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  1. #1
    Junior Member
    Join Date
    Apr 2007

    Why not diesel electric instead of gas electric

    I being an ex submariner know that diesels electric is the better way to go than gas electric.

    A small tdi type of european 3 cylinder diesel in a hybrid would go further than a comparable gas electric.

    also we could employ a cvt transmission if we like because at a realistic horsepower levels needed to drive a car or truck efficiently off of "torque" motors" a cvt would be the cat's pajamama's,

    also we could use super/ ultra capacitors, high temperature superconducting motors and generators and regenerative braking.

    factor in new steel alloys and lithium aluminum alloys that are super strong and light weight and carbon fiber body panels to save body , chassis and wheel weight as well as aerodynamics.

    We could then think of Biodiesel made from crops and waste oils as a viable solution.

    Why they even run buses in California on Aqua diesel which is diesel mixed with water to a degree.

    try that in a gas engine.

    Sean Ross
    A&P Mechanic
    Navy Submarine School graduate

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  3. #2
    Junior Member
    Join Date
    Mar 2007
    The Diesel is a more efficient engine, but the biggest problem would be the torque band and horse power peak.
    Would this type of electrical drive motor help a diesel engine.
    Low RPM torque and high RPM horsepower factors would make this kinda useless. The small diesel alone would get 80 to 120 MPG if setup properly.
    But the big auto makers don`t do things in the best interest of the people.
    They have special interest groups like the big oil companies higher profit margins and stock holders.
    Making money to stay in business is great, but let`s get the ball rolling in the correct lane.

  4. #3
    Dr. Diesel,
    I'm not sure why you think there would be a torque band or horsepower problem. The battery-electric drive side of the hybrid can easily handle as much torque or horsepower as needed. The diesel would only be asked to handle the average power requirements of real driving. You could use your 'small diesel' to get 80 to 120 mpg but use the electric so that you could get good acceleration.
    I don't know that there's really any need for the CVT but it would help with RPM matching a bit, just as it does in today's parallel hybrids. I prefer the serial topology for future designs.
    With an electric drivetrain, one also shouldn't need a diesel that is as sophisticated as the TDI. A simple, constant RPM, ultra-efficient diesel should be sufficient with a Serial hybrid.
    I definitely like the flexibility that a diesel can offer to a hybrid.
    Love the aluminum and carbon fiber idea. You need to check out www.teslamotors.com
    - ex-EV1 driver and ex-Navy

  5. #4
    Junior Member
    Join Date
    Apr 2007

    Why all the horsepower craze? Why not efficiency.

    American driving habits and horsepower craze is whats killing our nation.

    # 1 problem driving too fast kills. second you take an efficient engine and instead of using it for mpg with sensible horsepower we make it push more fuel and air through it at higher rates and that allows us to go faster in as few seconds as possible but it cost us fuel economy in the process.

    this puts further pollution in the air and puts a strain on the ammount of oil we import.

    The tesla could go further with a motor that produces only 120 hp or so and get 7 second acceleration may 8 seconds.

    no need for a 2 speed transmission with a cvt.

    with the recharge rate it takes to recharge the batteries you could put a small 1 cylinder diesel putt putt in the trunk to charge the car while camping, jogging in the park or chassis mount it with electric start to charge while the car is parked and shut off when charging is done.

    I would like to see a Ford Gt 40 replicar with a similar drive train and batteries but with cvt and super capacitors for that extra oomph at take off.

  6. #5
    Actually Rocketsci, while I laud your knowledge of the benefits of diesel technology, you need to read up on electric motor technology. In an electric motor, torque is directly proportional to current. Therefore, the torque of an electric motor is purely dependent on the battery voltage and the resistance of the battery and the electric motor. In order to maximize the economy of the battery + motor, one also wants to reduce the resistance of both of these. Therefore, unlike with an Internal Combustion Engine (ICE), with an electric motor, one gets more torque from a more efficient engine.
    The other benefit of an electric motor is that it produces its maximum torque from 0 rpm through some maximum RPM (over 10,000). An ICE only produces maximum torque only in a small speed range, thus requiring a gearing (or CVT) system. Electric motors do not need any transmission.
    The only reason the Tesla has a transmission is to get to 135 mph top speed. As you point out, there is no reason anyone needs to go that fast but, for business reasons, they need to be competitive with supercars so they put in the 2nd gear. One can start in either gear. The shortcoming of a electric motor is that there is a maximum RPM, above which one risks having the rotor fly apart because of centrifugal force.
    There is no doubt that the Tesla is over-designed for average driving, however, they do not sacrifice efficiency in order to get the high acceleration or high top speed. It would not go any further with a smaller motor, in fact, it would go less far since smaller motors are less efficient.
    Putting an ICE on the Tesla would have some advantages, however, in reality, one is seldom (your park may be a small exception) from the electrical grid and the electrical grid is much cleaner and more efficient than any mobile ICE so Tesla has chosen to go-for-it and remain a pure EV. In southern CA, most major parks, airports, and malls already have EV chargers in their parking lots.
    Keep up the good ideas though and we'll find a great solution.

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