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Little Lotus Range-Extending Engine For Electric Cars Proves Popular

 
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Lotus Engineering Range Extender

Most car buyers haven't even heard the term "range extender" yet.

But over time, expect it to become more familiar, as electric cars like the 2011 Chevrolet Volt introduce the concept of a gasoline engine that turns a generator to produce electricity to power the vehicle.

Tiny, powerful, efficient

At the 2009 Frankfurt Motor Show, Lotus Engineering unveiled a tiny, 1.2-liter three-cylinder gasoline engine designed solely for use as a range extender.

Now, 18 months later, Lotus has taken the wraps off an improved version of its engine, plus a new, more powerful supercharged model. Both designs have been heavily revised in response to customer feedback.

Lotus_Evora414E_Concept

And the company says it has "significant interest" in the new 1.3-liter engines from three separate automakers about supplying its Range Extender for use in future extended-range electric cars now on the drawing boards.

Projected volumes are in the tens of thousands, Lotus said, along with smaller numbers that might potentially go to specialty makers.

Close to Volt power

The first version of the Lotus Range Extender used an aluminum monoblock, meaning the engine block, cylinder head, and even the exhaust manifold are cast as a single element, reducing both weight (just 125 pounds) and parts count.

The version shown at the Geneva Motor Show in September 2009 produced 47 horsepower (35 kilowatts) running at a maximum of 3500 rpm. The new supercharged version raises power output to 67 hp (50 kW).

Proton Concept platform showing battery pack and Lotus range-extender engine, 2010 Geneva Motor Show

Proton Concept platform showing battery pack and Lotus range-extender engine, 2010 Geneva Motor Show

Enlarge Photo

That puts it close to the 74 hp (55 kW) of the Volt's 1.4-liter four-cylinder engine, which was adapted from a high-volume General Motors engine used in many other models.

Lotus expects its engine to offer considerably higher efficiency and lower fuel consumption, though no third-party test data has been provided as yet.

The Volt itself is rated by the EPA at 37 mpg in range-extending mode.

More conventional engineering

The newly revised version now has a more conventional separate head, making it far easier to manufacture. The exhaust manifold is still an integral part of the block casting, however, and a balance shaft is now optional.

And Lotus has cut the weight even further, to 112 pounds in standard form or 128 pounds with the supercharger, as well as making the engine-generator combination more compact. It can now be fitted either vertically or horizontally.

Proton Country concept, 2010 Geneva Motor Show

Proton Country concept, 2010 Geneva Motor Show

Enlarge Photo

The company is also working on a two-cylinder version of the engine.

Already a variety of manufacturers have fitted the Lotus Range Extender in concept vehicles.

Lotus itself showed its Evora 414E Hybrid prototype; Jaguar used it in a prototype "LimoGreen" full-size luxury sedan; and Malaysian maker Proton, which owns Lotus, showed the engine in a range of EMAS minicar concept vehicles.

[Lotus via MotorAuthority, InsideLine]

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Comments (4)
  1. Always wonder about this type of technology in the USA. Seems like a "light" car in the USA is now 2400 lbs. It is unlikely that 67 hp is going to provide enough power to adequately accelerate a 2400 lb vehicle. Perhaps in other markets with a 1500 lb car, this would be great.
    And yes I know it will be combined with an electric motor and can provide short bursts from the battery. However, eventually you will need to climb that long big hill.
     
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  2. @John C Briggs: In the Volt, and presumably other range-extended EVs to come, transient demands for high power (on acceleration, say) take energy from the pack as well, so the range extender doesn't have provide the peak power demand, just the average over some period of time. So that 50 kW *is* enough if you're buffering through the pack and accelerating from 0 to 60 and then simply maintaining speed thereafter.
    The most extreme demands--a 5% grade for 20 miles--will cause the range extender to run at its highest speed, and will likely cause some slowdown, but then many gasoline cars with lower power-to-weight ratios will slow down under the same circumstances as well.
     
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  3. @John Voelcker,
    Well perhaps my concerns are not warranted. The Chevy Volt is a pig at 3781 lbs. If 74 HP motor can provide adequate performance in a Volt than perhaps a 67 hp motor can easily drive a 2400 lb vehicle.
     
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  4. Great information John. This is very exciting to me as a Volt owner. I know that GM engineers have already improved on the Voltec drive-train for future GM cars. But to have third party competition in this space is what we need to really push it.
     
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