Thread: GT28RS Upgrade

Got the car back today. With the mbc at the same setting as it used to be, the new turbo only hit 7psi and it held it to redline. This was unacceptable so I kept cranking it until it would hit about 16psi, but it would fall to 12psi. What should I do? The only really different thing is the wastegate is different on the GT2860RS and the GTi-R T28. The one on the T28 is physically much larger. I have a dejon tool manual boost controller DEJON | Powerhouse, and it has a plastic barb the goes inline that has a small hole in it to remove spikes. I have this between the wastegate and the mbc. Should this be on the other side (between the mbc and the pressure source)? The mbc had been taken off by the shop and I don't remember exactly how it goes back on...

No, you have it installed correctly. That pin hole should be between the wastegate and the boost controller. It isn't exactly there to prevent spikes, it's to prevent holding the wastegate open between shifts and similar. Pressure can get trapped between the wastegate and the boost controller, and without that hole to let out the pressure, the wastegate can stay open when it shouldn't be open, which hinders spool and boost creation.

As for making 16 psi and then it falling off... You likely have a boost leak. =/

^ or very restrictive exhaust system...

^ or just a wastegate that can't hold it in higher RPMs..

I doubt it is my exhaust system (3.5" and it's maybe 2 foot long, just comes out of the front bumper). I guess it could have a boost leak. I just got it back from the shop so I hope not. It's the stock GT2860RS wastegate, those won't handle 18psi?

let us know if you find a boost leak

I'm trying to think where it would come from. All they did is weld the old factory discharge pipe from the GTi-R T28 to the GT2860RS compressor outlet, and there wasn't a boost leak before. I don't have pressure testing equipment anymore, they might have to look at it... Frustrating.

you can pick up what u need at a hardware store for not much. Then you just need to know someone with an air compressor.

Where is the best place to put the tester part, after the turbo? I still have the part with the bike tire fill valve and pressure part. Do I need to block off going into the intake manifold?

Put the tester on the intake of the turbo, or somewhere between there and the filter. You want to pressurize the turbo and everything after it. A bicycle pump can do in a pinch.