1dirtyZ

iTrader: (1)

here is my setup,
- iron block 408 @ 8.5:1 compression
- patriot stage 3 6.0 heads
- F1-R ATI head unit
- SDCE 8 rib tensioner
- 3.5 inch tubing from the blower to the intercooler
- 4-inch tubing from the intercooler to the t/b
- 4-inch thick bar and plate intercooler
- 238/244 - 608/612 114 ls1 cam
- 1-7/8 headrer with 3.5 collectors
- true 4 inch exhaust all the way ( 3.5 inches y and 4 inch after they meet)
- straight dynomax 4 inch bullet muffler ( you can roll a base ball from the tip to the y with out snagging anywhere)
- vortech mondo BOV

here is my deilemma: with the current pulley setup and after the recent cam swap to the cam you see above the boost dropped from 16 - 17 psi to about 11 to 12 psi. so i thought , no problem , i should pulley up . but when i crunched the numbers , i was at max impeller speed for the blower with the 3.75 pulley i had on there.

can this be true? can i be maxing out an F1-R head unit ? the car ran 9.8's @ 142 with the old cam and very low timing ( it used to have N2O and the timing was set up for it ) and pump gas with a bottle of torco.

i checked for belt slippage but there is very little ( there was hardly any dust where you usually check). can it be theat the BOV is opening some how and bleeding off pressure?

what do you guys think, this has got me banging my head!

i will be turning the scew on top of the BOV just to see if that helps or does anything at all. any other suggestions?

EPP

iTrader: (22)

You have to either have extreme belt slippage or a boost leak somewhere in your system. Bob

1dirtyZ

iTrader: (1)

i double checked all the connections and they seem fine.
can it be that the intercooler is now posing as a restriction with the added flow of the engine?

Slowhawk

iTrader: (12)

What Cam was in there before?

Bigger Cams can drop boost alot.This is ussually when you raise the static compression by milling the heads to go with the Cam.

BOONE

iTrader: (4)

I had to change my vacuum source on my raceready because it would not close tightly. Then my boost jumped a lot. I also adjusted my adjuster flush with the nut and it closed a lot quicker.

kp

iTrader: (34)

One thing I would try is putting a new belt on it and cranking up the tension as much as you can. You are really pushing any 8 rib setup with an F1R at max impeller speed IMO.

Also like Boone suggested make sure you have a very good manifold source going to the bypass, too small or ristricted and it will creep open no matter where the tension is set.

Pro Stock John

iTrader: (34)

My old cam was 236/246/114 and I went 144 blower only @ 18psi. Belt slippage is your constant foe.

1dirtyZ

iTrader: (1)

i'll double check the belt tension and the vaccume line.
i'll also screw in the BOV adjusting nut.

the cam in there befor was ( if i remeber correctly ) a 230/234 580/585ish 114lsa , or something real close.