Mazda rotaries. Pre mix and octane reduction

[Bruce]

Using the pump always for a very small amount of oil for idle.
Since you mention Road Racing, and the RPM you need to twist a rotary to go
fast, they at that stage about become disposable.  So the lose of a little
octane, or some detonation isn't really that critical of issue.  Also, some
of the 2 stroke oils are blended to be low ash, and I'd imagine might even
have some octane boosting chemicals in them.
Bruce

From: "Chris Wilson" <chris at formula3.freeserve.co.uk>
Subject: Mazda rotaries. Pre mix and octane reduction
> Speaking specifically of 3rd gen Mazda RX-7 rotary turbo engines with oil
> metering pump removed and an oil/petrol pre mix used for lubrication of
> rotors and seals, how does this affect octane? I had always believed oil
> contamination of the fuel reduced it's anti knock abilities, but
> carrying this to a logical conclusion 2 strokes using pre mix must
> really be hit by reduced octane when they run a high percentage of oil
> in the fuel? Or have I got this all round my head?
> The real reason for my question is i want to run after market ECU on my
> 3rd Gen RX-7, and the stock ECU controls the oil metering. Some
> knowledgeable people say run the purely mechanical metering pump from an
> earlier engine, some say remove it altogether and run a pre mix
> oil/fuel like a basic 2 stroke. The car will mainly be used on road race
> tracks. Mixing fuel/oil is something I could live with.
>            Chris Wilson
mailto:chris at formula3.freeserve.co.uk

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