Rattaan

Ok, since I'm driving an NA, lower octane is better for power and mileage not to mention cheaper. In my web travels and exploration of this site's references I've read that 83 octane was used in race car NA's in the past with good results. My question is, how do you lower your octane level? Everyone boosts theirs but how would one lower it say 2-3 points? Also, would this cause a problem without performing other tuning procedures on a FI NA rotary?

Is this something to think about or should I be smacked upside the head for asking?

J-Rat

iTrader: (2)

I wouldnt recommend LOWERING your octane level. YOur N/A is designed to run on fuel in the 87 range. RAISING your octane will net you NO benifits whatsoever, and lowering it is possibly dangerous.

Jarrett

20B-3Rotor

You should be smacked upside the head for asking

If you really want to lower it for what reason I don't know mix a bit of water with the gas.

I had a NA before my 20B and all I put in was 94.

Bigretardhead

just use the lowest octane you can get out of the pump.

theonlygreat

a little explanation of octane

lower octane: easier to combust

higher octane: harder to combust

why would you want it harder to combust you ask?
it needs to last all the way through a compression stroke of a high compression/high boost engine to prevent premature ignition

Bigretardhead

you put 94 octane in your N/A????? I felt my engine run better(not really more power, just ran better) after putting in 85 rather than 88(?) or whatever the next level up is here in boulder.

20B-3Rotor

I put 87 in one time and the exhaust gases was smelling like rotten egg after driving at high rpm. After that i put 94 and the smell was gone and the engine sounded smooth at high rpm.

Amur_

Don't put in water.

Why not put in an additive that will do something constructive as well as reduce the octane? Premix, Marvel Mystery Oil, a Fuel Injector Cleaner of your choice, etc...

CrackHeadMel

iTrader: (2)

Water would do the oppisit of what you want i think

People run water injection to compensate for not having gas with a hight enough octane

Icemark

It has been dyno proven that a 13B runs better on 87 oc than on 91 or higher unless the timing has been messed with.

The lower octane resists premature combustion better.

In addition it burns slower across the entire combustion cycle, which produces more power in a NA rotary than higher octane burns (more single sudden bursts at initial firing of the leading plug).

If your car runs better (and you have not messed with the timing) on higher octane than a lower octane gas, check the brand of gas you are using. Chances are that it will have a higher ratio of cleaning agents which is what you are proceiving to be better running. Adding a jug of techron would probably do the same thing.

And yes, water would just cause the tank to rust out, as well as lower combustion temps, leading to incomplete burns.

remember that a NA rotary really can't be comparied to a piston engine with a knock sensor, that really will produce maximum power when high octane gasolines are used. Just too different of a burn cycle.

20B-3Rotor

This has nothing to do with rotarys but i just found this when i was searching the site.

http://www.powellmotorsport.com/ultra94.html

Mr. 'Vert

Really?? I've been using either 87 or 88 (available at PDQ over on Table Mesa and near hwy 36). I'll give the 85 octane a try and see if that works better. at the very least it'll be cheaper.....

Icemark

87 is what you'll want to use in a stock NA 13B powered FC