Ported Gen 1 m90

hytorksc

Registered User
I just had the pleasure of showing my daughter for her graduation project from A to Z on how to port the supercharger inlet/outlet (and the other supporting components around it- intake plenum/return plenum/etc..). We worked on this for a 20 hour marathon, and we are both very worn out from this.

We took the SC out on it's first WOT journey with the ported sc, and I was kinda dissapointed with the seemingly lack of power increase- i could not feel the difference. in fact it felt like it lost some low end power. I do realize that porting a gen 1 is not going to feel like a 94/95 or s-port swap, but i know i should feel something.

But then i remembered from reading the mp3/s-port comparison posts here that if you increase the blower's ability to flow by porting it, you are not going to necessarily see a difference unless you spin it faster to bring it into it's slightly higher rpm operating efficiency range.

Has anyone tried or experienced using a 15% OD pulley setup (10% jackshaft/5% blower) on a gen 1 max ported blower setup? Or do you think i'm better off by having a custom OD pulley made, for say a 13% overdrive without killing horsepower from excessive heat on the top end too much? i have a 10% od on it now.

i have stock heads,cam, and IC so i know there's not going to be a massive huge gain in top end power to get here.

anyone? thanks-
 
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I guess teh first thing to ask is how does the boost # look. Second thing is that you may have potentially ported somewhere you shouldnt off. Try to attach some pictures
 
DamonSlowpokeBaumann said:
I guess teh first thing to ask is how does the boost # look. Second thing is that you may have potentially ported somewhere you shouldnt off. Try to attach some pictures

boost #s are about 1 to 1 1/2 psi higher than they were before- it was 13.5psi before, and now it's a solid 15 psi- referencing at 5,000 rpm in 1st gear at WOT. All this is with a 10% od and scp exhaust. Unfortunately, the pics i took are from a disposable CVS camera, unless there is some way to scan them into a file to post them up.

I cut off approximately 3/16" of material all the way around on both the inlet and the outlet, and shaved off all excess metal around the top edge and sides of the inner portion of the inlet to help increase rotor timing slightly (give the rotors more sweepable area to catch air). if anything this should have reduced intake temps and increased power a bit because in essense this is all that an s-port cut does. I did not significantly increase the size of the inlet or outlet, but i did just enough to increase it's flow capability- conservative changes always work better than radical changes unless you use supporting components for the radical change.

i drove the car this morning to work, and i think i noticed that it pulls harder up top, meaning above 3,800 rpm. maybe this was a gain of 15 ft lbs torque (seat of pants).
 
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Hey Randell i still have the old one from my car if you want that one. But you have to get the 94-95 blower trust me!! I still need to give you a ride.
 
I just put a ported 1st gen M90 on my car. There wasn't a seat of the pants feel of improvement, but I could notice a small difference. I too have a 10% od pulley and I'll be adding a raised top, if they guy selling it to me hasn't fallen off the face of the earth.:confused:
 
chadder1313 said:
Hey Randell i still have the old one from my car if you want that one. But you have to get the 94-95 blower trust me!! I still need to give you a ride.
yeah, i'm waiting for this one. i know where i can get a 94/95 right now, but i am trying to decide if it's worth it since i still have the stock cam. i really want to do this, but i just max ported my gen 1, and i think there is a little difference on the top end- just not enough of it though.
 
If you took 3/16" off all around the blower inlet, that's actually a significant increase in area. About 33%, I would say. If you still have the stock TB, MAF, and top, that means that your blower inlet is now about 50% larger than your TB, even more compared to the MAF and the pinch point in the SC top. So you can't really take full advantage of the mod yet.
 
S_Mazza said:
If you took 3/16" off all around the blower inlet, that's actually a significant increase in area. About 33%, I would say. If you still have the stock TB, MAF, and top, that means that your blower inlet is now about 50% larger than your TB, even more compared to the MAF and the pinch point in the SC top. So you can't really take full advantage of the mod yet.

My perception: maybe because of the increase in flow, but decrease in air velocity is why i felt a slight loss in low end torque. But i have to tell you after driving this for a couple of days, it's kickin alot harder up top now. i can pull 3 miles up a 5% grade interstate on a mountain now without struggling to get to 115 mph in 3rd (aod). It actually surprised me today that i was able to pull fast up that same mountain without bogging in OD still accelerating past 120mph at 3,100 rpm- simply amazing... it did not do that before, it would just bog slowly.

btw, i have the bbk 70mm tb, c&l 70mm maf, mag powers top, and scp exhaust. sounds like i might have reached 240 rwhp level.
 
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hytorksc said:
My perception: maybe because of the increase in flow, but decrease in air velocity is why i felt a slight loss in low end torque. But i have to tell you after driving this for a couple of days, it's kickin alot harder up top now. i can pull 3 miles up a 5% grade interstate on a mountain now without struggling to get to 115 mph in 3rd (aod). It actually surprised me today that i was able to pull fast up that same mountain without bogging in OD still accelerating past 120mph at 3,100 rpm- simply amazing... it did not do that before, it would just bog slowly.

btw, i have the bbk 70mm tb, c&l 70mm maf, mag powers top, and scp exhaust. sounds like i might have reached 240 rwhp level.

Aha, that sounds like a good level of mods to complement the blower work. That is pretty much where I want my car to end up in the next year. (Bigger fish to fry at the moment.) Thanks for filling us in.
 
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