External vs internal wastegate???

[zandrew]

I am going to be doing some work under the hood and have had an external gate for sometime. With my ultimate goal of around 350AWHP I am wondering how much of a difference the external gate will make over the internal? I know some people swear by them and I am sure it is a better option but I am wondering if there is any gains or specific advantages to running he external.

Also if I do run external is a screamer pipe better then circulating it back into the exhaust?

[Seerlah]

Waste gate dump or recirculating is a preference thing. I like quiet, so mine is rerouted back into the exhaust. As for external or internal wastegate, I think it had more to do with the t3 being used with external and t25 with internal. Sort of like the force of the hand type of deal depending on what flange you went with. But people have welded internal flappers closed and gone external. I think them to be more reliable as for as function goes. But with that being said, all EFR units are internal wastegate so...

[Poopie]

External is more serviceable and reliable as far as sealing goes. But I think in larger motors that move a lot of air you might get some boost creep with the internally gated housings.

[zandrew]

Welding them shut is a waste of time if you do not weld it completely around the flapper. I have bought turbos from people that welded them and they will crack and leak or dumb dumbs will not have the flapper sealed all the way. Also you can not go back to internal there after. I was actually thinking about using the N75 valve and my EBC. I would set the N75 to say 20psi and set my EBC for 17psi. That way I don't have to weld aything shut and it gives me somethin to fall back on if one screws up, which it shouldn't.

Sound stupid or is this possible? Its not so much for function but more so since the parts are already there and I prefer not to weld the damn flapper.

Seerlah I would "guess" that Borg Warner actually took into account the hp and flow potential of the turbos they made when allowing for internal WG port. Garrett turbos use compressor and turbine housing designs from atleast the mid 80's (and some from the 70s) well before they sold BB turbos. It is kind of disgusting when you think of it.

[Seerlah]

My Comp Turbo is like the size of my GT2871R but is a 530hp turbo. I found that really interesting. I'm still using my old turbine housing from my GT2871R machined to fit the larger wheel. It's like when I pop the hood more should be there. I'm not really complaining though. In this case, size does not matter.

[zandrew]

You running internal or external?

[Gumby]

Depends on what exhaust manifold you use if you go external too. I run an SPA manifold, and the wastegate is located upside down towards the rear of the manifold. The wastegate, and the recirculating pipe aren't visible from the top at all with my intake setup.

[M-Hood]

External WG is a better option if you have a boost controller that can be used to control the WG as a dual port.

WG dump is better for making power since you then have less exhaust gas after the turbo which means less back pressure.

[ZimbutheMonkey]

My Comp Turbo is like the size of my GT2871R but is a 530hp turbo. I found that really interesting. I'm still using my old turbine housing from my GT2871R machined to fit the larger wheel. It's like when I pop the hood more should be there. I'm not really complaining though. In this case, size does not matter.

Hey Seerlah, I forgot if I asked already, but what are the spool-up characteristics like on it? (ie, when does it start building about 5 PSI, 10, 15, etc...) I'm especially interested as you're using a .64 A/R (also internal or external gate?) and correct me if I'm wrong, but it's a 5152 IIRC (also extended tip or non extended tip?)

[Seerlah]

5152 non extended triplex with .63 A/T T31 (GT28xx) turbine housing machined to fit the larger wheel. Right now, my full boost (25psi right now) does not hit till 5k. Used to be much earlier. But I have a leak I did not tackle yet (need to wait till spring to get my car back up to par). I know where it is (need to tighten nuts on manifold to head). Before, I hit full spool (25psi) mid 4k range. When I get my car up to par I am going to hit up a dyno. You will see real world numbers when that happens, versus my conjecture.