Heads for 8.1 ?

Nikto · August 25, 2003

OK.

I found out CompCams make 3 bumpsticks for my 8.1.

Now, who makes heads for them?

ShortCrew · August 25, 2003

I'm not aware of any aftermarket heads yet. Even the 500hp Marine version uses these heads. I doubt you will see any aftermarket heads until GM starts selling 496 crate engines. The 496, though similar to the 454, uses a totally different head and has 6 head bolts per cylinder, while the 454 has only 5.

If the marine engines can make 500hp with the stock heads, there must be a lot of room in them. Hell, if a cam will take you from 340 to 420, maybe a port and polish will yield as much.

CMNTMXR81 · August 26, 2003

Think about it, the stock compression is 9.1:1 which leaves a lot of room for "enhancement". So filling in the combustion chamber therefore increasing the compression ratio in conjunction with bigger valves and of course one of those three Comp Cam grinds one could easily turn these 496'ers into an absolute monster. It's simply a matter of cost.

They are just simply very conservatively setup from the factory.

Tjwong · August 28, 2003

If when and ever that GM releases the HP3 variant of the 8.1L engine we will have some decent heads. They are 100% CNC machined heads from the General. Or you can get a set of standard truck heads and have them CNC ported, but little has been done to see what works and what don't in these new engines. The 8.1 engine has porting designs similar to that of an LS1 style intake port. The exhaust ports are about the same as a performance D port big block head that we are all familiar with.

The key to making horsepower is that everything, heads, intake, cam and compression ratio work well in harmony with one another. You don't want a set of heads that flow very well in the .500" lift region and up and select a cam with a maximum lift of .450"

GM did their homework with the HP3 variant of the 8.1L engine. At only 9.0:1 compression that 8.1L is producing over 525Hp and over 560ft/lbs of torque all on 87 octane pump fuel! Talk about things working in harmony This engine has about a half point lower compression than the 502/502 engine with aluminum heads and a high rise intake and carburetor with a lumpy cam. I am sure that there is plenty of potential just waiting to be unleashed. Hmm perhaps about 10 PSI of boost would wake it up to say.....650 or 700 HP?