Why is a V6 or V12 "smoother" than a V8 or V10?

V12's always get a man closer to Pi......

 

Pi are square, cornbread are round?

 

but cheesecake is sweet!

 

I believe the more cylinders in a line, the smoother the engine will be. It helps to balance out the movement of the engine's internals.

Thats the best response I can come up with..

 

doesnt it have to do with the balancing of the internals though. toyota's UZF V8 engine is incredibly smooth, apperently one of the smoothest!

 

Real men know the difference.......

 

http://www.autozine.org/technical_school/engine/smooth1.htm

The more cylinders you have, the more power pulses there are per revolution. In a V12, you get a power pulse every 60 deg. of crank angle.

An inline-6 is slightly better balanced than a 60 deg. V6 due to a slight end-to-end vibration which is cancelled out on an inline-6. V12 acts like 2 straight-6's, so end-to-end vibration is cancelled out plus you get more power pulses per revolution which smooths power delivery.

Pi may enter into the equation somewhere, but I don't think it's quite that simple.

 

On the other hand, five cylinder inline engines, or V-10 variants, are clearly Satanik, having consorted with the pentagram and the mystic ratio PHI*.

*QV on the wheelvase thread.

 

I apologize if it was not meant in jest - I guess I took it wrong since it was not in "technical".

 

.........and speaking of smoothness, gonna go to Shershah for lunch!

 

and Pi for dessert?

I've seen your better half - you lucky bastard!

 

There are two common terms related to internal engine balancing, primary and secondary engine balance. It is possible to achieve perfect balance in one of these, but only a few engine configurations have inherently both perfect primary and secondary balance. A non-flat plane V8 (not sure of the term) like a Chevy small block has fairly poor balance characteristics. A 5-cylinder, with its odd number of cylinders is also never going to be very smooth, even with the use of balance shafts. If you asked about a 10 cylinder because it was used for a decade or more in F1, as I understand it the universal adoption of the V10 had more to do with the best compromise of weight, rigidity, power, and fuel consumption between the V8 and V12. It wasn't because the engine was smooth.

This subject is very important to motorcycles, and probably much more noticable. A Ducati twin has perfect primary balance, but a slight secondary imbalance due to the offset connecting rods of the V-twin. The engine is very smooth (compared to say a Harley), but has a few points in the rev range where you can feel the secondary balance "thrum" of vibration that is more engaging than annoying. The Japanese inline fours are very well balanced (but an I-4 is never perfect) which allows the engine to be rigidly mounted in an aluminum chassis, greatly increasing overall bike rigidity.

 

If manliness is a function of smoothness, Wankle Rotary owners are Hercules.

 

How about the Vtec challenge ?.

 

Don't forget bore/stroke ratio's involvement. The more stroke you have the further the big end bearing leave the center of rotational mass on the crankshaft. The further that mass leaves that point, the larger the magnitude of force gets applied to the direction that is out of phase with what the rest of the cylinders are doing in that bank (if you have do not have enough pots on that bank to cancel eachother all out)

It's easier to balance large bore / less stroke.