Ilmor Engineering Builds a Five-Stroke Motor

08/12/2009 @ 9:00 am, by Jensen Beeler6 COMMENTS


Motor manufacturer and tuner, Ilmor Engineering, has branched out from its Indy Car, Formula One, NASCAR, and MotoGP duties, and produced what they call a five-stroke motor. With dual camshafts and an asymetrical three-cylinder configuration, the Ilmor is more than intriguing with its design, and promises to bring real benefits both to the race track, and to road-use. Most notably is a 10% increased fuel efficiency, and 20% weight reduction in power-plant weight.

With its 700cc, turbocharged, prototype motor, Ilmor is able to extract 130hp and 122 lbs•ft of torque. To achieve this, the motor employs two overhead camshafts. One is a “high pressure” camshaft, which turns at half the crank speed, while the other shaft is a “low pressure” camshaft, which turns at the same speed as the crankshaft.

The high pressure shaft powers the two outside cylinders, which operate like a normal four-stroke motor, while the low pressure shaft powers the larger center cylinder, which gathers exhaust flow from the other two cylinders. This larger cylinder can also adjust its expansion and compression strokes, allowing it to be tuned for specific applications.

Ilmor hopes that this new design will allow its motor to be more fuel efficient over normal four-stroke gas motors. With no exotic materials or elaborate construction processes, the design should be fairly simple to implement in a variety of applications. Of course the most relevant to our concerns is for motorcycle racing and production. Ilmor has tried on several occasions to join the MotoGP ranks, and with fuel consumption a fairly large concern with the current fuel tank restrictions, Ilmor may have a nice competitive advantage brewing here. They will of course have to overcome the fact their design uses forced induction, but anything could happen with future regulations.

Source: Ilmor via Autoblog

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  • Dr. Gellar

    This is one of the reasons I’d love to see a more open-style MotoGP series, with pretty much just an energy limit, an emissions limit, a min. weight limit, and spec tires. Allow unlimited engine displacement and unlimited engine types, loosen up the bodywork regs some…and let the manufacturers and teams have at it. It would be really cool to see engine technologies like this and other non-4-cylinder 4-stroke 800cc powerplants produced specifically for MotoGP machines!

  • 「Ilmor Engineering Builds a Five-Stroke Motor」


  • lago

    While this looks like a clever way to increase efficiency and its convenient how every time one of the outside cylinders is on an exhaust stroke the central cylinder will be on a down stroke salvaging waste heat for extra power, almost exactly this setup has been used to increase the efficiency of steam engines for centuries (see Compound steam engine). Does the 700cc figure include the central second stage cylinder or only the two outer cylinders I wonder? While I could see fuel efficiency increasing from this design I’d be surprised if power/weight ratio wasn’t worse than conventional designs (hence the turbocharger in order to get the 700cc engine to produce the same power 600cc Supersport bikes are making now).

    I’m also curious about how the reduced exhaust temperatures from the greater exhaust expansion affect emissions control equipment.

    I do love how the central cylinder is 180degrees apart from the outer cylinders and is larger. If the central cylinder is exactly as heavy as the sum of the outer cylinders this engine should balance like an inline4 and not need counterbalancing. Would be cool to see a more conventional I3 engine with a larger central cylinder take advantage of that.

  • lago

    Upon closer inspection the engine appears to have 2 valve/cylinder on its active cylinders. The central cylinder looks to have a single intake valve for each cylinder that feeds it and 2 exhaust valves. Might a later version have 3 camshafts, 2 high pressure and 1 low pressure, to help it breathe? I could really see an engine with this technology succeed in high gas mileage, hybrid cars, or even compete with hybrid technology in truck engines but race bikes don’t seem like the proper place to implement it. A truck with the extra weight capacity to not be impaired by the weight of the second stage cylinders on the other hand might be highly successful.

  • Kurian

    How is the cam angle timing?