Can you combine the best bits of gasoline and diesel engines to create a new powerplant concept? Mercedes says yes and has unveiled the DiesOtto prototype unit to prove it.
Engineers say the 1.8-liter four-cylinder unit offers the torque and fuel consumption of a diesel, with the power and emissions quality of gas.
Despite its small size, it can deliver a massive 238 bhp of power. That’s more than a standard 3.5-liter V-6 gas engine or a 3.0-liter V-6 diesel.
The DiesOtto is more efficiency because it’s a smaller, more compact design, and uses two-stage serial turbocharging. Running on gas, it has a spark plug at the top of each cylinder, but they don’t fire on every cycle. If the driver accelerates hard they will spark, but if he’s being more gentle, ignition of the fuel/air mix is caused by compression – as in a diesel – so the spark isn’t needed. Mercedes calls this innovation Homogeneous Charge Compression Ignition (HCCI).
Prof. Dr. Herbert Kohler, Mercedes’ vice president of advanced engineering, vehicle and powertrain, said: “We have long finished the lab test phase and can now show that this can be put into practice.”
As to when it will appear in customer cars, he would only confirm: “In the mid-term we will have something like this in production.” Realistically that means a minimum of five years.
One of the biggest issues will be cost to the motorist. Diesel cars are already more expensive because the engines cost more to make, and the expensive extra technology involved on the DiesOtto will be an issue vehicle manufacturers will have to address.
The DiesOtto engine will make its debut in a futuristic concept car at September’s Frankfurt Motor Show. The unusual name comes from combining the word ‘diesel’ with the name of Nikolaus Otto, the inventor of the gasoline engine in 1867.
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