Help with comp ratio

[yaristurbo]

I'm running a 5e and wanted to work out the ratio can anyone help

2.0mm head gasket

Piston specs

[AdamB]

You need to measure the cylinder head combustion chamber as well mate. Use a syringe, 1ml = 1cc.

[yaristurbo]

Head of then cheers bud

[AdamB]

No probs mate. I think they are around 39cc but obviously will change if any skimming or headwork has been done.

[yaristurbo]

What's the calculation for it using 39cc

[AdamB]

The Formula is :

CR = (CV + CCV) / CCV

Where CV - Cylinder Volume and CCV - Combustion Chamber Volume

Cylinder Volume = 1517cc / 4

= 379.25cc

Combustion Chamber Volume = (pi * 74.5mm² * 2.508mm) / 4000

=10.93276 + 39cc

=49.93276cc

Plugging back into the formula gives : (379.25cc + 49.93276) / 49.93276cc

CR = 8.595 : 1

It's the virtually flat top pistons giving it the high compression.

Hope that helps mate

Edited March 8, 2013 by AdamB

[yaristurbo]

Pretty high comp then

Edited March 8, 2013 by yaristurbo

[AdamB]

Yes mate, I'm sure thats right, been a while since I done it. Even checked it on a few online calculator things and managed to get around that sort of CR.

If it has had headwork the cc in the head will be greater than 39cc, making more volume decreasing the CR and the flat top pistons with no dish at all contribute.