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| Part of the Skyactiv D's innovative technology is variable valve lift of the exhaust valve during the intake stroke. This enable hot exhaust gas to heat the cylinder to improve combustion stability during warm up. The lift is changed by this hydraulic device on the cam follower which engages a rubbing pad on the center part of the unusually shaped exhaust lobe of the camshaft. |
The Skyactiv D engine does use a ceramic particulate filter and uses some unusual technology to improve its regeneration cycle. Unlike any other diesel, the Skyactiv engine uses a throttle body! When the throttle is partially closed while the engine is running, the EGT skyrockets due to a big increse of hot exhaust gas being retained in the cylinder due to the exhaust valve opening on the intake stroke and the suction created by the throttle plate, speeding the particle traps regeneration without using an outside power source. Pretty cool!
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| A close look at the exhaust cam lobe. You can see the lump on the base circle which slightly opens the valve on the intake stroke where it is normally closed. |
Another innovative feature is the Skyactiv D’s two stage turbo system. Like the 13B-REW found in the FD RX-7, the Skyactiv D has a small turbo for fast spool and quick responsiveness, especially at low RPM. At high RPM a larger turbo is engaged to provide power to redline. This does two things, first it gives the engine an exceptionally high redline and wide powerband, and second it ensures that the engine has sufficient air at all times for complete combustion and reduction of soot. Two stage turbocharging with low compression makes for an exceedingly peppy, flexible and clean diesel!
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| The pump for the high pressure common rail direct injection is driven off of the camshaft. |
The engine produces an amazing 325 ft/lbs of torque and over 185 hp nearly from idle to the high redline, all while delivering an amazing brake specific fuel consumption or BSFC for short, number of 0.26! As a comparison, just a few years ago 0.45 was considered pretty good for a typical gasoline engine. For those of you that don’t know BSFC is expressed as pounds of fuel per hp per hour. This is a whopping 20% improvement in fuel economy and CO2 production over the older MZR-CD!
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| A view of the common rail direct injectors. |
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| The injector is oriented vertically and the ceramic glow plug comes in at an angle. |
