JCMB Rm 1408, King's Bldgs, W Mains Rd., Edinburgh EH9 3JZ. 031 650 5164
Home: 12 (GFR) West Savile Tr, Edinburgh, SCOTLAND EH9 3DZ. 031 667 4854
sacrou...@vmsb.is.csupomona.edu
> In article <Feb14.185...@acs.ucalgary.ca> drha...@acs.ucalgary.ca (Darin Ray Hamilton) writes:
> ...........
>
> post is a question: Why is it that motorbyke engines have much higher power output per vollume than the
> car ones? A figure of 110-140 bhp/l is not an exception. And these are normally aspirated engines! Obviously
> this power comes from the high rpms - 11000 or more. But what makes it so difficult to implement these
> designs in the sport cars?
> Comments appreciated Stiv
>
>
sized automobile engine. Therefore, it can be lighter internally. The cooling
passages (in liquid cooled engines) can be much smaller also. The "motorbyke"
smog restrictions are not as, restrictive, as cars are, too.
Scott
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+G __________ ___o C ! H o___ __________ G+
+o ________ _`\ <_ R!S _> /'_ ______ o+
+o _______ (*)/ (*) A (*) \(*) _____ o+
+s "It's never too late to have a happy childhood" s+
+e Email: sacrou...@vmsa.is.csupomona.edu e+
------------------------------------------------------------------------------
acss...@acs.eku.edu
>>>>heads is mostly on the top end. 4v/cyl cars have a better top end because
>>
>>I'm not sure it's that simple. I think it also helps low and mid
>>range... just not as noticably.
>
> No, the original poster had it right. For low-end torque, you need some
> resistance on both the intake and exhaust sides. A single plenum intake
> will hurt your low-end power, as will open headers. This is a trade-off
I think the >> quote was from me. I still stand by that. What you said
is true, but none of the companies have gone to the extreme that you are
suggesting. They are maintaining a balance over the whole rpm range.
Opening up the flow a bit can help low and midrange torque as long as
you don't go to the point where you loose air/fuel flow velocity.
As I said before, I considered the low and midrange performance of the
'87 Supra I had to be very good. I also admit that the real kick in the
pants came at about 3600 rpm. So yes, higher rpm probably benefits the
most, but that doesn't necessarily mean that you can't still acheive a
small gain in the low and mid range.
dsc
Andrew Ayers
writes:
>Opening up the flow a bit can help low and midrange torque as long as
>you don't go to the point where you loose air/fuel flow velocity.
>As I said before, I considered the low and midrange performance of the
>'87 Supra I had to be very good. I also admit that the real kick in the
>pants came at about 3600 rpm. So yes, higher rpm probably benefits the
>most, but that doesn't necessarily mean that you can't still acheive a
>small gain in the low and mid range.
That kick you felt at 3600 rpm may not have been totally due to the
valves. I have an 87 Celica GT-S that uses a Variable Induction System
(VIS) that opens a second set of butterfly valves between the injectors
and the overhead valves changing the breathing properties of the whole
induction system. I'm not totally sure, but I bet your Supra uses a
similar system.
Darin Ray Hamilton
: In article <2jqh60$a...@amcnix.amc.uva.nl>, kalitzin@goedel (Stiliyan Kalitzin) writes:
: >
: > You dont need a F 512TR to reach Your limit. Take a Kawazaki ZZR 1100 (costs < than VW Golf). Acually this
: > post is a question: Why is it that motorbyke engines have much higher power output per vollume than the
: > car ones? A figure of 110-140 bhp/l is not an exception. And these are normally aspirated engines! Obviously
: > this power comes from the high rpms - 11000 or more. But what makes it so difficult to implement these
: > designs in the sport cars?
: > Comments appreciated Stiv
: >
: The "motorbyke" engine has a MUCH smaller load to lug around than a comparably
: sized automobile engine. Therefore, it can be lighter internally. The cooling
: passages (in liquid cooled engines) can be much smaller also. The "motorbyke"
: smog restrictions are not as, restrictive, as cars are, too.
I would also assume that motorcycle engines are designed for very high
bhp, but very low _torque_.
It doesn't take much torque to move <1000lbs. (relatively speaking)
RE: reaching the "limit"...
I'm not much for bikes--never driven one, and don't plan to.
I realize it wouldn't take a 512TR, but a '94 Supra would do. 8-)
...Darin
(. )(. )
-------------------###--\/\/\/\/--###---
| Darin Ray Hamilton |
| 4th year MIS (BComm) |
| University of Calgary, Alberta, CANADA |
| e-mail: drha...@acs.ucalgary.ca |
----------------------------------------