I am quite sure that some of you may wonder what the difference between a stock NA 1.6 motor and an M2 1001 motor may be.
Especially because the latter offers a mere 10 ps more than the NA 1.6 motor.
Upon release of Eunos Roadster in Japan, there were voices from users asking for more power (Japan version had 120 ps).
Thanks to the superbly designed suspension system, the chassis was capable of accomodating more power.
One important point to understand is that Mazda did not have an inline 4 cylinder motor that could be used for an FR vehicle at the time.
Hence, the B6 motor mounted in a Familia (FF) was re-engineered so that it could be mated with an FR layout.
Here are some of the the objectives upon developing the M2 1001 motor.
- Enable the engine to realise efficient combustion
The first thing Mazda engineer did was to employ a new piston with higher compression (9.4 → 10.67) and reduced surface area of the combustion chamber.
Furthermore, the piston clearance (play) was enlarged (0.045mm → 0.070mm) to prevent cooling and friction losses.
The image here is a set of M2 1001 piston.
For those of you familiar with stock NA 1.6 piston which has a bent roof construction, you will realize that the piston top is flat with valve recesses only.