Kart owner newbie here and want to DIY wrenching on the kart as much as I can since I enjoy it. This includes engine teardown/assembly and such, although I might leave things like cylinder honing to someone with proper machinery who does the procedure many times a day. My kart is a 2021 Kosmic (OTK); engine is X30 with old style ignition/exhuast/airbox.
I’m in the USA, and have decided to use only unleaded fuel for various reasons but largely because kids frequent the kart track. I don’t plan to race, so have no requirement to use any series’ specified gasoline, which IMO is silly that it’s not unleaded for all USA karting series already like it’s been in EU/UK for the past 25 years. Like, WTF is up with that?
In terms of no-ethanol unleaded race gas, I can most easily get Sunoco 260GTX Unlead 98AKI. E10 93AKI pump gas is also easily available, as is Sunoco 260GT Unleaded E10 100AKI.
In terms of timing and mixture, any tips on what EU/UK X30 folks use as baseline for junior and senior configuration would be appreciated! I can put a wideband into the exhaust to log in addition to the EGT already there.
In terms of service intervals, does anything change materially vs running leaded (VP C12, VP MS98L, etc)? I’m guessing theoretically maybe, but practically, no, since IAME’s own manual suggests 98RON (93AKI) unleaded, which is basically premium pump gas here in Eastern USA.
Washington, DC Area. The AKI values I listed is (RON+MON)/2. So AKI = USA = (RON+MON)/2. I’ll use USA for ease.
I’ll also use E[nn] nomenclature to specify the ethanol content in percentage (eg: E10 = 10% ethanol)
The unleaded options available to me in terms of ease of acquiring between me and the tracks are:
Premium pump gas 93 USA, E10
Sunoco
• Optima 95 USA, E0
• 260GTX 98 USA, E0
• 260GT 100 USA, E10
• 260GT Plus 105 USA, E13
VP
• C20 97.5 USA, E0
I went with 260GTX 98 USA, E0 since it has no ethanol, is easy for me to get, comes out of some Sunoco pumps, and there are others running it successfully in 2Ts in the USA per this thread:
If I can tune it to run well on pump 93 USA E10, then I may just use that. It’s the 98 RON / 93 USA as suggested by IAME, and literally 15-20% of the price of the race gas pails.
Yeah, I was happy to see it. Expensive in 5gal pails but more or less same price as VP and Sunoco 5gal pails, and easy to get.
Now I wonder why spec fuel for SKUSA and USPKS is not Sunoco 260GTX, but VP 98MS, a leaded E0 fuel that has the same octane rating of 98 US, AKI, (R+M)/2.
I’m not an engine builder / tuner, but barring any measurable advantage from simply having lead, I’ll assume a commercial deal since unleaded E0 98 US, AKI, (R+M)/2 is available from Sunoco in 260GTX and won’t expose kids to airborne lead.
While the developing brain is of more concern with lead, I believe everyone is negatively impacted by it.
You have mentioned 93 pump gas with E10, this should work but you would need to enrich the fuel supply, particularly on the H setting. I don’t know specifically how much but I would guess around 1/4 to 1/2 turn out more than baseline suggestion.
Thank you! That helps a lot. I’ll start with your suggestion when tuning for 93 E10.
I went ahead and put a wideband O2 and a bung into my list as well, since being a n00b at kart engines, I am more comfortable going off measurements (WB O2 + EGT) rather than feel and “how things look”.
Another benefit of not running leaded fuel is not fouling a wideband O2 as quickly. I assume the 2T oil might be detrimental to the sensor, but nowhere near as bad as lead. It occurred to me that the prevalence of leaded fuel in USA karting might be why WB O2 isn’t used more as a tuning aide. They’re cheap now… €99 for a Bosch LSU 4.9 with an Alfano pigtail already on it, similar price for one with an AiM pigtail.
Just need to figure out exactly where to place the sensor to avoid any misread from scavenging.
My father has a PhD in earth sciences and works with lead isotopes in ground water contamination. Lead is not healthy for anyone at any age. I would actually add if any of you are wine drinkers that the pliable foil at the top of a wine bottle does contain some trace elements of lead.
Good to wipe it off with a rag or cloth a couple times before you pour.
The only reason the US still has it is because of av gas (aviation fuel). As soon as it’s finally phased out, i’d wager that leaded race gas will also disappear. Leaded fuel is also still used within the EU for aircraft, but they took are phasing it out.
Supposedly leaded has is still used in some vintage race events like the Masters Competitor In France