jfruauff

Ok i went to dyno the other day with my freshly turboed gsr. I made a few runs and found i was losing boost. Heres what we did.

Dyno run 1. Dynos boost source teed into intake manifold. I would spike 5psi(thats my wga spring) @ 3500 and it would creep to 0psi by 6500-7000 or so.

Dyno run 2. Dyno boost source teed into compressor housing. I would spike 5psi @ 3500 and hold till redline..

Ok so i am losing boost between turbo and motor. I have replaced all worm clamps with t bolt clamps. Pressure tested intercooler and piping no leaks. Checked all lines that could leak and ziptied everything. I have found nothing. Not the wga because i held boost on pull 2. Not bov we held are hand over it on dyno run to see if it leaks. I am 120% sure no leaks in piping and couplings.

So what do I look for. One guy said to check valve adjustment that valves may not be closing properly. Anything else i can look for. I blocked off turbo inlet and interccoler pipe where it hookes to throttle body and filled them with 15psi and found no leaks.

HELP!!!!

DaveF

maybe your turbo is way to small.

jfruauff

no i have talked to at least 3 tuners who said the turbo is more than big enough for my 300hp goal. Plus my boy had a b16 with a little t25 that held10psi threw the rpms

Snailed EF

Was the motor in good running order before boost because if so chances are its not the valves.

turbodano

Lets start with the facts what turbo do you have? Please send pics.

We also need to see what wastegate you have and how the lines are routed. Is your wastegate leaking at idle?

jfruauff

Motor ran great no smoke. I ran a compression test and got all 240s.

OK i will throw a pic of the turbo below...Its a t3 with a .48I/.67E a/r. I know its a little smaller but for my 300hp goal its perfect. I tried both a ebay wga and a turbonetics wga. Both were teed straight into turbo compressor housing. Bov is teed into intake manifold. Wga is not leaking at idle i checked.

I am looking for anything. I just changed all the clamps for tbolt because i figured i had a leak at the couplings.

Someone help please i am about to give up.

jfruauff

someone please give me something. i just want this car to hold boost

nowtype

Measure the compressor wheel and find the trim of the wheel. I'm going with the WG function. I'm betting that internal WG is allowing too much air to go by the turbine. It could be the turbo being too small though. 45/50 Trim T3 won't make 300whp easily.

jfruauff

Well the internal gate was welded shut and I dont see it leaking because there is no signs of exhaust leakage around turbo to downpipe mounting.

Not really caring hp wise what i get. I would be happy 250+. Its just for a fun little car. I aint expecting it to hold 20psi and make 400hp. I just dont see why boost falls off. My boy has a b16 with a t25 that holds 13psi all day. So how does he hold boost in a way smaller turbo and i cant???

nowtype

Turbo's don't hold pressure for basically a couple of reasons.

1) Boost leak. Even with pretty decent size leaks, they will hold some pressure to redline. You'd have to have a massive leak to have this be your issue in my experience.

2) Turbo is running out of steam. You are pushing the turbo too hard, and it won't flow the necessary air so pressure drops.

3) Similar to number 2, not enough exhaust manifold pressure will result in not enough force to continue to have the turbine spin fast enough to spin the compressor. This could be a result of a leaky wastegate or exhaust manifold.

4) Turbo is fubar. This can be figured out pretty quickly. Look at the wheels. If they look like hell, this is your problem.

My experience makes me think your issue is #3.

jfruauff

OK i understand that but why would i have 5psi at the turbo the whole rpm range but it falls at the manifold. I know 5psi is always holding at the turbo from the dyno pulls and you can here wga stay open threw a pull.

Whats the best way to completely seal a internal wga flapper shut. We welded the arm for the flapper to hold it shut. I guess some could escape by but my downpipe dont show signs of any leaking

nowtype

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jfruauff &raquo;</TD></TR><TR><TD CLASS="quote">OK i understand that but why would i have 5psi at the turbo the whole rpm range but it falls at the manifold. I know 5psi is always holding at the turbo from the dyno pulls and you can here wga stay open threw a pull.
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Air flow basically. Essentially the compressor isn't able to flow enough air to pressurize the whole system. Same reasoning as I listed above. It's still 1,2,3, or 4. If you can, monitor the pressure at a few points. One at the compressor, the other right before the IC, the other right after the IC, and one at the IM. I bet by the time you get to the IC, pressure drop is already a couple of PSI. After the IC you are damn close to 0psi.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
Whats the best way to completely seal a internal wga flapper shut. We welded the arm for the flapper to hold it shut. I guess some could escape by but my downpipe dont show signs of any leaking</TD></TR></TABLE>

I'm really betting the farm this is your issue. You really need to make sure the flapper tight against the housing. You can weld the flapper to the housing or just rework the flapper arm again to make sure it's shut. I really feel this is your issue. You'll have to figure out how to make sure this flapper is really closed.