WQ Fiesta XR4/ST150 with Mazda SP25 engine

[Aaron]

I had a brief chat with an Engineer out going 2.3L. It still requires a certificate but it doesn’t require all the testing of things like brakes etc.

Personally I’m keeping a lazy eye open for a 2.3. Then it will either have a piggyback cam controller or I’ll have to disable the VVT. It’s my “if it pops” plan.

That’s a two two stage trick with a non-VVT cam gear required as well as a blanking plug in the head. The stock 2.0 ecu and injectors have sufficient latitude to run the 2.3, but the 60mm throttle body would be handy ;)

I keep thinking about the gearbox though. Mazda G35M-R and G36M-R (5 and 6 speed respectively) seem to look a bit more fitment friendly than the MTX75. In particular the end housing that has to work in the same space as the frame (even on an IB5).