Quote:
Originally Posted by BMRLVR
Here you go again!!! Remember what I mentioned to you in my last reply? Kyoshi71 is another one of the members who will give you the facts and no BS. If you keep rebutting answers to your questions with condescending remarks no one is going to respond any more, or the people who respond will only be the people who don't know.
I did read your apology to Kyoshi71 so I see you are realizing what we are all telling you.
Now on to the topic:
To touch on what Kyoshi71 was telling you about the pulleys reducing the rotational mass of the accessory drive system here goes: The reduction in mass of the accessory drive system is part of the power gain however the effective gear reduction is where most of it comes from. Think about riding your mountain bike....... The smaller chain-ring the chain is on, on the crankset (same as the crank pulley on an engine for all effects and purposes) the easier it is for you to pedal. The smaller chain-ring will not allow you to go as fast but it allows you to move while exerting much less energy onto the pedals.
So the underdrive crank pulley does two things to gain power. 1)It loses mass and therefore rotational inertia. 2)It gives the crank pulley more mechanical advantage to turn the accessories (and turns them a little slower as a result of that gear ratio change) so there is less drag on the engine regardless of wether the M3 disengages the alternator and AC under load or not.
In a way the underdrive pulley does the same thing as a lower ratio differential gear set. The big difference is that the power gained from a crank pulley is actually the result of less power being used to turn the accessories. This power is instead sent to the driveline through the PTO of the engine instead of being wasted driving the accessories. Differential gear sets don't make any power, they just give the engine more mechanical advantage to turn the drive wheels.
The only possible side effect of an underdrive crank pulley is that a low engine speeds (under 1.5KRPM or so) the power steering pump volume will be less and may make steering wheel effort slightly increased. This effect will most likely be extremely slight and I hear no complaint from members on the forum that use an underdrive crank pulley. A possible plus to this would be lower PS oil temps on the track since the pump would spend less time going over relief since the volume would be slightly reduced. When any hydraulic pump is over relief for extended periods of time the oil heats up.
I hope this helps!
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Correct
There are no issues running a properly designed underdrive pulley on these motors.