I need to fill up tomorrow as I’m now low on fuel. I found a local Sunoco gas station that sells 100 octane race fuel. From what I understand, it is pure gasoline. I’ve been contemplating filling up ¼ to a half a tank with it to experiment. However, it is expensive at $2.24 per liter.

Other than a total waste of money, am I likely to experience any differences in a 4.2 XKR? Would I gain, lose, or find no change in power?

 

https://www.sunocoracefuels.com/fuel/ss-100

I have done that several times. You should be able to sense the diference.
In the 80's, I got avgas 100 from local airport for my 69 Porsche which really liked it.

 

I once ordered shell racing fuel just to see. They delivered it in 5 gallon jugs. Price notwithstanding it was fun! What changed?
1) much better gas mileage.
2) it was pure gasoline, no alcohol
3) engine actually sounded different
4) more horsepower? Yes,but I'm sure 60% of that was in my mind. Who cares it was fun. Facts are facts gasoline produces more energy than alcohol. Is it noticeable at this % change? Imo yes.
5) smell - exhaust did smell better, meaningless but it was there.

Alcohol notwithstanding, the highest octane we can get around here is 93. I think these cars were engineered for even a couple of points higher than that. Does that tiny difference make any sort of power difference? I never looked into it, but retarding the timing to eliminate knock must have some effect. Is it noticable? I suspect not.

Now if you noticed I bought the gas directly from sunoco. Once I went to a local gas station that sells race fuel after that. Disaster, car performance suffered if anything. Did they sell so little of it at that price it was old gas? Did they lie about what I was getting? Did it dump dirt into my fuel filter? I'll never know.

If its relatively fresh real Sunoco racing fuel, have fun, give it a try. Certainly cant hurt anything except your wallet.

John

 

Oh yeah - heads up. Dont know about Puerto Rico, but some states prohibit dispensing this fuel into a vehicle. New Jersey is one. Re my story above, I bought it at a pump in Pennsylvania.
just didn't want you to be surprised.

John

 

That's encouraging. I definitely want to try it now. I will ask the guy about the age of the race fuel. I certainly don't want to put dirt into my system.

 

As we have the Bahrain Formula 1 race track here, I often used their race fuel when I track raced my previous Porsches. No ill effects there.

Also put it in my 99 XK8 to see and it’s definitely a wilder ride with better throttle response. In Sport mode engine Rev-ed even better. But....Reversing was a bit of a problem as it tended to judder when cold.

Note I don’t have the O2 sensors on my CATS and no enviro regulations here. But in the end it wasn’t worth the trip/cost for this premium race fuel.

 

I have experimented with it in the past. Now that i run nitrous, if i plan on spraying, blending the fuel is a must. Before i used nitrous what i noticed was that if i was running higher octane fuel, the car would add more timing and therefore more power. Nothing drastic, but i think its noticeable. I think this is because your knock sensors don’t detect any knock (or much less if any) and allow the timing to be advanced. I have not had a chance to prove that on a Dino, but I’m basing my opinion on the live data from my scanner i had plugged in and the overall feel of the car.

Just make sure its unleaded. I have gone through so many spark plugs messing with leaded fuels. I went through 3 sets in a month when i was using a legit octane booster. Gets expensive and time consuming.

 

Thank you! I had not even considered that it could be leaded. I will ask at the gas station before I fuel up.

 

I went to the Sunoco station today. I asked and they confirmed it is unleaded fuel 100 octane pure gas. He also said that it is as fresh as one week old. I spent $60, which filled somewhere between ¼ and halfway to ½ of the tank. I filled up when the Jag had 1 mile of range.

My first impression is that the Jag feels more zippy. It seems to rev faster, and bogs down less when the go pedal is pressed halfway from low RPMs. I haven't tried to take it to WOT yet. I may try to do a 0-60 and ¼ mile run if I can figure out how to get the GPS tracker app working on the iPhone.

 

A more speedster X100 is a thrill... hence the change from XK8 to XKR.

There’s no long term reports of problems, in this forum, by using race fuel in the car. So go and enjoy. Just don’t hit another pothole GD!

 

I've thought about this, especially for the ones I don't drive as much. Ethanol fuel is the biggest scam to me; before I had access to good "boat fuel" (non-ethanol gas) I literally witnessed it plug up the intake screen on my Weber 4 barrel carb on my boat. If it could plug that up with it's disgusting jelly, I'm sure it wreaks havoc on tiny injector nozzles, etc.

I remember as a kid, I never had to rebuild any of my father's lawn equipment, and it seems like it's a yearly chore now.