Dennis Moore

Jim, I don't think he is looking for that much power. A stock 502 short block with a Whipple supercharger doesn't need huge intake ports or great exhaust ports. I am sure that the stock exhaust ports will still flow more exhaust than the marine MANIFOLDS he will use. I don't know what camshaft he plans on running but I would doubt that it would be large enough to make full use of the high flow heads that you recommend. I think he is only looking to make 525 - 550 horsepower.
Do you think that $2000.00 worth of heads would make that much difference with a 525 horsepower supercharged engine @ 5,000 rpm? I don't think so but correct me if I am wrong.
It depends upon where he wants to spend the money to get the most bang for the buck. I don't think changing heads would be very cost effective in this case.

Respectfully
Dennis Moore

29scarab

I thought the numbers with a stock 502 and a whipple were around 620?? I have added stainless marine exhaust. I also have crane gold HP roller rockers, if that helps any.

I was told with a different set heads that it should add 60 to 90HP without a cam change. This does sound possible. I also was going with a different pulley on the Whipple. My last change,I was going to make was a special grind cam for Whipple.

I also want to make sure this thread doesn't take a wrong turn. I'm just asking for some tech tips.

Thanks

blown1500

Crane 741 cam, heads modified by me, Whipple on a 502EFI made 757hp on the dyno. Slightly different cam, ProCharger SC-1 and Merlin 310 heads made 930. Not MPI, but quite similar. The heads make BIG diferences!!! You do need the good exhaust, a better cam helps. Heads, aftermarket or JimV will give a big boost in performance and aluminum heads are more forgiving. If you boat in salt water, hard anodize the heads of just use cast iron like the Merlin.
29scarab, I agree with your last post. Different heads can give different results, but almost any aftermarket head will help!!!

29scarab

Thats what I'm talking about blown1500!!!!!

Smile from ear to ear with those numbers!!!!! Yeah baby!!!

Ratchet

29,

You putting that kinda power in a 29 scarab w a single ?

It should fly if you can keep a drive on it. I know 26 scarab has somewhere around 650-675 hp in his 26 footer, and it's a bit of a handful !

Just curious,

Ratchet

29scarab

I know the boat can handle it. I just may have to beef up the drive a little. I already put a full dual ram IMCO hydraulic steering on it when I added the Whipple. I know it will terrorize the lake I hang out on!!!! ( I'm smiling!!)

bobby daniels

yes by all means change heads to a good aftermarket aluim. it will help blown or not ,,
It will relly wake up most blower motors the intakes are important but the exhaust is what really wake it up,Jim v can help
clean up the flow
the aluim carries off the heat from the blower much better than iron and is much safer and repaired easily !!


GET SOME HEADS

29scarab

Now,

One more question. Is there any different head gasket that is required if I'm going to be raising the boost of the blower. I know I haven't got my block O-ringed. I did happen to blow a head gasket two weeks after running the engine, but after it was changed I haven't had any problems.

I do want to thank you guys for your input on this thread!

bobby daniels

Nope what happened to you was almost normal ! after a short time using the stock head gasket will blow ,I replace the bolts and use felpro headgaskets and it works well .
we've not been real sucsessful with o-ringing heads ,so we stopped ! Now we use fel-pro or cometco gaskets with no problem

Breathe Later

29scarab,

You're using the Crane gold rockers on an MPI motor. Did you use the stock valve covers? Were any mods necessary for clearance?

Thanks,

Mark S.