Camaro_Zach

iTrader: (19)

Is it just that an internal wastegate cannot bleed off a lot of air and that the externals can? im just trying to understand it. thanks in advance!

marleyskater420

Well wouldn't it only be determined by how big you can make the wastegate puck hole on the turbine housing? I mean I imagine boost control could be an issue at higher boost ranges, but I've used my wg up to 27psi before and it has been fine.

chuntington101

well there are loads of high boost (30psi) ford cosworths over here and most of them run internal gates! and the EVO turbo can be run at 2.3 bar (34psi) and they use internals, plus all the turbo diesels that run stupid boost!

anyone help?????

thanks CHris.

Camaro_Zach

iTrader: (19)

Yeah i mean its obviously easier to mock up a kit with an internal wastegate hahah

just curious as to why no one is using it if the option is infact available.

72firebird

I think it has to do with not being able to bleed all the air out fast enough. That's why most internally wastegated cars run a BOV to prevent the compressor surge that you experience. This is just my guess but I'm sure there's probably other reasons.

bryson

The biggest limit is the size of the wastegate. On an internal wastegate, you will have a tough time bleeding off enough exhaust gas to keep the turbo spinning slow enough to only make a couple psi. At higher boost it isn't a problem, because the wastegate doesn't have to bleed off as much boost. A situation with a turbo (especially a smaller turbo on a large displacement engine) running low boost is where wastegate sizing is most important. You have to be able to bypass enough exhaust to where the turbo won't build more boost than you want.

FastKat

iTrader: (10)

The problem with wastegate size is whether or not it's big enough... if it's too small, it can't bleed off enough air, and you overboost! That's the problem with size... If you want to run very low boost on a large engine, then you will have problems because the small wastegate will not be able to bleed off enough air to keep the boost low.

FastKat

iTrader: (10)

I read somwhere that turbo setups with external gates flow air through the system smoother and with less restriction than internal gate setups. The internal gate setups create turbulence when they dump back into the turbine housing which leads to a small increase in backpressure. I think this was in Maximum Boost by Corky Bell. Pretty sure he recommended dumping the wastegate back into the exhaust system no less than 18" downstream from the turbine.

Are there any clocking issues with an internal wastegate setup??

On the plus side, I think design strength would be in your favor. Simpler design, less flanges, less tubes... everything heating up and cooling down at the same rates - which is good.

chuntington101

yeah, thinking about it, what you guys said makes perfect sence! and i think i have read it before to! lol

also i guess that OEM stuff is generaly internaly gated because its cheaper and easier to pack into tight engine bays. plus a lot quieter! and gernarly OE turbos are a little undersized and thus wont requier as much gating as the bigger aftermarket stuff!

thanks Chris.

1FST99Z

iTrader: (9)

plus if somthing ****** up in the internal wastegate. the whole turbo has to come off if I am correct. as with an external you can just replace it.

Louis

iTrader: (7)

There is more to it that meets the eye.

Typically, with lower boost they have no control issues given the proper size and blend. However, if you run too large of a flapper, you increase the possibility of the flapper actually blowing open under high boost. Its common with DSMs that run high boost that still retain the stock style flapper.

Some internally gated turbos do not have a large enough flapper, and cause boost creep.

Its a fine line. Too small=creep. Too big=blow open.

LPE TT kits are internally gated, and they seem to do just fine


For your goals and budget Zach, I would run internal gates.

-Ross-

iTrader: (2)

Too big actually creates too much flow resulting in lower obtainable boost levels.

When you have a problem with the puck blowing open too soon, that is a WG spring problem (weak spring).

There are a lot of Buick guys running very very fast with integral WGs. I'm not sure you actually refer to them as "internal" WGs.