Custom 3" GTR downpipe.

[88FESTIVAGTR]

Alot of work. I wanted a divorced pipe, But there was no room with 3" pipe. I could have gone with 2 1/2" downpipe and made it divorced, But I really wanted 3" from the turbo back. And I think this one will do just fine. :wink:



Looks good, fits good.









See the o2 bung and the rear mount that attaches to the rear of the block. That reduces the load on the turbo under acceleration.


Notice the o2 bung in the rear also? That is for a wide band.




3"


The merge Made out of 2 1/2" pipe




Picture next to the stock gtr down pipe. A little difference huh?

Here it is again....Once again, notice the difference. Boost???? 8)


More comparison


Stock.


It goes as small as 2"


MMMMMMMMM.....................

[mattswabb]

Looks real tough. Great job.

matt

[booster1976]

Nice work Matt. Good idea running the wideband. With that kickass turbo breathing big you might run lean. But then, what do I know about GTR electrics...

[SimonTuffGuy]

Every new post you make about your project amazes me even more man.

[EVOGUN]

Looks good to bad about the splitting waste gate and turbine outlet. You putting a 3 Inch flex section? Coating> DOoo IT!! DOoo IT!!!

Thanks :wink:

[88FESTIVAGTR]

yes 3" flex pipe.

[aithanmier]

hate to show my ignorance but whats a divorced downpipe?

[88FESTIVAGTR]

when the waste gate has a completely separate pipe that merges into the exhaust later on down the exhaust.

[oxbrain]

Whats the benefit of having it seperate?

[Rumnhammer]

divorced wastegate

The advantage is that the gasses going through the wastegate, don't interfere with the flame kernel gasses coming out of the turbo, with the stock dp pictured, the wastegate gasses come out 90deg and immediately turn into the turbo outlet, this causes turbulence and back pressure right at the turbo outlet, which is the worst place for it. By separating the wastegate flow and reintroducing it farther down the dp, you eliminate this turbulence. The best solution is a totally divorced wastegate pipe, but you get most of the benefits with providing a larger area for the wastegate gasses such as he has done with his dp. When you run a totally divorced wastegate pipe, you get benefits similar to using an external wastegate, also by providing a much more free flowing exhaust route for the wastegate gasses you get rid if a lot of boost spiking that you can get if you fit a free flowing exhaust. The exhaust flowing more free after the turbo, reduces the amount of gas opening the wastegate so it tends to want to stay closed more, resulting in boost spikes. By letting the wastegate gases leave the turbo more easily, you sort of equalize the flow and let the wastegate open easier. How's that for a ten dollar answer to a ten cent question. :wink:

If you want a pic of a divorced wastegate look at the dp I made for the B6t it uses a bit of wall to separate the wastegate gasses at the turbo, then has a separate pipe that reconnects farther down the pipe.
Chris Rummel