I’ve heard OK/N is a cheaper attempt at doing the OK class, how much cheaper is it? And is there any spec differences.
Cost wise probably not to be at the sharp end of the field.
From what I hear from the teams around here it isn’t that much cheaper and reliability isn’t great.
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I’ve been scratching my head from across the pond here in Europe, trying to understand how so many reeds seem to break in the US. I have (from memory) never even seen a single one let go during running here in Europe, on the OK/N.
The same happened with the ROK carbon reeds as well back in the day, as i recall. My theory is that the leaded fuel used is somewhat incomtabile with the harmonics of the thin carbon reeds and for whatever reason they break. Either that or everyone runs them way too rich, but i doubt capable engine builders have not figured out an adequate carburation after two years of running…
It really is a mistery nonetheless, as people here have been abusing the hell out of them and the platform really doesn’t seem to care much.
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We have this issue as well on X30 in Sweden, carbon reeds just disintegrate. We run Aspen 98 octane
Nowadays the carbon is banned and only ventronit is allowed to keep cost down
For the local comeback of X30 this year they also banned the carbon reeds, because you had to change it every day
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Do you have any feedback from over the pond on comparative costs for OK\OK-N?
Operationally speaking (as reported from the initial adoption of the platform in the wild) all engines are very solid and require relatively low upkeep when used in practice configuration (much like any other 2 strokes). The main diferentiator is the fact that the market is open and as such parts’ cost varies from manufacturer to manufacturer (no surprise that the vast majority of the market gravitated to TM…) The intervals for parts is in the following ballpark:
Piston - 8 hours ( 5H in racing config)
Rod - 25 hours
vs an OK
Piston - 3 hours (1H in racing config)
Rod - 10/15 hours.
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Yep… same issue over here
In every other classes the carbon reeds is totally fine and no problems
One issue could be how the driver enters the pits, if you dont push Down the decom valve the last few meters on a OK/OKN system engine it will put a lot of strain on the reeds.
From what i Can see the running cost of the OKJ is really good you Can put a very high amount of hours on it without issues.
The OK on the other hand are to exspensive to keep running, with to many failures, this has more or less killed the class off the i live.
The OKN i have yet to see one in action.
Good tought, i didn’t think about that.
The OK-N is very comparable to the OK-J in terms of use case due to it’s design features (less compression, 1k less RPM, more favorable exhaust geometry and all of this built on the OK platform, which is designed to take more load.)
Depends how you arrive at the term ‘cost’. Cost isn’t always related to reliability and piston life. This is why Rotax MAX budgets can often dwarf what people were spending in the 100cc era.
The ‘cost’ of OK is heavily down to the ‘F1-factor’ which puts an enormous inflationary pressure on it, as well as it becoming a Veblen Good for rich people to show off how rich they are. It’s a very bizarre thing to get your head around but because people keep saying how expensive FIA Karting is, the more likely it’ll attract even more wealth into it. It doesn’t help the FIA let F1 people into the karting paddock, but there you go.
Pure spec-to-spec and OK-N, on paper, should be more cost effective, just due less revs and load due to no power-valve. But cost is related to so many other factors.
The actual cost difference of maintaining an OKN vs an OK is minimal, the only real difference is an OK will need a new big end crank bearing at (at most)10 hrs, while the OKN can go 15 to 20 hrs. The bottom ends are quite stout, and the crank rarely goes out of true. The cost difference, as Alan pointed out, is not in the engines themselves, but the races where OK’s are raced; FIA karting is incredibly expensive.
We have found the reed issue is track dependent; tracks with very long, sweeping turns, where the driver is off-throttle and rolling for a long time, are very hard on reeds. Reeds don’t break at WOT, but when the butterfly is closed for a long period. I have not broken a single reed on the dyno in many, many hours of testing OKN’s. Charlotte was a super hard on reeds, as drivers were breaking reeds left and right in both Jr and Sr. We did not break a single reed at New Castle both last year and this year. We broke 3 reeds (among six Sr drivers) at Trackhouse, and our Jr driver was on the same set of reeds all weekend. I’m sure in Eurpoe there are many tracks with similar corners to Charlotte, so that does not explain why they don’t seem to break reeds over there.
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In the western US and at national events we use race gasoline which contains some awful solvents that may dissolve some of the resin.
If these ran in local races on the east coast they wiuld be burning premium pump gas and these problems would go away.
I was going to suggest something similar. I know some fuels have detergents designed to deliberately target carbon deposits, whether that would effect a reed or not i, i don’t know.
Whereas I imagine spec fuel in FIA events is pretty much just high octane gas without many additives or detergents.