Does anybody have any first hand experience on the new Aspen fuel in a KZ engine? I’ve always run VP so far, I was wondering what’s required for the switch…simply fine tune advance (reducing) and jetting (richer)?
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I can’t offer anything on jetting, but there’s some general info on Aspen fuel here:m. It needs to be stored and tested a little differently than we’re used to.
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Thanks! During last KartChaser podcast I believe they were talking about several engines seizing and having detonation issues at ProTour, so I guess there is some work to be done. I have some data with Panta from Europe, between that and VP the difference is huge, so I guess we may have a similar differential here
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We did our first session with our Vortex RKZ and Rotax Max on Aspen+ this weekend. The advice I got from the other mechanics was to set the jetting as with pump gas. We didn’t change the ignition timing now, but I’ll check with some other kz mechanics if we should do that.
It has been discussed here in Sweden, especially for the IAME X30 engines, is that it seems like there is increased wear on the reeds with Aspen+. The carbon reeds seems to be more affected than the ventronit ones. I haven’t checked ours yet, but we didn’t have any issues this weekend.
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Thanks! Just to get the math right, what are you running for regular pump gas? In US we historically used VP racing or similar high-lead fuel which has a massive impact on jetting. I’m not an expert on the vortex but as an example for a TM R1 I run DQ268, main jet 135, K28 needle as a baseline (California) with absolutely no detonation issues. Same engine on European pump fuel runs with a 175/180 main jet, same atomizer but you always need to watch out for detonation. So if I connect the dots, it looks like the new fuel will require larger main when compared to VP leaded, probably the same when compared to pump. Surprised to hear it causes reed wear, I’d have never guessed
I don’t know how much has changed since I ran KZ in UK in 2008 (not much I’m sure) but we were running in 1teens and 120s on main jets back then.
Just be aware that the way octane is described is different in Europe to the US. In simplest terms 95 in Europe is 90 in the US, 97 about 91 etc. Its just the difference between Research Octane Number (RON - Europe) and Pump Octane Number (PON - US).
You’ll need to use bigger jets to get the same lambda - it has less energy per gallon than leaded non-oxygenated gasoline. You’ll make more power in the end. Make sure to keep it out of the sun as UV degrades the MMT used to boost octane rating.
why did the older KZs need to be jetted so lean?
I would say it was more down to nozzle selection vs the time period or engines. The nozzle can make a big difference.
Update from SuperNationals 26: 0 KZ engine failures in the 38 karts that started the Pro Shifter last-chance qualifier and the 40 karts that started the Pro Shifter feature, all running on Aspen. Latest formulation also seems to be compatible with SSE 175 engines as we didn’t suffer any failures.
There were approximately 10 failures among all teams early in the week but this is being blamed on a bad batch of pistons from an unnamed manufacturer.
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