383 Questions

[2 Horse]

Anyone know the diff in a marine 383 and the HT383 truck motors? The HT383 has 340 HP and 435 Ibs of torque at 4000 rpm's, max rpm is 5000. Looking to upgrade a 5.0 in a 95' Baja Hot Shot. Will my Alpha 1 handle the HP and torque ?
A little more info: Boat weight is about 2600 lbs dry
Prop is a stock 19 Aluminum Quicksilver
Alpha has 1.87 gears

 

[Bondo]

Re: 383 Questions

Will my Alpha 1 handle the HP and torque ?

Ayuh,... That'll depend on just how Badly you beat it....

Welcome Aboard,...

Tell Us somemore about this HT383,....

I rather doubt there's very much Different about 'em...

 

[John_S]

Re: 383 Questions

If you mean the GM crate engine HT383 I have browsed through the spec sheet. It looks to be a rather mild 383 and think it uses the standard Mercruiser 350 marine roller cam, or the specs are very close to it.

 

[2 Horse]

Re: 383 Questions

If you mean the GM crate engine HT383 I have browsed through the spec sheet. It looks to be a rather mild 383 and think it uses the standard Mercruiser 350 marine roller cam, or the specs are very close to it.

Yes, that is the one. I was wondering about the cam, can't seem to find any tech info on marine cams, or for that matter marine motors. Any place I can look? I take it the gearing in the drive is like rear end ratio in a auto, the bigger the faster you'll top out rpm's?

The reason I'm looking at the HT is because I can save about $1800 by going thru a dealer instead of a marina. Just wanted to make sure I'm not making a costly mistake.

 

[John_S]

Re: 383 Questions

As for cams, I was reviewing the roller cams on GM Performance website, and the one that matched Merc marine specs, was said to be in the HT383.

I think the standard disclaimer on the GM crate engines is "Not for marine use", but think a number of them would perform fine. I have not purchased or used any, though. If you provide a link to the HT383 specs, I'd bet others would chime in.

 

[2 Horse]

Re: 383 Questions

Link for GM Performance Center HT383 crate motor
http://www.gmperformanceparts.com/E...Id=HT383&engine=HT 383&sku=12499101&engCat=sb

Still looking for tech info on GM marine motors, anyone with a link?

 

[HT32BSX115]

Re: 383 Questions

Link for GM Performance Center HT383 crate motor
http://www.gmperformanceparts.com/E...Id=HT383&engine=HT 383&sku=12499101&engCat=sb

Still looking for tech info on GM marine motors, anyone with a link?

Here's what I found....maybe you already saw this.....

http://www.gm.com/experience/technology/gmpowertrain/engines/specialized/marine/marine_engines.jsp




For the HT383 and others.....

Must be installed in a street-legal automotive application.

It appears that they will void any warranty if you don't put it in a "street legal" application.


I like this one!

?LSA? 6.2L V-8 SC
Marine Engine
http://www.gm.com/experience/techno...s/specialized/marine/2010_6200_LSA_Marine.pdf


I'm sure it's cheep!!


Cheers,


Rick

 

[John_S]

Re: 383 Questions

First, you are not going to find the specs. for the Marine Cam, that is considered "secret sauce" by both Merc. and Volvo.

FWIW:


https://store.gmperformanceparts.com/store/SelectProd.do?prodId=7696&redir=true&manufacturer=GM&category=Camshafts&name=Small%20Block%20Hydraulic%20Roller%20&model=<!--14097395-->

14097395
Hydraulic roller design
I: 196 E: 206
I: .431 E: .451
109
For the HT383 truck engine with 1.5 rockers.


Specs look the same as what Dennis Moore and others have indicated for 350 marine roller. Lift, but not duration, is in the Mercruiser service manuals.

The Merc 377 (non-bored over 383) has a slightly higher lift and probably longer duration cam than above.

 

[2 Horse]

Re: 383 Questions

Just a few comments.

First, you are not going to find the specs. for the Marine Cam, that is considered "secret sauce" by both Merc. and Volvo.

The HT383 is an amazing torque monster and can/will put out over 400lbft at anything above 2500 RPM from the factory. The real beauty of this engine is it has a very strong bottom end and cast iron Vortec heads. GM recommends a 650 CFM carb but a 750 CFM with mechanical secondaries will deffinately wake it up.

Merc and Volvo buy stock GM motors, nothing super secret only we have it, so someone should know what cam is stuffed into it.

HT383 has all the good stuff in the lower end, Forged Steel Crank, 4 Bolt Mains, HD Rods. 340 Hp with injection, Carb it and the power comes down a tad. Should be a bear in a 2800 lb boat, but like I said just trying not to mess things up.

 

[2 Horse]

Re: 383 Questions

Tell ya what, spend say a month looking for the information and you will change your mind. GM builds the engines true enough, but Merc. and Volvo define the cam grind they want. Regardless, I have never seen the specs. published anywhere.

Found it. Merc Manual has the specs. 350 cam is almost the same as the HT383 roller, duration is a bit longer on the 350.

Talked to Merc Customer Service he said max HP for a Alpha1 is 310 at the prop. Drive eats about 25 HP, so anything under 335 is safe.

Nice site found Manuals in the sticky's

 

[2 Horse]

Re: 383 Questions

Here's what I found....maybe you already saw this.....

http://www.gm.com/experience/technology/gmpowertrain/engines/specialized/marine/marine_engines.jsp




For the HT383 and others.....
It appears that they will void any warranty if you don't put it in a "street legal" application.


I like this one!

?LSA? 6.2L V-8 SC
Marine Engine
http://www.gm.com/experience/techno...s/specialized/marine/2010_6200_LSA_Marine.pdf


I'm sure it's cheep!!


Cheers,


Rick

Just add wings and go

Don't know if I could handle it

 

[wca_tim]

Re: 383 Questions

the only other things I can think off off the top are head gasket material, freeze plug material (need to be brass) and water pump construction (the one specd on the crate engine is not marine)... otherwise that's a nice set-up from GM and every bit as good as a merc engine for the application. imho...

I would also tend to agree that a 750 cfm carb on top of a weind stealth or edelbrock air gap intake would be good for some additional power... maybe at the cost of a small amount of throttle response on the bottom end but would just have to try it...

 

[mkast]

Re: 383 Questions

I have never seen the specs. published anywhere.

From Dennis Moore's book:
STOCK CAMSHAFT SPECIFICATIONS
Chevrolet has used only two different camshafts in the marine small block over the years, a flat-based hydraulic lifter camshaft and a roller-based hydraulic lifter camshaft.
Flat-based hydraulic lifter marine camshaft used on the stock 305 and 350 marine engines
Chevrolet Part Number 340284
Duration
200 degrees intake duration measured @.050" lift
258 degrees intake duration measured @.006" lift
212 degrees exhaust duration measured @.050" lift
270 degrees exhaust duration measured @.006" lift
Lift
.400" intake valve lift with 1.50:1 rocker arms
.266" intake lobe lift at the lifter
.410" exhaust valve lift with 1.50:1 rocker arms
.273" exhaust lobe lift at the lifter

Timing
110 degrees intake to exhaust lobe centerline separation angle in camshaft degrees
108 degrees after top dead center intake lobe centerline position in crankshaft degrees
112 degrees before top dead center exhaust lobe centerline position in crankshaft degrees

Note: This is the stock hydraulic lifter marine camshaft.
Note: A moderate increase in power (5-10 horsepower @ 4500 rpm) can be achieved with this camshaft if the intake lobe centerline is moved to 110 degrees after top dead center and 1.6:1 rocker arms are installed on the intake and exhaust valve trains.

 

[jy118lfd]

Re: 383 Questions

The "395" cam in the ht383 is the same cam I pulled out of my 5.0l and the same cam in the 5.7L Motor I just built. It will be even a little small for a 383, but it is a torque monster in the 383 and would make a great boat motor. I can tell you the stock Chevy head gaskets are the marine ones and It might even have brass core plugs. I dont think it is listed for marine engines cause of warranty and contractual terms with marine motor companies. No warranty but it would be a good motor.