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-   -   wrong combo??? (https://www.racingjunk.com/forums/showthread.php?t=21827)

ejf 09-11-2008 01:51 PM

wrong combo???
 
My 454 bbc has 11 to1 closed chamberd pistons and square port open chamberd heads (990 casting).Is this really hurting my HP or should i go after closed heads?I race this engine and turn mid 11s in a 3500# monte ss.Trying not to break the bank on a total rebuild because engine has low miles on it.Thanks gene.

zipper06 09-11-2008 04:40 PM

IMO, you are losing atleast 2 points in the compression, with the open chamber heads. I think the easiest way out would be to change to some 13.1 open chamber pistons. i don't know how much you would pick up but i would think close to 2 to 3ths. ofcourse you would have to rebalance the engine with these changes.

JMO

Zip.

cepx111 09-12-2008 03:26 AM


Originally Posted by zipper06
IMO, you are losing atleast 2 points in the compression, with the open chamber heads. I think the easiest way out would be to change to some 13.1 open chamber pistons. i don't know how much you would pick up but i would think close to 2 to 3ths. ofcourse you would have to rebalance the engine with these changes.

JMO

Zip.

I second that>

Tod74 09-12-2008 05:11 AM

I 3rd that.
You want to keep the open chambers , they are a better head in my opinion.

itsabird 09-12-2008 06:27 AM

I 4th that, keep head, more compression on piston.

ejf 09-12-2008 04:25 PM

well i think im going to get BIG PISTONS :) Thanks guys.I also thought that these heads were better.

badrad 09-16-2008 05:28 AM

You have ~9:1, your set up is exactly what GM did to the '71 LS-6 454. It lost 25HP and a little more TQ.

ashbros 10-03-2008 02:20 AM

Just jerk the top end off and put a set of aluminum heads on that baby. Thats easier than pulling the engine out and apart and the additional cost may weight out after you consider all the additional time you spend tearing her down.

aquilesopkarg 06-12-2021 02:56 AM

keep head, more compression on piston.








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