Controlling high boost in third gear.

[WARBIRD1989]

Controlling high boost in third gear.

I have a wastegate manufactured by applied technologies, the boost is easily regulated in first and second gear at 15 pounds, but whenever the car moves into third at wide open throttle the PSI immediately goes past 20 pounds. I have tried changing the Spring to a 10 pound and a 15. I have even cut one of the springs in half, and I can still run over 20 pounds in third.

I have also replace the diaphragm. I have checked actuation using my air compressor, is it possible that the wastegate is too small for my PT 51 Turbo??

As the weather becomes colder the issue becomes worse.

My next step is to remove the inside of the wastegate, and see how much boost is made without the valve and place.

Any help would be appreciated

Steve

 

[Razor]

All Buicks will boost creep in higher gears. The factory through the little valve on the passenger valve cover would control this through chip programming.

Once you go to any other boost control, you will have to work around this issue.

Some cars are worse than others. An aftermarket electronic boost controller will help solve the problem.

And you may have the puck hole too small on the turbo. If the hole has been ported for the external, then the above statements apply.

HTH

Careful on running 20 PSI in top gear without sufficient octane. Its a recipe for bad things to happen.

 

[WARBIRD1989]

If possible for somebody explains to me how boost creep occurs, I actually do not see how it is possible, if the wastegate is under pressure, it should be opened, and therefore passing any unwanted exhaust gases. more boost more passing ,,,Right?????

 

[postal]

And you may have the puck hole too small on the turbo.

Pull your down pipe off and measure the waste gate hole in the turbine housing. If it around 3/4" or so then you need to open it up with a die grinder to around 1".

If possible for somebody explains to me how boost creep occurs, I actually do not see how it is possible, if the wastegate is under pressure, it should be opened, and therefore passing any unwanted exhaust gases. more boost more passing ,,,Right?????

The waste gate can dump more than enough exhaust to clamp the boost where you want it. The problem is that it has to squeeze through the stock size waste gate port in the turbine housing. When your into third gear and have the motor loaded down hard the waste gate can be wide open but not enough exhaust can squeeze past the under sized port in the turbine housing so the boost will rize.

All Buicks will boost creep in higher gears.

I only have that when I hit the NOS. Its more of a boost jump of about 7 psi. Didn't you have a NOS kit you where thinking of playing with? I was really looking forward to messing with the NOS this year but my car has sat ever since BG.

Jason

 

[LV GN]

Originally posted by postal
Pull your down pipe off and measure the waste gate hole in the turbine housing. If it around 3/4" or so then you need to open it up with a die grinder to around 1".

Jason

jason is right on the money! i just did one on sat. if the pipe has been on the turbo for a little while. it will have a perfect mark from the hole on the dp. just open it up to that size and you will be good to go. you mite need a new spring now. to low of tention spring will make for slow spool-up