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.
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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.
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.
I run Renegade 110 that I’m able to get at the pump for 10 bucks a gallon. Works well for my application (shifter)
So you get more power at a lower octane?
Often heard octane rating doesnt matter that much with 2 strokes.
The guys in Calgary run 91 octane in their VLR’s and are saying they have no issues. I guess we will soon find out!
Higher octane does not produce more power. That’s a street myth.
Chances are the car was running EFI with knock sensors and was able to add ignition advance due to the higher octane. The fuel itself won’t add power.
Your kart of course is carbed with an analogic ignition… so at the least you would have to change ignition advance to match the octane rating if you bump it up enough points. That said, you may or may not pick up performance, it’s hard to say with so many variables and the fact that we tend to overrev kart engines past peak power and ignition advance can impede this.