DaveFJ
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| posted on 4/3/07 at 09:28 PM |
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Pinto compression ratio
I'm sure there is a fairly simple solution to this but it has been annoying me all weekend, can't seem to get my head around the
maths....
If a standard 2.0l pinto has a cr of 9.2/1
skimming 1.5mm off the head gives 10.2/1
so given that, how mouch do i need to remove from my head to give about 10.5/1 with a 2.1l block ?
Help! 
[Edited on 4/3/07 by DaveFJ]
Dave
"In Support of Help the Heroes" - Always
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novacaine
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| posted on 4/3/07 at 09:54 PM |
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is the standard comp ratio of 9.1:1 is right then the combustion chamber is 55cc, so if you bore out to 2.1 you have a bore of 93.2mm so to acchive a
comp ratio of 10.5:1 you need a combustion chamber vol of 50 cc exactly so i recon that if you have a 2.1L engine you need to skim 0.77 mm of the
head. but that is assuming that the part of the chamber you are skimming is perfectly cylindrical, please dont hold me to this but i recon that with
the above assumptions 0.77mm should be about right
hope that helps
Matt
And you run and you run to catch up with the sun but its sinking, Racing around to come up behind you again, the sun is the same in a relative way but
your older, shorter of breath and one day closer to death
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novacaine
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| posted on 4/3/07 at 09:58 PM |
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hold on a miniute that doesnt sound quite right....give me a moment
And you run and you run to catch up with the sun but its sinking, Racing around to come up behind you again, the sun is the same in a relative way but
your older, shorter of breath and one day closer to death
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novacaine
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| posted on 4/3/07 at 10:03 PM |
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removing 1.5mm off the head of the 2.1 will give a compression ratio of 10.75
is that close enough for you?
cheers
Matt
And you run and you run to catch up with the sun but its sinking, Racing around to come up behind you again, the sun is the same in a relative way but
your older, shorter of breath and one day closer to death
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MikeRJ
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| posted on 4/3/07 at 10:07 PM |
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It's basically impossible to calculate this accurately, because the area of the combustion chamber reduces as you machine the head down, e.g.
the first 1mm skim will reduce the volume of the chamber more than the next.
To work this out accurately you need to measure the combustion chamber height required by filling the chamber with the desired volume using e.g.
paraffin to reduce meniscus, and then measuring from top of liquid to the gasket face.
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DaveFJ
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| posted on 4/3/07 at 10:13 PM |
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think I'll just say sod it and go for 1mm off.....
Dave
"In Support of Help the Heroes" - Always
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