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SG: Getting back to the fuel injection system for the two stroke, now with the three different manufacturers building them, you’ve got three different ways of doing it. BRP’s is pretty complex, Polaris has a different approach with its Cleanfire system. Speak to your unique advantage of your new system – what makes it unique and better, from your perspective?
EIDE: Cost and weight like we’ve talked about, and we have more control of when we’re injecting the fuel onto the piston vs. the Polaris. The Polaris is further upstream, getting in the crank case and boost port. They inject into the boost port, where we inject onto the dome of the piston. We have better control of the fuel spray and trapping; less escapage out the exhaust port.
HALLSTROM: And this slide addresses a lot of that [pointing at slide].
EIDE: The drivability of the engine that you rode in [West] Yellowstone is a product of where the injector is sitting and what it’s doing. And the easy starting. We inject the fuel right on the piston where it belongs, and a lot of other things – it makes the calibration much more simple compared to an EFI system where you’re priming the bottom end or priming the pump before it gets to the piston.
HALLSTROM: And the other thing, John, and I’ve had a chance to work with Eide for 30 years now this August, and Greg since 1994. You’re not going to find anybody in the industry that knows more about two strokes than these two guys right here. I don’t care who’s at Polaris or who’s at Ski-Doo or wherever. I mean, Donn’s two stroke background going way back to old Arctic Cat and the rebirth of this company in 1983 and how the engines have progressed. I mean, he’s had an opportunity to pretty much see it all. And the same with Greg. So when you get guys of this caliber and this talent and, really, this experience, who are still in the industry, and have got that knowledge. They can kind of weed through what works and what doesn’t and where they think it needs to go.
SG: So getting directly to the unique injection system and the slot in the piston, where does this idea come from?
EIDE: It’s not completely new – there’s prior art, I think Yamaha and Honda had it in the early 1990s as well as Bimoto motorcycle company in Italy, they had it, in terms of cylinder wall injection.
SG: So, it was on their dirt bikes?
EIDE: I don’t know if I ever saw it in production, but there were papers on it.
SPAULDING: But I don’t know if there’s ever been a combination of an injector into the cylinder with the purpose of the slot being for duration [of the entry of the fuel charge]. I mean, there’s been pistons with holes in them and whatnot forever, for a number of different reasons.
EIDE: People use a single round hole just to give it a shot to lubricate the piston pin bearing.
SPAULDING: Yeah, and Yamaha for years, they had an oblong hole, but not a slot. But the reason for that was they had a reed on the cylinder, and they’d have a port right above the intake port for the fuel to go out that hole and make a route through those passages.
EIDE: As far as what the slot does, it gives you that whole duration time when needed. It gives you good injector dynamics.
HALLSTROM: And that’s where, these guys have seen what works, what doesn’t work, who’s had what.
SPAULDING: That’s where the system gets the value that Donn has talked about, but you don’t need the heavy magneto or to generate the power to drive a pump for a higher capacity injector and all the heat and the complexity. You don’t need that to get to where you need to be, efficiency wise.
SG: Are there any physical parts on this engine that were either sourced from Suzuki, or that are sourced from the same sources that Suzuki used? Any true, 100 percent crossover parts?
SPAULDING: It’s totally different. I guess the only parts that Suzuki also used are a couple of recoil parts.
EIDE: Like with Kokusan, we’re using the same supplier, but the parts are a little different. We tooled and made them, but they come from the same supplier. Kokusan makes the batteryless ignition and EFI system.
SG: Joey [Hallstrom] talked about your tenure in the sport; to that point, when Phil Mickelson was writing our Tech Professor columns, he wrote about how much more control designers and developers have now through the ECU – there are sensors on so many different things that are feeding information to the
ECU, and there are programmable maps for all of those inputs. How has that changed your jobs?
SPAULDING: You know, you can vary the quantity of fuel, the ignition timing by so many different functions of the engine. For example, the exhaust temperature, to tailor that to how the engine operates is so critical on a two stroke. Baro [barometric pressure] sensors, water, air temp, throttle
position – I mean, everything. It just let’s you continue to become more powerful and more efficient but also more clean.
HALLSTROM: To put it in real layman’s terms, you talk to customers today and they ask you how do I change plugs, or where do I put the plugs. I mean, when’s the last time you’ve changed spark plugs in the field? I don’t want to say it’s impossible to foul a plug, but the possibility now is so much more remote.
SPAULDING: Obviously the injection technology, that radically changed on the new engines and all of the sensors that monitor the environment that you’re in. The exhaust temperature control is – on our packages anyway, because it’s our technology – we use exhaust gas temperature because the variation of exhaust gas temperature, in essence, means you’ve got multiple motors. If you have a pipe that’s 200 degrees Celsius inside, that motor package will act like this, but if that temperature operates at 400 degrees Celsius, it’s a whole different function in many respects. The timing required, the fuel required, the time the exhaust valve opens – all those things are different as [exhaust] temperature changes. So our pipe sensors not only controls ignition timing but we can tailor with pipe temperature to ignition timing, fuel, baro, acceleration, exhaust valve opening, and we can finesse that motor to be ideal in so many different parameters that we never previously had control of.
SG: You guys both started out working with spark and fuel and doing the best you can. Was it difficult to evolve with technology? Is that a constant challenge, to keep up? Was it almost like always going back to school to keep up with the evolving technology?
SPAULDING: It was almost the other way around. The improvements were often requested by us. We were saying, “Hey, we need to get control of this, this and this, and we need to get some software that will allow us to do it.” You’re preparing them for what you want.
SG: We talked about the injection system. When you first showed us this engine in St. Cloud, you talked a lot about the crank design and the reed design. Are there a couple of elements that you are really proud of or that you want our readers to be aware of?
EIDE: You mentioned the obvious ones. But there are other things. We now have a completely sealed center gear oil bath, but that’s not too exciting except to some of us. All of our engines in the past pretty much had the center gear being lubricated by a mechanical oil pump, where we had to simply inject some quantity of oil into the gear area and later when you shut the engine off the oil would accumulate in the bottom of the crankcase and when started later had to be used up by the motor, so you had a lot of smoke start up. Now this system is a sealed, controlled oil bath full of oil at all times and never consumed by the engine.
SG: Is that one of the things that allowed you to go lighter? You also got 10 pounds lighter with this engine through a number of means, including using finite element analysis (FEA) to make a lighter crankcase. Talk about that.
SPAULDING: Not that in itself. I think FEA and our experience of where we’ve been and what we know. You combine that with the guys that are in our groups that design these things with the FEA, that’s where we got lighter. The lighter weight was phenomenal. It’s 10 pounds lighter with the throttle body on it and the spark plugs and whatnot. We looked at every part pretty much, and designed it, and then we applied stresses and loads to that part based on either what we can measure and/or what we knew from experience. And then because we did have a real qualified FEA design engineer, we just started modeling these things. We applied loads to those components and, again, we either knew what the forces and loads were and then we could change the design and try to find the weak points, and change it again to improve those points, always watching the weight. We did that on as many features as we could.
SG: I assume that like designing many things on a snowmobile chassis nowadays: A computer will give you great information and direct you in certain ways, but you still have to build one and test it in the field, right?
SPAULDING: Yeah, and that’s just ongoing learning. Because, what was helpful because of our relationship with all those years Suzuki, and the things we did here, on the design and development end, we had a lot of good understanding of what forces and loads are applied to some of the components. Certainly we have to do a lot of measuring and we continue to, and that always improves. All of that helps and is required in making FEA models and making them more and more accurate.