Obviously they help with cornering as the weight reduction is unsprung weight, but I wonder if because they are lighter overall as well if it will help somewhat in acceleration, as any lightening procedure of any significance should also do?

 

Minimum at best. On the quarter mile they figure every 100 lbs you save in weight is worth 1 tenth of a second. Or adding 10 hp is worth 1 tenth.

 

-100lbs=10hp?

 

well, not the hp/weight scenario changes significantly when you start getting into fast cars

 

In Rotational Mass (intertia), I am certain different logic applies.

 

I would think acceleration should be significant, but I don't understand how they would help cornering.

G

 

yes they should help everything. They help acceleration
because of the light weight, *and* because this is rotational
weight the polar moment is smaller so the disk provide less
resistence to spinning up. Lastly, they help handling because
they are unsprung weight (less) so after a bump, the
suspension can push the wheel back down onto the road
quicker. The tire stays on the road and you get more stick. The
shock absorbers need less damping too.
Joe

 

It should help somewhat. Hard to know the magnitude of the effect, but think of the physics. An engine is a device for putting out energy (power being energy per unit time). So, where does the energy from the engine go when you hit the gas in a straight line?

1) Heat (engine/tires etc.)
2) Overcoming friction in the drivetrain (hence dyno RWHP numbers being lower than flywheel HP)
3) Pushing air out of the way
4) Spinning up the rotating components of the drivetrain (all the way from the crankshaft to the wheels, including the brake rotors)

Total engine energy is the sum of those, so when you put on the PCCBs, the 4th one is reduced, leading to an increase in the other three, which requires you to be going faster. This is why people put lightweight flywheels on their car (well, one of the reasons anyway). This is also why the F1 teams don't win any races with 24" spinners.

And everything Joe said about handling benefits was spot on, too.

 

Well, my Turbo S feels a heck of alot faster than my '02 Turbo. How much of this seat of the pants difference is due to the seemingly underrated X50 versus the PCCB is for practical purposes untestable. I do notice that the car feels *lighter* on turn-in and seems to *set up* for corners more easily.

Unrelated, but it also seems that the speedo is more accurate and less optimistic than in my previous car.