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Old 01-26-2012, 08:37 PM   #21 (permalink)
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Maybe would be the easiest option but then tune them to produce the power a little lower for reliability, newer bike engines shouldnt be too hard to get a hold of i wouldnt think either even with the improved technology of today on them still.

But also this isnt for my fiero its a project in the future. Maybe some design cues of the fiero but im not sure. But custom built to be alot lighter , unless I just find a really light car chassis and or body that I might would want.

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Old 01-26-2012, 08:46 PM   #22 (permalink)
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Motor cycle engine maybe would work , althought idk the weight of a stock geo not to mention a gutted one. Atleast gives me something to think on.

Long as its fast enough speed and acceleration to keep from being dull and have me bored when I drive it while also handling amazingly I'd be happy.
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Old 01-27-2012, 06:40 AM   #23 (permalink)
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Originally Posted by NeilBlanchard View Post
It takes a transmission specifically designed for electric motors. Regular car transmissions cannot handle the instant torque -- ask the good folks who built the Illuminati '7'. Even the differential was destroyed by the electric motor.
They started with a METRO transmission/diff neil!!! and put it to a powerplant that does 0-60 in 6 seconds (down from maybe 14 seconds for a stock metro). electric motors don't have some magical "instant torque" that destroys any transmission you show to it, and even if it did, it could be fixed with a software patch to the controller. Plenty of mild EVs on evalbum that are using them.

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And Tesla tried a 2-speed transmission, and then discarded it. Direct drive is better, and more efficient.
better? more efficient? You have not thoroughly analyzed this to make such a blanket statement. Lets look at some of your assumptions:
1. electric cars should have 300HP motors
2. There was no engineering issues in the gearbox
3. Drawing higher currents and providing more cooling (making more heat) is more efficient than having gearing options.

My low power electric scooter was much "better" when I made it a two speed, it could climb hills and had better top speed, trust me on this. Yes there is a fixed efficiency hit for having selectable gears, in this case it is the extra chain and freewheel drag, but that could also be addressed directly (two chains with 4 dog clutches to completely disengage the unused chain and sprockets).

http://ecomodder.com/forum/showthrea...ter-14889.html


Tesla had engineering problems, they really wanted two speeds because that makes sense. Electric motors do not have a flat efficiency curve either and might have to be oversized (inefficient) if they don't have a transmission:
Discussion of the Nissan Leaf Transmission and Efficiency
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Old 01-27-2012, 10:29 AM   #24 (permalink)
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So they took a METRO transmission designed to take a 2000 lb car from 0 to 60 in 14 seconds, and put it in a 3300 lb car where it goes from 0 to 60 in 6 seconds.

Recall that F=MA (Force=Mass*Acceleration). M is 1.65 times greater and acceleration is 2.3 times greater so they were overloading the transmission forces by about a factor of FOUR times its design capacity!! (3.85)
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Old 01-27-2012, 11:39 AM   #25 (permalink)
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Right, and the difference in efficiency between 3rd gear and 4th gear was about 2%. You lose that much by introducing the best gear reduction "transmission" like the Borg Warner unit used in the Aptera. And Tesla used a "proper" transmission, and they discarded it after having similar problems. The torque of an electric motor is much harder to deal with than an ICE. There is an order of magnitude of difference in the quickness of the increase in torque, and this is very hard on the gears.

Back on topic: it is the buffering function of the battery that gives a series hybrid all of it's major advantages. So, I don't think it should be eliminated.

1) You can plug in and charge the battery which is the most efficient way to get electricity in the car. An electric motor is the most efficient way to power a car, so this makes sense.

2) When the battery is nearing depletion, the ICE can be started to spin the generator. This is best done at a fixed RPM, so the engine can be run at it's peak efficiency. The valvetrain and intake and exhaust can all be optimized for this RPM; with no need for variable valves. (Although on one recent genset, they designed it without a throttle and used the valves to control the RPM, I think?) It might be possible to eliminate the throttle altogether?

3) The ICE needs to only meet (or slightly exceed) the average load, and not the peak load. So the displacement of the ICE is minimized, and then along with that, the cooling system can be minimized (which pays dividends in lowering the aerodynamic drag), and the fuel tank and exhaust systems are smaller and lighter weight. The ICE will warm up more quickly.

4) Since the genset can charge the battery more quickly than it gets depleted, the ICE only has to run periodically. This obviously save a lot of fuel, too. The cooling system can have an active louver to closed when the ICE is not running, or during warm up to get to optimum temperature as quickly as possible.

So, having a battery pack of a certain size depending on the efficiency of the car makes a very big difference.
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Old 01-27-2012, 01:35 PM   #26 (permalink)
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Quote:
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Right, and the difference in efficiency between 3rd gear and 4th gear was about 2%.
Actually they are saying a 3 speed can improve EV efficiency by about 20% in real world conditions.

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Originally Posted by NeilBlanchard View Post
... The torque of an electric motor is much harder to deal with than an ICE. There is an order of magnitude of difference in the quickness of the increase in torque, and this is very hard on the gears...
Do you have even one link or source to back that claim up? Ever seen the oscillations pistons introduce to a driveline? The tesla isn't a two speed because of marketing pressures and poor design:

Tesla CEO on Brush With Death Due to Transmission Troubles — Cleantech News and Analysis
"We learned that the car industry is unbelievably good at delivering what they’ve done in the past with a little tweak — faster, or in yellow. But if you want something a lot different — a simplified transmission that’s electrically actuated — that’s too radical. The designers and engineers who can do radical changes all left Detroit forty years ago."

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