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Pipe length
Did you know that the exhaust pipe length affects power also?
Look at this graph plotting changes in delivery ratio (.8 means the cylinder is filled 80% with air/fuel mixture which equates to engine power) and pipe length. It's from the same crankcase_volume pdf.
I measured my stock pipe to be 9" from cylinder to muffler.
Between 30 and 40 inches really boosts the delivery ratio for mid-range rpms and probably 20 inches would be best for high rpm power.
I'm going to start experimenting on pipes.
Also some airplane engines utilize straight pipes that slowly taper outward. They supposedly give the best power over the whole spread of engine rpms.
Did you know that the exhaust pipe length affects power also?
Look at this graph plotting changes in delivery ratio (.8 means the cylinder is filled 80% with air/fuel mixture which equates to engine power) and pipe length. It's from the same crankcase_volume pdf.
I measured my stock pipe to be 9" from cylinder to muffler.
Between 30 and 40 inches really boosts the delivery ratio for mid-range rpms and probably 20 inches would be best for high rpm power.
I'm going to start experimenting on pipes.
Also some airplane engines utilize straight pipes that slowly taper outward. They supposedly give the best power over the whole spread of engine rpms.