Engine shaking moments
Engine shaking moments
(OP)
Hey!
I am currently working on a V4 engine. I have already calculated the primary and shaking forces but am struggling to understand how shaking moments arise in the engine. It has got something to do with the non eccentricity of the cylinders but how can one calculate the magnitude and direction of the moments caused by the shaking forces in a V engine? It would help a lot if anyone here could just push me in the right direction. Thanks!
I am currently working on a V4 engine. I have already calculated the primary and shaking forces but am struggling to understand how shaking moments arise in the engine. It has got something to do with the non eccentricity of the cylinders but how can one calculate the magnitude and direction of the moments caused by the shaking forces in a V engine? It would help a lot if anyone here could just push me in the right direction. Thanks!





RE: Engine shaking moments
RE: Engine shaking moments
RE: Engine shaking moments
RE: Engine shaking moments
RE: Engine shaking moments
RE: Engine shaking moments
Each 90-degree V-twin on its own, if the crank counterweights are correct for the weights of the pistons and rods (see posts above for figuring this out) will have perfect primary balance with the exception of a slight primary shake because one cylinder is slightly ahead of the other one on the engine (due to the con-rods being side by side on the crankpin and thus not *completely* offsetting each other).
If you have two back-to-back 90-degree V-twins with a 180-degree crankshaft (one of the two "normal" arrangements for a V4 crank) then the primary shake of one will offset the primary shake of the other because they are 180 degrees out of phase. But with your 150-degree crank, they won't *precisely* cancel. It will be close, but not exact.
There will be some secondary imbalance with this layout, and there will be some uneven-firing-order roughness.
Even a straight 90-degree V-twin can be a reasonably smooth-running engine as long as the revs are high enough (to cover up the firing pulses) and the crank counterweights are correct.
RE: Engine shaking moments
RE: Engine shaking moments
RE: Engine shaking moments
PJGD
RE: Engine shaking moments
RE: Engine shaking moments
The question is, what application needs a 90 degree V-4?
RE: Engine shaking moments