Supercharged '81

[bassman]

Maybe someone has some input on this. My son and I have an '81 350 cu. in. in our car. On the road, in NJ at sea level, we can get approx. 20 lbs. of boost at 6000 rpm's. On a Chassis dyno in Carlisle PA, it only made 10 lbs. of boost at 6000 rpm's. I don't know the altitude there. The only difference that I can think of is the altitude and a lack of wind resistance on the dyno. How much of a difference would one or both of these factors make? Is there anything else that could have produced half as much boost?

[c4c5specialist]

Hi there,
A few questions, did you make the same power as you did at sea level??
Is the gauge accurate??
Possibly a bad blowoff valve???
Belt slippage??
Other then the altitude, this is what I can think of.
Allthebest,