gnarlykaw

mine pegs at 24-25 psi. max setting on the six gun, OR stock setting.........
clamping ther wastegate hose, means that little black vacuum line on the turbo is either crimped shut or plugged shut.

Hal

043500QC -

On the pre 04.5 models without the electronic wastegate control there is a rubber hose on the turbo that runs from the compressor to the wastegate actuator (not sure that's the correct name) which is diaphram operated. When boost hits some preset amount, the diaphram moves a rod which goes to the exhaust side of the turbo to open the wastegate. When the wastegate opens the exhaust is allowed to bypass the turbine which prevents additional boost from building.

Boost elbows or clamping the hose simply reduce the amount of air that reaches the wastegate actuator and either delay or completely prevent the wastegate from opening...that gives you more boost. In my case, even with the quad box, I can't exceed the 24 PSI setting unless I do something to prevent the wastegate from opening. With a set of vise grips clamped on that hose, but not fully blocking it, I'm good for around 28 PSI.

The other side of the story is there have been quite a few threads concerning the efficiency of the pre 04.5 turbos. Since they are small, at some point above around 30 PSI, they heat up the air more than they compress it so it shows on your gage as boost, but may just be less dense hot air which no longer helps to build power and cool things down. The key appears to be to get the right size turbo to do what your engine needs. I can't begin to explain all that. Seat of the pants experimentation leads me to think my 28 PSI mod works well for me until I decide to buy that bigger turbo. There may also be durability issues from running our small turbos outside of their normal boost range. Hopefully I won't experience that.

N.Johnson

Have a look at this link. All you need to know about 2003/04 305/555 engine as far as fueling boxes/stock turbo/exhaust.

http://www.drperformance.com/TDR48.pdf

MikeyB

Doug did a good job on that report.

MikeyB

N.Johnson

You bet Mickey B, what I really like was his conclusions about the stock hy35 turbo max boost set point at 24 psi. Any more pressure by boost fooling gained nothing but hotter air. When I first read the report I was shocked at the dyno graph on the VA3.2. Thought I was going to get it since it didn,t mess with rail pressure but decided I'll hold off till I can pony up the bucks for piers modded hy35.

BLKHO600

yeah my TST with it off i hit the same 34-35psi... with it on at level 2/2 i hit 35psi or so... 3/3 and above I am at 38-40+psi

does this sound normal????

MikeyB

Yeah, I talked to Doug about the VA3.2. He said it's a wicked box, and only recommended running it at level 1 unless you have some serious mods, like intake and exhaust, clutch, and possibly a turbo upgrade. Adding timing also helps.

MikeyB

043500QC

Thanks for explaining that Hal, and thanks for the link N. Johnson. I understand it all alot better now.

2500WHITERAM

CLAMPING THE WASTEGATE HOSE ACTS LIKE A FIXED ORIFICE ELBOW, LIKE I HAVE ON MY 03 2500...

THE ELBOWS ARE AVAILABLE FOR SALE...BTW

dogger

I recall I my stock 03 boost was what most of the guys mentioned 24-25 psi with fairly high revs. With my "box" I have seen it spike to 32 psi. I've been thinking about an aftermarket turbo but am not interested in racing, just heavy towing. My next mod will be an aftermarket boost cooler then will go from there. Probably be seeing exhaust mods in the furture.

L8r,............dogger

2500WHITERAM

stock i was getting 23# on mechanical gauge, and also on the DRB.