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PostPosted: Fri Sep 29, 2017 6:29 am 
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Acme Speed Shop wrote:
When did the club quit testing fuel, as most unleaded fuels fail the test.


to further digress.... Fuel is checked a couple times a year in SW Div races. don't remember which ones, but I remember having to go get tools (still need to fix fuel sample port!) at MSRH, TWS, and NOLA in the last couple years.
I run 93 pump gas with premix in my rotary and have never failed a fuel test. the fuel testing rules were updated a couple years ago to remove the 'pre-mix exemption for rotaries', and now all cars must pass the same rules.
Obviously this is completely not applicable to a higher compression Honda motor, but goes for the point about unleaded and even premix fuels passing fuel tests.

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PostPosted: Fri Nov 17, 2017 8:13 am 
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Joined: Tue Sep 03, 2013 1:03 pm
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Location: Upstate SC near CLEMSON!
Its been a few years, but I had fuel pulled at CMP. Running SM at the time.

I use the Sunoco 260 for my FP Miata.


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PostPosted: Mon Nov 20, 2017 7:38 am 
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Location: Huntsville, AL
If you aren't running an oxygenated fuel is there really any reason you won't pass a fuel test (not counting the Ruboffs specific fuel)? I would like to be able to run a 95-100octane unleaded as I don't think modern engines need the lead race fuels (provided the compression ratio is compatible with octane ratings of the unleaded fuels).

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PostPosted: Mon Nov 20, 2017 11:59 am 
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Just be aware that there are several Sunoco 260s, in fact High Plains sells one that is legal, and one that (I believe) Is not.

https://www.sunocoracefuels.com/fuels/c ... els?fid=24

The 100 octane 260 gt is oxygenated, and therefore I believe illegal.

The 98 octane 260 gtx is non oxygenated, and for lots of other reasons, legal.

I just remember to avoid the 100 octane.

FWIW, I quickly looked at the fuel rule in the GCR, and didn't see anything specific about oxygen additives being illegal. If someone knows the part of the rule that allows both these fuels to be legal, please post it.

"aah, you should be good, I've never been protested" doesn't cut it.


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PostPosted: Mon Nov 20, 2017 12:09 pm 
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Location: Philly
260GT is certainly legal. It was sold at the runoffs.

Oxygenated doesn't make a fuel illegal.

-Kyle


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PostPosted: Mon Nov 20, 2017 12:57 pm 
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Good to know.

At one point, it was in fact illegal to run oxygenated fuel. It's been a few years so the rule must have changed.


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PostPosted: Mon Nov 20, 2017 2:15 pm 
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blamkin86 wrote:
FWIW, I quickly looked at the fuel rule in the GCR, and didn't see anything specific about oxygen additives being illegal. If someone knows the part of the rule that allows both these fuels to be legal, please post it.

"aah, you should be good, I've never been protested" doesn't cut it.

This is from the Sept 2017 GCR:

page 75:
9.3.25.A. (first sentence only) "Permitted fuel is herein defined as gasoline or diesel fuel meeting specified dielectric constant standards and
not containing any prohibited substance in excess of stated limits. "

Page 76 (still 9.3.25.A) has a list of prohibited or restricted compounds, including but not limited to:
MTBE, Max 3.0%
Ethanol, max 10.0%
Methanol, Max 1.0%

All of the above are common oxygenators found in pump gas, and are allowed in the fuel. Exactly why I can't say, but I would surmise the whole oxygenated fuel part of the rules was updated when E-10 started becoming the norm many places in the country. Here in TX, you cannot buy ethanol-free pump gas. (you CAN buy ethanol-free race gas, but it's not road legal). It would be silly for SCCA to require something like a Touring, IT, SM, etc car with limited engine prep to run anything hotter than pump gas, so the rules would have required updating to allow for the inclusion of whatever might be in 'plain old gas', which would include 10% ethanol in many parts of the country.

regarding the testing itself, the ethanol in the pump gas causes the dielectric constant to go up a fair amount. The max listed for the Digitron meter is 166 now, and E-10 fuel tests somewhere around 130 straight out of the Shell gas pump. Randy Smart and I played around with the stuff adding drops of water a little while back trying to get the meter to fail, and with a little water, we could get the E-10 to read up to about 160 or so, and then the additional water saturated the alcohol and started making the alcohol and water come out of solution, which caused the dielectric readings to go down as we added more water and took more ethanol out of solution.

So if you want to run said oxygenated Sunoco 260GT, I'm not sure if you could get a chemical breakdown from Sunoco on the referenced GCR list, or send that to a Sunoco rep and have them verify (and state on company letterhead?) that the 260GT meets those requirements. Just a thought.

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PostPosted: Tue Nov 21, 2017 4:37 am 
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Joined: Thu Dec 04, 2003 4:29 pm
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Location: Laurel, MD
You don't need to write to Sunoco.

With regard to Dielectric Constant (DC), Sunoco lists this for each fuel in their detailed specs. Go to https://www.sunocoracefuels.com/fuels and click on a fuel you want to know about. For example, for the 260GT Plus, scroll down the Technical Details until you find the DC, which in this case is 19. This number is for the old G-01 or FTK-O1 meters. The allowed GCR DC range for those meters is 0-15. Thus, the 260GT Plus will fail the DC test. On the newer meters, this will read over 200.

260GT DC is 11. 260GTX DC is 1.6.

All of the leaded fuels have negative DC readings.

At least at the time that the new (several years ago now) fuel rules went into effect, Sunoco told SCCA that nothing on the list of prohibited substances were in any of their fuels (except for high alcohol in some fuels).

Dave


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PostPosted: Tue Nov 21, 2017 5:45 am 
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Location: Portland, OR
Does anyone know what fuels are sold at Sonoma?

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PostPosted: Tue Nov 21, 2017 6:12 am 
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Matt93SE wrote:

All of the above are common oxygenators found in pump gas, and are allowed in the fuel. Exactly why I can't say, but I would surmise the whole oxygenated fuel part of the rules was updated when E-10 started becoming the norm many places in the country. Here in TX, you cannot buy ethanol-free pump gas. (you CAN buy ethanol-free race gas, but it's not road legal). It would be silly for SCCA to require something like a Touring, IT, SM, etc car with limited engine prep to run anything hotter than pump gas, so the rules would have required updating to allow for the inclusion of whatever might be in 'plain old gas', which would include 10% ethanol in many parts of the country.

regarding the testing itself, the ethanol in the pump gas causes the dielectric constant to go up a fair amount. The max listed for the Digitron meter is 166 now, and E-10 fuel tests somewhere around 130 straight out of the Shell gas pump. Randy Smart and I played around with the stuff adding drops of water a little while back trying to get the meter to fail, and with a little water, we could get the E-10 to read up to about 160 or so, and then the additional water saturated the alcohol and started making the alcohol and water come out of solution, which caused the dielectric readings to go down as we added more water and took more ethanol out of solution.



Matt, interesting info. Thanks.


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