V.P. C-11 vs. C-12
 

We've got a 1992 Camaro J/SA car, 350 TPI. We run C-11 now, and
are happy with it. All I can get for this weekend is C-12. What should
we expect, and what should we watch for. Thanks, J.R.

Re: V.P. C-11 vs. C-12
 

The car will be slower due to higher octane in the C-12...
You may be able to lean out the carburetor and/or run a little more timing as detonation will be less of an issue...

Re: V.P. C-11 vs. C-12
 

I doubt that you will see any difference between the two fuels. I switched back and forth several times between 11 and 12 and did not see any real difference. I typically run C12 in my car.

Re: V.P. C-11 vs. C-12
 

Mine is just a tick quicker on C11, but mine has to be fattened some up to see it.
I doubt you will see much difference.

Re: V.P. C-11 vs. C-12
 

Guys, Thank You for the help. Mike & Ed, your answers this morning
were right in line with what V.P. told me this afternoon. We don't try
to complicate things, but living in Canada can have its challenges.
To get C-11 shipped to me for this weekend with freight was $50.00
a gallon. A local snowmobile racer and V.P. Dealer has fresh C-12
in stock for the "Rock Bottom" price of $25.00 a gallon. The joys of
being Canadian. Thanks again everyone. J.R.

Re: V.P. C-11 vs. C-12
 

Renegade has a fuel called Pro Crate 108 that will work very well.

Re: V.P. C-11 vs. C-12
 

Mike, I just printed NHRA's approved fuel list, looking for something else. I don't see that one listed. Lowest Renegade shown is "110+".

Re: V.P. C-11 vs. C-12
 

Renegade offers a lineup of race fuels for virtually every application, but they didn't submit all of their fuels to NHRA to be added to the accepted list. So for now, the Pro Crate 108 can only be used where the accepted fuels list doesn't apply. But Renegade may look at adding more of their fuels to the list.

Re: V.P. C-11 vs. C-12
 

Mike, I might suggest you get Renegade to do just that! Now might be the time for them to jump right in there! I use C11 and am happy with the numbers it produces but it is very expensive. I used C12 for many years in another car but never knew from one race to another if it would pass. Jim

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Re: V.P. C-11 vs. C-12
 

NHRA may not want to add any more fuel blends to the list, but we'll see.
I'll give you some info on fuel specs.
Sunoco 110 motor octane is 106
VP 110 motor octane is 107
VP C-12 motor octane is 108
The Renegade Pro 110 motor octane is over 108

Re: V.P. C-11 vs. C-12
 

Mike, could you give us a little info on how motor octane vs research octane differ? Is motor octane what's important to us?

Re: V.P. C-11 vs. C-12
 

The designation of "110" race fuel is derived exactly the same way the "87" octane designation at your local gas station pump is. And they both mean the same thing, so you have something to compare race fuel and pump gas.
Both race fuel and pump gas are tested in two ways. One test is called the Research Octane. The results of the research octane test are more pertinent to low compression, low rpm engines. The other test is the Motor Octane test. It relates much more to racing engines, higher compression and high rpm.
Each fuel goes through both tests, then the results are added together to get the R+M/2 number that you see posted on gas pumps and on the specs for race gas.The higher the Motor Octane number, the more race gas you're getting for your money. For instance, the Renegade Pro 110 is listed as R+M/2 of 110.5. The Motor Octane is 108,and the Reserch Octane is 113. Added together and then divided by 2 gives you 110.5 octane.

Re: V.P. C-11 vs. C-12
 

There are other important aspects of racing fuel of course. Specific Gravity, and RVP ( Reid Vapor Pressure ) are two that matter.
All brands and all blends of racing fuel have different specs. 4 different brands of 116 will all have different Specific Gravity and RVP numbers. If there was only one RVP, or one Specific Gravity that was the best, all manufacturers would just plug those numbers into every blend and be done with it. Each manufacturer works very closely with racers and engine builders to come up with blends that make power, make torque, and most important, control detonation and pre-ignition.

Re: V.P. C-11 vs. C-12
 

https://en.wikipedia.org/wiki/Octane_rating

Usually the short chain alkanes like methane and ethane have the higher octane ratings. And they usually are the ones that boil off first, so the old stale/flat gas has probably lost the good stuff and eventually you end up with paint thinner or varnish.

That chart I think is wrong on benzene. I've always heard it's off the chart and they couldn't get an engine to knock on it, so MON of 130 or so. I think that is the top number in the rating system.

All these ratings are performed on a single cylinder engine made by Waukesa. It probably doesn't look like anyone's racing engine. Perhaps closer to a farm tractor engine.

http://www.waukeshacfr.com/f1-f2/