Lawnboy

iTrader: (54)

A D1-sc with 4" pulley and 7.65 on the crank, how much boost should i see
stock LS1 (346) stock heads + Cam with FLP long tubes, no cats.

EPP

iTrader: (22)

Probably around 12 psi, too much for the stock bottom end. A 4.50 pulley will normally get you 8 psi. Bob

lmt0705

iTrader: (7)

sick it on there, break some ring lands then get a forged short block then you can put a 3.4 on it and get 16 psi just kidding stick with the 4.5 or the 4.25at the most, but your tune better be real safe

Lawnboy

iTrader: (54)

the 4.5" is slow for me, 4.25 made good power ,

Jake@EPP

A 4" would be playing with fire definatly. Its allmost not worth it anymore to get max hp out of a stock piston motor. Parts will break at the added stress, regardless if the tune-up is good. I remember seeing one member on here explode the engine + trans in a video, not pretty and had the possibility of harming the driver (oil down).

If it was my car, i would fly with the 4.25. While i was doing so, i would be building a new engine so if that one goes i have something to look forward to.

Lawnboy

iTrader: (54)

I have a realy rich tune, i was at 11.2 A/F with the 4.25 pulley a 9-10 psi
And 11.0 on methanol, just spraying a little meth, my timming is back to about 18-20 degs,

I figered the 4.0 pulley would lean me out a little on gas and then i can put more methanol into the A/F

lmt0705

iTrader: (7)

while the tune is important its not the issue here, its the power and stress on stock components that is the problem, you could be at 9.5/1 AFR and you will still break stuff quick if your pushing 500 rwhp or more enjoy what you have at a safe level till your ready to do a forged motor, dont blow yours up and have the car down for months

Lawnboy

iTrader: (54)

I hear ya

EPP

iTrader: (22)

I agree John, I've seen it happen too many times. Bob