Compression ratio

[garyc]

Has anyone ever worked out the compression ratio of a 1.3 SR? if so what is the volume of cut outs on the pistons?

[rgv_stu]

if your trying to work out the c/r then you dont really need to know as piston volume is the same at bottom and top of the cycle.

[Stuart]

finally someone who agrees with me on that one.

[j1400]

Doesn't it say the CR in the hanyes manual??

[_JH_]

The Haynes says the 13S has a CR of 9.2:1. But I don't know the volume of the cut outs on the pistons

[j1400]

I'll be bring my spare 13SR block back to cardiff tomorrow, you can come over with some fuild and a synringe and measure it before I strip the block down if you want

[2litreturbo]

about the piston bowls.

Lets say an object has a volume of 30cubic cm. And was compressed to 10.
this gives a compression ratio of 3:1

Now if we assume the piston has a bowl of 1 cubic cm, the bowl does not disapear at any point in the cycly, so the volume will go from 31 to 11.
This gives a compression ratio 2.818:1

So i'm afriad bowls in pistons DO make a difference to the compression ratio. Not quite as much as in the above example because the cylinders in cars have a bigger volume than 30cubic cm.

Hope this helps