Project [Rotary] FD RX-7: Part 4 – Turbo System


Now that we've introduced you to the turbo and manifold used on this build, it's time to talk wastegates. The Full-Race manifold comes with provisions for twin 44mm wastegates and this is perfect for the RX-7 because we want to be able to control boost below 10psi if so inclined (low boost requires high wastegate flow). To populate these provisions we are using 45mm wastegates from Turbosmart that use the same mounting flange as popular 44mm wastegates.

Here is the Turbosmart Hyper-Gate45 and all its included components. The only piece shown in this picture that won't be used is the wastegate inlet flange. This is because the Hyper-Gate45 can be installed to a standard 44mm wastegate flange like those found on our Full-Race manifold.

Hailing from Australia, Turbosmart has a history of producing race winning products that are used by some of the fastest time attack cars in the world including the Sierra Sierra Evo and FXMD NSX. Turbosmart wastegates have also been featured in several MotoIQ builds like Project 240SX – Land Speed Racer and the Team America World Time Attack BNR32 GT-R.

The Turbosmart Hyper-Gate45 is a 45mm wastegate that is extremely compact. A pair of these will be installed on the RX-7 to keep boost stable and prevent any chance of boost creep at lower boost levels.
Since we are using two of these Turbosmart wastegates here is a shot of the two wastegates together. It's hard to tell how compact these wastegates actually are in a picture like this, but it's clear that technology has come a long way in the past 10 years.

Before mounting any components we had to prep the engine for them. The factory turbo studs, gaskets, and nuts are all used on this install. The factory studs and nuts are made of Inconel to handle the exhaust heat that rotaries are known for. A bit of copper anti-seize is added to the studs as well for good measure.

Here are the factory exhaust gaskets installed to the engine. Using the OEM gaskets, studs, and nuts is the preferred way to seal the exhaust manifold to the block.
Full-Race manifold mounted to the engine. Ignore the fact that all the studs aren't the same in the following pictures…it has been corrected.
To keep with the progression of things, here is the Borg Warner turbo mounted to the manifold. This turbo location is significantly higher and further forward than what is found on most RX-7's. Having the turbo located further forward means that less radiant heat from the turbine housing will heat up the lower intake manifold, however it also means that fitting intake and intercooler piping is a bit more cumbersome.
The manifold, turbo, and wastegates all mounted to the engine before starting the fabrication of the downpipe and wastegate plumbing.

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