CR & plugs
Thread Starter
Race Director
Joined: Jul 2000
Posts: 11,007
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From: Probably in the paint booth....
CR & plugs
How much would removing .025" from my cylinders increase the CR. (.005" in the heads + .020" in thinner head gaskets.) Could this little bit force the plugs into a different heat range ?? Just trying to look at everything.
Thanks
Neal
Thanks
Neal
Le Mans Master
Joined: Oct 1999
Posts: 9,713
Likes: 3
From: Sachse Texas
Cruise-In I Veteran
Cruise-In II Veteran
Re: CR & plugs (Arisa)
Using the compression calculator here ( http://www.turbofast.com.au/Tfcomp.html ) I cam up with an increase from 10.8:1 (stock LT4) to an 11.55:1 which is a pretty big jump.
The figures I used are :
54cc head volume
.0535 deck height
.039 Gasket thickness
3.48 stroke
4.000 bore
I know the stock gasket is a little thicker and I am not sure what the actual deck thickness is, but it calculated out right. That gave me 10.806 which was close to LT4 compression. To simplify it, I reduced the deck height to .0285 and redid the calculation and it came out to 11.55.
You can also use a deck height of .05 and a gasket thickness of .043 which I think is stock and come out at 10.79:1. Actually modifying the numbers to a .023 thick gasket (-.020) and a deck height of .045 (-.005) you still come out with 11.53.
The figures I used are :
54cc head volume
.0535 deck height
.039 Gasket thickness
3.48 stroke
4.000 bore
I know the stock gasket is a little thicker and I am not sure what the actual deck thickness is, but it calculated out right. That gave me 10.806 which was close to LT4 compression. To simplify it, I reduced the deck height to .0285 and redid the calculation and it came out to 11.55.
You can also use a deck height of .05 and a gasket thickness of .043 which I think is stock and come out at 10.79:1. Actually modifying the numbers to a .023 thick gasket (-.020) and a deck height of .045 (-.005) you still come out with 11.53.
