Mercruiser 4.3L vs 5.7L
islander
I'm looking for a new 20' runabout and it seems my choices (I/O) are a
4.3L V6 and a 5.7L V8. Is the bigger motor worth it? HP wise the
difference is not that big but I'm sure it is not that simple. Any info
would be greatly appreciated.
Thanks,
Sandro Grima.
klkevin
On a boat, what counts is torque. The bigger displacement engine produces
much more torque.
On another note, I understand they have some problems keeping those 4.3 v6's
lined up. Something about them putting a lot of pressure on the motor mounts.
The 5.7's have no alignment problems.
--
Kevin Loseke
klk...@sky.net
Robert Allen
klkevin wrote:
>
> islander wrote:
> >
> > I'm looking for a new 20' runabout and it seems my choices (I/O) are a
> > 4.3L V6 and a 5.7L V8.
>
> On a boat, what counts is torque. The bigger displacement engine produces
> much more torque.
Or, what matters on a runabout is weight. And the 5.7L will be about 500 pounds more than the 4.3L.
That's like 2 fat guys sitting in the jump seats all the time. Also, I have never been all that
impressed with the low-end torque from the small block. Out of the hole they can drag a skier for
quite a while in a heavy bowrider. Get the 4.3L and a good prop for the hole shot.
Bob Allen, Kansas City.
Chuck Jackson
islander wrote:
>
> I'm looking for a new 20' runabout and it seems my choices (I/O) are a
> difference is not that big but I'm sure it is not that simple. Any info
> would be greatly appreciated.
>
> Thanks,
> Sandro Grima.
Sandro,
If you're looking at a Sea Ray, then by all means go with the 5.7. The
Sea Ray is a heavy boat. The main reason for going with 5.7 in any boat
is that the acceleration and top speed will not be affected as much when
loaded or pulling a skier.
Steve McAlister
I opted for the 4.3 on my 19. Weight of the engine was a consideration plus
fuel econmy of the 4.3 was a biggie. I would compare the wt of the boat with
the 4.3 with the wt of the boat with the 5.7, 5.7 is a lot of engine and
drinks a lot of gas, but is the 4.3 man enough to move the boat you are
considering?
4.3 is a great engine with lots of torque!
cusdn
The 5.7 will not labor under extreme loading. The V8 will give great
fuel mileage if the revs are under 2800rpm. The boat will accelerate
better and the resale will be higher. Get freshwater cooling if
the engine is used in salt water it will not suffer and the resale
will also be higher and the engine will last a long time.
Bryon Kass
webmaster and
Custom Design in
THE ENGINE ROOM http://www.ici.net/customers/cusdn
Arranger1
The 5.7 is also a much smoother more balanced engine, and I think it is
quieter too!
CECHSTR
GET THE 350, IT WEIGHS ABOUT 150 LBS MORE AND WILL GIVE YOU MORE TORQUE
OUT OF THE HOLE. FUEL ECON WILL NOT BE AS GOOD AS THE 4.3, BUT YOU NEVER
HAVE ENOUGH POWER IF YOU ARE GOING TO USE THE BOAT FOR SKING. RESALE WILL
BE BETTER WITH THE 350 TOO.
Chuck Jackson
>
> Or, what matters on a runabout is weight. And the 5.7L will be about 500 pounds more than the 4.3L.
> That's like 2 fat guys sitting in the jump seats all the time. Also, I have never been all that
> impressed with the low-end torque from the small block. Out of the hole they can drag a skier for
> quite a while in a heavy bowrider. Get the 4.3L and a good prop for the hole shot.
>
> Bob Allen, Kansas City.
...On what planet?????...Not a 5.7 Mercruiser, but a complete Dodge 360 (this happens to be the only engine
I have the weight for) for automotive applications only weighs 540 lbs. So the 4.3L weighs what?....zero?
Actually, the 4.3L is a 90 degree V6....2 cylinders short of a 5.7. I don't have the specs but I would guess
that the 5.7L weighs about 100-150 lbs more than a 4.6L. That's like one skinny guy sitting in the jump seat
all the time....but with a 5.7L you won't know he's there!
Joe Kao
For a 20' boat the 4.3l or LX would be just right.
The 350 (5.7) is a great motor, but it is alittle heavy sitting
in the back of a 20'.
A 20' sky boat can handle the weight better since the placement
is centered (Inboard)
Enjoy!
The Great Granny
Steve McAlister wrote:
: I opted for the 4.3 on my 19. Weight of the engine was a consideration plus
I opted for the 7.4L on my 22. Weight of the engine was a considerable
gain, plus the fuel economy of the 7.4L was a biggie (consumption that is).
Get real people! It's a Boat!!! If I wanted fuel economy when I
purchased my most recent internal combustion engine, I would have bought a
GEO. People buy boats to have fun (last time I checked). Nothing is
worse than realizing your brand new boat is underpowered. Also, is gas
mileage REALLY that big of a concern? The difference between the 4.3 and
5.7 would be irrelevant in terms of weight and economy (or lack of...).
Yeah, I'm sure the 4.3 would suit the boat fine, but then why not just get
that much more of a good thing.
Go 350!
I've never heard of a fellow boater complaining about having "too much" power.
------------------------------------------------------------------------
Andrew G. Bayley
agba...@mtu.edu
Michigan Technological University; Electrical Engineering
TRW VSSI Competitive Analysis - Inflatable Restraints
1969 Yamaha AT1-M 175cc (ready to donate to Smithsonian)
1977 Datsun 280Z28
1983 Ford Ranger 2.3L Turbo (soon)
1985 Toyota 4WD SR5 Wagon 1.45L 24.6 @ 64 mph
------------------------------------------------------------------------
1329C1000-Garry Heon(MT4084)NOBIN
In article <4tlihg$8...@techsrv1.tech>,
The Great Granny <agba...@mtu.edu> wrote:
>I opted for the 7.4L on my 22. Weight of the engine was a considerable
>gain, plus the fuel economy of the 7.4L was a biggie (consumption that is).
>Get real people! It's a Boat!!! If I wanted fuel economy when I
>purchased my most recent internal combustion engine, I would have bought a
>GEO. People buy boats to have fun (last time I checked). Nothing is
>worse than realizing your brand new boat is underpowered. Also, is gas
>mileage REALLY that big of a concern? The difference between the 4.3 and
>5.7 would be irrelevant in terms of weight and economy (or lack of...).
>Yeah, I'm sure the 4.3 would suit the boat fine, but then why not just get
>that much more of a good thing.
>Go 350!
>I've never heard of a fellow boater complaining about having "too much" power.
>
>------------------------------------------------------------------------
>Andrew G. Bayley
Very well said. I'm glad there are a few out there that have the same
point of view I do. Another concern I'd have with the 5.7 vs 4.3 is
the 350 is an easy engine to find performance parts, should you want a
little extra power in the future. As Andrew said, I too have never heard
a complaint about too much power, I have heard lots of complaints about
not having enough power. Right now I'm one of those complaining.
Garry Heon
First Stepp
ga...@holly.mt.lucent.com
My Opinions....Lucent's Network.
acss...@acs.eku.edu
In article <4tktg4$ool$1...@mhade.production.compuserve.com>, Joe Kao <73501...@CompuServe.COM> writes:
> For a 20' boat the 4.3l or LX would be just right.
The 4.3s are great engines and work well up to about 20-21' boats as
long as the boats are light and designed to plane with less than optimal
power. BUT, my personal preference for anything over about 18' is a 350
with at least 260 crank shaft hp.
>
> The 350 (5.7) is a great motor, but it is alittle heavy sitting
> in the back of a 20'.
I don't agree. It sits very well in the rear of my 19.5' Baja... not a
problem. I think a 350 in the 260 crank shaft hp or more range is the
best all around choice for most 19-21 foot boats. There are exceptions
like the Baja 208 that beg for big blocks though.
> A 20' sky boat can handle the weight better since the placement
> is centered (Inboard)
On the other hand a "recreational inboard" may not need the extra horses
of the V8 as planing is much easier in an inboard.
Dudley Cornman
Systems Programmer
Academic Computing Services - EKU
ACSS...@ACS.EKU.EDU
********************************************************************
*** When it comes to boats... ***
*** I'd rather have a new boat than a used boat... ***
*** I'd rather have a Baja than a Bayliner... ***
*** I'd rather have a used Bayliner than no boat at all... ***
********************************************************************
Steve Coates
acss...@acs.eku.edu wrote:
: In article <4tktg4$ool$1...@mhade.production.compuserve.com>, Joe Kao <73501...@CompuServe.COM> writes:
: > For a 20' boat the 4.3l or LX would be just right.
: The 4.3s are great engines and work well up to about 20-21' boats as
: long as the boats are light and designed to plane with less than optimal
: power. BUT, my personal preference for anything over about 18' is a 350
: with at least 260 crank shaft hp.
: >
: > The 350 (5.7) is a great motor, but it is alittle heavy sitting
: > in the back of a 20'.
: I don't agree. It sits very well in the rear of my 19.5' Baja... not a
: problem. I think a 350 in the 260 crank shaft hp or more range is the
: best all around choice for most 19-21 foot boats. There are exceptions
: like the Baja 208 that beg for big blocks though.
Well I agree that the 350 would be the best choice, but I have a Baja 208
with the 5.7LX (250 PHP) and while a big block would be nice I figure that
55-58 mph is not bad with a small block 8-)
ONe thing I have always been told is, when buying a boat always get the
largest motor yoou can afford. The 350 does not seem to use much more gas
than the 4.3 (as long as I stay out of the secondarys (sp?)).
Steve
Joe Kao
It's not as simple as "more power, more fun". The way boat
manufactors measure boats today (20'today was a 17')which
includes swim platform and pulpit. The weight distribution for
hull area may make the boat totally ass heavy. It all depends on
the manufactor.
Best advice, find people with that exact boat and talk to them,
but poll a few people, human nature what it is, they usually give
stats with the boat running in a vacuum.
Check-out the new 4.3l block from Mercruiser, looks like some
nice improvements
Good Luck
Dan
73501...@compuserve.com