5.7L EFI B3 versus 7.4L MPI B3
Bob Winchell
> We are considering two different boats, specifications listed below,
and
...
> We've been told by the person with Boat #1 that the 5.7L will get
better
> fuel economy than the 7.4L and we've been told by the person with Boat
#2
> that the 7.4L will get better fuel economy than the 5.7L.
>
> Thoughts?
>
> Debi
Me thinks each seller wants you to buy *his* boat:) Seriously, my axiom
is to get the largest engine _offered_ in any particular boat. 1) Fuel
consumption has more to do with throttle position than engine size (in
this boat size range), 2) the larger engine will be working less than
the smaller at any given speed/load and 3) resale is generally higher
with a larger engine (or at least resale is lower with an underpowered
boat). The cliche is: "there is no replacement for displacement".
Bob Winchell
Todd Hudgel
>
> Bob Winchell
"There is no substitute for cubic inches." - Carroll Shelby
--
A nation that protects fools from themselves, will become a nation of fools
No Spam Please
Todd Hudgel
>
>
Rick
"Debi L. Billing" <dlbi...@uswest.net> wrote in message
news:7Jx05.409$oc3....@news.uswest.net...
> We are considering two different boats, specifications listed below, and
> underpowered, but at the same time are looking for the best overall fuel
> economy at cruising speed.
> We'll be using the boat mainly on the Mississippi and St. Croix Rivers
with
> some limited use on one of the Great Lakes (Lake Superior).
>
>
> Boat #1
> - Dry weight: 6,200 lbs.
> - LOA: 26' 0"
> - Engine: Mercruiser 5.7L EFI Bravo 3
>
> Boat #2
> - Dry weight: 5500 lbs.
> - LOA: 26' 5"
> - Engine: Mercruiser 7.4L MPI Bravo 3
>
>
> We've been told by the person with Boat #1 that the 5.7L will get better
> fuel economy than the 7.4L and we've been told by the person with Boat #2
> that the 7.4L will get better fuel economy than the 5.7L.
>
> Thoughts?
>
> Debi
>
Is a bigger engine always better?. that is the headline of an article in the
June issue of Boating magazine. In a nutshell, no. The tests were conducted
on the same boat , in this case a Scorpion 24' sport boat , weight was 4,000
lbs. The two boats ur looking at are similar in length and weight although
heavier than the Scorpion. The test engines were Mercury 350 built by Merc
racing and a stock 454 Mag MPI. The article ends making a comparison with
stock engines and goes something like this "You have a choice between a
300hp Merc 350 Mag MPI and a big block 310 h.p , 7.4 Mag MPi, (a 133 lbd
difference), chances are good that you'd see a fuel economy advantage with
the lighter motor without losing much in speed. When it comes to power a
little less can mean a lot more.".
In the actual test boat there was a WOT difference of 1 mph with a
significant advantage fuel wise to the 350 engine. At cruising speed of 3500
rpm the 350 actually was .03 mph faster and burned less fuel.
I realize that the engines your looking at are likely not the 300 h.p 5.7
model but it was interesting reading.
Rick
H82LUZ1
>"There is no substitute for cubic inches." - Carroll Shelby
Gawd I love that guy...
Mike G.
Bad_Sneakers
"Rick" <reng...@home.com> wrote:
>..."You have a choice between a
> 300hp Merc 350 Mag MPI and a big block 310 h.p , 7.4 Mag MPi, (a 133
lbd
> difference), chances are good that you'd see a fuel economy advantage
with
> the lighter motor without losing much in speed. When it comes to
power a
> little less can mean a lot more.".
>
> In the actual test boat there was a WOT difference of 1 mph with a
> significant advantage fuel wise to the 350 engine. At cruising speed
of 3500
> rpm the 350 actually was .03 mph faster and burned less fuel.
>
> I realize that the engines your looking at are likely not the 300 h.p
5.7
> model but it was interesting reading.
>
> Rick
Would you consider the smaller engine working hard to achieve the same
speed? That is, would you consider the 454 is lumbering along well
below its stock limits while the 350 stressed is torqued/stressed up to
give the same knots? Since boat motors are always working (unlike cars
where this is a lot of coasting) would you consider this to negatively
impact the motor life?
Sent via Deja.com http://www.deja.com/
Before you buy.
H82LUZ1
On the other hand, He who has the most horsepower, usually wins.
If you can get the same HP with less weight, that's a definate plus!
Especially in a boat.
The High Output 350 and the new Merc 377 Scorpoin motors are somewhat a
different ball game. Big HP but you need the stroke of a big block for the
torque.
Mike G.
hkr...@capu.net
I read the article in BOATING and concluded its findings were fallacious.
It compared two completely different kinds of engines, a stock big block and a
racing smaller block. Unlikely a customer is going to choose between those two.
The story would have been valid if two stock engines were being compared.
--
Harry Krause
------------
I'm mad! This 386 doesn't spel any better than the XT.
Rick
<hkr...@capu.net> wrote in message news:3947A4C9...@capu.net...
Agreed, however the article does make the comparison to several stock small
block vs big blocks in the Merc and Volvo lineup and the conclusion is still
the same , at least for the newer engines but your right, the article would
have been better if stock engines were used. How many of us are going to pay
the premium price for that racing small block.
Rick
Russ Glindmeier
hkr...@capu.net wrote in message <3947A4C9...@capu.net>...
>H82LUZ1 wrote:
>>
>> When it comes to stock engines, I'll say that bigger is "usually"
better.
>> On the other hand, He who has the most horsepower, usually wins.
>> If you can get the same HP with less weight, that's a definate plus!
>> Especially in a boat.
>> The High Output 350 and the new Merc 377 Scorpoin motors are somewhat
a
>> different ball game. Big HP but you need the stroke of a big block for
the
>> torque.
>>
>> Mike G.
>
>
>I read the article in BOATING and concluded its findings were fallacious.
>It compared two completely different kinds of engines, a stock big block
and a
>racing smaller block. Unlikely a customer is going to choose between those
two.
>The story would have been valid if two stock engines were being compared.
>
Unlikely, as is this case, that the customer will be given such a choice.
Not many boat models are given the high performance engine options, such as
Merc's Magnums. To keep costs down, manufacturers limit engine choices in a
given model to those they feel will be most popular and most appropriate.
Rarely will you find a high performance engine option available in a family
runabout or cruiser model. Those options are reserved for the sport models,
as makes sense. The high performance engines carry a premium price tag that
most buyers other than the go-fast guys would not want to foot the bill for.
In the case of the original post, the choices were the stock 5.7 TBI EFI or
7.4 MPI EFI. As I stated earlier, for this application I'd want nothing
less than the big block. The 5.7 is a perfectly fine engine, I've got two
of 'em in my boat and love 'em, but one is barely adequate in a 6k pound
boat, in my opinion.
Russ
hkr...@capu.net
> > >
> > > When it comes to stock engines, I'll say that bigger is "usually"
> better.
> > > On the other hand, He who has the most horsepower, usually wins.
> > > If you can get the same HP with less weight, that's a definate
> plus!
> > > Especially in a boat.
> > > The High Output 350 and the new Merc 377 Scorpoin motors are somewhat
> a
> > > different ball game. Big HP but you need the stroke of a big block for
> the
> > > torque.
> > >
> > > Mike G.
> >
> >
> > I read the article in BOATING and concluded its findings were fallacious.
> > It compared two completely different kinds of engines, a stock big block
> and a
> > racing smaller block. Unlikely a customer is going to choose between those
> two.
> > The story would have been valid if two stock engines were being compared.
> >
> >
> >
> > Harry Krause
> > ------------
> >
> > I'm mad! This 386 doesn't spel any better than the XT.
>
> Agreed, however the article does make the comparison to several stock small
> block vs big blocks in the Merc and Volvo lineup and the conclusion is still
> the same , at least for the newer engines but your right, the article would
> have been better if stock engines were used. How many of us are going to pay
> the premium price for that racing small block.
>
> Rick
Not me, and further, a racing block engine is not a new boat option for most
boats. Only our friend in Kansas seems willing to pay the price and burn the
gas!
--
Harry Krause
------------
Go shopping. Buy Stuff. Sweat in it. Return it the next day.
Rick
"Russ Glindmeier" <ru...@att.net> wrote in message
news:_VN15.1248$Uw3....@bgtnsc04-news.ops.worldnet.att.net...
>
> Unlikely, as is this case, that the customer will be given such a choice.
> Not many boat models are given the high performance engine options, such
as
> Merc's Magnums. To keep costs down, manufacturers limit engine choices in
a
> given model to those they feel will be most popular and most appropriate.
> Rarely will you find a high performance engine option available in a
family
> runabout or cruiser model. Those options are reserved for the sport
models,
> as makes sense. The high performance engines carry a premium price tag
that
> most buyers other than the go-fast guys would not want to foot the bill
for.
> In the case of the original post, the choices were the stock 5.7 TBI EFI
or
> 7.4 MPI EFI. As I stated earlier, for this application I'd want nothing
> less than the big block. The 5.7 is a perfectly fine engine, I've got two
> of 'em in my boat and love 'em, but one is barely adequate in a 6k pound
> boat, in my opinion.
>
> Russ
>
Guess it depends on how fast you want to go. You have a wide beam boat where
most 26' are in the 8 to 8'6" beam size. My 26 Doral aft cabin with the 5.7
, 260 h.p merc would top out at 40 mph and cruise at 3200 rpm at 30 mph very
efficiently. I would not even have considered a big block for that boat, but
then again for those who want to go 50 mph in a 26' cruiser then the big
block is the way to go.
Rick
RBStern
>less than the big block. The 5.7 is a perfectly fine engine, I've got two
>of 'em in my boat and love 'em, but one is barely adequate in a 6k pound
>boat, in my opinion.
I think you'd be surprised. The 5.7 B3 does very well with a 26' 6000
express, even when loaded. Having driven such a combo for about 100 hours, I
am very comfortable stating that. I credit the B3, because other 5.7's I've
experienced with different outdrives didn't feel as strong.
-- Rich Stern
Russ Glindmeier
Rick wrote in message ...
>>
>
>Guess it depends on how fast you want to go. You have a wide beam boat
where
>most 26' are in the 8 to 8'6" beam size. My 26 Doral aft cabin with the 5.7
>, 260 h.p merc would top out at 40 mph and cruise at 3200 rpm at 30 mph
very
>efficiently. I would not even have considered a big block for that boat,
but
>then again for those who want to go 50 mph in a 26' cruiser then the big
>block is the way to go.
>
>Rick
>
>
I really don't look at it from a top speed perspective, although that
certainly is a valid criteria for some, I suppose. A 40 mph top end is
plenty fast enough for a family boat, IMO. That's all mine's good for and
I'm just fine with it. I'm more concerned with the ability of the boat to
plain out quickly and under minimal stress when fully loaded. For this,
there is no substitute for the torque that the additional cubic inches the
big block provides. In a smaller boat, the extra weight of the big block
could in fact become a liability, but I don't think this applies in a 26'
cruiser. A quicker plane time reduces the period of limited visibility
while coming on plane, and reduces a stressful period on the engine. In
other words, I'm more concerned with how hard the engine has to work to
achieve and maintain my 30 mph cruise than I am whether or not the boat will
reach 50 mph. Additionally, I would rather be in the position of having the
additional power available and not needing or using it than wanting or
needing it and not having it. I don't believe there is a fuel consumption
penalty for having such an option. Add to that the higher resale of the big
block, and the decision is an easy one for me.
Russ
Russ Glindmeier
RBStern wrote in message <20000614125743...@ng-cg1.aol.com>...
Perhaps, but my 270, which carried a dry weight of 7500 pounds felt under
powered with the single 7.4 B3 in it. I'm not saying that the 5.7 B3 in a
6k# boat wouldn't get out of its own way, but at that size the option to go
small block/big block is there, and given the choice, I would opt for the
big block without a moment's hesitation.
My 25' Four Winns was in that size category and it had a single 7.4 EFI with
the King Cobra drive. It was very responsive under normal usage. However,
taking it to Lake Powell, with increased altitude, 4 people with provisions
for 4 days made it feel very sluggish, even after dropping 2 inches in
propeller pitch for the trip. I just couldn't imagine that boat with a
small block in those conditions. No thanks.
Russ
Patrick B.
>June issue of Boating magazine. In a nutshell, no. The tests were conducted
>on the same boat , in this case a Scorpion 24' sport boat , weight was 4,000
>lbs. The two boats ur looking at are similar in length and weight although
>heavier than the Scorpion. The test engines were Mercury 350 built by Merc
>racing and a stock 454 Mag MPI. The article ends making a comparison with
>300hp Merc 350 Mag MPI and a big block 310 h.p , 7.4 Mag MPi, (a 133 lbd
>difference), chances are good that you'd see a fuel economy advantage with
>the lighter motor without losing much in speed. When it comes to power a
>little less can mean a lot more.".
The article discusses the Scorpion 377 block versus the 454 Magnum
block though, with a weight difference of 185 lbs. Under those
circumstances, the 377 Scorpion is *potentially* the better engine,
given the closeness of horsepower (360 vs 385), and the lighter
weight. It is however, a vastly more expensive engine, given it's
racing heritage.
If the debate were between the 350 Magnum (300 HP) and the 7.4L MPI
(310 HP), then I'd take the 350 Magnum, given the lighter weight,
slightly lower cost, and insignificant power difference.
However, the boat in question in this article *appears* to be the
stock 5.7L EFI (260 HP) vs the 7.4L MPI (310 HP). 50 HP is a
significant number, and easily overcomes the 185 lb weight difference,
and will easily garner extra resale value in the future.
The extra torque from the big block will especially come in handy in
holeshot and cruising speed determinations. If the price is not a
concern (or is close enough to allow you freedom), then the smart
choice is the bigger motor. If the option exists, you may also want
to look at the Mercruiser Horizon engines, which are the ultra low
maintenance models. I believe the only models currently in the
Horizon line are the 350 Magnum and the 454 MPI (not Magnum).
Pat
hol...@flash.net
this over the 7.4mpi for three reasons. first, The fwc on the horizion
along with many extended maintainence items ad more value at resale.
second,The torque on the mag is about 360ftlb vs 435ftlb a wide
difference you say? But take into account the extra 130lbs and the
difference is maybe 50ftlbs. Enough to make some difference I guess.
Also the 350 has a flatter tourqe curve than the 7.4. Both engines
peake at around 3200 rmp but with the 350 you get to use it longer.
Hp goes to the small block base on weight to hp ratio. Third is cost!!
even with the horizon goodies on the 350 mag it was 1000 bucks cheaper.
Fuel burn at cruise is better on the small block also. Now this is no
light boat either. It comes in at around 7k loaded and planes and
cruises easily at 3200rpm @24mph.This is not your fathers small block.
It actually has 20 more propshaft horsepower than the 7.4 did just a
few years ago. and about the same torque! and a B3 to the mix and you
get one well balanced well performing cruiser. Now I'm not saying that
the 7.4 would not be a good choice just that in my case when you crunch
the stats the small block got the nod.
RBStern
>the King Cobra drive. It was very responsive under normal usage. However,
>taking it to Lake Powell, with increased altitude, 4 people with provisions
>for 4 days made it feel very sluggish, even after dropping 2 inches in
>propeller pitch for the trip. I just couldn't imagine that boat with a
>small block in those conditions. No thanks.
>
Fair enough. My experience is limited to about 1070 feet above sea level. I
don't doubt another four or five thousand feet matters. Any time I've gone
jogging in Arizona, New Mexico, or Colorado, my lungs agreed with your point of
view.
-- Rich Stern
Dudley Cornman
> Is a bigger engine always better?. that is the headline of an article in the
> June issue of Boating magazine. In a nutshell, no. The tests were conducted
> on the same boat , in this case a Scorpion 24' sport boat , weight was 4,000
> lbs. The two boats ur looking at are similar in length and weight although
> heavier than the Scorpion. The test engines were Mercury 350 built by Merc
> racing and a stock 454 Mag MPI. The article ends making a comparison with
> stock engines and goes something like this "You have a choice between a
> 300hp Merc 350 Mag MPI and a big block 310 h.p , 7.4 Mag MPi, (a 133 lbd
> difference), chances are good that you'd see a fuel economy advantage with
> the lighter motor without losing much in speed. When it comes to power a
> little less can mean a lot more.".
>
> significant advantage fuel wise to the 350 engine. At cruising speed of 3500
> rpm the 350 actually was .03 mph faster and burned less fuel.
First - that's not a practical test. Instead tell me how much fuel each
consumes and how far they can go at their most efficient setting.
Second - what gear ratios and prop sizes were used? If they were the
same, the test may be bogus.
Third - how was the boat loaded... lightly or heavily? The more you put
into it, the more I would favor the torquey bigblock.
Forth - how much is "less" fuel?
dsc - acssysdsc
Dudley Cornman
>
> I read the article in BOATING and concluded its findings were fallacious.
> It compared two completely different kinds of engines, a stock big block and a
> racing smaller block. Unlikely a customer is going to choose between those two.
> The story would have been valid if two stock engines were being compared.
Except the results may be different. :)
Just out of curiosity what is the cost of these two engines?
dsc - acssysdsc
Dudley Cornman
> When it comes to stock engines, I'll say that bigger is "usually" better.
> On the other hand, He who has the most horsepower, usually wins.
> If you can get the same HP with less weight, that's a definate plus!
> Especially in a boat.
In a race maybe... but I'd venture that the HO 350 can't match the torquey
BB out of the hole or in heavier/slower boats.
> The High Output 350 and the new Merc 377 Scorpoin motors are somewhat a
> different ball game. Big HP but you need the stroke of a big block for the
> torque.
Exactly...
dsc - acssysdsc
Jerry Hahn
ratio from the SB. They used the same boat AND outdrive. A more true test
would have been to changed the outdrive to match the motor.
Jerry
--
You can lead me to the water, but not away from it.
"Rick" <reng...@home.com> wrote in message
news:8vM15.2410$rB4....@news1.rdc1.ab.home.com...
>
> "Debi L. Billing" <dlbi...@uswest.net> wrote in message
> news:7Jx05.409$oc3....@news.uswest.net...
> > We are considering two different boats, specifications listed below, and
> > would like opinions on which engine would be best. We don't want to be
> > underpowered, but at the same time are looking for the best overall fuel
> > economy at cruising speed.
> > We'll be using the boat mainly on the Mississippi and St. Croix Rivers
> with
> > some limited use on one of the Great Lakes (Lake Superior).
> >
> >
> > Boat #1
> > - Dry weight: 6,200 lbs.
> > - LOA: 26' 0"
> > - Engine: Mercruiser 5.7L EFI Bravo 3
> >
> > Boat #2
> > - Dry weight: 5500 lbs.
> > - LOA: 26' 5"
> > - Engine: Mercruiser 7.4L MPI Bravo 3
> >
> >
> > We've been told by the person with Boat #1 that the 5.7L will get better
> > fuel economy than the 7.4L and we've been told by the person with Boat
#2
> > that the 7.4L will get better fuel economy than the 5.7L.
> >
> > Thoughts?
> >
> > Debi
> >
>
> Is a bigger engine always better?. that is the headline of an article in
the
> June issue of Boating magazine. In a nutshell, no. The tests were
conducted
> on the same boat , in this case a Scorpion 24' sport boat , weight was
4,000
> lbs. The two boats ur looking at are similar in length and weight although
> heavier than the Scorpion. The test engines were Mercury 350 built by Merc
> racing and a stock 454 Mag MPI. The article ends making a comparison with
> stock engines and goes something like this "You have a choice between a
> 300hp Merc 350 Mag MPI and a big block 310 h.p , 7.4 Mag MPi, (a 133 lbd
> difference), chances are good that you'd see a fuel economy advantage with
> the lighter motor without losing much in speed. When it comes to power a
> little less can mean a lot more.".
>
> In the actual test boat there was a WOT difference of 1 mph with a
> significant advantage fuel wise to the 350 engine. At cruising speed of
3500
> rpm the 350 actually was .03 mph faster and burned less fuel.
>
> I realize that the engines your looking at are likely not the 300 h.p 5.7
> model but it was interesting reading.
>
> Rick
>
>
Russ Glindmeier
hol...@flash.net wrote in message <8i8v0u$j20$1...@nnrp1.deja.com>...
I agree that the Horizon model of the 5.7 skews things quite a bit. The
extended maintenance of the Horizon as well as the higher HP over the
standard 5.7 makes it an attractive option. I'm quite surprised that Rinker
offered the Horizon as an option. Good for them. I'm surprised that the
cost of the 350 Horizon was less than the standard 7.4 MPI. Given those
facts, I'm not sure I wouldn't have made the same choice as you.
Russ
Dudley Cornman
>
> If the debate were between the 350 Magnum (300 HP) and the 7.4L MPI
> (310 HP), then I'd take the 350 Magnum, given the lighter weight,
> slightly lower cost, and insignificant power difference.
Correction... insignificant horse power difference... but what is the
torque difference? In some boats, good low to mid range torque is more
important that maximum high speed hp.
dsc - acssysdsc
c_ho...@my-deja.com
out 400ft lbs of torque. That is massive for a small block.Back to the
original post, I think alot of peaple would be quite suprised with the
performance of the 5.7EFI B3 in a 26' boat. Although not a speed demon
it is quite capable. The big thing is cost. On my Rinker there was
almost 3k price difference in these two engines. If those are your only
options and you have the $$$$ go with the 7.4MPI
Rick
"Dudley Cornman" <acss...@acs.eku.edu> wrote in message
news:EoF4Kf...@acs.eku.edu...
the
> > June issue of Boating magazine. In a nutshell, no. The tests were
conducted
> > on the same boat , in this case a Scorpion 24' sport boat , weight was
4,000
> > lbs. The two boats ur looking at are similar in length and weight
although
> > heavier than the Scorpion. The test engines were Mercury 350 built by
Merc
> > racing and a stock 454 Mag MPI. The article ends making a comparison
with
> > stock engines and goes something like this "You have a choice between a
> > 300hp Merc 350 Mag MPI and a big block 310 h.p , 7.4 Mag MPi, (a 133 lbd
> > difference), chances are good that you'd see a fuel economy advantage
with
> > the lighter motor without losing much in speed. When it comes to power a
> > little less can mean a lot more.".
> >
> > In the actual test boat there was a WOT difference of 1 mph with a
> > significant advantage fuel wise to the 350 engine. At cruising speed of
3500
> > rpm the 350 actually was .03 mph faster and burned less fuel.
>
> consumes and how far they can go at their most efficient setting.
>
> Second - what gear ratios and prop sizes were used? If they were the
> same, the test may be bogus.
>
> Third - how was the boat loaded... lightly or heavily? The more you put
> into it, the more I would favor the torquey bigblock.
>
> Forth - how much is "less" fuel?
>
> dsc - acssysdsc
>
>
>
The same hull, same fuel levels, same drive (Bravo one) with gearing of
1.5:1 was used. Propping was different with the 377 running a 14 by 21 and
the BB using a 14 by 23. Horsepower to weight ratio was 2.28 lbs per h.p for
the 377 compared to 2.55 for the BB. At 5000 rpm's the 377 used 6gph less
that the BB. At WOT which was 5000 at 68.1 mph for the BB the range was 123
n.miles . The 377 at WOT which was 5200 at 58.3 mph had a range of 141 nat.
miles.
At a cruising speed of 3500 rpm;s the BB is running 42.9 mph and burning
16.1 gph with the 377 running 43.1 mph at 14.8 gph (faster and more
efficient).
The boats were loaded identical however this Scorpion is a light boat at
3900 lbs.
Also of interest is that the small block was quicker out of the hole.
Anyway to each their own . I appreciate the comments made about the value of
a BB however as far a resale value goes in a 26' trailerable cruiser they
are not in demand in our area however say in the case of a Bayliner 26' by
9'6" beam then I would certainly want the big block.
Rick
Rick
oops the WOT for the 377 should have been 67.1 mph, same range.
Rick
Patrick B.
>out 400ft lbs of torque. That is massive for a small block.Back to the
>original post, I think alot of peaple would be quite suprised with the
>performance of the 5.7EFI B3 in a 26' boat. Although not a speed demon
>it is quite capable. The big thing is cost. On my Rinker there was
>almost 3k price difference in these two engines. If those are your only
>options and you have the $$$$ go with the 7.4MPI
Another thing. The ratio has to do with torque available, and not the
displacement of the motor.
The test was completely fair, due to the fact that it compared engine
to engine, with NO difference in outdrive, ratios, etc.
The only difference was in prop(s) used, as the engines have different
operating ranges. In effect, the different props changed the *ratio*
of the outdrive.
Pat
Patrick B.
>1.5:1 was used. Propping was different with the 377 running a 14 by 21 and
>the BB using a 14 by 23. Horsepower to weight ratio was 2.28 lbs per h.p for
>the 377 compared to 2.55 for the BB. At 5000 rpm's the 377 used 6gph less
>that the BB. At WOT which was 5000 at 68.1 mph for the BB the range was 123
>n.miles . The 377 at WOT which was 5200 at 58.3 mph had a range of 141 nat.
>miles.
You wouldn't want to change ratios on the drives anyway. Mercruiser
really only offers a limited selection of ratios for the Bravo drives
(1.32, 1.50, I may be missing one in between) anyhow.
The other factor to consider, is with the drive ratio the same, it
compared apples to apples. And with the prop change, it effectively
changed the overall ratio anyhow, so this compensated for any
differences that may be perceived. The objective was to get each
engine to run at it's peak potential, given an identical outdrive and
boat.
The test was completely valid in that sense.
Pat
Patrick B.
>> On the other hand, He who has the most horsepower, usually wins.
>> If you can get the same HP with less weight, that's a definate plus!
>> Especially in a boat.
>> different ball game. Big HP but you need the stroke of a big block for the
>> torque.
>>
>
>
>I read the article in BOATING and concluded its findings were fallacious.
>It compared two completely different kinds of engines, a stock big block and a
>racing smaller block. Unlikely a customer is going to choose between those two.
>The story would have been valid if two stock engines were being compared.
Actually, that's not true. Yes, for more *entry-level* consumer
boats, the option does not exist to purchase a motor from Mercury
Racing vs one from Mercruiser.
However, both engines are valid options on several offshore race
boats, such as Ultimate Warlock, Baja, Fountain, Powerquest, Cougar
etc.
The *stock* engine is usually the 454 Magnum, and the upgraded engines
are those from Mercury Racing (377 Scorpion, 500 HP, 500 HP Bulldog
etc).
They are both *stock* engines, and not custom built. Both are
orderable from the Mercury catalog (price on the Scorpion is
outrageous though!).
Pat
Patrick B.
>> On the other hand, He who has the most horsepower, usually wins.
>> If you can get the same HP with less weight, that's a definate plus!
>> Especially in a boat.
>
>BB out of the hole or in heavier/slower boats.
Once again, you have to consider the boat that you're putting the
motor into. The 377 is a stroked 350 (stroke is identical to the 454,
bore is different). Torque output on the 377 is quite good, and
apparently quite flatter than that of the 454. It doesn't have the
peak torque of the BB block though.
>> The High Output 350 and the new Merc 377 Scorpoin motors are somewhat a
>> different ball game. Big HP but you need the stroke of a big block for the
>> torque.
Actually, stroke on the 377 Scorpion and the 454 Magnum are identical.
It's only the bore that is different. Bigger displacement however,
generally means greater torque.
Pat
Patrick B.
>extended maintenance of the Horizon as well as the higher HP over the
>standard 5.7 makes it an attractive option. I'm quite surprised that Rinker
>offered the Horizon as an option. Good for them. I'm surprised that the
>cost of the 350 Horizon was less than the standard 7.4 MPI. Given those
>facts, I'm not sure I wouldn't have made the same choice as you.
That is a more valid test, given the tastes of this NG boating crowd.
For the go-fast fans amongst us, the test in Boating was (and still
is) valid. They tested a boat which had both motors as orderable
options on it, the same as many similar sport boats.
An interesting test would be the same parameters, with the 350 Magnum
vs 7.4L MPI (300 vs 310 HP) as the motors. And to do it in a 26-27'
cabin cruiser. (ala, 270 Rinker, 270 Sea Ray etc). It's a test I'd
be interested in seeing, actually. All things considered though, once
a boat gets to be the 27' ++ size, I tend to prefer twin engines
anyway, be them inboards, I/O's or outboards. Much easier to maneuver
than any single, B-3 or not.
Pat
Dudley Cornman
> Lets remember the Scorpion is a small block but not a 350. It cranks
What are the specifics of that engine... is it a 350 or isn't it?
> out 400ft lbs of torque. That is massive for a small block.Back to the
> original post, I think alot of peaple would be quite suprised with the
> performance of the 5.7EFI B3 in a 26' boat. Although not a speed demon
It sounds like an even better fit... in ours. :)
dsc - acssysdsc
Dudley Cornman
>>Lets remember the Scorpion is a small block but not a 350. It cranks
>>original post, I think alot of peaple would be quite suprised with the
>>performance of the 5.7EFI B3 in a 26' boat. Although not a speed demon
>>almost 3k price difference in these two engines. If those are your only
>>options and you have the $$$$ go with the 7.4MPI
>
> Another thing. The ratio has to do with torque available, and not the
> displacement of the motor.
>
> The test was completely fair, due to the fact that it compared engine
> to engine, with NO difference in outdrive, ratios, etc.
That's horse hockey. It does matter that the outdrive is the appropriate
one and that the ratios are the appropriate ones and that thr prop is an
appropriate one. In this case teh choices seem reasonable.
After looking at the post of what exactly was tested, it appears to be
more fair than I first thought and that small block does appear to be a
real performer. But I'm still not sure about the choice of 3500 rpm for
crusing speed.
> The only difference was in prop(s) used, as the engines have different
> operating ranges. In effect, the different props changed the *ratio*
> of the outdrive.
True...
dsc - acssysdsc
Patrick B.
>> (310 HP), then I'd take the 350 Magnum, given the lighter weight,
>> slightly lower cost, and insignificant power difference.
>
>Correction... insignificant horse power difference... but what is the
>torque difference? In some boats, good low to mid range torque is more
>important that maximum high speed hp.
Actually, another correction though. Torque is actually force, not
power (splitting hairs, I know). The power delta remains
insignificant. And since torque can be multiplied (outdrive ratios,
prop selection), this *could* negate the differences in torque between
the two motors. Whatever difference in torque exists is unlikely to
be noticeable by the pilot of the boat.
However, given a boat which feels *sluggish* with the 350 Magnum, it's
likely to feel sluggish with the 7.4L MPI as well; the specs are that
close.
However, I'd suspect the BB to have greater durability under those
circumstances simply due to being a motor that is farther from it's
limit of tolerances than the small block.
The small block is likely near it's limit of solid, reliable HP in the
350 Magnum model, whereas the 454 MPI is merely starting out, and can
reliably hit as much as 415 HP (502 Magnum) without difficulty.
Pat
Dudley Cornman
>
> However, given a boat which feels *sluggish* with the 350 Magnum, it's
> likely to feel sluggish with the 7.4L MPI as well; the specs are that
> close.
I didn't realize that. Do marine big block engines not develope their
torque at much lower rpms than marine small blocks... as in the truck
engines?
> However, I'd suspect the BB to have greater durability under those
> circumstances simply due to being a motor that is farther from it's
> limit of tolerances than the small block.
Yea...
dsc - acssysdsc
Patrick B.
>
It's a 350 block, with a different crank. Two things determine the
displacement of the engine; bore, and stroke. The bore of the
Scorpion 377 is identical to the bore of the 350. The stroke is
longer however, by using a different crank. Therefore, more
displacement. It's the same block, just different internals.
>> out 400ft lbs of torque. That is massive for a small block.Back to the
>> original post, I think alot of peaple would be quite suprised with the
>> performance of the 5.7EFI B3 in a 26' boat. Although not a speed demon
>
>It sounds like an even better fit... in ours. :)
It's from Mercury racing though, and not Mercruiser. It's big
dollars; in fact, it's more expensive than the 454 Magnum. It's not
likely something the average boater would have the opportunity to use,
though the Hi-Perf boater is quite likely to.
Pat
Patrick B.
>> displacement of the motor.
>>
>> The test was completely fair, due to the fact that it compared engine
>> to engine, with NO difference in outdrive, ratios, etc.
>
>That's horse hockey. It does matter that the outdrive is the appropriate
>one and that the ratios are the appropriate ones and that thr prop is an
>appropriate one. In this case teh choices seem reasonable.
The outdrives for the two engines are identical, and the primary ratio
for both engines on the B-1 drive is 1.5:1. That's standard, and
wouldn't have varied in a stock configuration for either engine.
Under twin engine applications it's likely one might see the 1.36:1
ratio, or in high altitude, the 1.65:1 ratio. But those are the only
three ratios offered factory for the Bravo-1 drive, and two of them
are for specific applications. 1.5:1 is the standard, and as I said
before, changing the propeller changes the effective ratio anyway.
Which is why they used two different propellers for the motors.
Pat
>After looking at the post of what exactly was tested, it appears to be
>more fair than I first thought and that small block does appear to be a
>real performer. But I'm still not sure about the choice of 3500 rpm for
>crusing speed.
3500 RPM is pretty standard (70% of WOT, 5000 RPM). My boat cruises
beautifully all day at 3500 RPM, and minimal wear and tear on the
engine under those circumstances.
c_ho...@my-deja.com
options.5.7L 250php,5.7L EFI 260 php,350magMPI 300php,7.4LMPI 310 php
or 454magMPI 385 php.With most of the cruisers not offering the 454mag.
I pretty much would rule out th 5 litre offering on anything above
20ft.All of these engines perform very well when mated to the B3.I like
the 350 mag the best, It gives you a little of everything with a little
bit of thriftyness thrown in.
Rick
> In article <394c64e8....@news1.on.sympatico.ca>,
no....@leave.me.alone (Patrick B.) writes:
> >>Lets remember the Scorpion is a small block but not a 350. It cranks
> >>original post, I think alot of peaple would be quite suprised with the
> >>performance of the 5.7EFI B3 in a 26' boat. Although not a speed demon
> >>almost 3k price difference in these two engines. If those are your only
> >>options and you have the $$$$ go with the 7.4MPI
> >
> > displacement of the motor.
> >
> > The test was completely fair, due to the fact that it compared engine
> > to engine, with NO difference in outdrive, ratios, etc.
>
> That's horse hockey. It does matter that the outdrive is the appropriate
> one and that the ratios are the appropriate ones and that thr prop is an
> appropriate one. In this case teh choices seem reasonable.
>
> more fair than I first thought and that small block does appear to be a
> real performer. But I'm still not sure about the choice of 3500 rpm for
> crusing speed.
>
> > operating ranges. In effect, the different props changed the *ratio*
> > of the outdrive.
>
> True...
>
> dsc - acssysdsc
>
Actually I used the articles cruising reference point. Other figures are,
2500 rpm , BB 29.7 mph at 9.1 gph, the 377 27.9 mph at 8.4 gph. At 3000 rpm
the BB was 35.6 mph at 11.7 gph and the 377 was 34.5 mph at 11.5 gph.
Rick
Rick
> In article <8i9kek$2dd$1...@nnrp1.deja.com>, c_ho...@my-deja.com writes:
> > Lets remember the Scorpion is a small block but not a 350. It cranks
>
>
> > original post, I think alot of peaple would be quite suprised with the
> > performance of the 5.7EFI B3 in a 26' boat. Although not a speed demon
>
>
>
>
Just because you asked, :-).
The 377 is 350 ci GM block with a bore of 4.0" with a stoke of 3.75" which
generates an additional 27 cubic inches. Compression ratio is 9.o:1. It has
a Lunati forged steel crankshaft, Federal Mogul hypereutectic pistons on GM
hot forged connecting rods, a Crane hydraulic roller cam with Crane Gold
roller rocker arms, and a Manley stainless steel intake and exhaust vales.
Fuel is a multiport electronic injection system and all those goodies will
cost you a cool $4,900.00 more than the stock 454. They had hand assembled
and oh yeah, there is no extended warranty available :-)
Rick
Russ Glindmeier
Rick wrote in message ...
>
>The 377 is 350 ci GM block with a bore of 4.0" with a stoke of 3.75" which
>generates an additional 27 cubic inches. Compression ratio is 9.o:1. It has
>a Lunati forged steel crankshaft, Federal Mogul hypereutectic pistons on GM
>hot forged connecting rods, a Crane hydraulic roller cam with Crane Gold
>roller rocker arms, and a Manley stainless steel intake and exhaust vales.
>Fuel is a multiport electronic injection system and all those goodies will
>cost you a cool $4,900.00 more than the stock 454. They had hand assembled
>and oh yeah, there is no extended warranty available :-)
>
>Rick
>
>
Sweet, but I'm afraid a little too rich for me. I'd only throw major engine
upgrade dough at modern high-tech diesels. Longer amortization, less
depreciation.
Russ
H82LUZ1
>important that maximum high speed hp.
Considering we are talking about a somewhat heavy cruiser here, I think you
just hit it right on the head. In a heavy single engine boat, torque is more
valuable than high rpm horsepower. In a larger boat, the extra torque of a
big block will usually overcome the extra weight of the motor. In this case,
we are dealing with a 377 Scorpion that puts out a butt load of torque for a
small block.
Mike G.
Rick
"Russ Glindmeier" <ru...@att.net> wrote in message
news:pZh25.4060$Xx5.2...@bgtnsc06-news.ops.worldnet.att.net...
>
> >
>
> Sweet, but I'm afraid a little too rich for me. I'd only throw major
engine
> upgrade dough at modern high-tech diesels. Longer amortization, less
> depreciation.
>
> Russ
>
Likely too much for most of us Russ . We kinda got off track (what else is
new ) from the original post however the writer of the article is of the
opinion that similar comparasions between smalll and big block engines can
be made in other than hand assembled racing engines however they do qualify
that statement by saying "if your looking at a 24' or less size cruiser".
Rick
Patrick B.
>options.5.7L 250php,5.7L EFI 260 php,350magMPI 300php,7.4LMPI 310 php
>or 454magMPI 385 php.With most of the cruisers not offering the 454mag.
>I pretty much would rule out th 5 litre offering on anything above
>20ft.All of these engines perform very well when mated to the B3.I like
>the 350 mag the best, It gives you a little of everything with a little
>bit of thriftyness thrown in.
As I've said earlier, the 377 Scorpion is Mercury Racing motor, not
Mercruiser, and as such, is not readily sold to manufacturers who are
not building serious sport boats.
It is nonetheless, a catalog available engine for anyone to purchase,
if they wish to. It is also a factory orderable item from numerous
boat manufacturer's in the sport boat market.
However, for the *typical* rec.boats boater (is there such a thing?),
it's not likely to be available. I'm not going to hold my breath
waiting for Bayliner or Sea Ray to make one available in any of their
small runabouts anytime soon, primarily for cost.
My favorite engine from Mercruiser is still the 350 Magnum (I'm
biased, I have two of them!). Small block, plenty of power,
especially in a twin I/O arrangement, and very cost effective both
from initial purchase and for fuel consumption.
My boat is really not designed for twin big blocks in the engine bay,
and to put twin 454's in there would significantly alter the handling
characteristics of my boat, not to mention a possible compromise in
safety. The 350 Magnums allow me to maintain factory configuration,
with maximum power available and no handling / safety penalties.
It's a great engine.
Pat
saco...@my-deja.com
cannot find any info on the net as far as where it is manufactured. I
need some specific parts to repair mine. I'd rather buy than build.
Thank you for any info.