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V8 Motor Options and Questions

  • Thread starter Thread starter Geewest
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Geewest

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Hoping TB or other informed members could shed some light on the various Motor Options Bennington offers. Wanted to know the Pros' of each of the Motor Options.

Do you have any Speed or GPH for the Various V8 Motors

#1 MerCruiser 350 MAGC MPI - 300HP (Catalyzed)350MAGCB1DS $75,007

#2 MerCruiser 350 MAGC MPI Bravo 3 - 300HP (Catalyzed) 350MAGCB3DS $76,406

#3 MerCruiser 350 MAGC MPI DTS Bravo 1 - 300HP (Catalyzed)350MAGCB1DTSDS $76,111

#4 MerCruiser 350 MAGC MPI DTS Bravo 3 - 300HP (Catalyzed) 350MAGCB3DTSDS $77,510

#5 MerCruiser 377 MAGC MPI Bravo 3 - 320 HP (Catalyzed) 377MAGCB3DS $79,947

#6 MerCruiser 5.0L MPIC - 260HP (Catalyzed) 50MPICB1DS $72,903

#7 MerCruiser 8.2 MAG HOC Bravo 3 - 425HP 82MAGHOCB3DS $0

#8 Volvo 5.0 GXiC - 270 HP (Catalyzed) 50GXiCDS $70,865

#8 Volvo 5.7 GiC - 300 HP (Catalyzed) 57GiCDS $72,533

#9 Volvo 5.7 GXiC - 320 HP (Catalyzed) 57GXiCDS $75,364

#10 Volvo 8.1 GiC DP - 400 HP 81GiCDPDS $0
 
Everything is about to say is only MOSTLY true. I have indulged in a little oversimplification because the answers you seek don't really require us to get into the weeds, or for you to suffer through a 30+ year regurgitation of my hot-rodding past.

___________________________________________________________________________

ALL of these engines are General Motors "Tall Blocks" wrapped in a Marine engine support system that enables them to be installed in boats.

This is a 5.0 Liter (305 cubic inch) Chevrolet small block:

  • MerCruiser 5.0L MPIC - 260HP (Catalyzed) 50MPICB1DS $72,903
  • Volvo 5.0 GXiC - 270 HP (Catalyzed) 50GXiCDS $70,865

These are 5.7 Liter (350 cubic inch) Chevrolet small blocks:

  • MerCruiser 350 MAGC MPI - 300HP (Catalyzed)350MAGCB1DS $75,007
  • MerCruiser 350 MAGC MPI Bravo 3 - 300HP (Catalyzed) 350MAGCB3DS $76,406
  • MerCruiser 350 MAGC MPI DTS Bravo 1 - 300HP (Catalyzed)350MAGCB1DTSDS $76,111
  • MerCruiser 350 MAGC MPI DTS Bravo 3 - 300HP (Catalyzed) 350MAGCB3DTSDS $77,510
  • Volvo 5.7 GiC - 300 HP (Catalyzed) 57GiCDS $72,533
  • Volvo 5.7 GXiC - 320 HP (Catalyzed) 57GXiCDS $75,364

This is a 6.2 Liter Chevrolet small block:

  • MerCruiser 377 MAGC MPI Bravo 3 - 320 HP (Catalyzed) 377MAGCB3DS $79,947

These are, respectively; 496 & 502 Big Block Chevrolet big blocks:

  • Volvo 8.1 GiC DP - 400 HP 81GiCDPDS $0
  • MerCruiser 8.2 MAG HOC Bravo 3 - 425HP 82MAGHOCB3DS $0

All of these engines are modern versions of the classics. I won't bore you with a lot of details, but at the very least you can expect the engines to have forged pistons, Powdered metal rods and probably forged crankshafts. The small blocks have the Vortech heads and in fact, I think they're all considered Vortech engines now, but even with GM these things get complex.

At the risk of oversimplifying, the 305 engine is a small bore version of the 350 and the 377 is a long stroke version of the 350. If you hear about a 383, that's a 377 with an .030 overbore.

The 8.1(496) big block is a somewhat more modern version of the big block series than the 8.2(502) but the differences are a bit on the esoteric side.

The reliable power limit for the 350's is around 500hp. It's a bit less for the 305's and a bit more for the 377. All things being equal the 377 will be the better "grunt" engine because its longer stroke makes more torque and it's longer rod means more dwell time at TDC for the fuel to burn.

The big blocks are too similar to worry about differences and can both safely produce 650-700 hp and still have a long engine life.

Obviously, they don't make that much power out of the gate.

If you want to add aftermarket forced induction, you need to buy a mercury engine. If you don't care about doing that then either Mercury or Volvo will do fine. I should point out that this has nothing to do with the relative strength of the engine, its simply a case of what is AVAILABLE in the aftermarket. If you want to spend the money you can supercharge a Volvo just like you can a Mercury. It'll just cost a lot more because you'll be buying custom work, not "off the shelf" parts.

My personal opinion? The best overall engine is the 377.

If you want the fastest boat on the lake either from the factory or after you modify it, just buy a big block and be done with it. There's no point in pretending fuel consumption is even an issue if you're after power and speed.

If you want fuel economy, the seemingly obvious choice would be the 305's. However, you'd probably be better off with a 350. You just done pick up enough economy by giving away those 45 cubic inches to justify the loss in power. In fact, you may find your economy to be WORSE. It depends how you use your boat.

ANY of those engines would be a good, reliable power plant. Make your selection based on which drive unit you want and what you can get a good deal on.

One thing...

Any upgraded fuel and oil filtering options you can buy are a good idea. For ANY engine.
 
Engines are air pumps. The bigger, the better. The 8.1 will pump a BUNCH more air than the 5.0.

One can't really discuss this topic based only on horsepower, displacement and brand. There are a bunch of variables of gear ratios, props, altitude, fuel quality/octane, hull design and many others.

I suggest you ride on others' boats until you find the one for which you like the performance best. Buy one just like it. To experiment for yourself is expensive and usually not very satisfying in the long run.

ericscher said:
Everything is about to say is only MOSTLY true. I have indulged in a little oversimplification because the answers you seek don't really require us to get into the weeds, or for you to suffer through a 30+ year regurgitation of my hot-rodding past.

___________________________________________________________________________

ALL of these engines are General Motors "Tall Blocks" wrapped in a Marine engine support system that enables them to be installed in boats.

This is a 5.0 Liter (305 cubic inch) Chevrolet small block:

  • MerCruiser 5.0L MPIC - 260HP (Catalyzed) 50MPICB1DS $72,903
  • Volvo 5.0 GXiC - 270 HP (Catalyzed) 50GXiCDS $70,865

These are 5.7 Liter (350 cubic inch) Chevrolet small blocks:

  • MerCruiser 350 MAGC MPI - 300HP (Catalyzed)350MAGCB1DS $75,007
  • MerCruiser 350 MAGC MPI Bravo 3 - 300HP (Catalyzed) 350MAGCB3DS $76,406
  • MerCruiser 350 MAGC MPI DTS Bravo 1 - 300HP (Catalyzed)350MAGCB1DTSDS $76,111
  • MerCruiser 350 MAGC MPI DTS Bravo 3 - 300HP (Catalyzed) 350MAGCB3DTSDS $77,510
  • Volvo 5.7 GiC - 300 HP (Catalyzed) 57GiCDS $72,533
  • Volvo 5.7 GXiC - 320 HP (Catalyzed) 57GXiCDS $75,364

This is a 6.2 Liter Chevrolet small block:

  • MerCruiser 377 MAGC MPI Bravo 3 - 320 HP (Catalyzed) 377MAGCB3DS $79,947

These are, respectively; 496 & 502 Big Block Chevrolet big blocks:

  • Volvo 8.1 GiC DP - 400 HP 81GiCDPDS $0
  • MerCruiser 8.2 MAG HOC Bravo 3 - 425HP 82MAGHOCB3DS $0

All of these engines are modern versions of the classics. I won't bore you with a lot of details, but at the very least you can expect the engines to have forged pistons, Powdered metal rods and probably forged crankshafts. The small blocks have the Vortech heads and in fact, I think they're all considered Vortech engines now, but even with GM these things get complex.

At the risk of oversimplifying, the 305 engine is a small bore version of the 350 and the 377 is a long stroke version of the 350. If you hear about a 383, that's a 377 with an .030 overbore.

The 8.1(496) big block is a somewhat more modern version of the big block series than the 8.2(502) but the differences are a bit on the esoteric side.

The reliable power limit for the 350's is around 500hp. It's a bit less for the 305's and a bit more for the 377. All things being equal the 377 will be the better "grunt" engine because its longer stroke makes more torque and it's longer rod means more dwell time at TDC for the fuel to burn.

The big blocks are too similar to worry about differences and can both safely produce 650-700 hp and still have a long engine life.

Obviously, they don't make that much power out of the gate.

If you want to add aftermarket forced induction, you need to buy a mercury engine. If you don't care about doing that then either Mercury or Volvo will do fine. I should point out that this has nothing to do with the relative strength of the engine, its simply a case of what is AVAILABLE in the aftermarket. If you want to spend the money you can supercharge a Volvo just like you can a Mercury. It'll just cost a lot more because you'll be buying custom work, not "off the shelf" parts.

My personal opinion? The best overall engine is the 377.

If you want the fastest boat on the lake either from the factory or after you modify it, just buy a big block and be done with it. There's no point in pretending fuel consumption is even an issue if you're after power and speed.

If you want fuel economy, the seemingly obvious choice would be the 305's. However, you'd probably be better off with a 350. You just done pick up enough economy by giving away those 45 cubic inches to justify the loss in power. In fact, you may find your economy to be WORSE. It depends how you use your boat.

ANY of those engines would be a good, reliable power plant. Make your selection based on which drive unit you want and what you can get a good deal on.

One thing...

Any upgraded fuel and oil filtering options you can buy are a good idea. For ANY engine.
Click to expand...
 
Eric: Thanks for taking the time to reply and break it down.

The Bravo 3 is what Im looking at set up with the 350. I was just wondering if there was More top speed with the 377 Vs the 350.

It would be very intresting to see the #s of what each motor cost's Vs top speed. Or 0mph to On plane ect.
 
For the low price of $5,500 retail you could put one of these on it. I wonder how much it would help a pontoon.

Eric, tell me this is a bad idea so I don't waste my money. :P

gallery_82_73_883997.jpg
 
Gee -

If you want max speed, just go big. I would choose the 502.

On the 350 vs the 377, the 377 will have more grunt. Not just from the 27 extra cubes but also from the longer stroke and connecting rods. That generally means that all things being equal, you can swing a bigger prop. (either diameter or pitch)

Ultimately of course, the choice is yours and it will likely come down to multiple variables for you.

Butch -

I could tell you its a bad idea, just not with a straight face.
 
Butchkid I have already been in touch with procharger on this.They do not make a kit that fits my 2007 small block chevy..he said he has a kit for up to a 2005 Mercruiser..So i am drawing straws as wheather to buy the 6.2 and just swap out the 5.0 or to buy the procharger for the older model and make it fit..Procharger told me the difference is in the fuel and water routing.i would kind of like to keep the 5.0 for the fuel economy but add 100 more horsepower for the thrill on topend....
 
Eric: Do you know if these engines are based on the old 350 cubic inch Chevy's, and are any of Mercruiser's engines the "new generation" LS series motors?

In the auto world, it seems like most builders now prefer the LS series motors. It's hard to believe that the LS series motors have been out for 14 years.

I wonder if the Mercruiser motors are CAN/BUS equipped engines--like every auto/truck car produced since 2008? They are some of the premier engine builders anywhere, and somewhat underrated in the engine department. GM has never attempted to make engines with the cubic inches, horsepower, and general durability at high rpms as Mercury.
 
Bama -

As far as I know they are still using the Vortech engines, which you probably also know as the Center-Bolt engines. That is, they have center bolts in the valve covers instead of the perimeter bolts as on the older SBC's. They also have all the upgrades to the original.

That would have been the most current development prior to the introduction of the LS engines but AFTER the Gen II "LT" engines like the ones they put in B-Bodies in the mid 90's.
 
I'm about to place my order for a 2012 2575RCW and have a related question... I've narrowed down my engine choice to:

MerCruiser 350 MAGC MPI Bravo 3 - 300HP 350MAGCB3DS $75,728

OR

MerCruiser 350 MAGC MPI DTS Bravo 3 - 300HP 350MAGCB1DTSDS $76,832

Does anyone have experience with the DTS MercCrusier? I have a 2008 RCW 2575 today that I'm planning to trade in on the new boat and I've had some challenges with the throttle cables/controls constantly needing adjustment. The thought of a digital controlled throttle sounds appealing to me but I'm not a mechanical guy and worry if it's actually more trouble than it's worth! All comments and opinions welcome.

Thanks!
 
The Mercury I/O will probably be electronic throttle control, no cable...Good system. Beyond that, what about a 300 or 350 Yamaha. Bet either one runs faster. You can add "Air" to the 350, void the warrantee, etc., etc. and still be out run, IMHO.
 
Outboards generally outrun inboards, in large part due to weight.

However, I don't see a blown 350 merc with 500 HP getting outrun by a 350 Yam on otherwise identical boats.
 
The typical 350 I/O requires tech maintainance, add performance and it needs more. Fresh out of the box, you can argue for the blown I/O....However, without that tuning maint. it won't be long before.....there goes the outboard. Then, when the outboard brakes, Yamaha's 5-6 year warrantee will be nice. Or, throw a new one on for $20,000.00 or less. Good luck matching that with your blown I/O.

Our blown engines have a max. life of 200 hours...$30,000.00 to go through one, if nothing is hurt. Granted they make 1,100 HP. However, any well kept, blown marine I/O is not fun to just jump in and go for a Sunday romp. After everthing is checked, warmed up, then power can be gently fed in. Conversely, the Outboard will handle more abuse. Just my humble opinion.
 
Well, everything needs maintenance. And yes, adding a blower adds stress. No argument there.

But I'm not talking about 1,000+ hp engines here... I'm talking about about starting with a 350hp engine and adding 33% more power with less than 1 Atmosphere of boost.

It seems to me that we're talking about two different kinds of blown engines here. I'M talking about a what is basically a solid, reliable chevy small block with a small belt driven supercharger and a very conservative power boost.

YOU'RE talking race motors.

I certainly agree with what you said about them. As a former drag racer I know what you're getting into when you run out on the ragged edge. But we're in apples/oranges territory here.

Truthfully, I'd have to give the outboard the nod for reliability and ease of maintenance, but you can't really modify them. Not as any sort of a practical matter.

It's also worth mentioning that when you go I/O you get your entire rear deck back.
 
The point we agree on is, Outboard simplicity.... The blown small block and blown big block are similar, if not comparable. They are both air pumps, only one is heavier and pumps more air. Granted, the small block is capable of more RPM, Subject to being set up to Nascar Spec. However, the subject engine is rev-limited, because it doesn't have the high RPM internals. Any boost added comes at a price, starting with Mercury approving the modification for warrantee purposes. Mercury is known for selling Horsepower, and if they don't get their profit margin from the added boost, they may be reluctant to make that approval.

The bravo drive has a "Good" reputation and should handle more than 300 HP. There again, any increase may effect warrantee, service intervals, props and life expectancy.

Then Bennington may question a 300/500= 60 % power increase ???

Summary: I opt for 350 Yamaha, accessable to easy service, prop shaft Ht. adjustable, durable, simple and it works. Earlier, I mention 5-6 MPH left to be had. The only reason that hasn't been done is the hull may not "like it". I "feel" we are pushing the envelope now. The present speed is above most lake boats and with some degree of operator skill, "SAFE". To say nothing of residual value.

It would be interesting to hear your argument for the I/O.
 
CcanDo said:
Summary: I opt for 350 Yamaha, accessable to easy service, prop shaft Ht. adjustable, durable, simple and it works. Earlier, I mention 5-6 MPH left to be had. The only reason that hasn't been done is the hull may not "like it". I "feel" we are pushing the envelope now. The present speed is above most lake boats and with some degree of operator skill, "SAFE". To say nothing of residual value.

It would be interesting to hear your argument for the I/O.
Click to expand...
You stated "I mention 5-6 MPH left to be had", but unless I missed something, I don't see where you listed the top speed numbers for your 350 Yami??? What speeds are you attaining with the 350 and on which Bennington platform is it mounted?? My dealer mounted a Yami F350 on a 2011 25 QXi. It ran 54mph right out of the box. I thought it was a decent speed for a 800 lb. outboard. I have yet to see a "stock" 350 I/O put up those numbers. The outboard gets my vote here.

Now for comparison, a friend has a 25 footer (3 Std. tubes) with a 383 blower motor that runs 66 mph. Stone reliable motor. The Alpha drive(s) didn't last long though LOL! He now has a Bravo on it.

I have to wonder.....with its ~300 lbs lighter weight, if the 4.2L 300hp (F300) would run close the speeds of the F350. Personally, I don't like a stern heavy pontoon. I don't care for the ride attitude while idling along or at cruising speeds. I've played with jackplates on my Benny and didn't like the overall results because of the aforementioned. Sure it's gonna handle better (turning wise) and go faster @ WOT with the weight farther back on the stern, but I certainly don't enjoy cruising around a 25mph feeling like I'm driving on an incline. I'll take the lighter outboard and nice flat driving attitude any day. If I wanted a faster, better handling pontoon......I'd own a (cough cough) Manitou SHP (almost vomited on that one). But.....I prefer quality. I'll stick with my Benny.
 
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Appreciate all your viewpoints. While I will never have the ability [or desire] to be an expert on mechanical issues always a pleasure to learn a little. Thanks for all your posts
 
CcanDo said:
I just found this forum...The Bennington we have is test boat used/listed/pictured under the Yamaha 350 performance specs on the Yamaha web-site. The boat was originaly purchased w/a 250 and traded up for the 350. The salesman claimed 50 mph plus with the 250, "no way". The 350 sees 56 plus, GPS....There is probably another 5-6 MPH to be had. One noteable found: the center tube developed a "Hook". The problem has been solved, but that hook did scrub speed, deter ride and effect handling. The boat rides on a Road Runner trailer, I designed. Several features were designed in, such as loading assist, CG location, brakes, coupler, frame, tie downs, steps and etc.This is our first Pontoon...The pontoon was added to a couple other boat toys. We have a 28' Skater w/2 ea. 300 X, Mercury and a pristine 35 Motion. The Skater will run 120, the Motion will run over 150. Some of you may have seen the Motion build, to pristine on www.offshoreonly.com. The gooseneck, dual tandem, trailer under the Motion is one of our designs.The Fast cats are fun, the pontoon is a ball...The "Guy" has his new cruiser that just cost him several hundred thousand...(Two engines, etc., etc.) His family, buddies and their family, on board, all look at the Bennington with contempt. Thirty MPH or there abouts, the pontoon struggles along. Well, it's now time to add a little power and get this new cruiser down the lake. "But wait", the dumb pontoon is still there....FULL POWER, can't have that !!!Then the pontoon decides to "GO ON". The new cruiser owner will not even look as the Bennington "smokes the cruiser". The poor guy is frustrated, being chastised by his lady and friends, while this "Thing" ruins his day. (That happened several times and the reaction is always the same).
Click to expand...
Ben & Suzy said:
You stated "I mention 5-6 MPH left to be had", but unless I missed something, I don't see where you listed the top speed numbers for your 350 Yami??? What speeds are you attaining with the 350 and on which Bennington platform is it mounted?? My dealer mounted a Yami F350 on a 2011 25 QXi. It ran 54mph right out of the box. I thought it was a decent speed for a 800 lb. outboard. I have yet to see a "stock" 350 I/O put up those numbers. The outboard gets my vote here.Now for comparison, a friend has a 25 footer (3 Std. tubes) with a 383 blower motor that runs 66 mph. Stone reliable motor. The Alpha drive(s) didn't last long though LOL! He now has a Bravo on it. I have to wonder.....with its ~300 lbs lighter weight, if the 4.2L 300hp (F300) would run close the speeds of the F350. Personally, I don't like a stern heavy pontoon. I don't care for the ride attitude while idling along or at cruising speeds. I've played with jackplates on my Benny and didn't like the overall results because of the aforementioned. Sure it's gonna handle better (turning wise) and go faster @ WOT with the weight farther back on the stern, but I certainly don't enjoy cruising around a 25mph feeling like I'm driving on an incline. I'll take the lighter outboard and nice flat driving attitude any day. If I wanted a faster, better handling pontoon......I'd own a (cough cough) Manitou SHP (almost vomited on that one). But.....I prefer quality. I'll stick with my Benny.
Click to expand...
Ben & Susy, The ride attitude improved considerably after the transom was reinforced. Originaly, the center tube was found to have a hook, because of the engine wt. That was before the jack plate was added. However, rigidizing the transom eliminated the hook, dramaticaly improved handling and increased speed.

Subject to the center tube flexing, a study may find positive, as well as negative movement. Such movement may cause material to work harden. (EX: Airbus 380)

My personal preferance remains the 350 Yam, there may be another 5-6 MPH and the I/O bilge is a bit complicated, for me. The 4.3 may not have enough torque.
 
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spinzone said:
+1
Click to expand...
spinzone/Ben & Suzy, FYI, two each, tuned, w/factory drivers, Manitou's w/300 Evinrudes, running together, tried to compete....They couldn't handle the Benny, LOL.

Call it obnoxious or not, I prefer to be competitive.
 
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