Compression Ratios

[roost]

Nice work on the solidworks!
You re right, the best way to check the compression is to fill the combustion chamber with liquid.
Once I made a head for an alcohol running engine, the target CR was 18:1. But the engine detonated, then have checked the compression like mentioned above, it revealed that it was 23:1!!

 

[pats]

ok but 11.6:1 with calculation.

15:1 with oil (..)

where is the problem in my calculation... it's not possible...


in GP they are a commpression ratios of 13.5:1, not more...

 

[roost]

It's easy to wrongly measured. 0,5 cc is little of material, but means a lot on a combustion chamber that has 4cc total volume.