Chassis dyno and wear a face mask

 

Would bet it is on shifts. At that moment the supercharger and other accessories have tremendous inertia trying to overspin the rapidly decelerating crankshaft, the tensioner will be yanked hard and the water pump side of the belt goes slack. Are your shifts set up to be extra-firm? If so softening them up will solve the problem (and prolong the life of the hard parts in the transmission.)

 

When you say the tensioner is yanked hard do you mean that it is yanked to the slack side or yanked to tighten? Is it possible my belt is too short? I can get it on the pulleys easily but the tensioner is against the stop then when I let off of it it comes up about 1" to tighten the belt so it has a lot more room to tighten than it does to loosen if that makes sense? I always thought the shorter the belt the better cause it can tighten up more when it stretches under load but I can be wrong? Thanks

 

From what you're describing the belt length is perfect. The tensioner has a lot of potential to take up the extra slack from stretch under load - you are right.
What I mean by the tensioner getting yanked is during a rapid engine rpm deceleration, like during a shift. The crank rpm drops more rapidly than the accessories would so for that instance the crank becomes driven by the accessories. The blower, especially, has a lot of mass turning at high RPM. Looking at your belt path imagine the blower driving the crankshaft. The tensioner is in between and that spring force is a lot easier to overcome than driving the crank shaft, so the tensioner during a rapid shift and rpm drop will literally bottom out for just an instant. When that happens the serpentine belt will go slack on the other side of the crank and this is where the potential for jumping off comes into play.
It's not load that causes belts to jump, it's slack. The alignment problems are fixed - it's not the alignment.

 

Well I went out today cleaned all the pulleys with water and a scrub brush from the rubber and dust that gets stuck in them from the belt fraying. I spaced out that smooth pulley so the belt is more centered on it. And the bracket that came with my Maggie kit has a slot in it for the passenger side smooth idler not sure if they are all like that? I always had it at the bottom and I decided to move it half way up to give more slack on the belt so now the tensioner is about 1/3 of the way instead closer to being bottomed out. I just went out and did 4 pulls and after every pull I pulled off the road and checked the belt it was fine for the first 3 I got excited and did another and checked it and the belt jumped back towards the motor 1 rib but only on the tensioner pulley... It's still lined up with the laser... Could it be from the pulley magnuson send with the tensioner doesn't have a lip on it? It's flat with grooves cut in it. I'm at a loss for this. I hate playing the game of will the belt blow off this time or not. Guess I gotta get a buddies go pro and see what happens under there. Thanks guys

 

Here's a picture of the tensioner pulley compared to the alt. Pulley. The belt is flush with the lip on the alt. Pulley. The tensioner pulley the belt is pretty much completely above it its just sitting on the grooves.

 

It would certainly help if the tensioner pulley had shoulders on it. Sound like the entire tensioner is flexing.

 

in the first pic of the tensioner, it seems the gap is tighter on the top and wider on the bottom, could there be some degree of deflection in the pulley loaded up?

 

Put an extension in the tensioner and pry away watching for movement.

 

I'm jumping in late, but I'd be willing to bet a cold beer on that tensioner being your issue.

Since you haven't seen your own setup work under load, check these videos out to see how crucial it is for that thing to swing straight and square and stay plenty tight. I know this has been posted here before but it most definitely pertains to this thread...

Before:

After: