I finally got around to cc'ing my H75 head to see if it is in fact of larger capacity than the H89.

So it turns out it the combustion chambers are larger than a H89, but only by 2cc (that is assuming the H89 29cc measure is in fact correct). So in reality it isn't THAT much of a lower compression ratio head. People go to the effort to source these head specifically for forced induction suitability. Is the 2cc really worth the hassle?

I have a H89 here that I can check but it appears it may have been milled at some point in time.

I did the test using a CD case cover with a vent and feed hole drilled into it (which I should have drilled further apart!). I put grease around the edge of the chamber to get a decent seal and I pressed the case down hard onto the face of the head, I used a 10cc syringe to feed the oil. It was a little crude but it works (I've lost my acrylic cc disc). Does anyone see any errors with this method? The only variables I can see are spark plug and valve face.

Chris

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  10cc.JPG (169.05 KB)


  20cc.JPG (172.65 KB)


  30cc.JPG (186.14 KB)