Originally Posted by Chip

It depends what fuel you are using and what CR you are on etc. as does any engine, any spec

Essentially, with the fuel they were on the original rod ratio was probably optimised for about 2Krpm effectively, so even a longer rod that moved it up the rev range only moved it to the midrange.

If that makes sense? not really, the fuel was the same, the crank stroke was the same, but a simple rod change (as they where now allowed to do so)


The effect of the longer rod is the piston hanging around longer at TDC to work the fuel harder, this is particuarly useful at highrpm, but its also potentially useful at lower rpm in certain cases.