Okay after searching the turbo section for a hour, what are the advantages and disadvantages of a internal or external wastegate. The only thing I came up with is the interanl is a cheaper route to control boost. What do you guys think about this?

Normally the external is better, especially in higher boost applications. It normally lets air out better which really helps with boost creep. It doesn't really matter which one you get if you have a low boost setting.

What boost levels is internally gated still good for?

Originally posted by Boossted420a2g
What boost levels is internally gated still good for?

They're still good for 20+psi, but you're going to need to get the wastgate hole ported and possibly a bigger flapper eventually. At what levels you need to do this? Depends on whenever you start creeping pretty bad. And if that doesn't work, get the external. Or just get the external to begin with and be done with it. But I doubt you'll be out flowing the internal any time soon.

personally i think its all personal preference. with an internal gate you cant really run an open wastegate unless you have a nifty looking flange coming off the turbo.

internal gates can hold up to 30+ psi, just depends on the turbo.

an advantage of having an internally gated turbo, is obviously much less piping and equipment.

and like 420anthewrks ^^^ said, external is typically used on really powerful turbo cars because you can get pretty huge sized external gates to prevent boost creep.

a DISADVANTAGE of having an internal gate, is when the flap opens...the inside of the 02 housing goes crazy with multiple streams of exhasut flow coming both past the turbine, and out the wastegate. if you look at how a vf turbo on a stock wrx looks, the exhaust flow actually slams RIGHT into the turbine when the internal gate flap opens...obvious this isnt the best designed system, but theyre not all like this.

theyre both very functional, but if you want the best flow...and the best possible advantages to avooiding boost creep..go with external gate. you also have the option of plumbing the external gates dump to the atmposphere, as well as farther down in the exhaust stream.

But can't you build your o2 housing so that it's dual piped and setup so that the exhaust streams don't hit each other until they're in the downpipe?

The other issue with ported internal gates is that the flapper door can blow open, which winds up killing your boost. It's equivilant to having an enormous exhaust leak pre-turbo.

Originally posted by a_miller_76
But can't you build your o2 housing so that it's dual piped and setup so that the exhaust streams don't hit each other until they're in the downpipe?

Originally posted by turbo8u
with an internal gate you cant really run an open wastegate unless you have a nifty looking flange coming off the turbo.

perfect example...

So I can get an internal wastegate since my plans for my car to produce 330-350FWHP on 15-18LBS of boost? The turbo will be t3/T4OE 57 Trim with .63 A/R

internally gated should be fine, but you'll probably gonna run 20 or more psi to hit 350whp i think, but don't quote me on that

Originally posted by BlackMagic
internally gated should be fine, but you'll probably gonna run 20 or more psi to hit 350whp i think, but don't quote me on that

nope all depends on the turbo....20PSI on t3 42 A/R turbo is not equal to 20PSI on a t3/t04e 57 trim turbo. You will have a higher HP number with a higher CFm flowing turbo. PSi is just the amount of pressure in your charge pipes. CFM is the flow of air.

Terry

Originally posted by Star Turbo Talon

Originally posted by BlackMagic internally gated should be fine, but you'll probably gonna run 20 or more psi to hit 350whp i think, but don't quote me on that

nope all depends on the turbo....20PSI on t3 42 A/R turbo is not equal to 20PSI on a t3/t04e 57 trim turbo. You will have a higher HP number with a higher CFm flowing turbo. PSi is just the amount of pressure in your charge pipes. CFM is the flow of air. Terry

yea i know it depends on the turbo, but i just wasn't sure if that one was big enough, but i guess it is

The only real major advantage of the external gate is more precise boost level control using a larger turbo, at a lower boost pressure. An internaly gated turbo will work fine at any boost pressure, providing you are in the turbo's pressure/flow range. It has nothing to do with running over 20 psi, ect..Think about it, you have most exhaust bypass gasses through the wastegate at LOWER boost pressures, not higher. To get higher boost, you close off bypass exhaust gasses going through the wastegate, so more actually goes into the turbine housing over the turbine. Internally gated turbos, when quite larger, have trouble running lower boost pressures, as the wastegate exhaust flapper/passage may inhibit flow, and you can get boost creep at higher rpm. Interal gates work fine, are very simple, and have less piping to fab up. But, external gates provide as much bypass flow as you want, and can be very accuarate. This is why you wont fine too many really "large" internally gated turbos..I believe the HRC S25G is the largest that I know of anyway

A 500hp capable internally gated turbo:



If the turbo manufacture knows how to correctly design it for proper flow the only difference is easy of clocking (internal gate holes can be just as large as external), and packaging.

Sexy!