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| 5kw metro engine? | |
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| Tweet Topic Started: Nov 20 2010, 11:06 PM (1,879 Views) | |
| metroschultz | Nov 22 2010, 09:55 AM Post #16 |
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Please just call me; "Schultz"
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If you AeroModded your Geo to reduce your parasitic drag, then 7hp would be enough to cruise at 55 on the highway. Look at the 'Sun Racers' in Australia. They rely solely on sunlight to provide the electricity to propel them down the road. They don't produce 5kw. But they accelerate to 100kph (62mph) and maintain through the course. Some even go faster than that when they are racing the clock. -------------BUT------------- They have essentially zero drag. If a Geo had zero drag (or any car for that matter) hp would be irrelevant for cruise. and MPG would be astronomical. Weight then would be your only factor in determining engine size, based on how quickly you want to get to cruising speed. |
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| dayle1960 | Nov 22 2010, 10:28 PM Post #17 |
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Fastest Hampster EVER
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So, Nerys says yes, my friend could be right and EVERYONE else says he(my friend) is full of BS. There is only one way to find out, of course. "Test, do not guess". Anyone know what size (amps, volts, etc...) of electric motors I would need to spin the wheels on a metro? I will assume a base weight of 1600 lbs. for the car. No engine or tranny. Their weight will be displaced by the gas powered electric generator and four electric motors. Braking system for now will be pebbles and bam-bam style. Everything else will be stock. No batteries will be used. My friend did not stipulate that batteries could be used in conjunction with the generator, so they will not be considered in any calculations. My friends idea is to go out to the car in the morning, pull the starting cord on the generator, sit down in the car, apply power to the electric motors in some fashion and.....GO. There is no way that will happen. thanks terry |
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| Woodie | Nov 23 2010, 07:24 AM Post #18 |
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Efficiency has nothing to do with it, 7 HP is 7 HP no matter where it comes from. We have 10 HP of work to do and we have 7 Hp available with which to do it. Unless you have a source for an electric motor which is 150% efficient, the equation is done. |
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| metroschultz | Nov 23 2010, 09:37 AM Post #19 |
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Please just call me; "Schultz"
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That is, I think, what Nerys is referring to. Electric motors are quite often run above their rated KW. They can run at 150% and still keep their guts intact. Not for long, you surely realize, but it is possible. Many of the EV builders take this into account when deciding on the motor they will use. A slightly smaller motor, for weight savings, and overclock it for short bursts of speed. I would like to know that I have all the power I need when I want it. If I ever build an EV, it will be after much research and deliberation. I will probably go the route of Ben Nelson and buy an old electric forklift. He ended up using the hydraulic's motor for his car. The traction motor was too big to fit in the Metro engine compartment. I don't remember how many KW it was. Use those parts as the donor and TaDa! electric Metro. |
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| nerys | Nov 23 2010, 12:12 PM Post #20 |
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Grr
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Nono he is talking about more out than in. Maybe my assumption is wrong here woodie. is our engine GENERATING 10hp or PUTTING 10hp to the ground? the difference is critical. if its generating 10hp but only half of that "makes it to the wheels" then you only need 5hp to do the same job if your efficiency is 100% or close to it (electric motors can be upwards of 95+% efficient. the "system" including charger is around 89 to 92 % efficient. so even higher since charger has nothing to do with power to the wheels. its also about TORQUE. I would imagine the more torque you have the less "hp" you need to do the same job depending on speed etc.. (I admit I do not fully understand that portion of this stuff) 4 motors? why in gods name would you use 4 motors. ONE MOTOR please. the point of an electric motor is cleaner cheaper less maintenance. all of thats defeated to some extent by the added complexity of "more motors" you leave in the tranny and bolt the motor right to it. Done. (well not quite that easy but you get the idea) and again I don't think you could ACCELERATE with that genny. you would need at "butt check here" at least 3 times the KW's for the acceleration. we are talking "cruising" at 55mph. I think a 5.5 would be enough. I am not saying it factually is. I am not saying I am right and you are wrong (as you imply) I am saying nothing more than this. I THINK a 5.5 kw genny would be enough to maintain 55mph. I have seen EV's with 4 hp electric motors do 60mph. so how are they doing it? Edited by nerys, Nov 23 2010, 12:13 PM.
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| dayle1960 | Nov 23 2010, 06:22 PM Post #21 |
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Fastest Hampster EVER
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Four small motors is less weight than our tranny with a big electric motor strapped to it. I'm thinking of efficiency. The 5 kw genny would not be able to turn a large electric motor, but might turn 4 small electric engines. My friend also asked a question about batteries in a EV. How much energy(HP,volts,amps,etc.) is avaliable from the battery pack in a EV? His thinking is that if an EV has X amount of energy, then the genny could generate that same amount of energy(over time)and move the vehicle. I'm doubtful. |
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| chads4dr | Nov 23 2010, 08:44 PM Post #22 |
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wait....... so can we put this electric powerplant in a geo then hook a big generator to the geo's engine and have the generator recharge the batteries? I want a 300hp geo!!!PS I know its not that simple! Edited by chads4dr, Nov 23 2010, 08:45 PM.
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| Stately | Nov 23 2010, 10:00 PM Post #23 |
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Geo cheerleader
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Not understanding the question--with or w/o batteries? As you mentioned in an earlier post its that potential energy storage that makes all the difference. Batteries could be trickle charged with a wimpy solar panel (over time) and be just as effective is if charged on the grid--just takes longer. |
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| nerys | Nov 23 2010, 10:06 PM Post #24 |
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Grr
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4 small motors is FAR FAR heavier and FAR FAR more complex and far less efficient. i larger motor is more efficient than 4 small motors and 1/4 the losses too. plus all the mechanical's you would need to install to USE 4 motors plus the extreme expense of these specialized motors and mechanical's. trust me. one single motor direct to the tranny. oddly the metro is less than ideal for electric. you really want REAR wheel drive. then you can do "direct drive" to the drive shaft no tranny. with some "custom" work and a double shafted electric motor you could make the motor the transaxle and direct drive it that way but then you have full locked axle and this is likely "bad news" unless its an off road machine. |
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| dayle1960 | Nov 24 2010, 06:14 PM Post #25 |
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Fastest Hampster EVER
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All I want to know is, Could a 5kw gas powered electric generator supply enough power to an electric motor and make the vehicle move from 0mph to 55mph and then keep the vehicle at a steady 55mph? I say no, My friend says yes. I think he is full of BS, he thinks there is somebody in the world that has done this and BigOil or BigAuto has bought off the inventor. He refuses to understand the laws of physics. I don't have enough techinical background to make my point and I'm just asking you guys on GMF to give me some ideas. thanks terry |
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| nerys | Nov 24 2010, 11:15 PM Post #26 |
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Grr
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the answer to that is again unanswered because you question is too open. define the vehicle? if you mean a normal gas powered car geo metro or larger then the answer is an absolute NO. that generator WILL NOT provide enough amps for acceleration. it "might" (big maybe here) have enough amps to SUSTAIN 55mph but even a small hill might overload it. YOU CAN use a generator to power a car it just needs to be a larger generator OR you need a small battery pack to handle the "high amp" load of acceleration. now CUSTOM build a small aero trike and it could EASILY have enough power to do all you wish of it. Edited by nerys, Nov 24 2010, 11:16 PM.
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| Stately | Nov 24 2010, 11:36 PM Post #27 |
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Geo cheerleader
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Assuming 5000W power, 0-60 in 30sec (anything longer would be suicide--even a ForTwo is 14.4sec), and a 100% efficient electric motor and zero frictional loss: P=5000W T=30s Work=PxT Work=150,000 N-M V(avg)=1/2(V(0)+V)=30mph distance=V(avg)xT=805Meters Force=Work/distance=187Newtons Acceleration=(V-V(0))/T=0.447Meters/s^2 Mass=Force/Acceleration=417KGrams=919lbs Therefore, car + driver would have to be no more than 919lbs (with a perfect motor and frictionless world). Edited by Stately, Nov 25 2010, 11:47 AM.
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| nerys | Nov 25 2010, 01:43 AM Post #28 |
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Grr
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yeah. not going to work except maybe a go cart or trike :-) not any normal regular car shell thats for sure. |
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| dayle1960 | Nov 25 2010, 09:30 PM Post #29 |
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Fastest Hampster EVER
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Thank you, Stately. I the formulas and numbers. My friend should understand that. |
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| Stately | Nov 25 2010, 10:21 PM Post #30 |
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Geo cheerleader
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You're welcome, dayle1960! |
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I want a 300hp geo!!!
7:18 PM Jul 10