Hi everyone, my engine builder is almost done with the 383's and I am wondering how many hp/torque should I expect from them, this is the set up :

Eagle rotating assembly
Steel crankshaft
Performer cylinder heads 70 cc
Hyperteuntic dome pistons
9:1 cr
PRW alum rockers 1.5 ratio
Performer air gap intake
Edelbrock 1410 750 cmf carb
Comp cam 12-318-4
222/226 at .50 lift
.464/.464 valve lift
110 LSA
Stainless marine "hi torque" exhaust w custom risers

Hopefully this is enough info for the estimate

I would like to get only constructive criticism pls , thanks

I couldnt give you a number but to me with 383's, your cam specs look tame. I bought the engines for my boat and had my guy go through them. He said we were leaving HP on the table with the cams that were in them but they would make good torque. In the end we left them in there. They're 355s and make over 400lbs T. With the twins the boat has all kinds of balls down low but wont rev past 5000. In retrospect I wish I had sacrificed some bottom end and let them rev and make some HP. Although it planes like a ski boat for all the work involved the boat isnt all that much faster top end then it was with the stock 270hp 350 mags.

Agree with you 100% ,cam could have been more aggressive ,had a talk with my guy about it , and since I am not going to be revving that high either ,we decided to go this way, a nice bottom end is not bad .

Thanks for your comments.

Ps: will be running mirages 25p

Anybody else? Where are the experts?

I know it is just a couple of sbc's but I really want to know your sincere opinion.

Thank you all in advance

I'd say about 360-385 at the crank - on a dry dyno through headers and no accessories. (or more appropriately the dynos accessories)

300 or so to the props with all accessories turning and with that exhaust.

Should idle well and last a long time. Id say you left about 40 HP on the table with your choice of sticks.



Uncle Dave

We used about the same bottom end. The top end we used world sportsman heads 202 vavles 200 cc runners Bullet cam grind #CHS288/296-10HR part #501000 spec 223/231 @.050 lift .530/.548 110 separation same intake edelbrock 750 cfm carb 425hp @ 5700 rpm stainless Marine exhaust with long risers. I dont remember the Tq. Hope this helps !!!!

Buddy, thats a sinifigantly lighter boat than mine with 383's, you'll have all kinds of bottom end. Put the camshaft to them and pull the big number.....I wish I did.

A cam change is in the works for me but it wont be this year.

I agree with this 100%, I think you'll be disappointed with that cam selection with the rest of the components you've assembled.

Do it now, or regret it later.

As for your question, the expert is right here. He can get you what you are looking out without making many sacrifices.
http://www.marinekineticsonline.com/

ummm,,your going to have allot more compression then you think! im using a .046 gasket,zero deck,,same heads as your usnig but a 355 and im at 10.2 to 1 with srp flat top pistons..thank god your using alunimum heads,shave 1 point their..

you will probably see 400 ponys and it will be all over with @ around 4500 rpm..i would go witrh the zz4 cam..

How would the lt4 hot cam compare to the zz4 cam in this application? I'm considering making a 383 out of my 350 and have a lot of the same questions as the OP.

My biggest concern if I went bigger with cam is reversion. I'm forced to run silent choice with short risers. I know cubic inches will mellow a cam but how far can it be stretched only adding 33 CID?