A century ago, steam engines had such complex valve actuation that it was even used to reverse the direction of rotation, and the Italian Army started a company to make themselves some staff cars. F.I.A.T. grew up to produce the classic Topolino and 500 models, and even sold the Lada factory to the U.S.S.R. Then, a bit over a decade ago, they developed the common-rail electronic fuel injection system which has revolutionized diesel engine design. It replaces a complex precision pump with an offshoot of desktop printer technology to meter the fuel out. Now, they have a system that meters air into a gasoline engine better than any previous mechanical or electrical system. Basically, they use a hydraulic lifter, and an electronic spill valve to tailor the effect the cam has on the valve. The system is efficient, versatile, and relatively failsafe. It finishes the job of civilizing the internal combustion engine, getting it to run at maximum efficiency with minimal pollution over a wide range of outputs.
The first world-wide application of the Multiair technology will be the Fire 1400 cc 16V naturally aspirated and turbocharged engines. The second application will be a new small gasoline engine (SGE - 900 cc twin-cylinder) where the cylinder head design has been specifically optimized for the Multiair actuator integration.
Here again, there will be both a naturally aspirated and a turbocharged version.
It's worth a read - it's clever technology that keeps the existing cam, but can be over-ridden by the hydraulic component.
It's worth a read - it's clever technology that keeps the existing cam, but can be over-ridden by the hydraulic component.
Does this mean that there are still cam/pulley/belt losses?
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Yes, and they are somewhat worse, on average, as the cam follower does not drive the cam as the valve closes, except at full power. There are potential savings by returning to "silent" chain in place of the modern belt drive, and by regulating valve spring tension according to RPM.
Maximum power is increased by up to 10 per cent thanks to the adoption of a power-orientated mechanical camshaft profile.
Low RPM torque is improved by up to 15 per cent through early intake valve closing strategies that maximise the air mass trapped in the cylinders.
Elimination of pumping losses brings a 10 per cent reduction in fuel consumption and CO2 emissions, both in naturally aspirated and turbocharged engines with the same displacement.
They also repeat that Fiat is planning a 2-cylinder auto engine using this tech. Surely we'll see that in a North American Chrysler product in the future.
Does it have a "limp mode" in case the electrics fail? I was thinking of the drive-by-wire problems the Toyota crashes were having. I am guessing yes, because there is still a Cam.
I think a failure in this system would only mean the reduced engine efficiency.
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