BimmerFest BMW Forum banner

1 - 20 of 202 Posts

·
Registered
Joined
·
172 Posts
Discussion Starter · #2 · (Edited)
]First thing I bought was the supercharger off of a 93 Thunderbird SC. I cleaned it up rebuild it and then I made the adapter plate to Bolt the BMW throttle body on to the inlet of the supercharger in the back. I used 3 pieces of 1/4" aluminum plate that I drilled cut and filed to get a smooth transition from the round throttle body to the rectangular intake Port of the supercharger. Don't Shoot Me , but I then cut the intake manifold runners. I heated of the ends up with a heat gun so I can round them out to clamp on the 2" ID silicone hose. The plentum I made out of 2"x 2" x1.5" copper T's and one 2" to 1-1/2" 90-degree elbow. I cut them down and used short pieces of 2 " tubing to solder it together. The bottom of the supercharger I drilled and tapped two 1/2" holes in the intake port. One is for the idle speed control. The other for the power brake booster and fuel pressure regulator. Supercharger mounting bracket is 3/8 plate steel. The bottom bolts to the 2 bolts on the power steering pump then steps back and up to the upper alternator Bolt. And I ground down the back of the idler pulley. Then I bent it back to form the supercharger platform. I use 1" wide flat Steel to run a horizontal brace from the back of the platform to the engine and a vertical brace down to one of the original intake manifold support mount. The front of the bracket I cut out to clear the original belt tensioner and a large round opening for airflow to the front of the alternator. The supercharger is driven by the second pulley that I mounted on to the front of the power steering pump. There was no room or place for a tensioner pulley so I have to use spacers under the supercharger to put tension on the Belt. The output of the supercharger runs down to the front of the car into the intercooler below the front bumper out of the other side back crossed underneath of the radiator up over top of the supercharger pulley and into the intake manifold. I put a chip in the DME that has a more aggressive ignition and injector curve. That seems to work pretty good. Plus it deletes the speed governor and raises the rev limiter to 7400. Even though the power starts to drop off at 6500. It is a lot of fun up to that point.
 

Attachments

·
NCC BMWCCA member
Joined
·
181 Posts
Interesting project, what do you figure you you have into it and how hard was it to fab up the other parts. Did you use a template or eyeball it.
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #4 ·
I would have to say around $800 so far. I use the old rule measure twice and cut once. I already had a good idea of what I wanted. But working in such a small space did make it very difficult. And I couldn't find any others that I could copy some from. I still have to relocate the power steering reservoir. Right now if I had to add fluid to it I would have to remove the supercharger to get to it. LOL
 

·
D'oh, You Kids!
1984 633CSi, 1985 635CSi, 1985 325e, 1987 325is, 1993 325is, 1995 318is, 1995 M3, 2003 F150
Joined
·
29,961 Posts
Very interesting. Drivinfaster is planning something very similar.

Do us a favor....please don't use 2 for "to" and 4 in place of "for". That got real difficult to read since you had 2" dimensions in there along with "2" and "4".
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #6 ·
Point taken. I'm still having some problems with idling after coming down off of the Boost. My best guess so far is that with all of the tubing and intercooler dropping down into 20 + square inches of vacuum that by the time the idle speed control tries to compensate for the low idle the engine has already stalled. I can manually turn the idle up and it will not stall. But I have to turn it up to about 1000 rpms. And I don't like to do things that way.
 

·
Registered
Joined
·
12,417 Posts
very interesting fab. i considered the m90 from the 3.8 supercharged fords but found none available in the salvage yards. settled for an early m62 eaton from gm. much wider base and has a portion of inlet on the housing.

initial plans were to throw it on the m50 in cadence but that fell through rather quickly. it is on the back burner as of right now since i have so many other things going on and am looking for another house with a garage to be able to tinker more.

current plans for the supercharger are now moving toward the m42 in piper, my 97 vert. i have a little bit more room to fab up stuff and am planning on using the tensioner from the gm 3800 instead of shims.

not sure if i am going to try to run it like an off the shelf sc with an intercooler or run it directly into itb's and add meth injection. again so many plans and stuff happening (i think some people call it "life"...) that these plans and ideas all get pushed back.


thanks for sharing, though. :thumbup:


and yeah, that ps reservoir is going to need to be relocated for sure., again, a little more room in the m4x engine bays than the m5x.




df
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #8 ·
I do hear what you are saying. I work over 60 hours a week and try to have a life at the same time. I bought the supercharger 9 months ago and little by little have been fabricating everything to put it on my car. When I blew 2nd gear out of my getrag 5-speed and my Vanos was acting up 3 weeks ago I figured that was the perfect time to put the supercharger on too. As for throttle body location , I chose to run it up stream because friends of mine have have tried running it Downstream on the M90 and the larger m 112 with air-to-air intercooler. The problem they ran into was when they let off of the throttle at higher RPMs and boost there would be a boost surge up against the throttle plate and we blow the hoses off. They didn't know how much boost but it did Peg the Gage. One of them even bent the throttle plate. Eaton's are Roots type positive displacement superchargers and as long as they have unrestricted airflow in they will blow air out. Good luck with your build , I would love to see how it turns out.
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #10 ·
Right now it's a stock Motronic 3.1.1 with a AC SCHNITZER chip. It seems to work pretty good. It's a little Rich at low RPMs. I used a friend of mine's gas analyzer. And did the old school method Running chop plugs. I checked the plugs at 2500 , 4000 and 6200 RPM. They we're a little on the rich side of perfect.
 

·
Registered
Joined
·
12,417 Posts
not sure how ford handles their decel from boost transition, but the gm unit has a bypass valve that is vacuum/boost controlled to reduce backpressures on the throttle plate.

also not sure what you mean by upstream/downstream on the throttle plate....:dunno:
regardless, i have seen multiple configurations of the eaton variants used remotely with a plate to fit the intake plumbing. i do not really wish to run lots of plumbing all over the place, even if i do have ample space in the m42 engine bay, so will probably look to add a meth kit.




df
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #12 · (Edited)
Upstream means that the throttle body is before the supercharger on the intake port. Downstream means that the throttle body is after the supercharger. Ford and GM both run Upstream setup putting the throttle body on the intake of the supercharger. So that way they don't have to worry about blowing gaskets and any other parts. The bypass valve is used on both to reroute the output of the supercharger back into the intake if the boost starts to go to high. And it means that they can make the Boost come on sooner with the right pulley setup and still not go over to the point of causing damage to the engine. The other advantage to running the throttle body Upstream of the supercharger is that at Cruise speed restricting the flow of air into the supercharger which cut back on the parasitic drag. Roots type superchargers spin very easy when they are under vacuum. One of the main drawbacks of these superchargers is that they heat the air by compressing it. Not as much as a turbo would. But anytime you heat up the air molecules they expand and this is counterproductive to what you're trying to achieve with forced induction. The running an intercooler with an Eaton is not much of an option it's kind of a necessity.
But before I did any of this. I upgraded the brakes. Installed Bilstein shocks and struts , 18 inch staggered wheels with 255 35 in the back and 235 40 in the front . A short throw shifter and stage 2 clutch with a single Mass lightened chromoly flywheel. And to cut back on gear chatter I'm using a 50/50 mix of red line D4 and 75 140 synthetic gear oil in the transmission. Polyurethane rear subframe mounts. New lower control arms front and rear. Tie rod ends. Sway bar mounts and links. And because I did all this myself , I started to learn how to curse in German. LOL even though I have over 20 years experience as an auto tech. The next step is the car is going to the body shop because I am lousy at body work. They are putting on the M3 side skirts bumper cover and rear diffuser. Then painting it cobalt blue firemist.
My baby is a 93 325is. With an M50b25tu engine.
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #13 ·
Just a quick update , I did have to go up to 24 lb. injectors. I realize that the stock injectors were pretty much maxed out at higher RPMs and the fuel wasn't atomizing properly.
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #14 ·
I'm back with another update. I'm still pulling my hair out trying to get the tune right on this engine. And I thought fabricating everything to put this supercharger on was going to be the hard part. This Bosch motronic really does not like a positive displacement blower. It is fighting me every step of the way. And since I can't afford 3000 for a good stand alone I'm going to try fic 6 piggyback. Don't get me wrong it does run pretty good but it's still not right. A little Rich download and it starts to lean out up-top. If I want it hard I turn the fuel pressure up. But then the idle is really rough and will stall. But at least I won't cook anything at 7400 RPMs. And the mid-range is so sweet :). I don't know how I ever drove any car without forced induction. But I will keep updating. So maybe others can learn from my mistakes.
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #17 ·
I definitely want to thank everybody on the Forum. I've read a lot on here and learned a lot. And I'm still learning
 

·
Screamin demon
Joined
·
883 Posts
I find this awesome! A friend and I are doing the same! I have the hardship of using the m90 with the longer snout, so it sits back another few inches. But would like to see more pics of the guts!

I plan on starting around a 5lb boost at first which doesnt need a cooler or tune. But I also have all the other na mods, so hopping for 275 at the wheels! Thanks for the coolness!
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #19 · (Edited)
Thanks for your reply. I'm glad to see somebody else doing it too. These M50 Motors are definitely tough. Mine has 247000 miles on it. And nothing's been touched internally. I bought it from the original owner. And after nine thousand miles with the supercharger the compression is still 180 to 190 across the board. But even at 6 pounds of boost I had problems with getting the tune right. The Bosch motronic with mass air flow sensor and no map sensor is really hard to make them run right when boosted. Stock tune stock injectors we're okay up to about 4000 RPMs. Then after that it started to get dangerously lean. Even with a boost referenced fuel pressure regulator and turning the pressure up. So I put in 24 pound injectors. But that started all the fun I'm trying to get it to run right again. The DME was trying to fuel like it had 17 pound injectors. I went back and forth for months with a tuner trying to get it right. He got it close. I just installed an AEM pic6. So far that is doing the trick. The big Advantage is that it has a built-in map sensor so I can add fuel under boost and leave idle and cruising set to stock. Bad part is that for some reason it won't let me interface with the timing. The pic6 doesn't like my crank position sensor. Other than that I like it. Oh and before I forget. Using a turbo intercooler kit will work but the problem is running this type of supercharger means that all of the piping drops under vacuum. And what happens is those silicone hoses will get sucked shut. So I tried to keep them as short as possible. The longer ones like the 90-degree coming out of the supercharger I put one of those metal Springs from a radiator hose inside to keep it from collapsing. Good luck and I would love to see pictures :)
 
1 - 20 of 202 Posts
Top