Forced Induction - More Boost?

I have the D1SC supercharger and i want to get more boost into the motor. How do i accomplish this without exceeding the max propeller rpm of the charger? I have forged pistons and yada yada........ I only get abour 8 lbs now. I want about 12-14lbs.

Go with a smaller pulley. What size do you have now?

Well i think it's a 3.??. it's pretty small and i think that it is close to it's max propeller rpm

No way that you are maxing the D1. My P1 puts out 10 psi with a cam and 3.4 pulley. Before you go any further you have to find out your D1 pulley size.

There should be a size stamped on the side of the pulley. If you have the eight rib set-up, my guess is you have a 4.25" to a 4.50" pulley. Do you have the older six rib assembly? Bob

No it's the 8rib. I put a bigger cam in the car and when i did i lost some boost so i put a 3.70 on the charger.

When I switched froma 3.7 to a 3.4 I got 3 extra pounds of boost for a total of 10 psi. You should get at least the same by going smaller.

The max on a D is 62-65000 rpm. Crank pulley divided by s/c pulley x engine rpm x 4.1. Go smaller on the s/c or bigger on the crank and tighten the belt. You should easily get 12 psi @ 6300 rpm.

The max on a D is 62-65000 rpm. Crank pulley divided by s/c pulley x engine rpm x 4.1. Go smaller on the s/c or bigger on the crank and tighten the belt. You should easily get 12 psi @ 6300 rpm.
Thanks for the formula to get this figured out. Now i need to measure the crank pulley.

Thanks for the formula to get this figured out. Now i need to measure the crank pulley.

I believe it is 7.65". Bob

I think i need to upgrade to a F-1 head unit. Got any?

I am wondering if you have your belt tight enough. It needs to be tight as a fiddle string so to speak. You should be able to get at least 13 or more lbs. With the 7.65 and a 3.7 you should be at 57.643 rpm at the blower at 6800 rpm, and 59.339 rpm at 7000rpm. If you went with a 3.4 you would be at 62.730 at 6800 rpm. I would make sure the belt is so tight it will almost twang when you snap it with your finger, and that it is not contaminated with oil or some fluid. You should get more boost than what you are getting with the pulley you have. Check all the rubber for leaks, I would check the whole system, every square inch. I have the 7.25 crank pulley and the 4.00 blower pulley, with the parts in my sig and I have 11lbs at 6800, just as an example. I would check every avenue, before investing in the F1. Then when you have all you can from this one, and are ready for more, get the F1. :devil: :devil:

I think i need to upgrade to a F-1 head unit. Got any?

When you're ready, I can get you one. Bob

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PM returned, thanks. Please call me at 260 244-4808 for the price, per ATI's low pricing guidelines. Bob