Turbo on RX-8

[Phoenix7]

Originally Posted by mazdamaniac

Its already a turbo car. Doesn't count for this comparison. Try making that power that cheaply on the GTU.

you got me there. You're right.

Power tapers in the high-end of the Renesis because of the flow restriction of the exhaust ports.
The Renesis has a very wide power band, but it isn't going to be all at the top like a peripheral port 13b.
Once the gas velocities get really high, the right-angle turn of the exhaust ports becomes a restriction.
The high power output Renesis applications you will see in the future will make their peak tq at 6200 and hp at 7200 max.

Makes sense, what exhaust manifold does the MM turbo use?

The problem with the FD turbos are they don't flow enough air.
You can tune all day, if the air is hot coming out of the turbos (low mass) the power won't happen.

[mazdamaniac]

Originally Posted by phoenix7

Makes sense, what exhaust manifold does the MM turbo use?

Its the GReddy cast iron manifold.
Pretty decent piece - the flow cross-section is about equal to the port area.
I've been thinking about an Extrude-Hone to increase flow a bit.

Originally Posted by Low Impedance

i think the problem is the turbos are getting out of their efficiency range when you start getting up there.

Exactly.
Even though the pressure is rising, the mass is holding because the heat is going up.