Head Skimmed.

[jonD6B 0]

How can I tell what the compression ratio has been increased to on a second hand modified head? It is running a Piper 285 cam. It is off a 1.6 and going onto a 1.9 (D6B)XU. I want to know because won't these engines have different compression ratio's anyway? I will need to know how much has been skimmed and how this equates to the what the compression ratio figure is, if anyone can shed some light all help is greatly appreciated.

[rjw205 8 3 Cars]

I believe that engine shops can measure what has been taken off by the depth of the oilways. or one particular oilway. I would also imagine they could take the reading from the bottom of the compression chamber (with the head upside down), to the height of the skimmed surface. Hope this helps, But if i am miles out, please kick my ass!

 

Rich

[jonD6B 0]

I believe that engine shops can measure what has been taken off by the depth of the oilways. or one particular oilway. I would also imagine they could take the reading from the bottom of the compression chamber (with the head upside down), to the height of the skimmed surface. Hope this helps, But if i am miles out, please kick my ass!

 

Rich

 

Cheers Rich. Has anyone got these dimensions or another method?

[phatgti 0]

Or you could work the CR out manually, it means stripping the head but it is the safest way of knowing exactly.

 

chamber is 34cc, taking 6cc out gives a 1.6 roughly 10.8:1 CR on that cylinder.

 

ps to take 6cc out meant skimming 52 thou off the head.

Edited February 19, 2006 by phatgti

[newdean0 0]

Puma racing has a compression ratio calculator on his site but you need to work out the volume in the head. To do this (I've never done it tho) is fit a spark plug then turn the cams so all valves are closed on one cylinder. Now turn the head upside down and using a marked syringe fill the chamber with oil until it is level with the top of the head to get the volume.