1st gear Knock,boost high...

[BLACK MAGIC RACING]

I was finally able to get some boost off the launch last weekend, but now a new problem arises. The boost just before the 1-2 shift jumps to about 21 lbs, scanmaster reads 4-5 deg. of kr, and the car slows right down, until midway through 2nd. i was able to pull off a 13.39 @ 105, about the same as before launching with signifigant boost, just a better 60'. all my mods are listed in my signature. Is the thrasher to blame? Thanks again guys.

 

[Donald McMullin]

You might have something hitting the exhaust during your launch. I have same problem when I launch when my rear end axel tubes hit the exhaust pipes.

Some have had problems with down pipe hitting upper A-arm if engine is not tied down.

Also, when I had a worn trans mount my front u-joint would hit the drive shaft loop during launch.

Check clearance between exhaust and drive shaft also.

Deep Enough

Donald McMullin

 

[tc86gn]

It is the high boost that is most likely causing it.

The boost just before the 1-2 shift jumps to about 21 lbs, scanmaster reads 4-5 deg. of kr, and the car slows right down,

Your KR is just befor 1-2 shift when the rpms and boost are high. Not likely something banging around. Have you checked the WG solenoid? Also the Y before the solenoid? The problem is most likely in that area. That's what Timmy thinks.