I am now replacing my 52mm BBK with an AS&M 54mm throttle-body. My BBK would hold a fast idle, 1500-2000 RPM, after a romp or two. I added a spring, but that wasn't the solution to the probem. It was tweaked!

Now let's think about the dynamics here for a moment with an M6 and no powershifting.
OR how about high RPM decelerations. High Vacuum (21-22 in Hg.) for a small duration (repeated 16,000 times) coming from a 383.

There is that moment when there are opposite pressure stresses on the throttle body valves and the shaft and other components.

 

I don't know a whole lot about this but isn't that what the bypass valve is for? To relieve the unused boost? I think if that were faulty then pressure would build on the tb like you're talking about and cause a problem. Like I said I'm not too wise on superchargers but I thought I throw out an idea.

 

a bypass valve is used to protect ur TB from damage when u suddendly drop RPMs or let off teh gass

if ur having a problem ur bypass valve may not be workign properly , also check to c of teh vacuum hose is hooked up

 

I would like to think that the SC wouldn't "dammage" a TB. Mabie install error.

The bypass or blowoff, is used to bleed off unused boost pressore to keep it from dammaging your engine.

When you shift pay attention to your boost gauge. Does it drop off quickly between shifts? Or am I thinking more along the lines of a turbo setup?

Check your TPS voltage.

 

Maybe you got a defective BBK TB. I have one of the very first BBK 52 TB's (purchased around 1996) and have over 100K miles on it, the last 50K with a 6# - 10# Vortech blower setup. It's still works like a champ. I have read about various quality levels with the BBK product which might be your issue.

 

I have a lot of miles on it, so I can't truly blame BBK. But it is tweaked now.

Also, I aree with the BOV statement, but while transititiong (between full throttle, off-throttle, shift, full-throttle,) it is momentarily out of sync until vacuum closes the valve (xxx msecs) and pressure should be present at the front of the TB and vacuum at the back, all being overcome by the return spring against the pressue on the throttle blades.

I'm going with the new AS&M. It is a jewel in comparison. No cast, all machined, smooth and very impressive looking.

My point is that our throttle bodies are not designed for boost, maybe they should be.