Internal or External wastegate

[1ViciousGSX]

Get the 44mm external wastegate

[niterydr]

It just comes down to packaging. We went with internally gated 50 trims on my stealth and I can get it to 15-16 psi no problem, and it doesn't creep. (heavy duty actuators).
The larger the wastegate, the lower boost you can run because you can bypass enough air.
I still perfer internally gated turbo's for street cars. Routing external wastegates is a pita and really adds to the cost of the build. Not to mention the room they take up. Granted, external wastegates are the way to go, but imho, you need to have a manifold designed for it. Just gafting a wastegate on a 1 exhaust runner is a piss-poor way of managing boost.

[BoostedTSI]

The highest spring pressure is "HP 1.6 Bar (23.20psi).I plan to run over 30 PSI and don't understand exactly what spring pressure im looking for. O and that is on a tial 44mm

[Jakey]

The highest spring pressure is "HP 1.6 Bar (23.20psi).I plan to run over 30 PSI and don't understand exactly what spring pressure im looking for. O and that is on a tial 44mm

The lowest boost level you can run with that specific spring is 23.20 psi.

[Speedfreak]

Yes but Swanny you have two wastegates for 50% more flow. Or in other words you have three cylinders your dealing with compared to four mighty 4G63 ones.:)

BTW, I have a 1 Bar spring, and I can run 30+ lbs just fine.

[niterydr]

Yes but Swanny you have two wastegates for 50% more flow. Or in other words you have three cylinders your dealing with compared to four mighty 4G63 ones.:)

BTW, I have a 1 Bar spring, and I can run 30+ lbs just fine.

Yeah I know.

We've put these 02 housings on scm61 cars w/o creep issues however.

[JET]

Because with a larger turbo, its harder for a smaller wastegate to bleed off enough air to keep the boost down. I have a scm61 on a Turbonetics manifold, and a Tial 40mm. I can't keep it from creeping on pump gas. I've ported the manifold as much as possible to get as much air to the wastegate, but with no avail. The placement of the wastegate on this particular manifold isn't the greatest, but in any case, the larger the turbo, the larger the wastegate needed to hold low boost levels.
I have a Tial 40mm off the O2 housing on my SCM61 and it is fine, runs 15 psi. Nash's was the same and didn't have an issue. It must be the placement.

[Super Bleeder!!]

Mo, how do you run a tial 40 on a turbonetics manifold? aren't they flanged for 38s? doesn't it hit the hood?

[Speedfreak]

Yeah, I'm sure it's placement. I made a short curved conversion pipe, for lack of better words... 38 flange to 40 flange.. And the 38 flange is opened up larger then the 40.

[Shane@DBPerformance]

The spring psi is the lowest boost that the wastegate can run. The bigger the valve or flapper for a wastegate, the more likely it will be blown open by backpressure. So without any help, a smaller wastegate will be able to handle higher boost.

Most external wastegates have an extra port on them though that can be used to push boost pressure to the top side of the diaphragm to help hold the valve closed in high boost/high backpressure situations. I ran a 35mm Tial with my 67mm turbo and it was fine, but I didn't run extremely low boost and it picked up right from the collector.

There are tricks, not really the best for power, that can be done to help control boost on an internally gated turbo. You could run an O2 housing, that has a big open chamber that causes the exhauast flows from the internal gate and exhaust wheel to collide and mix together right as it leaves the turbo. You see this with a lot of OEM turbos on other kinds of cars, Mitsu kept the two exhaust channels seperate on our O2 housings stock. PTE tries to force the same thing to happen with most of their Mitsu internal gate turbos by cutting a channel in the divider wall. When the two channels of exhaust flow are allowed to collide right as they exit the turbo, you end up with a lot of turbulence and backpressure that helps to control boost and hurts your power.