Tech question about combustion chamber suze
Thread Starter
ISIS SUCKS FAT CHOAD
Joined: Oct 2008
Posts: 8,124
Likes: 53
From: Earth, United States
Tech question about combustion chamber suze
Ok, I attempted to do some research before posting this thread but seem to be getting conflicting information. Ok here it goes.... I'm doing a head and cam swap on my 97 C5. The casting number of the heads I'm using is casting number 806. these heads have had .025 taken off them. I went from the graphite gaskets to the GM MLS gasket. (stock gasket) the bottom end of my engine is stock. I need to attempt to calculate my static compression ratio with this combo.... I need to know what the actual stock combustion chamber size is for my heads with casting number 806 is and what the compressed thickness of my stoc GM MLS head gaskets are?
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Gasket thickness is 0.051" per the GMPP catalog, page 210. Not sure I can answer the head chamber question but there is an LS1 compression calculation spreadsheet you can download and use that has all of the motor specifics in it already such as rod length, bore, etc.
Tech Contributor
Joined: May 2008
Posts: 2,843
Likes: 16
From: Howell Michigan
St. Jude Donor '09-'10-'11
I can see how you would be getting conflicting information. The chamber volume of your heads could be anywhere from 61.13cc to 71.06 cc depending on what head casting you actually have. Can you identify any other numbers on the heads? Look for the 8 digit casting number. If not and you really want the exact number then your only options would be to cc the head if they are off the engine as ipuig suggested.
Thread Starter
ISIS SUCKS FAT CHOAD
Joined: Oct 2008
Posts: 8,124
Likes: 53
From: Earth, United States
I can see how you would be getting conflicting information.* The chamber volume of your heads could be anywhere from 61.13cc to 71.06 cc depending on what head casting you actually have.* Can you identify any other numbers on the heads?* Look for the 8 digit casting number.* If not and you really want the exact number then your only options would be to cc the head if they are off the engine as ipuig suggested.
Thank's for all your help guy's.
Last edited by MVP'S ZO6; Jul 19, 2009 at 04:54 PM.
Former Vendor
Joined: Mar 2004
Posts: 1,518
Likes: 7
From: Valencia CA
CC the heads as others have suggested....all the guessing and speculation is a waste of time honestly.
Its an important detail of any build that needs to be quantified to accurately compute static CR
Even knowing what they were suppose to be I would never build an engine without verification.
-Tony
Its an important detail of any build that needs to be quantified to accurately compute static CR
Even knowing what they were suppose to be I would never build an engine without verification.
-Tony
Last edited by Tony Mamo @ AFR; Jul 19, 2009 at 05:46 PM.
Race Director
Joined: Dec 2004
Posts: 13,760
Likes: 75
From: Haymarket VA
CC the heads as others have suggested....all the guessing and speculation is a waste of time.
Its an important detail of any build that needs to be quantified to accurately compute staric CR
Even knowing what they were suppose to be I would never build an engine without verification.
-Tony
Its an important detail of any build that needs to be quantified to accurately compute staric CR
Even knowing what they were suppose to be I would never build an engine without verification.
-Tony
Have them poured.
Melting Slicks
Joined: Oct 2007
Posts: 2,464
Likes: 2
From: Cedarburg, WI
If you want a rough estimate and do it yourself just ductape a piece of plexiglass to the chamber with a small hole drilled into it. Set your heads on wooden blocks to level them. You can take medical syringes and fill known amount of water until if is full. Will give you a close idea for little or no cost! 
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Thread Starter
ISIS SUCKS FAT CHOAD
Joined: Oct 2008
Posts: 8,124
Likes: 53
From: Earth, United States
Thankyou gerntleman, I will cc the heads and let you know what I come up with. next is to figure out if im going to have to flycut my pistons for my cam or not.
I'm actually going to post up the flow numbers for my heads once I get home. I think they're pretty good for a set of LS1 castings. I think you guy's will be impressed with them. eventually on my build combo I will go with a set of AFRs or something but I just didnt have the extra cash to spend on a set of heads of that caliber.
I'm actually going to post up the flow numbers for my heads once I get home. I think they're pretty good for a set of LS1 castings. I think you guy's will be impressed with them. eventually on my build combo I will go with a set of AFRs or something but I just didnt have the extra cash to spend on a set of heads of that caliber.
Last edited by MVP'S ZO6; Jul 19, 2009 at 07:30 PM.