Engine Moment of Inertia

[reidh]

I need a bit of help for a project I am currently working on, and hopefully somebody can help. I am trying to determine the moment of inertia of an engine by performing some sort of bench test. Does anybody have a test method for this? I was thinking along the lines of removing the valves/spark plug to reduce the pumping losses and make some sort of fixture that I could drop different weights to spin the crank and measure the time it takes the weights to drop a certain distance.

I think there would be too much error trying to calculate this using all of the component's masses.

-Reidh

 

[GregLocock]

I think you'll actually find it easier to do analytically.


However, if you want to do a physical test then your method won't really work. You'll mostly be measuring friction in the rings and valve gear. The accurate way to do a test is to suspend each component from a trifilar suspension and measure the frequency of the torsional mode.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.