What are you using for race fuel?

What are the current opinions, options and prices for race fuel? Specifically for KA on the east coast, but this can include other classes and locations too.

My track sells Sunoco Standard 110 and Optima 95. Last season it was $95 a pail, we haven’t started racing yet this year but would consider other options especially if they cost less.

wonder if anyone has found extra performance with a race fuel in 2 stroke application - something like panta kart fuel etc…

Haven’t ran KA in a couple years but if I recall the go to was VP MS98 or 98MS (can’t remember how it is spelled). Lower octane rating, but it seemed to make the best power. I think almost all of the usual suspects for racing fuel is going to be around that $100/pail unfortunately.

What’s your engine’s octane requirement? An X30 or Rotax will tolerate 91 AKI / 95 RON fuel, a KZ won’t.
What’s your rules limit? Many tracks require MS98L even though no engine there requires anything more than 91 and there are a lot of kids at risk for lead poisoning just because it is VERY easy for them to check the compsition of the fuel.
Do you have any special limitations or problems you’re trying to solve with the fuel? In my case, a sponsor came up with a rich-mixture-tolerant, high-octane mix to make up for a carburetor with poor mixture control on an engine with 15:1 compression. Once they decided it wasn’t going to be commercially viable I had to run blowtorch EGTs (1450 F) on VP 110 just to keep it driveable off our tracks’ many hairpin turns.

In SoCal we’re spoiled - VP 101 unleaded is available at the Downs Energy pump for $9.00 per gallon. That works well in every engine.

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According to the IAME manual, it states “Use unleaded Premium gasoline 98 RON (minimum)” which surprised me a bit on the lead. I would like to see all leaded fuel gone and not just for the kids, it effects all of us. Engineering Explained did a video explaining this too…https://youtu.be/6HlUm7dXq5s?si=pELMkhvVgtrNj2NU

To be honest I don’t know if we have a fuel rule per se, as it is never checked. The track sells Sunoco Optima for the Rotax which is unleaded but also the leaded 110, bit of a mixed message.


Last year it was Aspen at TSRS and VP MS98L everywhere else.

This year it is Sunoco Supreme 112 at TSRS and the VP at local club.

Thankfully no more Aspen. It was awful. Smelled bad and produced lots of carving deposits and gave 2 strokes fits.

You’ve got an open-fuel rule on the East Coast? Then it’s easy. Marathon/Speedway 93 octane E10 or E15 premium gas, mixed with Elf HTX 909 or Motul 800, for any 2-stroke kart engine. Enrich by 1/8 turn (pumper carb) or 10 mainjet counts (slide carb) and enjoy some extra power and four-dollar gas.

I use a 5% mix with oil and 98 octane fuel for x30 all of that is mobil1

If I understand correctly 93 octane pump gas is 98 RON? What would be the issues/precautions with the ethanol?

Just make sure you get all the fuel out of the carb, lines, and tank so the ethanol isn’t chewing it up. It should be done anyways regardless of fuel. Keeps the lines fresher and the tanks from yellowing.


Basically the US is about the only place I can think that that still allows lead. Even in the 90’s unleaded was the norm for karting in Europe… Certainly from memory it was gone by the mid 90’s. It’s kinda incredible it’s been allowed fly radar the radar in karting. I won’t pull this topic too far off track and instead link to another topic on TEL:

In general, additional octane won’t hurt anything. A couple of common myths that get repeated are that higher octane fuels burn slower and/or cooler. Neither are true.

Welcome Theo. Can you clarify what fuel you’re using and/or the octane rating type?

Correct. It’s purely resistance to knocking/self-detonation. Higher octane just allows you to run higher compression or more boost in forced induction application before the ECU starts pulling timing.

So in your kart you should be safe at whatever the manufacturer recommends as a min octane rating, unless you’ve somehow developed self-detonation issues. Running anything over is a waste of money.

Makes running Rotax cheap, as pump gas works all day long and tends to make more power with the additional ethanol over the mandatory race gas we have to run.

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To add to this, it’s important to ensure you’re looking at the correct rating whether it’s RON, MON or RON+MON/2. Usually pumps are RON+MON/2.

VP MS98 fuel for example has the following ratings:

  • RON: 100
  • MON: 96
  • R+M/2: 98

If (for example) your application calls for MON 98, then you would need a different fuel.

Moved to 2 Stroke Kart Engine Forums since this is more critical to those engines in general.

Last spec sheet I saw for summer-blend “93 AKI” pump gas had it at 3.1% oxygen content, 88 MON, 101 RON, and .75 specific gravity. Yes, that does come out to a 94.5 AKI blend but my guess is that the butane and ethanol give them some margin for the rest of the fuel.

Our club this year is going to run Sunoco 94 for the ROK VLR class, hoping it won’t hurt the motor. There trying to keep the cost down for this class. When I was a kid all we ran was Sunoco 94 and never had any issues.

Looks like it’s oxygenated with Ethanol… So expect to jet up a little to be on the safe side at first and follow the usual precautions for ethanol.

What worries me a little about it is that I can’t (easily) find the specs for the fuel from Sunoco themselves… Makes me concerned that the composition (example ethanol content) might vary. Consistency is the main quality that makes a racing fuel, suitable for racing.

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100% agree, it’s designed as a pump gas so I’d share the same worries.

I personally use Sunoco Supreme for training, VP98 for race as the sanctioned fuel. Very cost-effective combo too.

Interesing, I personally use pump fuel for my kz kart 95ron E10. Only fuel available in my country.

I have tried octane boosters, nf octane as I have seen proven results on the dyno (car) of it actually improving fuel quality. Also a few others from motorsport suppliers

But in all honesty I can’t say there was any benefits running it over pump fuel, or that I have noticed.

If anything I found it harder to read to colour of the piston and pipe with the nf ocatane as it burned brown/yellowish. Same with the cars I ran it on. So I was never sure if I had the jetting 100%.

If you’re just banging laps in practice and not fine tuning for the race season any gold or premium pump gas will be plenty fine for the KA and actually burn a little hotter/cleaner. I would just be sure to go to a busier gas station that cycles through gas more regularly than a low volume place. Usual ratio for 6-8oz of oil per gallon of ~93 octane. If you want to save more money and actually create a little more power, add a little more oil and run 87 octane. If you’re fine tuning for the season then you should run the fuel in the rulebook.

Anyone in here saying it’ll ruin the engine, I’ve run this KA engines for 10-15hrs and all engines are national level front runners. I have all the old pistons and have never had a failure.