What type of fuel to run

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What type of fuel to run

Postby Jeremy Soule » March 16th, 2013, 7:27 pm

As our engines are fairly low compression so what type of fuel is recommended.
I'm thinking pump gas should be fine, but I am currently replacing my fuel cell (it leaks) and the foam was extremely deteriorated, Fuel Safe, the cell maker, sells different foam for ethanol vs gasoline based fuel but as we know "pump gas" now has ethanol in it.... You'd thoughts.
Thanks in advance. Jeremy Tucson Az.
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Re: What type of fuel to run

Postby SR Racing » March 16th, 2013, 7:44 pm

Pump premium is fine. More than enough octane and more BTU than race fuels. (100/110 etc.)
The cell manufactures have told me at PRI that 10% ethanol is ok. They said that they have some people running E85 but do not suggest it. Another problem also is that on SG tests we have done here and from what I am told that some pump gases are as much as 15% thanks to government subsidies.

So (again based upon the cell manufactures advice), after the weekend drain the cell and let it dry open. They also suggested that you make sure when it does have fuel in it that it is topped off.
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Re: What type of fuel to run

Postby FV80 » March 16th, 2013, 8:26 pm

If you have access to AvGas, (100LL) it would be the BEST thing to run long term. AvGas is STABLE, and does not leave a significant residue when it evaporates out of the carb. Regular pump gas will leave ENAMEL in the jets that is nearly impossible to get out --.. it will require complete dis-assembly and cleaning with carb cleaner ... extensively. AvGas will evaporate out and leave NOTHING for you to be concerned about as long as you run the engine a couple of minutes every couple of months.

In 35 years of racing, I have seen NO adverse effects of AvGas on any part of the car.. including the fuel cell. I rarely drain mine and have had to replace only ONE cell.. and it was 12 years old... long enough to suit me :).
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Re: What type of fuel to run

Postby SR Racing » March 17th, 2013, 2:23 am

I would agree on the better quality and less compounds left from AV Gas. However, it has less BTU, designed for engines with peak RPM of 2500-3000 RPM (low piston speed ), and was designed for high altitudes. Your engine makes its peak HP at 5000 RPM and above. A typical aircraft engine is designed to peak well under 4000.
On the dyno a premium pump gas always makes more HP when jetted for the right fuel.

IMO, the ethanol and fuel cells are the main downside.

It is a pain, but for serious racing the carbs have to be pumped out after the weekend and cleaned before any long term storage.
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Re: What type of fuel to run

Postby brian » March 17th, 2013, 3:49 pm

I second what Steven says and run av gas in everything except street vehicles. It's especially good in generators and lawnmowers that are stored for long periods of time. Stabil additive is good too but just another cost. SR dynos are quite superior to my old Stuska,so results vary, but I've seen very little improvement with unleaded race gases and it far more prone to going stale in storage.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
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Re: What type of fuel to run

Postby Jeremy Soule » March 17th, 2013, 4:51 pm

Thanks guys, I will probbly go with the Avgas to start, there are 2 small airports near me, actually on the way to the tracks! Evaporation is a fact of life here so I may drain the tank and bowl too if the car is to sit a spell.
About how much fuel should I plan to bring for a 3 day race weekend? Jeremy
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Re: What type of fuel to run

Postby RickyBobby » March 17th, 2013, 5:31 pm

Forgive me as I plead ignorance on this one, but when did SCCA allow "street" pump gas use in our cars? I was still of the knowledge that street pump gas is oxygenated and thus not allowed under the rules for our class. Somebody please set me straight before I buy another jug of 110 racing gas.
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Re: What type of fuel to run

Postby FV80 » March 18th, 2013, 8:22 am

Street gas is now "allowed" in most classes since the rules were changed last year and the track test now consists of ONLY a D.C. check. You are NOT allowed to 'impregnate' your fuel, or run rocket fuel by definition and if you are challenged, there is a process to take a fuel sample and send it off for further testing. I don't recall the numbers, but you can download the latest GCR from the SCCA website and see for yourself.

Jeremy - for a 3 day weekend, I leave home with 3.5 gals in the car and two 5gal jugs of fuel in the trailer. I generally come back with between 1 and 2 gals in the jugs and maybe 1 gal in the cell.
Hope that helps.

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