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Old 10-04-2002, 12:05 PM   #1
IndyRacer
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Question Race gas w/ mostly stock WRX?

I have seen that several i-clubbers (most with serious mods) run race gas when hitting the drag strip. I am planning to take my car to the track occasionally, and am concerned about the long term effects of using leaded race gas. I am fortunate enough to have 2 gas stations within 5 miles of my house where I can get Cam2 110 octane race gas straight from the pump. (Gotta love living in the middle of a racing community .) My car is mostly stock, but I was thinking that if I were to mix the race gas about 50:50 with premium unleaded, this would give me a nice safety margin for cranking up the boost a bit with my MBC. My question is, have any of you who use leaded race gas had a problem with O2 sensors or cats? Do you run straight race gas, or a mix? Any info would be appreciated.

Last edited by IndyRacer; 10-04-2002 at 12:43 PM.
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Old 10-04-2002, 12:25 PM   #2
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You can get high octane unleaded race fuel. I would use that instead of the leaded stuff. Don't risk the O2 sensor and cats they are very pricey to replace.
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Old 10-04-2002, 01:01 PM   #3
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DO NOT use leaded gas in your car. Remember, you have a cat that is pre-turbo. That leaded gas starts to break up the cat material and you can say adios to your turbo.

jason
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Old 10-04-2002, 01:07 PM   #4
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Quote:
Originally posted by mmurray75
You can get high octane unleaded race fuel. I would use that instead of the leaded stuff. Don't risk the O2 sensor and cats they are very pricey to replace.
Running a mixture of leaded gas with unleaded will cause problems with the O2 sensors, although a small mixture (25%) doesn't ususally cause permanent damage.... However the cats do not respond well at all, and may be significantly damaged by such mixtures.. I have run pure leaded, but removed the O2s and Cats.

The other option, which I also do sometimes, is either get unleaded race gas, or mix Toluene (20%).

jeff
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Old 10-04-2002, 01:18 PM   #5
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Default Re: Race gas w/ mostly stock WRX?

Quote:
Originally posted by IndyRacer
I have seen that several i-clubbers (most with serious mods) run race gas when hitting the drag strip. I am planning to take my car to the track occasionally, and am concerned about the long term effects of using leaded race gas. I am fortunate enough to have 2 gas stations within 5 miles of my house where I can get Cam2 110 octane race gas straight from the pump. (Gotta love living in the middle of a racing community .) My car is mostly stock, but I was thinking that if I were to mix the race gas about 50:50 with premium unleaded, this would give me a nice safety margin for cranking up the boost a bit with my MBC. My question is, have any of you who use leaded race gas had a problem with O2 sensors or cats? Do you run straight race gas, or a mix? Any info would be appreciated.


If you run leaded race fuel with your factory cats you can kiss them good bye. The lead will coat the cats and they will not fire off. This results in a check engine light. Front AF sensors and o2 sensors seem to last with the ocational use of leaded fuels but life will be reduced.

All major race fuel companies make unleaded race fuel for this reason. Vp has 103 motorsport that works great with EFI cars with cats. Sunoco has several unleaded grades including a 109 octane unleaded. I have used the 109 with great results. It contains aromatics so beware, it will smell and it will turn the tail pipe white. Most of the time my car lives on 101 octane Trick unleaded as it is available at the pump a few miles from the house.

A mildly modified car such as yours will benifit from the use any of the above unleaded race fuels. On my car for example, If I run 91 octane mobil I cant safely run over 14 psi of boost without knock. Running on straight 101 trick unleaded I can run 18 knock free. One thing to note: If you are running 14 psi knock free on 91 octane fuel and then add in 101 octane fuel you will not gain power. You will be waisting your money unless you end up with more advance and or more boost. The addition of the fuel will not produce power in and of itself. All of the fuels I mentioned will increase your AF around half a point on the rich side because they burn slower. You may actualy make less power. For this reason I recomend running a mixture of 91 and race fuel.

In the end of the extreme performance range nothing beats leaded race fuel. As some other Iclubbers can attest, C16 (117 octane leaded race fuel) just about curbs detonation even at extreme boost levels. I have used C16 in the past but my car is cat free and is not a daily driven car. As I mentioned before, Race fuel burns slower and C16 is like an old Turtle. AF's typicaly richen up a full point with C16. To extract power timming will need to be advanced a great deal and mixtures will need to be leaned out.

As we all know boost increases compression ratio. Keep this in mind when choosing a race fuel. Compute your end compression ratio at your boost level target. Choose a fuel accordingly. If you cant adjust your advance and boost choose a fuel or a mixture that will not burn slow.

Guidlines:

91 octane- Rich mixtres of 10.-1 to 10.5 to 1 for safety. 14psi max- more boost with reduced advance. When I have to pull more then 4 degrees to run a psi more I back off and run less boost.

101 trick- Cam- 11.5 to 1 AFs are safe. An extra 6 degrees of advance over 91 octane and or boost levels of 17-18 run knock free. Will richen up AF's so you need to lean out a step to make peak power.

103 VP- Designed for EFI turbocharged cars. Burns fast (like) pump fuel. Needs a pretty rich mixture to be safe. typicaly does not richen up mixture. Perfect for people with stock ECU's and more boost.

109 Sunoco. The serious "unleaded" race fuel. Uses ash and aromatics. Burns slow. AF's of 11.5 to 1 -12.0 on boost are safe. Can often times advance 10 full degrees without knock. Boost levels of 20 psi are not uncommon. Turns tail pipe white, Smells like Candy. Run this on a stock ECU car and you will probably loose power due to the slow burn effect.

C16 leaded. Burns Real slow like Kerosene. Must be mapped for this fuel to make more power. Adding to a pump fuel mapped car will net lower power. Sky is the limit on boost with this stuff. Can be used as a buffer.. Half a gallon to some 101 trick is a nice added safety margin. Kills cats and takes life away from sensors. C16 is just not needed unless you are out to break a record and are going to run insane boost and or nitrous at the same time.


HTH

CT
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Old 10-04-2002, 01:55 PM   #6
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Default Thanks for the info.

Thanks for all the feedback. That is what I was pretty much expecting to hear. Now if I could only get the local stations to carry unleaded race gas instead of the leaded stuff .
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Old 10-04-2002, 02:24 PM   #7
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Default Re: Thanks for the info.

Quote:
Originally posted by IndyRacer
Thanks for all the feedback. That is what I was pretty much expecting to hear. Now if I could only get the local stations to carry unleaded race gas instead of the leaded stuff .

If you are serious about racing you can order a 50 gallon drum of any of the above race fuels. It costs $234 the first time for the drum, fuel and pump and $213 to fill it after that. If you mix it a drum will last a long time.

An alternative is to purchase 5 gallon plastic Jazz jugs and store several of them. When I gas up the rex with 101 I take my jazz jug with me and fill it. This way I alwasy have some at home.

CT
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Old 10-07-2002, 06:10 PM   #8
IndyRacer
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Smile I found some!

Thanks for all the replies. I finally found a fuel company about 20 miles from home that sells Sunoco GT Plus unleaded. It is 104 octane and 4.85% oxygenated. Gonna mix that 50:50 with premium unleaded for my next trip to the drag strip. Should give me a little safety margin against detonation without worry about the cats and O2 sensors.

Kevin
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Old 10-07-2002, 06:16 PM   #9
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Default Re: I found some!

Quote:
Originally posted by IndyRacer
Thanks for all the replies. I finally found a fuel company about 20 miles from home that sells Sunoco GT Plus unleaded. It is 104 octane and 4.85% oxygenated. Gonna mix that 50:50 with premium unleaded for my next trip to the drag strip. Should give me a little safety margin against detonation without worry about the cats and O2 sensors.

Kevin

That is a good fuel. I have used it before. You can run it straight.

Tip:

Reset ECU
Set boost low like 10psi
Drive 20 miles and 4 or 5 restarts
Toss in race fuel
Turn boost back up to 15-16 psi.
Race....

CT
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Old 10-07-2002, 10:05 PM   #10
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Default AZScoobie...

I have a choice here in my town of either 76 or Sunoco 100 octane fuels. Do you know if there is any difference between these two? Any response would be greatly appreciated... All I have is full exhaust (including upipe), and a MBC set to hold at 16PSI. Thanks in advance...
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Old 10-07-2002, 10:53 PM   #11
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Listen to CT, he knows what he's talking about! I ran a 12.8 using 100 unleaded after I did this:



Quote:
Reset ECU
Set boost low like 10psi
Drive 20 miles and 4 or 5 restarts
Toss in race fuel
Turn boost back up to 15-16 psi.
Race....
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Old 10-07-2002, 11:06 PM   #12
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Wow!

Thanks a bunch guys!

This is very helpful.

Kevin
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Old 10-08-2002, 01:11 AM   #13
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Thanks Clark! That's some great info.
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Old 05-24-2004, 02:54 AM   #14
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Anybody know what sunoco 100 octane will do to your A/F ratios without a retune? What about sunoco 104 octane?

FSU
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Old 05-24-2004, 05:38 AM   #15
hotrod
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Default Sunoco is good stuff

I've run both the Sunoco GT100 and GT+ both as mixers to other fuels and nearly straight with no problems.

The stock ECU will take advantage of the extra octane if given a few miles to dial in better timing. Most improvement seems to be in the midrange rpms and you will feel the difference in only a few miles of driving. If your running a Utec or some other system that hard codes timing and fuel changes, then you will need to tweek your maps to get max benefit out of the higher octane fuels other than the safety factor of more octane to work with.

My recent best time on the 13G was run on the GT+ at 66% of the fuel in the tank.

The GT100 is good up to about 15 psi max boost here at 5800 ft altitude, but its on the edge, so I need the GT+ if I'm at the drags and running high boost.

Around town about 30% of the GT100 seems to work just fine mixed with 91 premium if your running sane boost levels. I go to about 50% or so GT100 when temps get up in the 90's.

The Sunoco GT100 is 2.7 % oxygenated so in spite of the aromatics it contains you shouldn't have much change in AFR. Its an approved street legal blend, where the GT+ is not technically sold for street use.

To my knowledge the GT+ 104 octane is the highest octane unleaded Sunoco makes, The Sunoco Standard 110 has lead in it.

The highest octane unleaded I know of is made by VP and is 110 octane, its a special blend fuel intended for water craft racing as I recall.

Larry

Last edited by hotrod; 05-24-2004 at 06:07 AM.
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Old 05-24-2004, 12:06 PM   #16
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Holy back from the dead batman!
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Old 05-24-2004, 04:13 PM   #17
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Quote:
Originally posted by eightballrj
Holy back from the dead batman!


FSU
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