100 Octane Fuel

[aeronca65t]

I went down to my local gas station to buy some 100 octane fuel for the race car. It occurred to me that some of you in the USA might be interested in locations for buying this stuff.
I realize that in Europe, Australia, Mexico, etc , it is possible to buy high octane fuel....but in America, it's hard to find anything better than 93 octane unleaded (and note that the octane rating system may be different in different parts of the world...in the USA we use the "(R+M)/2" system).
Anyway, here's a link for finding 100 octane Sunoco in the US (also known as "CAM2"):

https://www.racegas.com/gt100locals/gt100localsmainASP.asp

To be sure *most* of you do not need this, in fact most British sports cars can run fine on 89 octane unleaded fuel. Also, GT100 is $5.25 (USD) a gallon. It costs me almost $80 to fill three 5-gallon containers.

 

[Steve_S]

Many Unocal stations also offer 100-octane racing fuel. I paid $4.69 per gallon last week.

 

[waltesefalcon]

114 octane costs $4.59 here. I'm not sure who the supplier of it is, but I do know it is some great stuff.

 

[Steve_S]

I'd love to get my hands on some of that. My car runs very well on a 50/50 mix of 100 and 91. If I had 114 at a lower price I could do 60/40 and save money.

 

[waltesefalcon]

Steve, I typically add a couple gallons of the 114 to my spitfire when I fuel up. Thats about 70/30 and it works great for me.

 

[Guest]

We've also got CAM2 nearby, my buddy cuts in 50/50 with premium when he takes his Supra out to the track. I used to run the stuff occasionally when I was a kid in my Stangs and Chevy's, whenever I wanted to do big burnouts or other idiotic stunts. Seemed like the tires broke loose so much easier with that stuff in the tank.

 

[aerog]

I used to run 100LL in my VW engine from time to time (and I put all the test fuel I drain from the cessna in there too).

 

[Dave Russell]

[ QUOTE ]

To be sure *most* of you do not need this, in fact most British sports cars can run fine on 89 octane unleaded fuel (R&M/2). Also, GT100 is $5.25 (USD) a gallon. It costs me almost $80 to fill three 5-gallon containers.

[/ QUOTE ]
So true. Using an octane rating that is higher than is needed to prevent detonation actually LOWERS power output & fuel mileage. Very few old British cars, or newer cars in general, have compression ratios higher than 9 to 1 & need higher octane fuel. The newer cars with compression ratios higher than 9/1 can run on 89 octane (R+M/2) because of the computer controlled engine management systems. A few of them will show slightly more power with a higher octane fuel as the EMS adjusts mixture & timing for optimum.

Additionally, AV gas is formulated to not vaporize too easily at high altitudes & thus isn't very efficient at low altitudes since it won't vaporize as well. It is rated on an entirely different system than the commonly used R&M/2 system used for automobiles.

The idea in our society that "more is always better" is hard to dispel, so probably some folks will continue to convince themselves that high octane is better. I guess that perception IS reality. Just because it may be needed in high compression special applications does not mean that it is better for all engines.

To each his own.
D

 

[piman]

Hello Dave,
as there appears to be differnet methods of calculating the octane rating, and as I don't know which the British used, does make comparison difficult.
However I know of at least one car that had a sticker advising that 100 octane must be used and that was the Rover 2000 (60's era) The high performance version of the Triumph 2.5, (Injection model) had 9.5:1 and I think the Hilman Imp had 10:1, Jaguars offered the option of 9:1 (8:1 being standard), but as you say anything over 9:1 was not commmon.

Alec

 

[Dave Russell]

[ QUOTE ]
Hello Dave,
as there appears to be differnet methods of calculating the octane rating, and as I don't know which the British used, does make comparison difficult. Alec

[/ QUOTE ]
Hi Alec,
There are two fuel octane rating/measuring systems in use for auto fuel. (Aircraft ratings use another entirely different method.) The Motor Octane Number - (MON), & the Research Octane Number (RON). The pump octane number as used in the USA is the average of the two ratings. Eg. (R+M) divided by 2. European countries & the British use the RON.

The approximate octane "translation";

USA - 87____Europe - 91____RON - 91____MON - 82____R+M / 2 - 86.75

USA - 89____Europe - 95____RON - 95____MON - 84____R+M / 2 - 89.5

USA - 92____Europe - 98____RON - 98____MON - 87____R+M / 2 - 92.5

Since the fuel grades used from batch to batch are allowed to vary quite a bit, the results from different pumps can be noticeably different at any given time.
D

 

[piman]

Hello Dave,
thanks for that, and I have to assume that there was some good reason for the different measurement standards.

Alec

 

[BlueRidge1]

When I used to race at Hickory Motor Speedway in Hickory NC we used 116 octane turbo blue, used real cold spark pugs BL
50 or 60 was the number. Started out running a/c plugs but the compression would launch the porcelin part of the plug ,just blow em right out of the metal base. Had to swich to the yellow accel plugs ,they held up good. Bob

 

[tony barnhill]

WOW! There's a place right down the street from me that sells 100-octane!

aero - what will I have to do to get my 3.4V6 SCCA SOLO II car to run on it? Or do I even need to bother?