So this morning I had to take my wife to work because she had to loan her car to her mom for the day.

I didn't plan on the extra drive and had to coast into a Chevron while burning into the reserve.

I hit the button for 91oct and the LCD was crappy it it wasn't showing the price while filling.

After I filled 12.4gal and I was entering the value into my phone app I realized it was too cheap for 91oct. Someone switched the labels for the octane buttons, and because the LCD for price was crappy I didn't catch it. So I filled my car with 89oct.

I'm familiar with people using Toulene and Xylene to bump octane, but from the reading I've seen it pumps 93oct to like 93.5oct. That's not enough for me, or is it?

Whats the best solution for getting my fuel "safe" as quickly as possible? How much toulene or xylene can I mix in with the 89oct ?

I know Sunoco GT is 100oct m+r/2, and because I fail at math, how many gallons of 100oct are needed to hit a 91oct average in the tank?

Thanks for the quick assistance

 

Looks like I asked too soon about the 100oct mix. I found a link referenced in a bmw thread that had this calculator

http://www.wallaceracing.com/octane-mix-calc.php

It's suggesting that a little under 3gal of 100oct and the rest 89 will average it out. I'm not crazy and this seems correct, right?

 

I say don't drive the car hard until the next fill up, cheap method as well. If you can get 100oct easily and insist on driving it hard, throw a few gallons of that in and it'll be okay.

 

totally, I left the station and went to lunch keeping it out of boost

 

I feel your pain.

 

just don't go racing, you can boost around fine. Nothing will happen if you hit 18psi on 91 instead of 93. Especially on a stock Evo, those have to accept 87-93 by law, all cars do. You're risking significant damage by attempting to mix xylene into your gas. Xylene is an epoxy thinner...you don't want to go running that through your fuel lines man.

I just saw your signature, so you're not stock. My bad. I'm curious how you hit those numbers with 100% stock hardware. Is your boost and timing just cranked to the max or what? Might want to stay out of it if that's the case.

 

Running ~25psi (EvoScan kept reading in kpa on my '11 ECU) with 11deg timing.

I'm definitely leaning more toward wanting to just ease my way through about 3gal and then fill with 100oct unleaded. Just the two places that used to sell it here in AZ don't have it anymore. I'll find some place though.

 

most racetracks should have race fuel. throwing some leaded 110 in there would more than do it and give a lot more piece of mind than using some unleaded 100.

*waits for someone to preach about cats and o2 sensors*

surely 2-2.5 gallons of leaded fuel wont hurt a thing.

 

man, I wouldn't do that, you're not going to know the exact volume of your fuel tank to try and mix it...if you miscalculate and wind up with like 95 octane rating, and hit 11 degrees of timing, you could get some serious knock. Better to just drain it or road trip.

 

people get too timid about certain things.

 

Sadly it's not the season so the station near the track (about 7 miles from me) doesn't currently have anything higher than 91 (they don't even have E85 there sadly enough)

If I was going to consider leaded fuel, I'd hit up the airpark. 100LL is easy to get, but after spending the past 10yrs around Mooneys and Cessna's, I would take the toulene route first for a boost. Just not sure of what the max is I can safely mix.

I did run 100LL in a 93 Escort GT with a BPT8 years back. I gave that ***** some boost, *****es love boost. Didn't last forever, but first time I hit 12psi with full timing on that lightweight car...it was an easy $85 bucks or so I made in gas money that night ^__^ Unsuspecting camaro was unsuspecting

 

too much octane won't hurt anything at all, but I'm not sure of the specific energy of the stuff, but I think it's less (like E85) and I really don't want to find the upper limits of my injectors.

Either way I look at it, the most I've ever done a mix was 16ozs and that was get like a half-point bump for assurance, not correcting bad fuel fill. So I agree. I would rather go the route of 100oct gas, just not so sure I want to do leaded.

It's easier to just drive all week and hope I don't get run over (people here drive like jerks)

 

wow people seem to be going crazy about this. Dont add anything to the gas. Just drive normal (try to stay out of boost as much as possible but if you hit a few pounds it wont make a difference) and run it till near empty, then fill with 91+. Unless you have a **** load of mods and tuned on 91+, its not going to harm the car, giving that you dont go beating the **** out of it.

 

Just burn it all off without boosting.

 

This, or throw in a can of Torco, as 91 with 32 oz of Torco for 10 gallons will make about 102.