RPM. 4bt versus 6bt.

[RonA]

Does the shorter crankshaft 4bt handle high rpm better than the 6cyl?

 

[Bigphil54]

I was under the impression that the harmonics of the 4 cyl are not as natural or whatever as the six cyl so it does not like higher rpm.

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[Joesixpack]

Second order vibration is a issue with the 4 bangers. It gets worse as displacement and stroke increases. We have the inline 4's that are VE's in some ag equipment and those things do vibrate more period.

Used to have large displacement 4 cylinder in a Cat scraper and each of the balancer's under the crank were likely as heavy as a 4bt crank.

 

[DEZLFREK]

its said that a fluidamper is supposed to help a lot with the vibrations.. I screwed up and used a ati so I have now experience with that.

 

[camccardell]

I paid the big bucks to have my 4bt rotating assembly balanced, and it hums along to 4k no prob. It doesn't even shake at idle.

 

[Bohab]

Used to have large displacement 4 cylinder in a Cat scraper and each of the balancer's under the crank were likely as heavy as a 4bt crank.

You should see the ones in a Series 50 Detroit.