Effective combustion chamber size
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
Effective combustion chamber size
I'm thinking about going to a set of 113 heads on my 86E. Although the CC of 58cc will give me much more compression than I want for my FI application. Is there a way to account for higher head gasked compressed thickness and calculate an effective, or net, CC size?
Just curious what using a .062 or .093 compressed thickness gasket would do to the compression ratio on my block and 113 heads.
Just curious what using a .062 or .093 compressed thickness gasket would do to the compression ratio on my block and 113 heads.
Racer
Joined: May 2006
Posts: 293
Likes: 0
With the bore diameter of the gasket, figure the ccs of the various gasket options. Head gasket volume is one of the factors needed to calculate the compression ratio. With either of those gaskets you will lose all benefits of a quench area. It may pay to open up the combustion chambers by unshrouding the valves and doing some figuring to find the best way of getting where you want to be.
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
It may pay to open up the combustion chambers by unshrouding the valves and doing some figuring to find the best way of getting where you want to be.
Anyway you would benefit from going to bigger valves; then unshrouding the intake and dressing the spark plug boss and cleaning up the cahmber will increase chamber volume a bit. You could use a CC plate & pipette to measure how much if interested or perhaps a good shop will know.
You're right, I have no idea what that is.
If you need to drop CR quite a bit it may be better to have a good shop open up the #113 chambers sufficiently or simply chose a better head for your needs.
Team Owner
Joined: Jan 2003
Posts: 20,306
Likes: 242
From: Summerland B.C. Canada
If your changing pistons, why not use one of the many compression calculators out there. You can enter all your info and then make changes with piston dish volume till you arrive at the dynamic compression ratio your looking for.
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Team Owner
Joined: Jan 2003
Posts: 20,306
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From: Summerland B.C. Canada
http://www.performancetrends.com/download.htm#crc
http://www.empirenet.com/pkelley2/DynamicCR.html
Performance trends calculator is free and you can pay them and get a better version. The free version is just fine for most builds.
Patrick Kelley's page is good reading and his calculator(bottom of page) is free and very good.
http://www.empirenet.com/pkelley2/DynamicCR.html
Performance trends calculator is free and you can pay them and get a better version. The free version is just fine for most builds.
Patrick Kelley's page is good reading and his calculator(bottom of page) is free and very good.
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
Thanks, guys. I had originally posted this as I thought my engine purchase was not gonna happen. Looks like it may go through, albeit it now with a .030 over bore. If so, I will keep the heads coming on the engine. If it doesn't, I will be doing the work I talked about earlier.
The calculators are great. I see that I have a ton of stuff I still need to learn about.
The calculators are great. I see that I have a ton of stuff I still need to learn about.
