Quote:
Originally Posted by livvie
Hmmm... cool. Can you explain the formula on how to take theoretical compression ratio and convert it to the "actual". I understand the delay, is it because the valve is open that the volume of the chamber is actually bigger therefore the compression ratio is smaller? So when cylinder is at TDC there is a valve (exhaust) that is still open?
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It is possible to work out the geometry but in the Prius community, we have access to the Toyota papers and maintenance manuals. The commonly believed values are:
8-to-1 - compression stroke
13-to-1 - expansion stroke
If you want to work out the geometry, the ratio should be roughly proportional to:
((intake_delay_close_in_degrees) / 180 degrees) * (max_cylinder_volume/min_cylinder_volume)
Due to the geometry of the connecting rod, there will be some variance but for a rough approximation, this should be close enough.
Bob Wilson