Thread: GT28RS Upgrade

What is it that stops the pressure, the valves? Just out of curiosity...

Yes the valves, if you have the engine in the proper rotation. There's a possibility that both intake an exhaust valves could be open, but that at point hopefully you're using an air compressor and not a bicycle pump. You'll be able to hear the boost leaks. And if you want to get fancy a smoke machine lets you see them too.

That's what I thought, but I've had it leak through the valves before I'm pretty sure, because I couldn't find a leak anywhere but it would slowly leak out of somewhere. I'll try it sometime soon. In the mean time, it shouldn't hurt it running it like it is will it?

As far as the wastegate being too weak. What are the chances of that? I think the wg that comes with the potato is weaker than the GTi-R one, but that's beyond me. I just want the thing to run right .

Yes, it will hurt it. You will over-spin the turbo. You can run the car but stay out of boost. You won't harm anything if you stay out of boost.

If things are working properly, you shouldn't have any problems with the wastegate that came with the turbo. That's not to say maybe you got a faulty unit, or the pre-load on the wastegate actuator is completely messed up.

Okay, I can drive it around pretty easily and stay out of boost. What's weird is that it doesn't really seem very laggy. I'll try pressure testing it tonight though and post back up. If it is the wastegate, how would I be able to tell? Just bypass the mbc and use a hose from the compressor pressure port to the wastegate and see if the pressure is close to stock (I'm guessing ~6psi, +-2psi for pressure loss throughout the system?)? My boost pressure gauge is tapped off of the manifold, whereas my wg source is off of the compressor housing...

You'll need to visually inspect it, and possibly run pressure directly to it and visually make sure the actuator is operating properly and that the wastegate doorway is working properly. This might not all be possible with the j-pipe on.

Okay so I found one leak, so I tightened the clamp more and it quit bubbling. It still wont hold pressure though. The boost headed for 20+ really fast so I turned it down and it would hit 18 and fall to 16psi. I know there are more leaks but I went to test it again and it just started breaking up on me. Felt like a fuel cut but only from 7psi and higher. Maybe the other leak became much worse since I fixed one of them?

Don't forget all the vac lines and the iacv etc. They could be leaking also

Would a big boost leak cause my breaking up over 7psi? I've never encountered this before... I don't have an iacv or cold air idle valve anymore. To be honest it sounds like its running through the turbo itself and through everything. I'll have to try the pressure test again tomorrow. It's hard to do in the dark.

the breaking up under boost would be your spark plug gap - what do u have it at?