Hello,

I would like to know the differences as well as the advantages and disadvantages of each.

Thanks in advance

 

F1 - big rod/crank ratio

nascar - small rod/crank ratio

 

big rod/crank ratio = high rpm, low tq at low rpm, piston speed relatively slower in TDC

small rod/crank ratio = more tq at low rpm, not suitable for very high rpm, piston speed very fast at TDC, ignition timing more tricky.

 

Thanks for the info guys.

So, when you mean slower piston speed on a long rod engine, does that mean it revs slower than a standard rod engine?

 

The differences are very minor in the grand scheme of things. Figure about 300 rpm gain in safe redline speed.

 

Would big rod be referring to long rod? and small rod be referring to short rod?

 

Yes big rod=long rod. The difference between the rods is the torque they produce and the mean piston speed. longer rod has faster piston speed and the torque keeps increasing a lot longer than the short rod.

 

So which set-up produces more low end TQ? Short rod?

 

This is what I wrote for the guys asking questions when we were building my LR motor.

https://www.evolutionm.net/forums/8282453-post28.html

My engine build thread

https://www.evolutionm.net/forums/ev...tor-build.html

Mikey