Cogged Pulleys and Boost.

[stevieturbo]

I am soon to be putting together my engine.
Its a 5.7 LS1, with a YSi. However, the pulleys I have been supplied with are 50mm Gilmer, 86T crank, and 34T SC which they claim will be about 9psi.

Does this sound right ??

I just have a bad feeling that with such a big crank pulley, im going to end up with a lot more than 9psi ??

Most other crank pulleys on different engines are only about 77T or thereabouts, with similar SC pulleys.

[BLOWNBY]

At 6,000 RPM, the blower will be spinning at around 52,350 rpm's. My 8 rib setup with 8" and 3" had the blower spinning at 55,000 rpm's at 6,000 rpm, not considering any slippage, and made about 16-17 psi. And this to was on a 351. I would say those cogs would net around 15-16 psi, since there will be no slippage.

Hope this helps.

Steve

[stevieturbo]

I calculated the rpm's myself, and I thought them to be rather high considering the size of the supercharger.
I would have thought at 9psi, it would have been spinning much slower. CAPA in Australia supplied the parts, so i would have though the knew what they were doing..

I take it that its experience that decides what sizes to use for a certain level of boost, having tried and tested various pulleys ??


Initial spec will be LS1, ported heads, LPE GT2-3 cam, MAC headers ( assuming I can get them to fit ), and the YSi, + fuel system to suit, forged pistons, on an otherwise stock bottom end, CR should be aboout 8.0:1, and a good IC obviously
Pump fuel only.