Blown06

iTrader: (32)

Previous combo: 3.73 gears and 14psi
New combo: 4.56 gears and 12psi

Could it be that the 4.56's aren't loading the motor as hard and therefore it's not building the boost it used to. Or do I have another issue?

DeltaT

iTrader: (5)

It's possible the faster reving with those steep gears is causing more belt slip than normal.

Jim

Blown06

iTrader: (32)

Good point, and I'll look into that.

However, if belt slip was taken out of the equation could the boost drop still be caused by less load caused by the steeper gears?

SilverSS

iTrader: (30)

less load, faster revving = lower boost. less load, less reversion. faster revving will eat up more air in a lesser time?? my guess.

OUTLAWZ RACING

iTrader: (9)

No load issue becasue the blower can spin as fast as the motor can make it. Turbos work better off of loads.

forcd ind

iTrader: (7)

my guess is belt slippage, hard to tell when driving, but if you could mount a camera and see if it goes high and drops back
did you refig the blower rpm, make sure your still in the range(max blower rpm)

BadgeZ28

iTrader: (28)

I thought there was a rule recommending higher gears with boost to allow the blower to make full boost?

Pro Stock John

iTrader: (34)

Maybe with less gear there is more load on the converter (if that's the right way to put it).

How tall of a tire are you running, 28, 29, 30? I'm thinking a tall tire + 3.73 would really put load on the converter.

Blown06

iTrader: (32)

My truck traps around 120 mph. I was running a 3.73 and 28" tire before and crossing the finish around 6000 rpm which is about 800 rpm less than my peak hp. So I tried this 4.56/29" setup and locked the converter, crossed the finish at 6650 rpm still around 120 mph. Obviously the truck is making more boost at the finish line cause of the higher rpm, but it lost about 2 lbs. at the peaks in 1st and 2nd gear. The only other difference between these set ups is that the truck lost about 165 lbs. and I put on a new blower belt. I'm running a 4.00" blower pulley (same as before) and have never really had any belt slip issues that I can tell. Boost rises steadily through the rpms.

EPP

iTrader: (22)

A dirty air filter will do it. Bob