The New Subaru EE20 Boxer Turbo Diesel, In Detail

Illustration for article titled The New Subaru EE20 Boxer Turbo Diesel, In Detail

We've known about the new Subaru diesel for some time now, but we haven't had a real good walkthrough of this first-to-market boxer turbodiesel. You know, the whole shebang — specs, dimensions, power, transmissions, tricks. It's high time we rectified that. Luckily, TechOn did a sit-down with the chief engineers of the program a little while ago and got the whole kit, caboodle and whatever else goes along with it. What we came away with — other than a severe case of information overload — is that this clever little 2.0-liter horizontally-opposed four cylinder has some serious tricks up it bores.


Though perhaps a small note in the story, the engine is over 2.4 inches shorter front to back than Subarus 2.0-liter four cylinder gasoline EJ20. That's impressive considering the new block is stronger and up to 10 kg lighter than it's inline competitors.


Subie's also shifted to a fracture split bearing for the crank end of the connecting rods. What does that mean? Well, the connecting rod is forged as one unit, complete with holes at the crank bore and wrist pin ends. Machining operations clean up the surfaces and create the threaded holes for the bearing cap bolts, then the rod is scored along the split plane of the crank end bearing with a high powered laser. An expanding mandrel is then inserted and breaks the end of the rod in a controlled manner inline with that laser etching. The rough surface remains and acts to positively locate the connecting rod cap in space without any fancy machining.

Fuel is delivered through a positively massive high pressure fuel rail operating at around 26,000 PSI. The actual injection is handled by Denso developed units and are based on solenoid technology. Subaru has indicated the next generation may utilize Piezo injectors, and thus operate at even higher pressures for the next level of emissions regulations. For a little fresh air to go with that fuel, the turbo is a variable nozzle geometry unit mounted close to the manifold to reduce turbo lag and can spin all the way up to 190,000 RPM. There was a bunch of other stuff having to do with emissions and all that good stuff, but thats boring, so go read that yourself if you like.

Interestingly, the engine is only currently planned with a 5 speed manual — with taller gears due to the high torque available. Speaking of power, lets remember this thing is planned currently to put out 147 HP at 3600 RPM and 258 lb.ft. at 1800 RPM. We're not what you'd call experts, but thats a pretty healthy bite of grunt down low. With the inherently smooth operation of the boxer design, and the apparently compact and relatively lightweight design, this seems like a winner without consequence. Though it's widely anticipated this engine will eventually make from Europe to the US, nothing has been confirmed yet, but we can only hope. [TechOn]

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Rob Emslie

I want one of these in a Forrester or an Outback- something station wagon-esque. 5-speed and AWD would be nice too. Diesel here in So Cal is about a buck more a gallon than regular, so that's what, a 25% increase? If I can get 32 combined MPG that's a 60% increase over the 20 I'm averaging now, so even with the higher cost of diesel I'd be coming out ahead. Bring it on!