Race gas tune question

[Blackened300a]

I have a second tune for 100 octane that I wanna try out in 2 weeks. I'm pretty sure the track sells 100,104, 107 and 110 octane race gas. I can't drain out all the 93 octane in the tank to fill it with straight 100 octane so do I mix the 93 with some 107/110 unleaded race gas to bring the octane up or do I run more 104 octane to what I have left in the tank to bring the octane up? I know running race gas without a tune will hurt performance and running the tune without the right octane will hurt the engine so thats why I'm not sure which way to go.

Thanks for any help.

[LANDY]

What I do is make sure I'm near empty and put 10gallons of the desired octane and it works fine

[Rkammer]

Well, if you figure out approximately how much 93 you have in the tank and put the same amount of 107 race gas in, the result will be about 100 octane. Just drive the car a couple of miles so the fuel mixes completely.

There is another way. You can add Xylene (or Toluene) directly to your tank to increase the overall octane. It's available at most hardware stores and the resultant mix is a lot cheaper than buying race gas. Xylene and Toluene are aromatic hydrocarbons used widely as octane boosters in automotive fuels.

Some of us with Turbo Buicks used to keep 50 gallon drums of Xylene in our garages before it was fashionable to add alcohol injection systems to our cars. Here's the formulas:

Xylene Octane Rating - R+M/2 = 117


The following effective octane ratings are based upon mixing Xylene in 10, 20, and 30% ratios with a good quality 93 Octane pump gas. I.E. 10% = 9 gals. of pump gas and 1 gal. of Xylene. 20% = 8 gals. of pump gas and 2 gals. of Xylene. 30% = 7 gals. of pump gas and 3 gals. of Xylene. Ratios of greater than 30% are not recommended.

10% mix - 95.4 Octane
20% mix - 97.8 Octane
30% mix - 100.2 Octane


Toluene has an R+M/2 of only 114 so, the resulting octane is slightly less.

[DOOM]

What I do is make sure I'm near empty and put 10gallons of the desired octane and it works fine

This is exactly what I do except I use 5 gallons af race fuel instead of 10.

Just run the tank as low as you can possibly get it then put in the race gas and hit the track! :burn:

[Marauderman]

This is exactly what I do except I use 5 gallons af race fuel instead of 10.

Just run the tank as low as you can possibly get it then put in the race gas and hit the track! :burn:

That may his problem--not fact of doing what you said^^^^^^^^^but having to drive a long way after that to the track with that much octane --maybe he can get it down to about empty before he gets there--but that can be risky ----

[Blackened300a]

The track is about 35 miles from my place in stop and go traffic, It would be a total crap shoot to guess how much gas I have and how the octane would mix to prevent a problem. Looks like a 93 octane run for me.

[wickedmerc]

There's nothing worse than sitting in traffic, brake lights as far as the eye can see, no close exits and staring at 1/16th of a tank of gas.

[Blackened300a]

There's nothing worse than sitting in traffic, brake lights as far as the eye can see, no close exits and staring at 1/16th of a tank of gas.

Yeah and running out of gas is not something I wanna go through, plus if I run out I'll have to put gas in the tank which will defeat the purpose in the first place. I need a trailer!

[Krytin]

Bring an empty 5 gal can and syphon/pump the tank out when you get there!

[Rkammer]

The track is about 35 miles from my place in stop and go traffic, It would be a total crap shoot to guess how much gas I have and how the octane would mix to prevent a problem. Looks like a 93 octane run for me.

This shouldn't be a crap shoot. Just start out with about 1/4 tank in the MM and put an empty 5 gal. can in the trunk. Even at only 10 MPG in traffic it won't take the full 1/4 tank to drive to the track. When you get to the track just fill the 5 gallon can with 107 (104 would probably do it), put it in the tank and go race.

If you want some insurance against running out on the way to the track, just fill a gallon jug with 93 before you leave and leave it in the trunk just in case. :burnout:

[LANDY]

If you get an aeroforce gauge it tells you the percentage of gas left in the tank that will help you do the math. That's how I do it successfully.

[napolitano]

Like he says."exactly "

[DOOM]

Paul this shouldn't be this difficult.

Leave your house with 1/4 tank of gas (give or take).

Get yourself one of these if you don't already have one.

http://i920.photobucket.com/albums/ad47/DOOMIE/a3172211.jpg

Have it in your car with your fuel of choice.

As you're driving to the track and you happen to get dangerously low on fuel then pull over load your tune and put in the race fuel.

Continue to the track and if you need more race fuel I'm sure they have plenty there for you to put in it.

This isn't hard. We do it all the time. What's the big deal???

[Paul T. Casey]

Driving around with higher than needed octane will only hurt your wallet. When you leave the track, just re-load your 93 tune and everything will be fine. 1/4 tank on your gague should be approx 5 gallons of fuel in your tank. If you were to 5 gallons of 110 into a quarter full tank, your octane would be 101.5. The best advice I've seen is the Xylene mix. Again, it's pricey. If you assume 1 gallon over what the gague reads for mixing, you will be okay. e.g. 19 gallon tank, reading 1/2 = 9.5 gallons. Add 1 for safety, and mix for 10.5 gallons.

[Blackened300a]

This isn't hard. We do it all the time. What's the big deal???

I never ran race gas before so I want to make sure that I do not hurt my investment by running my race tune with a lot more timing in it without the right octane. This is why I ask the questions, its a big deal to me.


Driving around with higher than needed octane will only hurt your wallet. When you leave the track, just re-load your 93 tune and everything will be fine. 1/4 tank on your gague should be approx 5 gallons of fuel in your tank. If you were to 5 gallons of 110 into a quarter full tank, your octane would be 101.5. The best advice I've seen is the Xylene mix. Again, it's pricey. If you assume 1 gallon over what the gague reads for mixing, you will be okay. e.g. 19 gallon tank, reading 1/2 = 9.5 gallons. Add 1 for safety, and mix for 10.5 gallons.

Thanks for the info, I think the local speed shop sells this stuff, but it is very expense. Right now I have over a 1/2 a tank and Ill never get it down to a 1/4 tank by the time I go racing. The 20th I may make another run with my other car club so I'll give it a shot then.

[sailsmen]

When my low fuel lite comes on I have 4.5 gallons, I reset the trip odo and take it from there.

A few days before I got to the track I wait for the low lite, calculate how many miles I will be driving and add that amount of fuel so the low lite comes on again when I pull up to the track.

[Marauderman]

This shouldn't be a crap shoot. Just start out with about 1/4 tank in the MM and put an empty 5 gal. can in the trunk. Even at only 10 MPG in traffic it won't take the full 1/4 tank to drive to the track. When you get to the track just fill the 5 gallon can with 107 (104 would probably do it), put it in the tank and go race.

If you want some insurance against running out on the way to the track, just fill a gallon jug with 93 before you leave and leave it in the trunk just in case. :burnout:


Paul this shouldn't be this difficult.

Leave your house with 1/4 tank of gas (give or take).

Get yourself one of these if you don't already have one.

http://i920.photobucket.com/albums/ad47/DOOMIE/a3172211.jpg

Have it in your car with your fuel of choice.

As you're driving to the track and you happen to get dangerously low on fuel then pull over load your tune and put in the race fuel.

Continue to the track and if you need more race fuel I'm sure they have plenty there for you to put in it.

This isn't hard. We do it all the time. What's the big deal???


This above^^^ seems like some very good stuff to remember--I will


I never ran race gas before so I want to make sure that I do not hurt my investment by running my race tune with a lot more timing in it without the right octane. This is why I ask the questions, its a big deal to me.



Thanks for the info, I think the local speed shop sells this stuff, but it is very expense. Right now I have over a 1/2 a tank and Ill never get it down to a 1/4 tank by the time I go racing. The 20th I may make another run with my other car club so I'll give it a shot then.


What you said about the 1/4 tank stuff^^^--well, that is what you must do before you add any higher octane for the results you want--maybe a bit lower--see previous comments above^^^^^


When my low fuel lite comes on I have 4.5 gallons, I reset the trip odo and take it from there.

A few days before I got to the track I wait for the low lite, calculate how many miles I will be driving and add that amount of fuel so the low lite comes on again when I pull up to the track.

That is again a bit to much math --that is why you don't like that method--so re-think the earlier points ^^^-I will --they are great pointers!!

[sailsmen]

For me no such thing as too much math.