Mazda rotaries. Pre mix and octane reduction

[dom]

Actually many of the ITA teams go 1-2 seasons on the same NA rotary motor.
The pisston guys rebuild every race or 2. Also Chris was asking about
turbocharged application, when any detonation can take out an apex seal.
Also none of the pre mix that I am aware of has any octane boosters.

As for Chris' questions, 100:1 lowers the octane by about .2 . FWIW, I
premix in my 3rd gen with a Haltech, because I think the OEM oil injection
location is a compromise. Also, why would you want to burn dirty engine oil,
When you can run a nice syntheic premix that was designed to burn clean.
There are some disadvantages to premix, it is inconvenant, messy, leaves
crap on your bumper and you can't adjust the mixture dependant on load.
-Dom

on 7/14/01 6:48 PM, Bruce at nacelp at bright.net wrote:

> 
> 
> 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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