Race gas

[The Beast 2014]

So, E85 isn't exactly plentiful out here in Seattle. I recently had some tuning work done by a local guy using pump gas but for track days he mentioned mixing some race gas into the fuel. What kind of race fuel should I be using and how much should I be mixing into my tank? I know Sunoco sells it out here but is it ok to add leaded race fuel to my unleaded gas?

I also ask because I will likely pulley down on drag days so I need to bump up my octane. He tried to tune it with the smaller pulley but was getting some knock at WOT so he put the original pulley back on.

 

[gt347mustang]

This is a good question for your tuner. Have you asked him?

 

[jn2]

I wouldn't run leaded if I were you. You could, but leaded gas has a nasty side effect, clogging up injectors etc etc. My local track carries VP fuels, I think unleaded 110 octane, something along those levels.

Usually for track days try and show up at the track close to empty, pick up 3 gallons of race fuel and you will be good, you want as close to 100% race fuel in your tank. Little to no pump gas. Your ECM has spark advanced tabes that will add timing to your base tables as long as no knock is being detected, I have mine set to add as much as 8*, yours may be set to something similar.

 

[The Beast 2014]

My tuner is on vacation and I didn't want to bother him. I respect his time outside the shop when he is with his family.

Thank you jn2.

 

[corepwn]

Few options here.

#1. Add Torco or Lucas Octane Booster, both contain MMT and will actually raise your octane level.
#2. Get E85 for track days, and a fuel system to support it. Mine's not a DD so I only run E85 at this point but when I fill up I buy extra 5g pails worth to keep at the house.
#3. Buy Pails of Race fuel, VP MS109 is about the best you can get in these parts. It's super expensive though, so I don't really recommend this. ($20/gal)

 

[11Sec_Lx]

I have ran Torco for a few years for street use. The tune had a little a little extra timing in it.

The last two years I have had a race gas tune for leaded race fuel. Just pick one and let your tuner know so he can adjust your tune for it. Different fuels have different stoic rates, so stick with the one he writes the tune for or have him update the tune for use with whatever you change to. 55 gallons later, my factory widebands still function normally. Buying it and swapping over it a pain though.

Leaded fuel does not clog fuel injectors.

Leaded fuel will kill spark plugs.

Your computer will not add loads of timing if their is octane to support it. You can achieve all that the tuner commands, or less if the knock sensors step in.

 

[helloWorld]

I also thought leaded gasoline accelerated wear and tear on oxygen sensors and catalytic converters?

 

[11Sec_Lx]

People claim it will instantly kill widebands. All I can tell you is from what I actually experienced.

 

[Cashbum]

Leaded fuel does not clog injectors. That's non sense. Does not kill plugs either. It only harms o2 sensors with extended use. I've used straight C16 on a race truck and the wide band was good for 2 race seasons. That tells you something right there. I've mixed C16 with lump gas for use with my nitrous setup. My o2s are fine. Too much bad info on the net

 

[11Sec_Lx]

Cashburn - I can tell you it killed my NGK 6510's. Perhaps you run a plug that is resistant to leaded fuel?

 

[The Beast 2014]

Interesting. The first meetup is just for fun so maybe I will just run an octane booster through it. The second one is a bigger deal and I will try to pulley down and run race fuel for it.

 

[jn2]

Your computer will not add loads of timing if their is octane to support it. You can achieve all that the tuner commands, or less if the knock sensors step in.

The ECM has your base spark tables, it then applies modifiers to those tables, IAT, ECT, etc etc, this leads you to the final spark timing value. From here, if the ECM is commanding say, 27* of spark advanced and it senses no knock, it can add timing up to the limit set in the "knock advanced" tables at the rate set in the "knock fast advanced rate" and "fast spark advanced" cell assuming this new value does not exceed the "Cylinder Pressure Limit" tables..

This is where you can set the KR retard and KR advanced settings


Here is my KR histogram showing the amount of timing it added vs throttle position. If you notice it added a bit over 4* around 4,000 rpm, and a few more up top. It would have added more in the higher throttle position area but it ended up reaching the cylinder pressure limit so that prevented the ECM from adding more spark advanced. But if I raise the pressure limit, it will allow it to go as high as the 8* I set.

For clarification, a negative KR value means it senses no KR so it added timing, hence the Kr value goes negative, if it has KR, then the KR value will be positive.

 

[11Sec_Lx]

I stand by my comments. The way you originally worded it, made it sound like the computer automatically adds timing to MBT if it senses enough octane.

 

[jn2]

I stand by my comments. The way you originally worded it, made it sound like the computer automatically adds timing to MBT if it senses enough octane.

I just re-read it, forgot to add the word "tables" after spark advanced. I can see how it would read wrong now

 

[11Sec_Lx]

Sounds good. I'll re-read it in the AM when I'm fully awake. =)

 

[bunits19714]

A few gallons here and there isn't going to hurt. I ran 30 gallons of race fuel last year through my car mixed with premium(93) keeping a average of around 98-99 octane whenever I was going to be at the track last year. Then retuned late fall last year and ran a average of about 100 octane all winter(only drove about 500 miles) Just installed a D1 and dyno tuned Monday for 98 constant octane and if it is cool out and am going to the track I will make sure I am over 101. This being said my plugs looked fine ( only about 15 pulls on them) *** I am catless though, I wouldn't run leaded fuel with cats, that is just asking for trouble. I know of a few people that mix leaded 110 race fuel with premium unleaded for boosted applications and haven't had any issues. I am fortunate that I can drive to the pump pay 6.50 a gallon and pump in as many gallons as needed then drive around to the standard pumps and pump in the premium. I run 17 degrees timing @ 11.?? psi

 

[MKMotorsport]

Find a petroleum distributor in your area. I have a local one that sells bulk (bring your own jug/container) VP Streetblaze (104 octane), as well as MS 109. I've also had good luck with the Lucas octane booster.

 

[Sledder]

I am running a Roush TVS kit with an 85mm pulley and a 93 octane tune. With the tuner’s blessing, on race days I go to a 75mm pulley and race gas. I use VP Unleaded Extreme (110.5 octane) mixed 50/50 with 93 pump gas. I mix the fuel in jugs, run the car to near empty around home then add fuel for the track.