The 2 litre version of the MX 5 engine is the Japanese version of the Ford Duratec (or perhaps vice versa). The main difference is that the Mazda uses variable valve timing. If you look at the dyno chart on the Aero Racing web site you can see that the Plus 4 SS engine, which has larger throttle bodies and a sports exhaust system, is significantly better than the Standard Duratec. There is a dip in the torque curve at about 2000 rpm. I am certainly not an expert but I believe that may be due to the size of the throttle bodies. I would imagine that slightly smaller throttle bodies and a slightly lower state of tune would eliminate that. In any case it is not particularly peaky as you can see from the curves.

Plus 4 Supersports versus standard Plus 4 - Power curve charts (from Aero Racing)

Peter

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