Question on Crank Pins

[Porker]

All V8s have 4 crank pins and cross plane V8s' crank pins are separated by 90 degree angle from the other.

 

Question... does it mean that all crank pins will be separated by the formula below...

 

360 (degree ie. one full circle) / No. of crank pins ???

 

That means inline 6 crank pins are separated by 60 degrees from the other...

 

Please enlighten

[Decksurgeon]

V8 crankshaft have 2 variations. one where the V8 crank pins are 180deg from each other i.e. if you put the V8 crankshaft on a flat surface the crank pins are flat on the surface.

 

the other type of V8 is a cross plane when you get the pins at 90deg from each other.

if you put thisd on a flat surface you will not be able in the first place as the crankshaft has crank pins at all 4 'corners' when viewed along the axis (90 deg seperation).

 

the seperation angle of the crank pins are carfully calulated by the engine manufacturer and designers.

they basically want to make the engine as smooth as possible.

 

in a 4 cylinder this is never possible, that is why they have balancer shafts on a 4cyl. ditto the V6.

in theory a straight 6 and V8 will have zero 2nd order differential equations giving perfect balance.

 

you can have a 60 deg seperation angle 6 cylinder. but the manufacturer can also make it 180 deg in a flat crank for a 6 cyl so your equation does not hold.

 

at the end of the day, the manufacturer is only concerned with the smoothness balanced with the cost of manufacturing.

Edited December 15, 2006 by Decksurgeon