Engine build suggestions.

[lmannyr]

For all you gear freaks out their, chime in any time

I have a boat (see sig) that had a 350/260 horse small block chevy hooked to an Alpha 1 gen ? The carburated engine was trashed.

Requirements:

Multi-port fuel injection
run on cheap gas
Cruise at 40 - 50 MPH
Cost ~6K including matching drive and assembly drive.

I could piece the engine together from scratch if I need to. I just do not know how to mate it with the transome assembly and drive. A GM crate would be nice though. Is this possible or am I talking out of my bungholeo?

If so, what are your recommendations?

THANKS!!!

 

[Don S]

Re: Engine build suggestions.

Multi-port fuel injection
run on cheap gas
Cruise at 40 - 50 MPH
Cost ~6K including matching drive and assembly drive.

Never hurts to want. Keep an eye on places like ebay and eventually you may get it all together.

 

[lmannyr]

Re: Engine build suggestions.

What do you think of the LQ9 Crate Engine from GM Performance?

MAX RPM 5600
345 HP
380 TQ
Throttle by wire

There is an LQ4 with a bit lower compression with a 20Hp Penalty.

 

[Bondo]

Re: Engine build suggestions.

Ayuh,....

I believe the motor you linked to is a Gen.III SBC,.....

It won't even bolt in to Anything in a Boat......
Chevy has moved all the bolt holes......

You need a Gen.I SBC,... or at Best a Gen.II can be bolted up,.. With some creative engineering.....

 

[TilliamWe]

Re: Engine build suggestions.

Requirements:

Multi-port fuel injection
run on cheap gas
Cruise at 40 - 50 MPH
Cost ~6K including matching drive and assembly drive.!

You may get the first two, but you'll not get the last two. You are completely dreaming and talking out of your arse.

Unfortunately, complete Mercruiser engine/drive packages are at least double the $6k you want to spend.
Just for example, the transom assembly from Marine Power Service for a Bravo is $2995 new. A factory reman 383MPI (325hp) is $6895 and a Bravo 3 drive is $4295.
And you'll not get anywhere close to 50mph in that boat unless you put a 502.
If you are a mechanic and a machinst and work for yourself for free, then you might get to your price goal. But to get a 50mph top speed out of that boat is gonna take some serious Horsepower.
Best of luck to you.

 

[TilliamWe]

Re: Engine build suggestions.

But watch EBay for a complete 502MPI engine/drive package (doubt you'll see the drive with it.). Most likely, you'll find a complete engine, then you'll have to piece together a Bravo transom assembly and a drive.
Since you have the drive stuff out already, if you went with a 350MAG MPI (300hp) you could use an Alpha 1 Gen 2 drive. That might be more plentiful as a complete used package. But you'll not be anywhere near 50mph with that engine. But it should do a decent job in the boat.

 

[ILOVEBEER]

Re: Engine build suggestions.

Take a look at these:

"http://www.michiganmotorz.com/Marine+Engines/Complete+Turn-Key+Engines/Turn-Key+Carbureted+Engines/5.7L+Complete+engine+package+%281987+and+later+Mercruiser+applications%29

"http://www.sterndrive.cc/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=106AUC


I think that's about as close to 6K as you'll get.

 

[dcg9381]

Re: Engine build suggestions.

"Cruise" speed is typically a speed above plain where you get the most MPG.
For my boat, 23.3' - sport boat style, that cruise speed is about 30mph at around 3000 rpm. Resulting fuel use is 10-11 GPH.

This is with a 385hp Mag MPI 454.

I don't know how heavy your boat is, but top end on my boat - which weighs around 4000lbs is over 60mph. Propped correctly, probably in the neighborhood of 63-64 loaded with fuel and 2 adults. Fuel ecomony at 50-60 mph, off the top of my head, is like 30-35 GPH.


I think you boat isn't really a sport hull - so your performance will probably step down from there unless you've got a really light boat.

The prices quoted above, I *believe* are for longblock motors - do they even include the MPI? You'll either need to match the mercruiser EFI system to the motor or you'll be spending some expensive time on a dyno with a speciality shop having your boat EFI tuned via a computer... I'd probably just carb it with a nice small block motor or consider buying a newer boat with the MPI that you want.

 

[lmannyr]

Re: Engine build suggestions.

What specifically won't bolt up? The drive? Will it bolt up to any other drives? So even a generation II will give me issues? Check out "2009 GM Marine Portfolio." Thats were I got the LS idea.

So merc uses Gen 1 with there lastest enignes?

Moving down to a gen 1 or 2 will be nicer on the wallet.

 

[mkast]

Re: Engine build suggestions.

Because of a lack of detailed pictures to work with I can only guess, 4200 Lbs. dry,
40-50 cruise,
$6,000 budget,
to phrase it politely, "Ain't gonna happen."

 

[lmannyr]

Re: Engine build suggestions.

I never dunked this boat so I had no since of it's speed. Thus, I threw out a number. dcg, your numbers now bring me to reality. My boat weighs about the same at 4200 pounds. I searched the net for performance numbers on this craft and was unsuccessful. I can live with 30 mph

I really appreciate ALL the replies today.

Thank You!!

 

[lmannyr]

Re: Engine build suggestions.

Is this the correct manual for the 350 MAG MPI?

 

[Bondo]

Re: Engine build suggestions.

What specifically won't bolt up?

Well,..... I see they have it listed as Marine,....
The Problem I see is the Exhaust Ports won't line up with any Known exhaust Manifolds......
The Vortec series shown above the others is what most of us have in their Boats....

Then again,...... Maybe I'm wrong....

 

[wca_tim]

Re: Engine build suggestions.

I recently bought a mercruiser 350 for a few hundred bucks that was supposedly running when pulled and included everything from the transom forward. IT was clear even from the outside that it wasn't in bad shape and once I got into it it was clear that it hadn't even been run hard and had never been rebuilt. It had been sitting and the guy just needed to get rid of it. It included the carb, intake, complete exhaust, ignition, distributer, most of the wiring, etc...

If I'm completely honest about the cost (I'll admit, I sometimes tend to ignore the little details, etc of what I really spend on some of my projects and toys by the time I'm done, just so I don't have to cringe quite as bad when I think about the money I spend playing around wth things...), I'll have another $4500 - $5,000 in the finished 383 engine when I get it back from the machine shop. That includes everything built carefully to marine spec by a shop that specializes in marine engine builds, blueprinted, balanced, forged, crank, rods, pistons, aftermarket heads, etc...

If weight and room weren't a concern, I would have gone with a big block, no question - and probably have spent less on the engine by forgoing the stroker kit and associated block machine work.

I realize that I left out the fuel injection... I guess I don't see anything wrong with a carbed engine...

I am going to stick with an alpha drive for the time being (probably until I destroy the two outdrives I currently have), but...

my point is that if you came up with a used bravo drive for reasonable money, it seems like you could still come up under the upper end of the budget if you take your time and wait until you come across the right things used...


50-60 top end maybe, right? cruising in the 40's?

 

[TilliamWe]

Re: Engine build suggestions.

Well,..... I see they have it listed as Marine,....
The Problem I see is the Exhaust Ports won't line up with any Known exhaust Manifolds......
The Vortec series shown above the others is what most of us have in their Boats....

Then again,...... Maybe I'm wrong....

Oh, Bondo, Crusader and some other inboard only marinizers are using the 6.0l "new" small block. So there are exhaust manifolds out that that will fit a 5.3, but they aren't painted black or red.

 

[Don S]

Re: Engine build suggestions.

Oh, Bondo, Crusader and some other inboard only marinizers are using the 6.0l "new" small block. So there are exhaust manifolds out that that will fit a 5.3, but they aren't painted black or red.

They also probably won't line up with a Mercruiser Y pipe, coupler, shift interrupt system (if Alpha used) or anything else "Sterndrive"