Boost control for supercharger (in cabin)

[GazM3]

Hey chaps. I’m running a m60b40 with a vortech fed with e85 up to around 1bar boost. Had a hose pop off which I have to remove the bumper to fix. As it’s before the blow through MAF, all the air fuels are still good though the rev range at various throttle loads. While driving with no boost the car was actually quite entertaining to drive through the corners at pace. It got me thinking about dialing down the boost from in the cabin would be quite useful for wet weather or when others drive it etc etc

Im a novice to the forced induction thing but perhaps could plumb in some sort of low spring pressure wastegate (say 4 psi) to the high pressure side then use a solenoid with an adjustable in cabin controller to have boost infinitely variable from the wastegate spring as a minimum up to what the boost is when I have it fully wound up.

Am I on some mind altering substance or will this work?
Discuss

[pbonsalb]

You cannot easily change boost like on a turbocharged car because the blower is connected to the crankshaft and there is no easy way to alter that relationship. A few people have experimented with bleeding off air, but the blower is still working just as hard and the tune might not be mapped well enough to support the loss of expected air.

[Matt Cramer]

I'm not a fan of bleeding off air that has already been compressed - it may make sense for an emergency boost reduction, but not for something I'd want to leave on all the time. If you are up for some major fabrication, the best way to control boost would be some sort of variable drive ratio. I've seen cone-type CVTs used to control boost on one Procharger kit - another possibility might be to use a two speed planetary transmission.

[GazM3]

That sounds pretty complex. Yes the boost adjustment is for the odd occasion. I’ll speak to my buddy in electronics to make a 12v variable and adjustable pressure switch to use on a 12v solenoid.

[pbonsalb]

I don’t see any reason to bother. If you want less boost, use less rpm. The bleed off can cause issues because most centrifugal tunes are draw through so you are venting pressurized air for which fuel has been metered. If you had a blow through tune, and vented before the HFM, it would work better but still not be very efficient since the blower is still doing hard work.