the sh*t just hit the fan

[yellerandahalf]

OK, so I went testing my wastegate today to try and evaluate why I'm getting MASSIVE boost creep. The turbo is a t3 super 60, with a .48ar turbine and a "super 60" .60ar compressor. It's internally wastegated. I looked at why i was getting creep. I completely disconnected the actuator rod from the swingvalve, effectively creating a completely open wastegate. So, effectively an NA car, right? no! At 4500 boost starts rising, and will creep to 15psi at 5700 if I let it. what in ******* hell? Boost creep at 0 boost? how in the hell is that even ******* possible? I'm beyond angry. Any ideas why this might be possible?
-Mateo

 

[CustomMSP]

Maybe the wastegate port is very small in diameter, therefore the gases are not able to escape as fast as they need to. Port it out eitherway so it flows better.

 

[KzA]

wow that really is rare...Im def not smart enough to answer this one...Subbin to see the answer...

 

[MPNick]

OK, so I went testing my wastegate today to try and evaluate why I'm getting MASSIVE boost creep. The turbo is a t3 super 60, with a .48ar turbine and a "super 60" .60ar compressor. It's internally wastegated. I looked at why i was getting creep. I completely disconnected the actuator rod from the swingvalve, effectively creating a completely open wastegate. So, effectively an NA car, right? no! At 4500 boost starts rising, and will creep to 15psi at 5700 if I let it. what in ******* hell? Boost creep at 0 boost? how in the hell is that even ******* possible? I'm beyond angry. Any ideas why this might be possible?
-Mateo

Is the swing valve moving freely or does it feel stucktight?

 

[igdrasil]

backpressure...looks like the valve is stuck in certain position that it will allow pressure to leak but not open enough to keep it low in high rpm, thus accelerating the turbine.

You said you have a .48, but which stage on the wheel?

 

[HiBoost TS]

If you have a Turbonetics swing valve assembly it is very probable that it is stuck closed. This happened to me many times. The shaft just won't move getting a closed valve all the time.

 

[yellerandahalf]

nope, it's not stuck closed. basically We've determined that the turbo was hodge-podged together and the components aren't working well together. Time to sell and move up. T3/T4 en route.
-Mateo

 

[anarchistchiken]

Well, I guess that's one solution.

 

[yellerandahalf]

indeed. but is it though? I figure there's about an 85-90% chance it'll work. discuss.

 

[hesitationhater]

What does your downpipe look like and how big is it? Any pics of it?

 

[yellerandahalf]

it's a custom 2.5" downpipe, pic is here.
why would that matter though? a restrictive DP would cause low boost, not high boost.

 

[yesiownaskyline]

Well, I guess this stand to be the reason why you got such a good deal on the turbo.

I agree, if the wastegate is not stuck closed, there is some sort of backpressure building through the turbo itself. There should be no reason for backpressure after the wastegate and DEFINITELY no aswer for 15psi of it with the wg OPEN!

 

[hesitationhater]

it's a custom 2.5" downpipe, pic is here.
why would that matter though? a restrictive DP would cause low boost, not high boost.

What size is the rest of the exhaust? Catless? I don't think that the DP is your only problem, but it could be adding to the situation. Creep like you are getting is usually either the wastegate itself not venting enough to slow down the turbine, or the exhaust is causing backpressure at the turbine/wg outlet and keeping the exhaust gas from venting out of the smaller wg port. You could test this fairly easily by taking off the downpipe for a quick pull and see if it still creeps.

 

[yesiownaskyline]

im telling you- There is no ******* way an aftermarket (meaning larger than stock) exhaust will create 15lbs of backpressure. Theres a few people running stock exhaust witht he t25 at 12-14psi and getting maybe like 2-3psi creep... I know the T3 is much bigger, but still not big enough to cause that dramatic of a spike.

 

[hesitationhater]

Like I said, it is unlikely that the DP would be causing the creeping all by itself, but a simple test with it unhooked would show if it was contributing at all. It has to be either the wg, or the exhaust, or a combo of the 2 to create boost creep. I personally never had any creep on my stock DP, so I agree that it seems unlikely that a 2.5" wouldn't be able to breathe enough to keep this from happening. If he tests it with no DP on the car and still gets massive creep like he is now, then the problem HAS to be the wg itself.

 

[BradC]

it's a custom 2.5" downpipe, pic is here.
why would that matter though? a restrictive DP would cause low boost, not high boost.

If the exhuast flowed well, but the WG portion didn't, the turbulence would cause it not to flow enough to bleed boost off quick enough.

 

[MPNick]

If the exhuast flowed well, but the WG portion didn't, the turbulence would cause it not to flow enough to bleed boost off quick enough.

Guys the stock T-3 wastegate oulet has made over 400whp in the past on all types of car.

 

[yellerandahalf]

ok. I'm going to run a series of tests. First, I'll disconnect the turbo from the DP, and see what happens(with the WG held open), then if that doesn't do it, I'll pull the entire WG off. I'm willing to bet big bucks that won't do anything either, and that the problem's due to a bad combination of internal turbo components. we'll see in a few hours.
-Mateo

 

[BradC]

Guys the stock T-3 wastegate oulet has made over 400whp in the past on all types of car.

I wasn't saying the internal gate was at fault, I was suggesting maybe the DP was too restrictive at the wastegate port.

 

[yellerandahalf]

ok, i disconnected the DP from the turbo, and went for a test run. it spool 1k rpm earlier, and creeps faster. pulls hard and turbo sounds cool as hell though! It would also be really helpful for tuning (you can really hear what the engine is doing).
-Mateo