I was chatting with my father (a long time Porsche tech) about my next mod--which was UD Stillen pulley-- and he said it didn't free up any power. He said
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12-17-2014, 12:47 AM | #1 (permalink) |
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Underdrive Pulley: Useless?
I was chatting with my father (a long time Porsche tech) about my next mod--which was UD Stillen pulley-- and he said it didn't free up any power. He said it was completely useless to underdrive the accessories because 1. when you're going in a straight line or dyno'ing you're not putting the power steering under a load, 2. when you're battery is fully charged there is very little load on the alternator, and 3. if you're A/C if off you don't have the AC clutch engaged and the pump is under little to no load.
These accessories are basically free spinning and drain very little power from the system so why waste money on an UD pulley? Got me thinking... |
12-17-2014, 12:49 AM | #2 (permalink) |
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... Holy crap...
It lowers rotational mass... And why spin the accessories when you don't need to?
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12-17-2014, 12:58 AM | #3 (permalink) |
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Underdrive pulleys usually are a performance enhancing item that increases the torque and horsepower output of an engine by reducing drag caused by belt-driven accessories.
Horsepower gains from underdrive pulleys alone are usually around 4-7 hp. |
12-17-2014, 04:53 AM | #5 (permalink) |
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Was debated here ................
Stillen U.D. pulleys help. IMHO opinion, the benefits are outweighed by the drawbacks, and since I am an old f4rt, I agree with your father Last edited by BGTV8; 12-17-2014 at 04:57 AM. |
12-17-2014, 10:12 AM | #6 (permalink) |
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learn something new every day
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2 plus 2 times 2 = ? ... hint, it's not 8 Stillen CBE, Stillen Gen 3, TP's, Uprev tuned - 324whp/264tq |
12-17-2014, 01:04 PM | #10 (permalink) |
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My 2 cent on this. Why take a chance with the underdrive pulley. It's well known that our our oil pump isn't the greatest. And any new induced harmonics on the end of the crank will have some affect on it. For a DD, it may take awhile. But for a trackday car......tick..tick...tick...tick...tick.... I've seen a couple of V8s with broken cranks. All had an underdrive pulleys. So from what I've seen. I don't what to take that risk for a couple hp.
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浪人 - 殺し屋 "The Difficult Anytime, The Impossible By Appointment Only" http://www.the370z.com/members-370z-...o-journal.html Last edited by Rusty; 12-17-2014 at 01:07 PM. |
12-17-2014, 02:01 PM | #11 (permalink) |
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I think the OP is talking about things like the oversized (to under drive) alternator pulleys and such -- I don't know about the difference they make, but a lighter crank pulley will definitely make a few extra ponies.
Of course, you are putting faith in the presumption that all automotive engineers are dampening the harmonics produced by their crank pulleys because they have nothing better to do...
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Enjoy it. Destroy it. Last edited by Jordo!; 12-17-2014 at 02:18 PM. |
12-23-2014, 02:32 PM | #15 (permalink) |
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I went against my ole man's recommendation and bought UD Stillen from Elmo370z
Stillen U.D. Crank pulley I hope my harmonics aren't affected |
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