What is the preferred method of mixing gas for the EVO?

Is it pumping Race Gas first into an empty tank then filling it up with 91?

Is it filling the tank up half way with 91, pump in some race gas, then topping off the tank with 91?

Is it filling the tank up with 91 then topping it off with race gas?

Thanks!

 

good question. i wanna know too. i always just did whatever.

 

I would say it doesn't matter. After filling with both just get the fuel to slosh around and mix.

 

I prefer to find the crookedest road and let loose.

 

not sure preferred , but i fill with low octane first then top it off with race gas

 

There's no preferred method; just do whatever the situation dictates.

I try to make sure I have less than a 1/4 tank when I go to the track, then I toss in 3gals of 104oct, turn up the boost, lean out the S-AFC and rip down the track...

In the past on my DSMs, I would drain the pump gas out through the fuel return line until it was empty, then I would add in straight C16 and go nuts, but I don't do that on the Evo due to the stock cat.

 

would it matter on a bone stock evo?

 

fuel is going to mix, it doesn't seperate. Just keep it in your mind that if you have .5 91 and .5 of something else, it'll split the difference. (Or whatever mix you've made.)

 

I know it doesn't matter, but I put in race gas first (100 octane) and then top off with 91.

 

For guys wanting to run the unleaded racegas you should look into VP motorsport 109. It has a 105 octane rating(R+M/2) and is still unleaded. I believe it is the highest unleaded gas out right now.

I usually try to plan my week around if I plan on racing or not on the weekend. By this I mean if it is Wed. and I need gas I only put a couple gallons in and try to get it under a 1/4 tank for race time. I add 1 gallon of toulene to "spike" what 93 I have left in the tank and then add 5-6 gallons of VP103 since it is what I have near me.

 

Will race gas help a stock EVO at autocross (95f 90% humidity). At stock boost will it cause to slow of a detonation or will the ecu sense a decreased knock and allow advanced timing?

 

With stock boost and stock tuning, there would be no recognizable gains, because you run so rich from the factory that there will be no knock at WOT and therefore no timing loss, which is where the race gas helps the most (decreased knock with higher boost in hotter conditions on a leaner tune).

 

what do you think the octane raises to when using 10 gal of 91 and 1 gal of 100oct?

 

Do the math. (10X91 + 100)/11 = 91.81818181818181

So, just under 92 = not worth it.

 

I use 100 unleaded and keep the boost stock. Cheap insurance against detonation on a hot, humid day.

-Vince