I recently installed a d1sc procharger(8 rib, 7.65 crank pulley) on my stock bottom end car. I have ported 243 heads with a 232/236 595/601 112 cam.

On a Mustang dyno with the converter unlocked, through a 12 bolt(3:42 gears), the car made 440 hp with 5.5 pounds of boost.

This is with the 4.25 blower pulley.


My question is how much more boost can the bottom end handle. I know everyone says that 8 pounds is the limit.

On a stock car the 4.25 pulley should make from 7-8 pounds.

I am thinking about putting a 4.00 inch pulley on the blower.

Is that too much or should I just leave it alone and be happy with it until I can get a good bottom end??



thanks everyone

 

I would shoot for 8psi


I ran 10psi with meth and got a cracked ringland.......tune was excellent and I was spraying meth......stock pistons just couldn't take it

 

i would leave it alone , enjoy what u have now till u can afford to upgrade the bottom end.Its no fun blowing up your motor and not being able to drive your car.Plus u never know what else blowing the motor could cause, which would cost even more than just the motor.

 

I guess I should leave it alone, but it's addictive just like the nitrous was. Plus I am running a little slower times than I was on a 100 shot.

 

Actually that was 12psi.... well, according to logs anyway

 

I know someone who had 8#'s of boost on a stock bottom end with all the supporting mods (intercoolers, good fuel system, tune ect.), and he didn't even make it to his first due oil change before he fried a piston (1500 miles).

This has been beat to death. Boosting a stock bottom ended car is a gamble, simple as that. If you're going to risk it anyways, your best chances are to keep the boost low (under 8#'s) have a good fuel system, good intercooler, meth injection, and a very conservative tune. Even all that won't garuntee you lasting a while. Most even with a setup such as I described last about 25,000 miles before something goes Even if you do make it a while, with the boost under 10#'s you're not going to see any killer power levels that could be had much cheeper otherwise. I just spent $3,000 in a heads and cam setup from TSP, and I dyno'd at 441 RWHP, and I am confident the motor will las another 80,000+ miles if I take care of it.

My point I am trying to make is this; if you want to go the boosted route, the best way to do it is to build the car to handle it. Bullet proof bottom end, forged pistons, all the supporting mods, suspension so it will actually hook, built tranny/clutch, rear end ect. You'll be looking at $15,000+ in parts and labor, but at least you'll have something reliable that will be a 600+ RWHP monster.

I never really understood why anyone would take a high CR car like an F-body, spend thousands in a supercharger, fuel sytem, intercooler, and tuning, and "try" to have it setup to last a little while all while putting down not too impressive RWHP numbers. Even then its all a risk on if it will hold together or not. If you only have that little to spend, just dump it in a H/C/I setup. You'll make the same power, but at least it will be reliable.

 

I expect to have the money to do the motor around november, I have the suspension for the power. I could always hook the nitrous even off the line.

I just didn't want it to blow the first time at the track. My tune is very conservitive 15 degrees timing with a 11.5 afr.

 

I went from a 4.5 to 4.0 pulley which netted me a cracked ringland. I wanted more and I got.. more.. sort of.

Now I'm running a 3.4" pulley on a forged bottom end.

I've got my old 4.0 pulley for sale if you want it.

 

Thats no way to sell a pulley........lol....... I already have a 4 inch pulley, just don't know if I need to use it or not. It looks like I need to wait about that until I have the motor ordered.