No way is the belt slipping with that little of a load (boost) on it....unless something is way out of whack with the belt alignment....like the blower pulley on backwards.

 

Running the numbers, theoretically, a 2300 on a 6.6l with a 2.7 blower pulley and a stock size 7.5 crank pulley should make about 13.75 psi before pumping loses. If it has a 8" crank pulley should make 15.65.

Sounds like you have a bypass seal problem or a belt slipping problem.

 

Its gotta be the bypass valve or a bad gasket leak...

 

X2
Something is way wrong!

I had a front drive tvs2300 on a 9.0 to 1 408 and was seeing 14.5 psi in Denver! At sea level that unit will make 15 or 16 psi.
Start looking... There is something NOT RIGHT AT ALL!

 

The guys from VA Speed over on tech are making 900 hp @ 12 psi on a 427 with the tvs2300 might want to check it out...

https://ls1tech.com/forums/forced-in...ed-901bhp.html

 

Give Joe a call at Leftcoast32. He will have answers for you.760.522.8669

 

Any possiblity of an intake seal leaking? Hopefully you aren't running a cathedral port with those spacers. Have you checked the valve springs over yet?

 

No chance of a gasket leak, we're the vac leak pros over here, got all the equipment to find those things. Plus, it would have to be one hell of a gasket leak.

 

we installed a 112maggie on my buddy's f-body two years ago, had a TSP MS3 and PRC stage 1 heads, made 4.5psi, we switched from a 3.4 to a 3.2" pulley and it made 4.5psi. It was all in the cam. With so much overlap the air was going right through. I know this is a custom cam but something to ponder at least.

on 4.5PSI the this car still made 575/505 to the wheels....

 

might be getting somewhere, we held the bypass valve shut and it's making 7psi.
Off throttle, it makes 6-6.5psi, shifts to second and makes 7psi.
Seems pretty stable now, but still not enough boost. Feels much better, but we need more.

thanks,