I am wondering the maximum overdrive on the square port (94-95) supercharger. I have a 10% od crank pulley and a 10% od supercharger pulley. I am wondering if that combination will be too much. I have ported the stock exhaust manifolds, upgraded the exhaust (true dual 2.5"), upgraded to a stage 1 camshaft, 76mm MAF and throttle body, 3" intake and also ported the heads. I have 42lb injectors and a 255lph fuel pump so exhaust, intake and fuel should be good. Any input would be appreciated.
Max boost on square port blower.
- Thread starter StevenL72
- Start date
20% is probably a bit much for that combination. You will wind up creating a lot of heat, and probably not make much if any more power. With what you have, I would use just the 10% crank pulley, and that should be good. If you want to step it up to 20%, I would want to have at least a MP inlet and a FMIC.
Yes, the square port does flow better, but the inlet is still a significant restriction. The more of a restriction you have on the inlet side, the more heat you will generate by spinning the blower faster. With a stock inlet, I wouldn’t go more than 10% total regardless of which blower. You can stick with the blower pulley and leave the crank pulley stock, I only suggested the other way around because that would be less likely to result in belt slip. I have a 10% blower pulley on the XR7, but in order to avoid belt slip I had to both swap to the heavy duty tensioner springs and also clock the tensioner for the supercharger belt. If you have stock tensioners in the stock positions, a 10% blower pulley usually results in belt slip.
What exactly do you mean by the mp inlet? The square port blower has the matching inlet.
Magnum Powers makes (or made, not sure if they still make it) an inlet for the square-port blower that has a much larger opening from the throttle body to the back of the blower. The factory inlet is only about a 60mm opening. With porting, you can open up the throttle body side to 70mm, but it will still neck down where it curves into the blower. The Magnum Powers piece has an 85mm opening, and is pretty much that large all the way through. It is much less restrictive, which helps the blower breath much better at higher OD speeds.
Not knowing anything about your car or tune. You will now be making more torque lower in the rpm so at torque peak you might need to pull timing. If auto you can shift at lower RPMs since you will be making 50-75 more for pounds of torque ( guessing ) at lower rpm. Fuel and timing tables might need tweaking since you will now be running at higher load then before, depends how good your tune was written.
Again not knowing your goals I would upgrade anything to do with intake side of the SC. Your are spinning that blower at around 18k rpm taking about 80hp to spin and sucking through a straw.
Again not knowing your goals I would upgrade anything to do with intake side of the SC. Your are spinning that blower at around 18k rpm taking about 80hp to spin and sucking through a straw.
Blower OD is not a magical power adder. It can help if the inlet is opened up enough to accommodate it, or it can be used to shift the power to a lower rpm, but without opening up the inlet, more than 10% OD will not yield any more power, and may actually result in less power due to the increased heat and increased parasitic loss from turning the blower faster. If an MPX isn’t in the budget right now, here is my recommendation for a good budget setup:
Buy a Magnum Powers inlet
Buy a 75mm TB
Buy or build a front mount intercooler, or at the very least a double intercooler
Spend some time porting the blower inlet
Run 15% OD with that combo and a good tune
That obviously will not match the power level of a MPX, but that combo will make for a very fun car to drive on the street, and the intercooler will be needed anyway for any future blower upgrades.
If you want to go one step further, also get an 85mm TB, 4” inlet and a slot MAF or 90mm Lightning MAF. All of those upgrades will be needed down the road for the MPX anyway, and will also benefit you with an MP inlet and ported blower. You also might need larger injectors with that combo, so plan for that.
After doing all that, when the time comes for the MPX, simply swap blower and inlet for the MPX pieces, and maybe bump the OD up to 20%, and resell your ported blower and MP inlet to offset the cost of the MPX.
Buy a Magnum Powers inlet
Buy a 75mm TB
Buy or build a front mount intercooler, or at the very least a double intercooler
Spend some time porting the blower inlet
Run 15% OD with that combo and a good tune
That obviously will not match the power level of a MPX, but that combo will make for a very fun car to drive on the street, and the intercooler will be needed anyway for any future blower upgrades.
If you want to go one step further, also get an 85mm TB, 4” inlet and a slot MAF or 90mm Lightning MAF. All of those upgrades will be needed down the road for the MPX anyway, and will also benefit you with an MP inlet and ported blower. You also might need larger injectors with that combo, so plan for that.
After doing all that, when the time comes for the MPX, simply swap blower and inlet for the MPX pieces, and maybe bump the OD up to 20%, and resell your ported blower and MP inlet to offset the cost of the MPX.
I already have the 75mm tb. There are no double or front mount intercoolers available any more. I would love to buy a double intercooler and the front mount is also no longer available. Same with the magnum powers inlet, no stock but still showing on the website.
Canada, it’s like they want you to be the working poor. Seems it’s time to learn how to weld and fabricate. The MP intakes are not that great and that’s why I bought just the MPX case and will make my own intake plenum for it. I’m sure you could piece together a front mount intercooler and piping easily. I was 18 when I started putting this sc engine in my 1994 mustang that was still under warranty. The IC is 2 SC intercoolers made into a large front mount. I got 3” pipe from a dairy that was re-plumbing and bought a cheap tig and learned to weld. Ironically my Canadian friend drove down to buy that tig off of me because it was about 1/2 of what it would have cost him
