Quote:
Originally Posted by mrg666
And it is not all about weight. There is vibration to consider as well. Reciprocating and rotating masses contribute to vibration differently. That is why race engines require a certain mass on the crank pulley. Because, while lighter crank pulleys improve throttle response, they cause vibrational power loss at high rpm. This has been discussed so many times but anyway. If I change my crank pulley, it will be Fluidamper which is not light but designed for damping of vibration at higher revs.
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Quote:
Originally Posted by SuperTom
Looks like it mainly better for motors that stay in high RPM's all the time. The stock & Lightweight pulleys had better #'s in the torque dip range where the Fluidampr picked up top. It looks we are only talking about 2hp either way which could be influenced by other factors such as where the IAM is at 1 or lower during the run.
The one thing for sure is that weight is easy and accurate to measure and I know with my pulleys I saved 5lbs off the front of the car.
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Depends how you want to present the data and the kind of the racing application. If you do a 5th gear dyno, then Fluidampr might give the theoretical 2hp top gain cause of the less vibration. However, on small race tracks or mountain roads you rarelly work on high gears. You are interested much more on corner exit speed acceleration mainly on 2nd or 3rd gear. Over there a lightweight pulley will have the advantage cause of the less rotational inertia. On 5th gear this advantage is lost and it doesn't show on a dyno because the RPMs are rising much slower. Additionally, as very well pointed by SuperTom in most racing applications you don't stay all time in high RPMs. Maybe NASCAR might be an exception, but these cars are not relevant with this area if you don't swap a motor.