Hey, Im having an issue here. I have an external wastegate and upgraded the spring to a 15lb spring but I see no change in pressure. It still only boosts about 6-7 pounds. I have seen threads where people have connected the lines in different places and got different results. I was wondering what the best route to do is to get the correct reading on my boost gauge. I have a manual controller as well but no matter what I set it at its still the same.

 

a turbo can also be limited by more factors than just the wastegate. exhaust backpressure, exhaust leaks, intercooler pressure drop, wastegate not seated properly, engine efficiency... these can cause boost to not rise regardless of spring pressure.

your wastegate should have some documentation somewhere. every wastegate is slightly different and we can't guess what you have.

if you changed the wastegate because you could not get more from the previous one then you are probably not looking in the right direction.

 

well the wastegate spring was changed when the engine was being rebuilt not the wastegate. when I bought the car 2 years ago it had the external wastegate already on it so im not sure which wastegate it is exactly.

what info would you need from me to help me to figure things out better?

 

do you have a boost controller?

 

I do, I have a manual boost controller.

 

Thats the best picture of the wastegate i could take. As you can see the top nipple doesnt have anything connected, but the side one does, is that the way its supposed to be?

 

looks like an older HKS knockoff or original.

do you get any boost increase by turning up your boost controller at all?

 

Slightly, usually in the higher gears I will see like 1 extra pound. With the controller. When it hits the 6 pounds it holds it there, it doesn't taper off like it would if it was at higher boost pressure

 

well you can do a few tests. one is to remove the pressure line to the wastegate and carefully drive the car into boost and see if it spikes higher(a boost cut in your ECU is your friend here), this will mean your boost controller is not setup correctly.

that however doesn't explain why the spring is not holding the proper pressure, it is possible you got the incorrect spring for the wastegate.

if none of that gets you a rise in boost then check your turbo for excessive play, if the turbo blades are contacting the housing then you will lose boost.

you can also test the wastegate by removing your dump tube and tee in a pressure gauge to a compressed air line, see if the wastegate is beginning to open around 5 psi or around 15 as it should.

you can also build a tester for the intake with plumbing fittings and a compressed air line while checking the intake for large boost leaks around where you are seeing your boost fall off. make a cap to clamp to your turbo inlet and install something like a tire valve stem with the schraeder valve removed for more air to push in faster(no system is ever completely sealed and even my 80 gallon tank at 130psi can usually barely push past 10psi with this sort of setup).

the other issues are more complicated to track down, which are restrictions in the intake or exhaust.

 

my boost controller was a problem, it was not allowing air to flow though like it should. i have it hooked up without the controller and it boosts to 8-10 pounds. still lower than what the spring is rated at though. Am I correct to say that the top line on the wastegate should be left open like in my picture and the side port should be the line to connect to?

 

something else you did caused the rise in boost. a boost controller can only raise boost, so removing it could only cause boost to drop, not go up. again, check your turbo shaft play, if the turbo is worn it may be rubbing and dropping boost. if the wastegate isn't getting any pressure signal, then that would explain the raise in boost.

top port should be vented, bottom port to boost controller or off the compressor housing.

the wastegate uses pressure from after the turbo to push open the wastegate, if the line is disconnected the wastegate will not open and the turbo will push as much boost as it can manage. if you supply intake pressure to the wastegate you will get the lowest boost that the wastegate can manage. with the boost controller in the mix you will get somewhere in between these 2 variables depending on where you have it set.

 

well that's weird since all I did was remove the boost controller, but I will check around just to make sure

 

then it probably isn't hooked up to a pressure source causing the wastegate to stay closed completely.