View Full Version : Rod length to stroke ratio 3

02-20-2010, 10:08 AM
The most pressure exerted on the crank pin is between 10 and 20 degrees on a gasoline engine.(LR higher end SR lower).One major deciding factor is working RPM range, Industrial engine with heavy cranks and limited RPM range can use excessively LR. they are tuned and balanced for about a 500 RPM working range.A properly design system will never drop below500 RPM.of toque peak at WOT.These type of engines aren't built to gain RPM but to sustain it.The LR. with lack of piston movement and not much rod angle is holding back the explosion just for a moment ,through crank momentum a more desirable rod angle is happening with not much piston movement.With 20 crank degrees of rod angle and a small combustion chamber and the extra actual time given to the explosion to expand in a small area.It is unstoppable.The SR.with it's quick piston movement around TDC.induces a more desirable rod angle sooner. Max pressure on c.rank pin has to be exerted while the combustion chamber is still small hens max pressure on crank pin is at less degrees ATDC.Opinion can't be wrong but can be modified.