engine swap to a 400hp 350ci

[CENTURY CUSTOM]

want to swap to a 400hp 350ci from a 228 will the out drive handle it any help will be great

 

[picklenjim]

Re: engine swap to a 400hp 350ci

Need to know what drive you have!

 

[CENTURY CUSTOM]

Re: engine swap to a 400hp 350ci

it is a mercruser 228 series

 

[Howard Sterndrive]

Re: engine swap to a 400hp 350ci

300HP max.

Hard to imagine a 350 making 400HP at 4600 rpm though. It would have to be a pretty exotic engine.

Ask for the specs and see what HP it is at 4600 rpm. If it's under 300 it might be ok.

But the gear ratio of your outdrive (upper gearcase) is set up for 228HP. It won't be right unless your boat is one heavy heavy lump.

If you are running a 13P prop now or something you might be able to work something out with prop pitch.

 

[fast50]

Re: engine swap to a 400hp 350ci

you can make 400hp from a small block chevy all day long with off the shelf parts

 

[CENTURY CUSTOM]

Re: engine swap to a 400hp 350ci

yea the boat is 4500# was going to try to change gear ratio and max rpm will be 6000 i will build the motor my self i have played with a lot of jet boats i just dont know about out drives want to get the boat up to about 55 0r more it did 37 before at 5000 rpms with the 228

 

[Howard Sterndrive]

Re: engine swap to a 400hp 350ci

max rpm will be 6000

4800 is the maximum you can safely spin that outdrive.

Gimbal bearing and u-joints would more than likely have a dramatic transom removing, boat-sinking, catastrophic failure at anything more than a brief 6000 rpm speed

If you steered, or touched the trim at 6K, all bets are off for those u joints

To get a 1970's two ton cuddy cabin to go 55mph, would realistically take TWO sbc engines

You would need 500+HP or so combined at the props

 

[Howard Sterndrive]

Re: engine swap to a 400hp 350ci

you can make 400hp from a small block chevy all day long with off the shelf parts

don't know what that means exactly , but the trickiest marine 350 ever made with EFI and all tends to max out at about 325HP at the sort of rpms an Alpha drive can spin

Thus the popularity of the 383 stroker in sbc boats needing more torque.

but even though we're talking about a 350, a marine 383 stroker still doesn't make 400HP at safe alpha outdrive operating rpm's

 

[wca_tim]

Re: engine swap to a 400hp 350ci

don't know what that means exactly , but the trickiest marine 350 ever made with EFI and all tends to max out at about 325HP at the sort of rpms an Alpha drive can spin

Thus the popularity of the 383 stroker in sbc boats needing more torque.

but even though we're talking about a 350, a marine 383 stroker still doesn't make 400HP at safe alpha outdrive operating rpm's

uh.... how about 425+ at 4500 rpms and kissing 500 by 5500 rpms? not that hard to do with a 383 with good heads, exhaust and the right package built around it. and an alpha is good at those rpms - if set up carefully / right maintained rigorously and running good synthetic lube. Most of the drives of any type that fail due to one thing or another... really fail because we don't take care of them....

 

[lmannyr]

Re: engine swap to a 400hp 350ci

Not sure what your budget is, but step up the drive and have at it.

 

[flargin]

Re: engine swap to a 400hp 350ci

Gimbal bearing and u-joints would more than likely have a dramatic transom removing, boat-sinking, catastrophic failure at anything more than a brief 6000 rpm speed

If you steered, or touched the trim at 6K, all bets are off for those u joints

LMAO

 

[Howard Sterndrive]

Re: engine swap to a 400hp 350ci

I guess this is called "bench racing". I'm not well versed in it and I'm not sure how much drama and excitement we're supposed to put in the posts.

I've seen a U joint/gimbal hsg after it failed at 3000 rpm cruise and it made a huge mess. The boat was taking on water as the gimbal hsg, busted where the bellows clamps on. I can't imagine a 6K failure.
I'd want a scattershield for personal safety.

With thousands of dollars of non-OEM equipment involved the boat can go any speed anyone desires. Whether anyone will insure it is another question to ask.

I just don't think this is where the original poster was going in this thread.

55mph for an old Century cuddy... budget $5,000 min. Probably $10K to make it happen.

just trying to educate about how heavy boats respond to power different than cars, and bring the guy down to earth a bit. Nothing wrong with dreaming of more power.

37 mph is plenty for that cuddy. A nice stock 350 crate with a 4BBL would get it over 40mph and make it more fun and more reliable and improve the resale. Might be able to swap props and leave the drive alone, but can't tell that until the engine swap is done.

 

[CENTURY CUSTOM]

Re: engine swap to a 400hp 350ci

Thanks Guys All Info Was Great I Might Stick With A 300hp And Go Have Some Fun

 

[mtnrat]

Re: engine swap to a 400hp 350ci

Now if you get a volvo 280DP or 290DP instead of that alpha you would be in business . Build a 383 and have at er. However like anything it would still cost 5000-10000 by the time you were finished.

 

[wca_tim]

Re: engine swap to a 400hp 350ci

as an aside on alpha drive holding up... through hull vs through prop makes a difference... through prop the exhaust helps heat the drive...

gear ratio makes a difference...

I run a 1.84 gear ratio and have held at over 5000 rpms - just a hair shy of wot for the prop that was on there - for as long as 30 or 40 min (carefully balanced 383, forged bottom end, oversize oil pan, good oil cooler and oil temp gauge for engine oil, have a drilve oil temp gauge installed to watch drive temp this year). With the higher upper gear ration and corresponding higher pitch prop, the lower unit is turing a lot lower rpms, but the upper gear housing takes more stress from torque on take off... Just some food for thought. and yea, the gas gauge took quite a hit, but covered a lot of water in a hurry...

I got one of those piles of alpha drive (pieces) including an ugly looking upper where i lost a ujoint while under power... as mentioned above, that's not a pretty sight, and when it happens, there's no question that something is really., really wrong..