Hi guys

My setup is 7.5:1 comp ratio non intercooled with alluminum head timing is 31° full in at 5000 rpm ru n on 91 otane. I have try two top pulley on that 250 blower
the 3.65" boost it at 5.5 psi and the other pulley 3" boost 10.5- 11psi.
So i think the best boost level with the engine setup that i have it will be 8 psi of boost.

Any suggestion would be great.

Thanks.

your safer with the 3.65 pully @ 5.5 psi,,if you go any higher you will need a intercooler...

with a 4 in stroke,and 7.5 compression ratio,i think you can safely run 7 or 7.5 lbs of boost,also,get the total timing up to 33.

Yes 4 in stroke but this question is for what reason?

I also think I'm safe at 7.5 psi of boost I will try a 3.25 in pulley
i think i will be right there. with the 3.65'' the boost is 5psi and with the 3'' pulley i have 10 psi of boost.

Directions give some suggestions on boost levels: https://dl.dropbox.com/u/42339868/25...directions.pdf

the comment on the 4 in stroke was not a question,with a shorter stroke their is less dwell time at tdc,so you need a little more total timing.

I ran almost 8# with no chiller on my 525SC with a bigger roller cam. Total timing was set at the stock 35*. I always ran 92 or 93 octane fuel. I had it jetted a little rich to be safe. I think I ran 102 primaries and 103 secondaries, but not 100%.
I would probably run a pulley around 3.4" or so to make 7-8#.