Hello from Europe,
Having raced with KZ engines and now with the Super Shifter 175 European version, here is my humble experience.
SS175 is extremely reliable and cheap to maintain (compared to KZ engines) bottom end over 20 hours no problem, although generally I like to replace the Piston, top and bottom cage every 15h and conrod every 30h. I’m using Castrol 747 (it won’t even stain the Piston)
Dellorto carburetor works fine but on racing days it can be a lot of work trying to fine tune it from Morning, to Afternoon, to Evening.
Tillotson works very well, AS LONG AS you have everything working perfectly inside the Carburetor, and yes as mentioned by @Muskabeatz, you may encounter a track where in one particular corner the engine will die (drove me crazy for several months at my local track) so a 48gr spring, rebuilding the Tillotson, setting a 1.05 Squish and very quick short shifting from 2nd to 3rd combined with delicate throttle application has solved the problem.
Oil at 5%, Temperature always at 55ºC as long as the ambient temperature is above 20ºC, if lower than that then 58-60ºC is better.
Do Not use New Line radiator RS if it’s cold, you’ll get cold water at the bottom, use New Line R (smaller) radiator instead.
EGT 680ºC is perfect at 13800 Rpm.
I see no problem combining KZ with SS175, and as to why KZ are so popular in Europe, well they’ve been around for a long time.
IAME needs to advertise the SS175 electric start a lot more, if people knew how reliable and cheap it is to maintain (compared to a KZ) a lot of people would migrate from KZ to SS175
Support for the engine is great here in Europe, and yes the engine is very popular in countries like France, Belgium, etc.
If you are going to race then the Tillotson makes things a lot easier, it’s less work tuning the engine on a racing weekend, everyone I know in Europe is very happy with the Tillotson (nothing wrong with Dellorto, just more work, as a friend said to me recently “I was managing 10 drivers at Le Mans, we were changing Jets and needle position three times along the day, that’s 30 times you have to work on Dellorto carburetor between races in one day.”)
The only “issue” about the Tillotson is that it has to be in top shape, let’s just say that Dellorto is more forgiving, the Tillotson has to be working perfectly for the engine to perform as it’s supposed to (Diaphragm, Gaskets, Pressure Spring, High & Low.)
There are very advanced computer programs that can help you tune the Tillotson (and the Dellorto) on a racing day if you are into that.
You can always test the Tillotson and the Dellorto and see how you feel about them, as I said, nothing wrong with Dellorto, a lot of people were using Dellorto and they were very happy. As you know IAME has been using diaphragm carburetors for a long time, all their Automatic engines (X30, X30 Super…) are using Tillotson now, so I guess they decided to get rid of the Dellorto and go for the Tillotson as they’ve been doing with all their other engines (I’m sure our friends in the U.S. know more about this topic.)
Keep in mind that I’m talking about Sprint racing, I have no experience with road racing, as you know here in Europe is all about Sprint racing (for example in about 4 weeks time the FIA Karting World Championship is taking place in my local karting track)
In general the Super Shifter engine (European version) is very nice, super smooth, great power, generally above 140km/h in Sprint racing, very, very reliable, you can run lean and no problem whatsoever, and very low maintenance compared to KZ engines (you know how it is with let’s say TM R1 engines, you go above 9-10h and that engine is going to seize, sorry TM) and the electric start works very well, you press that button and off you go!
Here in europe few years ago the 175 SS was a growing field at least on european level. But for now the class is shrinking very fast… in almost all iame series they dropped the 175 ss class due to low entries. Europe is still a KZ field and this wont change so fast.
Only rotax with the DD2 is the only single make shifter class which has quite qood entries all over EU.
Does anyone know what the percentage split was in the 2021 SuperNationals shifter classes as between KZ and the 175 SSE? Also, any comments on how the engines performed relative to each other (with regard to weight parity, or not)?
I think the writing was on the wall for the SSE. Look at how many new engines were imported lately in the US and the degree of interest of Iame factory in Italy…while the Screamer platform was developed at a steady pace, none of that got transferred to the SSE. Even for reliability parts that are under big stress on the 175(e.g. clutch), nothing was ported over even if it was 100% compatible and reliability only. I see the move to KZ as positive, hopefully with volumes and good distribution strategies costs will go down, parity is there already
Thank you Ricky and Andy for the comments/thoughts. Can’t say it makes much sense to me given the promise and potential of the 175 SSE. But I suppose the proof is in the pudding and the market has chosen. Still, given all of the effort by SKUSA and many others in support of the endeavour (testing, promotion, financial incentives etc), it must be very frustrating. I had thought there was very good race parity (indeed, for while, I understood there was a slight weight advantage afforded to KZ over the SSE under the SKUSA class rules until late last year). Throw in the materially lower maintenance demands (and thus running costs), there’s a logic break for me. I would have thought that going from a CR125 to KZ would have been a huge leap for many. Anyway, some more head scratching. I now have my dispensation to test a 175 SS here on long circuit in race conditions (we’re going to use both the Dellorto and Tillotson) and I don’t want to give up on it. Just waiting for delivery of an engine (now looking like early March at the earliest - the whole Covid impacted global freight logistics thing to Australia is a nightmare and a story for another day). I’ll post results/thinking in due course once we get a start on the testing.
Yes, it was running costs that I was referencing. On my CR125, I’m doing a top end once a season (say 15 hours) on long circuit racing. Our KZ/125 Open guys (DEA and TM) on long/road circuits are doing a piston once every two to three meets (at least). Certainly the chat locally on those running a 175 SS (Euro version) either for fun on sprint tracks or in our open sprint classes is a similar maintenance regime to the CR125. I understand it’s a similar regime for the 175 SSE (but you guys in the USA know better than me). BTW, we have never run the CR125 in Sprint racing here, only as a Superkart class on long circuits.
I can’t agree more. We keep trying to find out what’s the next best spec engine, only to end up creating a cycle that will inevitably burst. Look at spec Honda, great until it lasted but then how many people spent a lot of money for a used engine and now they can’t race it or if they crack a case or need a crank there are no spares or they cost an arm and a leg. SSE is next on the sunset list, while KZ has been around for decades, plenty of spares, plenty of choices in terms of engines, very predictable. I understand it’s more hands-on, shorter intervals, but cost overall is not that big of a jump when you consider the entire lifespan(think how many years you could have used a TM10c, still competitive today). I have strong opinions about parity too but regardless…having a stable category also helps with turnout, you can all see what happened here in US when Skusa opened up the shifter category. Long circuit or non-sprint may be different considerations though, I’m not that familiar
