I have had an ASP underdrive pulley for about 4 years now and it has worked great, never had a problem. 3 months ago I put a 150 shot of Nitrous in it and that works great. After the track or if I am having fun with the Nitrous on the freeway I keep throwing belts. The belt doesn't pop off until hours later after driving. Why does the Nitrous cause the belt to jump and why is it happening so long after shooting it.

 

Are you using the same belt over and over?

If so, thats part of the problem. After a belt gets thrown off, its no good.

The 'shock' the nitrous put on the motor may have stretched the belt b/c of it being old and re-using a stretched belt will cause it to keep kicking off.

 

I have gotten a new belt every time beacuse they get a little chewed up or have fallen off on the road somewhere. When I put a new belt on it barely fits over the tensioner and the tensioner feels like it is still really strong.

 

Your balancer may have worked it's way out a little. I've seen them come right off with superchargers or nitrous because of how they rev up so quickly. Use a torque wrench and check the specs on it. You may need to have your balancer pinned to the crank.

 

Check the crank pulley bolt torque like hamrdown said.

One of the pullies are out of line sounds like, if its throwing new belts.

 

Mine did that every time i hit the nitrous when I installed my 150 shot.....a KATECH solid tensioner took care of it....hasn't done it since.

 

I would replace the spring loaded tensioner. That fixed my belt throwing problems.

 

Put a manual tensioner on it like Katech, That should take care of it, but still check your alignment of the pulley just to make sure.

 

My Crank pulley was loose the first time and I removed it inspected it and re tightened it. It looked good after that. I will probably get that manual tensioner, I have never heard of that before, Thanks Everyone

 

When you say you re-tightened it did you use a new bolt? The crank pulley bolts are TTY bolts and can only be used once. I think there about 6 bucks at the dealership.

 

Are you using a torque wrench and tightening down to 250 ftlbs? Also like shortchevy said, you did get a new bolt to use right? they can only be used once then they're trash and you have to buy a new one.

 

Yep did all that

 

if thats all good then the solid belt tensioner is the way to go. I bought one through Thunder Racing and it works great.

 

Another more affordable option is getting an ASP high wall tensioner pulley. It fixed our problem and several friends that had the same problem. If everything is in alignment, then the belt throwing is from the quicker higher reving the engine is no experiencing with the nitrous. The ASP high wall tensioner pulley is cheaper and it's just the pulley itself and slides right on in place of the stock pulley. You may have to call them as I don't think it's on their website, but it'll solve the problem

 

or, depending on how many miles are on the motor, the stock tensioner may just be worn out! you are supposed to swap out a stock tensioner after a certain amount of miles.