Acceptable Exhaust Manifold Pressure?

Mongler98 said:

WHAT??? WHY??? So is the gasket supposed to seal that? looks like its not sooty, so was it leaking or is this the issue for real??? Does it give way if there was a melted cat or potato in the pipe????

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LOL! Yes, apparently the metal gasket is supposed to seal that, which it does just fine. I confirmed that it's fine as is and there's no leakage past that spot when the turbine is under pressure.


I ordered a new GTB1756VK CHRA and installed it a couple days ago. The engine already runs noticeably better than it used to. The compressor and turbine wheels spin MUCH better on the new unit, there's a ton less resistance.


However I found out the hard way that my custom GTB1756VK was more custom than I realized. It has a 44.5mm inducer on the compressor wheel rather than the normal 41.5mm, and the compressor housing is machined to accept that. So that means that with a standard CHRA, there's now a huge gap around the inducer when using the modified compressor housing. This is preventing the turbo from running efficiently and causing other issues. I've got a standard compressor housing from JFettig on the way to resolve this issue, but in the meantime I'm still driving a crippled car


One other issue I came across: how necessary is the O-ring on the compressor housing? Mine has never had one ever since it was new, and I always wondered how the compressor could remain sealed under pressure with just bare metal surfaces touching each other. I only just found out that there's supposed to be a 95mm rubber O-ring in there...

i have ran turbos with and without o rings, when mocking up turbos, they get removed so it can easily be rotated for fabbing up the pipes. never noticed a difference with them on or off but they do leak oil and make a mess if the system has a scavenge CCV like TDI's do.

one thing i have noticed with turbo cores, there are like 4 or 5 different ones that will call for the same darn turbo, the difference is int he builder or brand of the turbo.

what does the turbo boost map graphs look for the custom vs the standard compressor. you should be able to get that info from Garrett, if you can even get ahold of them.