Zasker1

So I am once again debating pullies and was curious if anyone knows if the KA24a2 is fully balanced & counterweighted like the RSX cousin K20A2
whereas the K20A3 does not, it has balance shafts added.

sauceman

The K24A2 has balance shafts. But to my understanding, that doesn't exclude that it's crankshaft could also be fully balanced and counterweighed. Both don't pursue and reach the exact same goals.

Balance shafts are designed to cancel out lateral vibrations caused by the whole rotating equipment, while the crankshaft balancing will only cancel the vibrations caused by it's own rotation. It doesn't include con rods and pistons. At least not that I know of.

Also, a balanced crankshaft will enable an engine to rotate quicker safely, while the balance shafts do not necessarily accomplish that. The balance shafts will however allow for smoothness in operation. We can see that with the TSX.

I would expect though that a big breather like the K24A2 revving at 7400RPM needs to be balanced at the crankshaft as well though.

JTso

iTrader: (2)

My H23 Prelude has balance shafts which requires an additional drive belt, but I don't believe the TSX has them.

TSX

sauceman

I'm positive the TSX has balance shafts. Such smoothness of operation would simply be impossible to achieve without them on a 2400cc 4cyl.

sauceman

Yup. It has them: http://www.acura.com/models/model_pe...sp?module=tsx#

Interesting how they call it a second order balancing system. I guess then the primary balancing system would be the crankshaft, and if we're really lucky, balanced con-rods and pistons as well.

Zasker1

Hmm if this is the case than maybe a set of UR pullys would not be so bad.

vwong

TSX has balance shafts



I think balance shafts are used in 4-cylinder engines that are 2.0L and up.

JTso

iTrader: (2)

Ha... I've found it (#1 & 2)! The shafts are inside the oil pump assembly, apparantly driven off the the main drive chain!



Edit: vwong beat me to it!

Zasker1

Hmm, I bet that picture would make a great Tatoo

ldubuc

As far as I know a 6 cylinder engine is naturally balanced, this is why BMW used a inline 6 in their 323 series and why Ferrari V12 is so smooth. This is inherent of 4 stroke engine.

The more you reduce the number of cylinder in a row the more you increase vibrations, these vibrations are called second-order harmonic. In order to reduce this, you have conter-balance shaft. These shafts run conterclockwise in order to reduce vibrations. On the TSX this shaft run at the double speed of the crankshaft. So when you hit the cutoff at 7,400 this shaft is already at 14,800rpm.
You are not to far from the speed encountered in a F1 engine (20,000rpm on crank). I don't know for sure, but you can't obtain this kind of engine smootness on the TSX whitout having both crank and balance shaft.

I am no mechanical engineer but someone out there can confirm this ?

ld

sauceman

About right.

Here's a good read about engine balancing. It's almost an art in itself. It's at least a very exact science.

http://www.babcox.com/editorial/ar/eb10330.htm

TinkyWinky

Where would you put it?