Connecting rod length

EverySparePenny Tue 10 Dec 2019 - 21:05

Is there any association of tuning window to rod length?

As in, the longer rod narrows the tuning window where a shorter rod can broaden the window. Or vise versa

c.evans Wed 11 Dec 2019 - 0:45

Some people think there is, due to the piston acceleration with shorter rods, away from TDC. However, when you do the math, it might amount to a small difference such as .003". IMO that's flyshit, and is a non issue. I would rather go with longer rods and reduce rod angularity on the cylinder side wall.
Charlie

BOSS 429 Wed 11 Dec 2019 - 1:32

EverySparePenny wrote:Is there any association of tuning window to rod length?

As in, the longer rod narrows the tuning window where a shorter rod can broaden the window. Or vise versa

It depends on a few things,What you are doing with the engine. Deck height, Runner lenght,and planed RPM

rmcomprandy Wed 11 Dec 2019 - 11:30

EverySparePenny wrote:Is there any association of tuning window to rod length?

As in, the longer rod narrows the tuning window where a shorter rod can broaden the window. Or vise versa

The difference is minimal other than where the downforce of the piston combination exerts pressure.
A shorter rod will exert more pressure on the cylinder wall and less on the main bearing saddle as a function of rod angularity in the bore where the power forces are taking place above the piston. A longer rod will do just the opposite.
Unless you are talking about an inch of difference then it will not be much.
A longer rod will move the piston very slightly slower near the top of the bore but, faster than a shorter rod near the bottom of the bore

The biggest difference will be with a stroker engine where the shorter rod will expose more of the piston to the crankcase below the bore at the bottom of the stroke.

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Connecting rod length

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