Firstoff i'll tell you about the setup, its a custom built rearmount setup with a holset w1 or something like that. Stock mani's with 2.5 y and 3in to the turbo, heatwrapped from front to back. 50mm wastegate (bought to run with big boost & 88 later on a 408, maybe bad idea?) Its FMIC'd, 2in charge pipe to the FMIC, then 2.5 from the intercooler to the MAF. All silicone couplers and t bolt clamps.

It seems to be losing boost pretty bad somewhere, we thrashed all night (6pm to 8am)to get it put together and tested today a little. First it wouldnt build boost at all, we forgot to tighten the BOV. Fixed that and still no boost. Then we unhooked the wastegate and it will build 5lbs at about 4000, but would start losing boost at 5000 and keep falling off. This is with no wastegate hose hooked up. All couplers are tight with t bolt clamps.
first question is the 2in charge pipe too small and turning into a bottleneck? second is there has to be a boost leak right? cold side now checks out 100%no leaks. Even if you brake boost it it will only make a couple lbs, then climb to 5 once you wind it up a little.

It will run 11.5afr with 14.5 degrees of timing and never misses a beat, but don't pull worth a damn. IATs this morning never went north of 35 degrees (its was a litle cold out) I'm thinking a little more timing down low and a couple degrees up top may help, but that dont fix the fact that we are blowing our boost out the window somehow, I mean, this turbo is designed to efficiently make 28lbs all the time, theres no way we are maxxing anything out, and it will only hit 5lbs if you load it hard for a while, with no wastegate basically.

Any insight would be extremely appreciated.

Car is a LS1 2000 M6 camaro

 

first off the turbo you are using is a little small, it only has 54mm compressor wheel, maybe a 56 if you got the newer model

so it is not surprising the hx35 turbo falls on it's face at 5000rpm

 

my thought would be to check what size the compressor outlet is, you dont want your charge pipe any smaller then that. So if its a 2.5 outlet, then it should be a 2.5 pipe.

also, i agree, the hx35 is tiny. Maybe good for twins, but not a single on a 346ci motor.

 

Ok its my buddies car I was wrong on the turbo. Its a holset I just don't know the number of it, ha

 

You either have a bad hot side leak that isn't allowing the turbo to spool or you have a leak on the charge side. Can you hear the turbo?

 

Its definately not the charge side, I ripped it apart tonight checking everything for leaks, checked the intercooler etc. You can hear the turbo trying to spin it *** off with no result. tonights grand total of 2lbs after brake boosting it in 3rd gear and giving it hell.

The hot side has no leaks up to the turbo. All I can guess is the hotside on the turbo has a problem. Its small and should be boosting like stupid and running out at high rpm, but its doing the opposite. I wonder if the internal wastegate (welded shut) is broken loose?

Calling turbo auto here in nashville tomorow. I had nothing to do with the turbo itself, this is my buddies car.

 

pull the air filter of the turbo, and see if the compressor wheel is coming in to contact with the compressor housing, and also check for shaft play

 

It wasnt that, the turbo is fresh.

The wastegate was leaking. what a POS. We took it off and block the flange off. Makes boost like crazy. Of course you cant drive it like that ..

Picking up a 38mm wastegate tomorrow, it will be fixed. I knew it had to be something stupid easy.

thanks a ton guys