I have a HKS knockoff 50mm wastegate.Last year with the masterpower t70 and a 14 psi spring it would hold 14 psi.Then boost control it to 17.Now I have upgraded my turbo to a GTS78.Same size exaust housings.Not when I put the 8 psi spring in it makes 10 psi.The 14 make 18.Whats the deal here?Think maybe all the extra air being moved with the new turbos causing problems with the wastegate palcement?Its close to the turbo but in one of the crossover pipes?Please help me.Thanks

 

I guess noones had this problem before?

 

I had no luck with knockoff gates. Get a tial big enough to handle th boost and i bet u wont have problems.

 

put a tial 60 on there and be done with it!

 

Sounds like the wastegate will not flow enough cfm. Try either a larger gate or a name brand 60mm. I have used HKS and also TiAl 60mm gates and both flowed enough to hold constant boost from a 101mm turbo.

 

Don't over pay for a Tial or an HKS get and American made JGS.

Before you spend any money:

Tell us about how your exhaust is ran.
What is you back pressure?
What controller do you have? or do you.

 

The exaust it 3 1/2'' routed throught the k member dumped right after the passenger seat.Dunno on the back pressure.And I had a mbc on there but took it off to try and run off the spring.With the mp t70 I had the exaust ran the same way just in 3''.

 

What about the w/g open or returned to the pipe?

 

Dumped.Thought that couldve been a problem since the opening was 2'' and I had a 1.75'' tube welded to it.Welded a 2'' to it and no difference.On the vac line goin to the wastegate from turbo.It was a like say 1/4'' line.We redid the lines with what was at the shop which was smaller.The boost would keep climbing.Put the bigger line back on and the boost would come up and flatin out like it should.Only at 18psi instead of 14.

 

my car does the same thing, always a few pounds higher then the spring pressure. I just live with it. I thought it was my gauge but the map sensor and the dyno boost gauge read the same as my in car gauge. I am tired of swapping springs, I need to buy a nice EBC.

 

Mine never did it with the old turbo.I couldnt get that thing to make enough boost.

 

Jim there is a good chance the problem is the turbo.
Since we don't before and after bp's. hard to tell.
But I would image the old turbo would choke and could not make boost.
The new turbo is better suited to the motor has less bp and is make more
boost more efficiently than the old set-up.

 

So how do I go about fixing this problem?I think I replied in one of your threads in the sponser section also needin a pm.

 

Replace the gate or except the fact the is make a couple more pound than the old set-up.
Depending or placement, tune, turbo , b/p etc... pressures can vary. Tis is as long as it is a
fixed pressure difference. If you have boost creep then you need to go to a larger set-up.

 

I agree with Robert. I simply changed from a chanbered exhaust to a straight through exhaust and picked up 5lbs of boost across the board. Jims SVT I believe since you went with a larger turbine wheel you have less back pressure and your wastegate will open according to boost pressure + back pressure. Since you have less back pressure it is opening at a higher boost pressure.

 

Im thinking the placement of the gate is wrong anyways.So im moving it to see what happens.

 

Got it moved.Havent got it back on the dyno.But its still at the shop so maybe this week.Do you guys think this could be a problem?The wastegate being in the wrng location bleedin only one bank?

 

It is about efficiency your turbo can make more power with less back pressure.
So, it may move the the boost pressure up due to the reduced back pressure.

 

Damn...So do you know if anyone makes a 12 psi spring for a 50mm gate?Got a 14 in there and making 18.So if I do 12 it might get me 15-16.More along the lines of what Im wanting to run on pump gas.Then control it up to 20+.

 

Ok...Moved the wastegate and took it for a drive.I guess it is what it is.Didnt make a bit of difference. Would just put it on race tune but doubt the transmission will hold out for that either.