BBSC only making 2.5lbs of boost?

[Serviceman24]

I've recently finished the install and tuning of the BBSC on my 97. I have the Novi 2000 w/ aftercooler and I'm running the 9.5lb pulley. During street and dyno tuning I'm only making 2.5lbs of boost? (measured on a autometer gauge, the AEM, and the mechanical gauge on the dyno) I've checked all of the couplers for boost leak and tightened the belt as much as I could w/ no luck. I removed the blow off valve and capped the output from the aftercooler and still had no gains. Does anyone have any insight on this?

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[amo]

hi mate you runnin standards

will try and ask the ppl who fitted mine
as im runnin the 7lb pulley and got 5lb of boost

thx amo

 

[MiamieNeSeX]

Keep looking even the smallest bosst leak will net you your numbers.



Armando

 

[Serviceman24]

Is there anywhere specific that i should be looking for leak? There are only two couplers between the output of the blower and the throttle body. Is there any tricks for finding leak other than the obvious?

Just to clarify..... It is normal for the BOV to output high volumes of air until the car is in positive manifold pressure? It just seems like there is allot escaping!

 

[MiamieNeSeX]

If you have the original BBSC charge elbow I would look at the rubber gasket and its placement. As far as the BOV, it is normal for it to vent while the car is not under load.


Armando

 

[Serviceman24]

I'll take some pics so you can see what I'm working with.

 

[theman1990]

Mix soap and water and spray it on all your hose connections, then rev the engine to boost it.... that may work?

 

[peiserg]

unlikely to be the cause in your case, but i know when my air filter is dirty (15000 miles of dirt) I lose up to 3 PSI at max, and picked up 38 rwhp on the dyno by cleaning the filter.

just a thought.

 

[WOODY]

There are only 3 places that system can leak boost-the paxton to intercooler connection or the intercooler to intake hose, and the blowoff valve. It appears that they are O.K. The other problem could be that you are not making the boost which could only be one of a couple things- loose belt, stripped pulley, non functioning paxton.
I would:

1. cap blowoff and soap/water the hoses connected to the aftercooler. A little throttle action will create enough positive pressure to bubble it with the blow off capped
2. swap out blowoff valve
3. does belt twist to 90 degrees with difficulty? If it is easy to twist then it may be too loose.
4. check the hexagon shaft bore on the pulley, make sure it is intact.
5. Any odd sounds from the paxton?

BTW nice setup(its my old one :biggrin: )

 

[Serviceman24]

Re: BBSC only making 2.5lbs of boost? (Update)

So I have checked everything for boost leak, including the BOV and everything seemed fine. I had some time tonight and decided to remove the Pulley for inspection.

First problem.... While removing the bolt, it cracked off inside the shaft!@#$ (I was able to remove the broken piece with no damage to the shaft)

Second problem.....The pulley which I believe was the 9lb pulley was completely stripped out. (see attached pics) I'm suprised that it was making any boost. The drive shaft seems to have a small bit of wear also.

Third problem..... After putting the 10.5lb pulley and replacing the belt, the drive shaft makes a horrible screeching/squealing noise when the engine is not under load and under 2k rpms. I used a stethoscope and listened to the drive shaft at various places. It makes minimal noise directly at the blower, but as you move towards the pulley the noise gets louder. It sounds like bad bearings? I would assume that there was no strain on it with the stripped pulley and now with new pulley there is?

It is now making approx. 6lbs of boost with the 10.5lb pulley?

So my questions..... Where do I get a new 9 / 9.5lb pulley? (It is 4 and 1/8 inch in diameter) How do I get the drive shaft repaired? Can I send it to Mark Basch? How do I get in touch with him? Why did this happen in the first place and how do i keep it from happening again?

 

[MiamieNeSeX]

It is highly unlikely that the shaft has been damaged, although the pulleys will wear as they are made of alluminum. The noise you are hearing stems from the pulley vibrating. I would try adding a large fender washer to the tightnening bolt on the pulley.



Armando

 

[WOODY]

Hold a pencil point up the the pulley as the car idles, if it touches intermittently the pulley is not perpendicular to the shaft and needs to be aligned. I believe I had a fender washer on there already, did you replace it with the new pulley?

 

[Serviceman24]

I'll check the pulley ASAP. There was a washer on the inside and the outside of the pulley. Is this right? How tight should this bolt be?

 

[MiamieNeSeX]

I'll check the pulley ASAP. There was a washer on the inside and the outside of the pulley. Is this right? How tight should this bolt be?

If you put a washer on the inside of the pulley it will not line correctly. We found that the larger the washer on the outside the better, we also broke a few of the pulley bolts. I dont know for sure if there is a carrect tq for that particular bolt.



Armando

 

[WOODY]

I'll check the pulley ASAP. There was a washer on the inside and the outside of the pulley. Is this right? How tight should this bolt be?

The ridge that butts up to the pulley on the end of the drive shaft is very small. When you torque down the pulley bolt it can crush the aluminum pulley over and past the small steel ridge. I put the steel washer on the inside of the pulley to prevent this. I was able to get the pulley to spin perfectly in line (zero wobble) with this method. The width of the washer was not enough to cause any misalignment of the belt and other pulleys( at least not that was evidenced) Use a file to clean the edge of the ridge on the drive to prevent the pulley from being crooked due to metal or other grime.

 

[Serviceman24]

Alright, so we removed the pulley and the washer in between the drive shaft and it. It was very greasy and obviously had a octogon shaped center to be able to fit on the drive shaft. Is this supposed to be here? ( pics attached ) I have been unable to check the operation of the unit, as we broke yet another bolt during reassembly. This time it was the alternator tensioner bolt.

 

[RacerX-21]

I took (2) short sections of aluminum pipe, made caps for one end and tig welded the caps in place. On one of them I inserted a Schrader valve (Like on your tires). With both of these I can test my whole boost system for leaks including the intercooler. I also made (2) plates for the intake manifold gasket flanges to check it for manifold leaks. The Schrader valve will allow you to also check for slow leaks. You would be surprised how many of the aftermarket blow-off valves leak after a short amount of wear. I highly recommend the Tiel brand. Weld as many aluminum tubes together as possible with only enough couplers as needed for removal. Also use a Goodyear Gatorback belt; they have a patent on a serrated design that gets better grip with less tension. This will equate to less hp loss, less chance of bearing failure, less belt heat, etc.

 

[WOODY]

Alright, so we removed the pulley and the washer in between the drive shaft and it. It was very greasy and obviously had a octogon shaped center to be able to fit on the drive shaft. Is this supposed to be here? ( pics attached ) I have been unable to check the operation of the unit, as we broke yet another bolt during reassembly. This time it was the alternator tensioner bolt.

I made that washer to keep the pulley from riding over the shaft ridge

 

[coldhammer]

Just thought i would throw my .02 cents in. I had most of the same problems you are having when i first got my system. Over three months this is what I ended up doing to fix all problems:

1.boost leaks. I had several small leaks that all added up. I made a new elbow to replace the one that comes with the kit and used silicone couplers. That stopped all my leaks. Of course i didn't have the added variable of an after cooler.

2.pulley vibration issue #1. My pulley was starting to round out. Took a feeler gauge set and made shims to tighten it back up. This also stopped it from rounding out any further.

3. pulley vibration issue #2. I was getting that loud screeching sound you are talking about. I had forgotten to put the washer back on when i swapped pulleys. Put the washer back on and no more issues.

4. went with a gator back belt that was slightly smaller than the original belt that came with the kit. This stopped all my slipping.

5. broke the tiny little tensioner bracket from over tightening my belt several times. Bought a new one and learned not to over tighten the belt

After all that the kit has been running solid for 2 years now putting down 398 whp at 8.5 psi.

 

[peiserg]

fwiw there are several boost leak systems for sale on the internet. pressurise system while engine is off!