sn2000 3psi@5k

[88t.birdsc]

My 88 t-bird w/87 ho motor sn2000 was putting out 1 psi per 1000 rpm up to 6 psi @ 6000. Now it only puts out 3psi @ 5000. The belt is brand new. The pulleys are 6 on the crank and 4.5 on the blower. Recently, a small amount of ac dye was added to the b&m trick shift fluid to help see the level with a black light. Could this have caused the problem and what parts are likely damaged?
Thanks,
Mike

[88t.birdsc]

Just finished swap out to spare sn89. Will post results tomorrow but it feels stronger.

[88t.birdsc]

It's stronger alright but NOT because of the swap from the sn2000(3psi) to the sn89(2psi), but because of the fmu swap. Turns out the fmu I just installed didn't increase fuel pressure at all unlike the original which put out 80psi. Since it wasn't running pig fat rich with little boost, the car seems to be making more power. Good thing because last night a Nissan Titan would have handed me my a$$. It is fun to imagine how well the car would run with a good supercharger. Oh well, I will remove the belt, fmu, and have fun without it. It's a shame because it seems as though there are several people that are quite high on these blowers. IMHO as of yet I can not agree. Hopefully that will change. Maybe the chargers are getting ruined from the belt being too tight?

[speedytang]

To begin with use only Type 'F' and forget the Trick Shift. Anything that is added to the fluid becomes a slick lubricant which includes foreign fluid and B&M Trick Shift standard or Synthetic. Don't fault the product if not using the correct fluid.

[F=MA]

Sounds a bit like the blower is the last of your troubles. Honestly, if you're having trouble with this blower, it's because of something you or somebody else did, not due to any inherent flaw in the design.

I'm pounding the shyt out of mine at the track every second weekend with absolutely no problems, and I cheap-assed the rebuild by just replacing the races, everything else was resused. It makes its rated 5 pounds by the high end of the 5s, just as advertised, with the factory supplied shim stack in the drive side.

My full weight car, at 3350 lbs is hitting high twelves, as it sits. Mid twelves are a few more passes on the drag radials away, I predict. Yours is just some systematic tuning/repair, away from running right, too, I'd guess.

F=MA

[88t.birdsc]

Ii

[88t.birdsc]

Maybe my expectations are too high, but even 14's seem far far away. The 160 degree thermostat is going out for a 180. All of the vacuum lines are going to be replaced. Maybe that will cure the in gear idle surge from 600-800 rpm with the vac. going back and forth 14" to 11". Pulling 17" on the map with a hand vacuum pump should smooth out the idle. I know speed density doesn't give a rat's a$$ about vacuum leaks, but if it was large enough to drop the vacuum that much, the leak shouldn't be that difficult to find. If there are no other issues, running the ho cam at -4 may be causing intake reversion and the map to go stupid. The vehicle will be driven/tuned without the fmu and the blower belt. If necessary the cam will go straight up. The times will improve. It may have been a case of trying too many "tricks" (no pun inteaded) at one time

[speedytang]

Always start with a good running motor first.
This is not the 70's all those timing tricks have been built into the cam profile and the computer does the rest. Also it is hard if not impossible to tune with a FMU so get everything correct first then hook up the Blower and FMU. The FMU will vary a little every time you are at WOT that is why when building 6+psi you should always use larger injectors.

[88t.birdsc]

FYI, There were some differences between the 2 units: the sn89 pulley rotated easier than the sn2000, but the sn2000 had more fore an aft(axial?) play than the 89 which had almost 0. The dial torque wrench and dial indicators will be added to the tool box, but only after it is running good. Hope for some improved times!

[F=MA]

"It may have been a case of trying too many "tricks" (no pun inteaded) at one time"

Yep, I think you hit the nail on the head right there. The systematic, linear approach allows isolation of a problem as it materialises.

F=MA