With a 540 with all the good stuff in side, Can I run a 250 B&M blower with 4-5 lbs of boost with out blowing head gaskets everyday ? I know cylinder pressure is increased with boost . With 8.6.1.compression I ran 7 lbs of boost with no problems in a 454 and a 502.Next question is If my dyno numbers are 575hp at 5100 rpms and 635 ft lb of torque what kind of increases could I see With the 4-5 lb pulley ? I also run gil offshoe exhaust would I have to upgrade to a cyclone or CMI type exhaust ?

The Gil's will be OK, I would run no more than 4 LBS boost with 9:1 CR. Talk to Dean Nickerson as he has done many of these setups with higher static CR.

I doubt that you'll be able to make 5 pounds with the B&M 250 on a 540 unless you're overdriving the daylights out of it. I think you'll be more than happy with 2-3 pounds, which will also be acceptable with the 9:1 c/r.

Dave, there you go thinking again. Get back on the drugs and stop working so hard.

Sorry, Payton. I should know better than to think,,,,,,,,,
How you been? We should get together for a drink, maybe with Steve AKA Rampage too. Maybe even at Steve and Maria's place.

I have a 420 blower running a little over 5 pounds with 9 to 1 comp. on a 572 ran the boat all summer with no problem. I think what will limit your boost is the size of your blower with respect to the size of your motor too much boost will create a lot of heat with that size blower. I wish I had a bigger blower like a 10:71 but I am trying to sell the boat.

Boatman here are some pics of a 540 ci we finished in Dec. for a 35 here in Miami with the 250 blowers the customer had originally 454s with the blowers and wanted more HP and torque so we went with the 540s and ported a set of heads for him and set him up with carbs and hydraulic roller set up the engines made 788HP at 5400rpm and the torque was a flat line across the board from 780 ft lbs at 3100 rpm to 832 at 4400 rpm and coming back down to 785 at 4800 rpm the pulley I used was a part #155193 and made 5 lbs on pump gas carbs were 650 cfm double pump and pri 65 jet sec 67 with 4.5 power valves and 33 degrees of timing.

I ran a 598 ci with 8.75:1 comp. and 9#'s boost all summer with no problems. I think may have been a little aggresive but that was the way my builder dynoed it and it worked fine. I am running aluminum heads which is suppose to help.

The heads we used were a set of new GM castings the customer supplyed us with and we remachined the seats and the ports for the combo Sincerely Laz Mesa

But what compression ratio are you guys running ?