Underdrive Pulley thoughts

wstar

The GTM writeup was based on an SC install where they had to remove it. The important bit there was that the Aluminum pulley had virtually welded itself to the crankshaft due to metallurgy/torque/heat over time. They had to go after it with a torch and a giant 3/4-drive torque wrench and barely got the thing off. So yeah, if you ever want to remove it easily, don't put an Aluminum pulley on the crankshaft

That issue aside, the other important point is if you ever plan to do an SC, you'll probably want to take it off because (a) the pulley gains are pointless at SC-gains levels, and (b) you'd have to account for it with custom SC-pulley diameters to get the intended PSI from your SC, which is a needless pain.

The harmonics thing: nobody will ever conclusively resolve that issue. It's been debated for years on so many different cars, and someone will always disagree strongly one way or the other. If there's a real harmonics issue, the oil pump is the least of your concerns. The big issue would be failed crankshaft bearings wearing them out from the excess runout from the harmonics, or total crankshaft failure at high RPM. Personally, I have yet to see a case on an engine comparable to ours where the pulley was definitely to blame for an engine failure. I'd think the numerous companies selling pulleys like this for all makes and models of performance car out there would've been sued out of existence by now if that were the case.

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