Quote:
Originally Posted by 68WarDog
Why would anyone want to underdrive the waterpump and alternator?
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Typically, Pontiac had their non-A/C engines underdriven by 8 to 15%.(water pump driven at 85-92% of crank speed).
The CVF pullies I have on my non-A/C GTO are both 6.2", (crank and WP), for a 1:1 ratio, (or 100%). The High-flow that CVF offers is the same 6.2 wp pulley with a 8" crank, for a 129% overdrive. I'm going to try a 8" wp pulley to underdrive it to 77.5% of crank speed. My engine idles at 1000, (manual trans), so the water pump will still be turning at 775 rpm. I run a flex fan with no cooling issues, but I don't like the fact that the fan is turning 6000 rpm at my shift points. By underdriving it 77.5%, at my 6000 rpm shift point, the fan will now be turning only 4650 rpm. Less stress on the fan blades and less drag.
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66 GTO, 495, M22, Strange S-60 w/4.10
Sold new at Royal Pontiac (Dealer# 07-679)
70 Formula 400/auto