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Lotus Proton Concept – Click above for high-res image

Lotus claims that three undisclosed automakers have shown "significant" interest in its dedicated range-extending three-cylinder gasoline-fueled engine that was unveiled at the 2010 Geneva Auto Show. To date, the Lotus engine has appeared in the Proton Emas, the Jaguar Limo Green and Lotus Evora 414E hybrid, but odds are we'll see it powering at least one more vehicle soon.

Lotus' chief project engineer, Lee Jeffcoat, told Inside Line that, "no one has signed up yet," but says that "several OEMs" have shown interest in ordering "5,000-10,000 units annually, for a potential annual output of 30,000 engines."

Lotus' three-cylinder gasser was optimized from the get-go as a generator. As such, it's most efficient when operating between 1,500-3,500 revolutions per minute. Lotus' range-extender has been significantly redesigned since its initial introduction. It now features a more conventional layout and is claimed to be cheaper to manufacture and easier to service.

[Source: Inside Line]


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    • 1 Second Ago
  • 23 Comments
      • 3 Years Ago
      I take it you are joking. The Lotus/Proton is a 47 HP rig, probably not enough to push the generator on a Volt (whose genset is a 1.4 l rig is 84 HP 64 KW), you would probably need a smaller car with less Aero drag to use it.

      I am starting to think that the small motor/ genset idea is not a good idea as a backup strategy for a low EV range plugin hybrid.

      Yes you can ditch the tranny and use a smaller engine, but the inefficiencies of converting to electric and then back to kinetic can't be made up. The Volt's disappointing range extending mode is a case in point. Cheaper (although not cheap) and possibly more efficient would be a small ICE running as a through the road set. Just use the batteries for commute range, 4 wheel drive conditions, and to get up to speed for a highway trip.

      Then European small diesels that provide "insufficient" power somehow on this side of the Atlantic, can be supplemented by EV to give "adequate" 0-60 performance boost for heavy pedal conditions. They would still be outstanding mileage on the highway (handicapped only slightly by the weight of the batteries), and can be EV for around town.

      The smallness of the motor will only come at perhaps a thousand ($, pound or Euro) saving, so the electrics will certainly be at a premium, but again you won't have to cart all the batteries of a Leaf never mind Tesla
        • 3 Years Ago
        green-eh

        The Volt has a 4-cyl only because GM didn't produce a US-emmissions compliant 3-cyl like they originally designed the Volt to have. They made the choice to change from the original 3-cyl engine to the current 4-cyl engine due to timeline issues to get the Volt to market in the shortest time possible. Otherwise, the Volt would have a 3-cyl.

        The Karma has a turbo 4-cyl because they want to burn rubber and score kills against the luxury cars they plan on competing against. So they needed a 400 hp.

        Pike's Peak is a sales gimmick. It isn't even a public road. It's a private road you have to pay to drive up, the same way you have to pay on track day at a race track.
        • 3 Years Ago
        green-eh said "Passing on an uphill would not happen unless you dip into the battery, which at 25bhp you are not going to be able to replenish."

        You would be correct IF we were talking about a 25 hp engine. The Lotus engine is not a 25 hp engine. These Lotus engines "provide 47 horsepower in normally aspirated and 67 hp in supercharged tune". That is plenty of horsepower to allow the car to dip into battery power to accelerate and go up hills, and still be able to recharge the battery.
        • 3 Years Ago
        I have no argument with smaller engines being used. I am a bit suspicious of your assertion that we can use ones half the size. Remind me again why the Volt (and the Fisker for that matter) have engines that size and why there was concern that running the engine genset might not be enough oomph to climb an extended incline in the Volt (hence the Pikes Peak headline and the Mountain mode so you can run the range extender to top up the battery ahead).
        • 3 Years Ago
        I stand corrected. When I think about it my friends Morgan had only 40 bhp, and it could make 75mph. My Fiat X19 had 60bhp and could just hit 100 mph. The Fiat 500 (origional) managed with 20 bhp and made 53 mph.

        The Volt is over three times as big a car but with reasonable Aero, I grant that you might be able to sustain 60mph at slightly over 25 bhp applied to the wheel. To generate that bhp I follow your logic and agree that a 500cc 2 cylinder job would be plenty, and it would be much more economical.

        Be that said, unless you drop such a Volt off a cliff, like some of those older cars, it will take minutes and not seconds to make its top speed / 0-60. Passing on an uphill would not happen unless you dip into the battery, which at 25bhp you are not going to be able to replenish.
        • 3 Years Ago
        actually the volt has mechanical connection from ICE to wheels at high speed.
        and 84HP is way overkill for a range extender. 47HP is more than enough even for conventionally heavy steel cars. motorway cruise might be 25HP.

        and making the car lighter and more aero helps a lot still. done right it really only requires a scooter engine to cruise a car at say 110km/h.
      • 3 Years Ago
      That's a significant number of engines, at the same kind of level as GM's projected Volt output - unless of course 'The General' is thinking of scrapping it's own engine and using the Lotus!
        • 3 Years Ago
        Interestingly, this research was initiated while GM owned Lotus
      • 3 Years Ago
      2-wheel

      rotory engines do much better at constant RPM's than they do in a standard car configuration in a Mazda, going up and down in RPM all the time. You can't generalize Mazda rotory engines in their cars to how all rotory engines would perform when used at constant RPM's as a generator.


      Turbines suffer the same problem when they were used before. They can't be revved quickly, so they don't work well in applications where the engine speed has to change all the time. Gearing and torque converters get trashed trying to modulate turbine engine speed to match tire rotations. REEV's take care of all of this, because the battery acts as the buffer between engine speed and tire speed. Again, you can't apply the failures of trying to directly power wheels with turbines, to using turbines as a charger running at relatively constant RPM.

      Throw out everything you once knew, little of it applies to using these engines as charging motors.
        • 3 Years Ago
        You're quite correct in pointing out the fallacy of assuming
        that an engine's efficiency is constant across all application and situations.
        As to that 25 HP figure being bandied about - the Corvette cruises at 65 MPH and uses less than 12 horsepower to do so (assuming no AC). Of course, your argument does assume that the output of the engine goes into the battery, which acts as a buffer, and not directly to the electric propulsion motor. In that case the range extender would have to be capable of revving up and down to match demand from the motor.
        Personally, I've come to believe that range extenders are merely (failed) attempts to make electric propulsion available at price points that make sense. Unfortunately, the $15K values Volt is selling for over $42K. GM didn't exactly hit its promised "sub $30K" price target when the Volt was originally announced. That wasn't fraudulent, just ignorance - GM was amazed when LG quoted battery prices for the Volt pack - they were more than twice what GM had originally assumed.
        See how much 100 years of automaking experience counts for when the autos go electric?
      harlanx6
      • 3 Years Ago
      It's a great idea, but when we are paying in the range of $40K or so for the base EV before the little kicker engine, where is the savings? We would be using anti-grav and cold fusion before you could ever amortize the initial cost.
        harlanx6
        • 3 Years Ago
        @harlanx6
        They do make sense for short commuters.
        • 3 Years Ago
        @harlanx6
        Last time i checked, the leaf and other entry level EVs were in the low $30k range.

        With the right tech, you can easily cut the price of the battery down and replace that with a $2k-$4k engine unit.

        .. so sorta like what GM did with the Volt, but at a non-inflated cost.
      • 3 Years Ago
      Lotus : your doing it wrong.

      Piston/cylinder engines are just a bad match for the application, regardless of configuration. Look at rotary engines, turbines, or linear combustion engines instead.
        • 3 Years Ago
        rotaries have horrible efficiency and bad hydrocarbon + particulate emissions from both burning oil and wasting fuel *by design*.

        How useful would a range extender be that got 25mpg?

        Seems like range anxiety would be replaced by range extender anxiety!

        Turbines? dunno about those, but they are noisy. Why do you think they would be ideal? they seemed to have been ruled out on cars many decades ago.
        Linear combustion? i've never heard of this...
      • 3 Years Ago
      If a range extender (aka series / serial hybrid) is charging the battery, and not generating electricity for direct use by the electric traction motor, then it only has to produce power at or slightly above the *average* power level used to move the vehicle. Which is *significantly* lower than peak power required to accelerate the same vehicle; say uphill as fast as possible from 45-75mph.

      A really efficient car would need less than 10HP to travel at say 65mph on level ground. The FVT eVaro has a ~20kW genset, which can charge the 21kWh (total capacity) pack in about 1 hour *while* also driving at highway speed. It isn't the displacement of the ICE so much as the peak torque at a fixed RPM. The FVT uses a GL-1100 (Honda Goldwing) block with custom intake set up -- this can be tuned to a narrow RPM range, so no need for variable valve timing and all that; let alone need a transmission.

      So 35-45HP sounds about right to me. And quick warmup time is important.

      Neil
      • 3 Years Ago
      range extender is good but I think they need to be more aggressive than that. that layout is too close to two full drivetrains and that will hurt cost and weight and cost.

      try a two cylinder. bare minimum size. keep it simple. if possible not cast metal but very thin walls of quality metal to keep it light and small. after all the forces are not that great. and I'd really try a rocker piston, one with a pivot moving in a curved cylinder so it is not friction based. if oil lubrication cab be taken out of the picture that can help a lot.
      I'd also try a different generator design (the electric motor). the picture http://media.il.edmunds-media.com/lotus/ns/lotus_eng_ns_32211_717.jpg
      makes it look very heavy. I'd try a neodym copper motor with fiber plastic casing. none of that 20mm solid steel casing nonsense. it's built like a tank.

      what we need is the elegance of a battery car with only a tiny ICE genset tugged away under the rear floor. the idea of junk ICE filling a large nose of a car has to end.
      the ICE should be in the corner and be ashamed of itself. it should think about what it has done :)

      it should be thought of as an EV foremost and the ICE as an emergency generator.

      all that said, lotus seems to be an expensive partner so I wouldn't recommend that anyone buy their product. Tesla motors should have done it alone and they would have been much better off. well.. if they did it right.
        • 3 Years Ago
        "the idea of junk ICE filling a large nose of a car has to end.
        the ICE should be in the corner and be ashamed of itself. it should think about what it has done "

        Yeah, how about those nasty ICEs. They only allowed the world to
        create livable spaces outside of urban ghettoes and provided freedom
        of mobility for the entire planet and 90% of interstate commerce. Now, exactly what have EVs done? Answer : nothing. What are they going to do? Who knows. So far they make driving a car available only for the financially advantaged. It certainly won't lower carbon emissions anytime soon. Pushing EVs at this stage is pure fraud. You should be ashamed of yourself. Go sit in the corner.
        • 3 Years Ago
        I should add that making the car super light and aerodynamic helps make the ICE smaller and cheaper.
        • 3 Years Ago
        curious name you chose for yourself
      • 3 Years Ago
      Remind me again of which EV you have built?

      None, right?

      Well, remind me again of which EV's you own?

      None right?

      So with no actual or practical knowledge, you once again criticise those who have really built and marketed EV's, citing nonsense about non-existent technology.

      Create something of your own, something you can point to and say, "here is the 'DF Grampus Special' proof of my knowledge, with its gleaming flux capacitor!

      You destroyed all your credibility by advocating the barking mad 'Arial Atom EV conversion', as the perfect consumer personal road transport vehicle .
        • 3 Years Ago
        hehe first of all you didn't reply to me. you just posted a comment to the article.
        second, I never said an ariel atom is the perfect consumer vehicle. you have tremendous chaos in your mind. a nonsense storm. you have whipped yourself into a mindless frenzy and as a result you make oceans of mistakes.

        and yes I tell lotus what to do. and tesla. and GM. and Nissan. all of them. and I'm right. deal with it : )
        • 3 Years Ago
        You've forgotten your medication again haven't you?
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