GTM Performance Engineering: MHI Twin Turbo Official Release

esfourteen

Every factory turbocharged car in the world comes with internal wastegates, for the obvious reasons of: cost, weight, and clearance/space issues, so aside from those, I would say its a good idea to run externals just because internals have certain limitations.

Since the volumetric efficiency of our engine is so high, I would say if you have the extra money just go external so you avoid any boost creep issues with our engine. However, claiming that external wastegates are safer and give "better power" (whatever that means) and more power is just a joke.

The biggest problem typically encountered with internal wastegates is controlling higher amounts of boost (> 20psi). Theres 2 reasons for that, first most factory actuator springs are in the range of 7-14psi, so with an EBC solenoid at max duty cycle (about 90%) that would mean a maximum of 14-28psi. The second issue is the size of the wastegate openings. Internally gated turbos wastegate opening is limited by the size of the turbine housing itself, external wastegates do not have this limitation. This is why the .64 AR suffers from creep issues while the .86 does not.

I currently run 15psi and have no issues holding that to redline on internal gates with .86 housings.

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