I am planning to do something "experimental" to this old engine. In an 88 S4 N/A, I wanna fabricate brackets and mount a roots-type blower. I plan to put them where the power steering and AC used 2 be. Also, I'll have to move the battery, coil packs, etc. The intake is in the rear side of the blower. The discharge will be out the top. How will I have to plumb it into the intake ( which is fed from the other side of the engine compartment)? Can I simply plumb it to the AFM and then to the UIM? What about the metering oil pump, do I have to worry with it? Anything else? Oh yeah, is a BOV necessary? Any other tips or information will be helpful.

Sounds like it'll be fun.. but not too familar with superchargers..

bov is not nessicary. id look for a different type of blower. like a vortex for a stang or something that has the inlet towards the front, and outlet to the right side so you can plumb easier to the uim.

I just noticed I posted this in the wrong forum. Shoulda' been "Performance Mods" or something.



So a BOV isn't necessary? Then where does all that extra air go? Like @ idle speed, U don't really need air being forced in. Papasmurf, the type of blower U R talking about is a centrifugal type. Mine is a roots type. The reason I chose it is because it is made more for low end power (torque). There are exceptions, but most centrifugals are made for mid-range power. Then U have turbos for top end power. I've already got all the mid-range power I need and definately enough top end. I just need some bottom end, which is why I got a roots type. Yeah, it would be a lot easier to plumb, but it's not what I needed. An FD & 2 Mustangs, man, you're livin' the life!!!

You need to remember that the level of boost a supercharger makes is directly tied to engine rpm. At idle the supercharger isn't spinning fast enough to make boost so you don't need to worry about it. People always say superchargers are better because you get boost down lower. This is true but the down side is they don't make full boost till the red line. For example if you ran a supercharger and I ran a turbo both set to 20 psi with an 8K read line. Sure you may have 5 pounds of boost at 2K where I have none, but from 4k to 8K I have 20psi. You won't see 20 till the read line. It all depends on what you are building the car for.



Has for the BOV, I would still use one. Superchargers usually don't have them because they are running low boost, so its not has important. Also most roots blowers mount right on the engine and provide no place to put one. Roots blowers tend to be inefficient, so I hope you intend to intercool it.

I'm not to familiar with Blowers, but as far as I know, I've never seen or heard anyone run em more than 6-8 PSI. Why do they run em so LOW, I mean, how much boost could a standard Eaton Blower produce?

Actually they are the more efficient ones. It is the only type you see on factory supercharged cars. The car I got it off of had 213,000 + on it. Yes, it has an intercooler. It was built into the intake on the car I got it off of. Comparing a SC to a turbo is like comparing a rotary to a conventional piston. It doesn't produce near as much boost, but the same power. Look @ all the pro's. Do U think John Force uses a turbo? No, a roots type. N E wayz, the setup I'm going with is similar to the car it came off of. A Turd Bird Super Coupe. The blowers were mounted upside-down on the intake of these cars. Then the air was plumbed into the stock intake. i'm doing the same thing, except mounting it off to the side. BTW, I have decided to mount it on the passenger side rather than driver's. It wouldn't clear the plugs over there. The part about it not spinning fast enough @ idle...well that can be controlled. Smaller blower pulleys would increase boost all the way around. Plus, the N/A I have has a huge crank (excuse that terminology) pulley where the P/S used to connect. The bigger the source pulley, the more boost. Thank for advice on BOV, though.





Srce94FD, the blower I have is an Eaton M-90. Stock, they produce 10 psi. It is one of the smaller roots types you can get, i.e. the M-112's or 114's on Lightnings and Cobra's. My setup, I estimate, will be around 15 psi, which is a very high # for an M-90.





Any other advice or suggestions to help? Are stock injectors sufficient? What about FPR? FP? And the drivetrain? As U can tell, I haven't done a lot of planning as of yet. To avoid upgrading the drivetrain, I would lower boost, but I hope I don't have to.

You should get A. Graham Bell's book "Forced Induction Performance Tuning" before you proceed.



Roots blowers ARE inefficient. The advantage they have is full boost pretty much right off idle. John Force can get away with a roots because his fuel cools the charge. I don't think you'll be running the same fuel . . . I'd look into plumbing up a water-to-air intercooler.



Good luck



J

Again, I have the intercooler.