Calculating compression on 5.3
09-09-2002, 11:15 AM
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Calculating compression on 5.3 Where am I going wrong here? I need to solve for the truck head gasket thickness. Here is what I have to work with:
Truck bore = 96.01mm
5.3 compressed gasket thicknes = ???
5.3 cylinder head volume = ~62cc
5.3 stock compression = 9.5:1
5.3 Displacement = 5328
cylinder volume = 666
Using the CR of 9.5 and volume of 666, I get the total chamber / gasket volume of 78.35 then pull out 62cc for the chamber and have 16.35 left. That 16.35 should be the compressed gasket volume plus volume above the top ring minus the piston above deck height.
If I estimate the diameter of the gasket @ 99mm, I get a compressed gasket height of 2.14mm or .084". Compare that to the gasket thickness of a LS1 - 1.33 or .053".
Does this sound correct? This seems like a very thick gasket.
<small>[ September 09, 2002, 11:19 AM: Message edited by: BigTex ]</small>
Truck bore = 96.01mm
5.3 compressed gasket thicknes = ???
5.3 cylinder head volume = ~62cc
5.3 stock compression = 9.5:1
5.3 Displacement = 5328
cylinder volume = 666
Using the CR of 9.5 and volume of 666, I get the total chamber / gasket volume of 78.35 then pull out 62cc for the chamber and have 16.35 left. That 16.35 should be the compressed gasket volume plus volume above the top ring minus the piston above deck height.
If I estimate the diameter of the gasket @ 99mm, I get a compressed gasket height of 2.14mm or .084". Compare that to the gasket thickness of a LS1 - 1.33 or .053".
Does this sound correct? This seems like a very thick gasket.
<small>[ September 09, 2002, 11:19 AM: Message edited by: BigTex ]</small>
09-09-2002, 11:39 AM
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Re: Calculating compression on 5.3 Put a dumb *** note by my name. I forgot to throw in the fact that I have dished pistons on my 5.3 truck. oops
09-10-2002, 10:06 PM
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Re: Calculating compression on 5.3 Hey Big Tex,
Been working on this same deal myself. Can you tell me the volume (c.c.) of the piston dish? Cant find these specs. anywhere and dont have a truck piston to measure. I've been told that the heads measure 59.5-60 c.c. and the gaskets are the same as the 5.7, 053-054. Thanks!
Been working on this same deal myself. Can you tell me the volume (c.c.) of the piston dish? Cant find these specs. anywhere and dont have a truck piston to measure. I've been told that the heads measure 59.5-60 c.c. and the gaskets are the same as the 5.7, 053-054. Thanks!
09-10-2002, 11:12 PM
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Re: Calculating compression on 5.3 I was kinda looking at getting my heads milled off to raise the compression to a little over 10:1. Does .025-.030 sound right to you guys?
09-11-2002, 03:44 PM
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Re: Calculating compression on 5.3 GERALD - I am using 62cc for the 5.3 chamber volume. Some say its smaller, who knows. I wish I had some firm numbers on that. If the 5.3 gasket is the same thickness as the LS1, then I get ~ 10.17cc for the gasket volume.
So if the chamber is 62cc, that makes the dish about 6.15cc. If the chamber is 60, then the dish should be ~ 8cc.
JWRENCH - I think a .030 mill will give you very close to a 10:1 compression ratio. Heres my thought - the gasket is .053" and makes 10.15cc. If you mill it .030, thats about 57% of the gasket thickness, so thats 5.7cc. The chamber is roughly (I'm guessing here) 75% of the gasket area, so thats removing ~ 4.25cc. That would give you a CR of ~9.988.
So if the chamber is 62cc, that makes the dish about 6.15cc. If the chamber is 60, then the dish should be ~ 8cc.
JWRENCH - I think a .030 mill will give you very close to a 10:1 compression ratio. Heres my thought - the gasket is .053" and makes 10.15cc. If you mill it .030, thats about 57% of the gasket thickness, so thats 5.7cc. The chamber is roughly (I'm guessing here) 75% of the gasket area, so thats removing ~ 4.25cc. That would give you a CR of ~9.988.
