Hey guys. New to the forum. I came here because I'm planning to build an old ('61-'93) Pontiac 4 cylinder using an M90. I already have an M90 to play with (porting, pulleys, etc to do yet) but I've been reading up on twin charging. If I understand it correctly, you are using the supercharger in it's stock location, using it for it's low end response capabilities, but running a turbo into the blower. I think I have a handle on all of that. My installation is completely custom. The M90 will set on a custom plate mounted off the side of the 4 cylinder, which means it can set in any installed location within the engine compartment. Owing only to a belt drive connection.
Here's my question. Has anyone ever used the blower to drive the turbo?
I understand that what you are doing in a normal twin charge system is using the low rpm response of the blower and then using a turbo with much more potential air flow for higher rpms and power. But then the blower eventually becomes a restriction. I saw mention using the internal bypass before the rotors to open a larger pathway thru blower, which has got to help a lot under turbo boost.
My thought is to drive the M90 into the turbo to spin that thinking that it may give the turbo some spin up right at idle and just off idle. Then the turbo can go thru an intercooler and directly into the motor. But my questions are, can the M90 develop enough pressure/flow to properly spin the turbo at low RPM (off Idle) to make any pressure for low rpm response, and conversely, can it make enough pressure/flow to spin the turbo up at mid and high rpms?
I have no info to go on that would tell me whether the blower can do this or how much pressure/flow is required to do all of this. I was just brainstorming this as the supercharger can heat the air as much as it wants, it will not hurt the turbo. What little heat from the supercharger will be so much less than the exhaust running thru it and heating everything in the engine compartment. The turbo will still heat the air from the compressing, so I would still use an intercooler. The exhaust system is completely free of any restrictions but you will still have the drag from the supercharger.
Again it would be whether the supercharger can flow enough to spin the turbo up to make any appreciable boost? Can the blower make more pressure down low than the cars exhaust?
I hope I explained this right. It's just a brainstorming question, as I may end up doing a single turbo and be done with it. But that old Pontiac 3.3 liter 4 cylinder is half of a 389 so it can run some pretty big porting/valves and a pretty big cam, so it will be lacking low end grunt. I thought the regular twin charging system would fit that bill. The supercharger spinning the turbo is just another design off of that.
Thank for listening guys. I appreciate all the experience in this forum.
Mark L
