using a 90 degree crank on a four cylinder engine

[r4360]

i have been wondering if you use a 90 degree crank on a 4 cyl. 4 stroke engine, firing a cylinder every 90 degrees, then pause one revolution for the engine to do its four cycle thing, then fire them at 90 degree intervels again, would this be a smoother, and better sounding engine, above idle speed, and make more power. i know that some motorcycles that are vertical twins use a 180 degree crank and fire the cylinders 180 degrees apart, and pause one revolution, and fire them 180 degree intervels again

 

[JStephen]

I would think it would make a rougher running engine.

As far as that goes, why not just have them all four fire at the same time?

 

[007Driver]

Hello,

I do not this that type of crank you describe is a dynamicly balanced crank. I have done work on drum style brush cutters and balancing was a big problem. Its easy to build a STATICLY balance crank shaft, but when it turns it could shake like mad. Thats why you see cranks in funny orders. The 180 crank shaft it easy for the cylinders are staticly AND dynamicly balanced. Check out some Vector Mechanics books for static and dynamic situations. You must take into account the impact loads of the cylinders to see if it with shake its self to bits. Good luck