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Detroit, 3:32 PM
Sat Nov 21
29 posts in the last 24 hours
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09/23/09
"Electric supercharging also avoids the enormous expense and complexity of integrating an electric motor directly into a powertrain to create a mild or full hybrid electric vehicle."
Well, they would say that. But if you're going to add an electric component to the drivetrain, it seems the FIRST thing car makers are doing, especially in Europe, is use it for stop-start and regenerative braking, i.e. a mild hybrid. Meanwhile the CPT car still burns gasoline at a standstill.
09/23/09
09/23/09
That's the nature of awesome things. They get done, and then done again, and then again.
09/22/09
09/22/09
No wonder cars today suck.
But I hate being forced to accept power windows and door locks, so I guess I'm just a luddite. Don't mind me.
09/22/09
Surely there's a way (such as the aforementioned Stirling or TEG?) to make silence a byproduct of further power generation. Right? All that pressure and heat, just passing by...
09/22/09
Also changing energy from one phase to another is very inefficient. A good example is the difference between crank HP and wheel HP, when energy is moving from reciprocating to rotational to a different rotation etc. Mechanical to electrical is among the worst.
Using waste heat and pressure from exhaust gases is much more efficient than overworking the generator. KERS maybe? I guess there are benefits to being able to retrofit but this still smells like snake oil to me...
09/22/09
[jalopnik.com]
Here's the thing, with the advent of starter alternators and high-power controllers, ever shrinking engine bays, and ever more stringent emissions controls, concepts like this afford flexibility to packaging, momentary power boosts, improvements to drivability, etc. The era of the accessory belt is quickly coming to an end, and I for one welcome experimentation like this.
Is it perfected? hell no, but it's a start.
09/22/09
09/22/09
i don't feel like reading through this, but you do realize that's not at all going to work, right? I would hope someone posting for jalopnik.com would know a bit more about cars
An electric supercharger is going to produce a max cfm of air movement. In a little 4 cylinder, the car might take 400 cfm of air draw to run right. by shoving 1000 cfm (as an example) down the throat of that little 400 cfm throttle body, you will produce signifcant boost.
A larger, high horsepower V6 or V8 will take much more air itself. Something like an Z06 corvette probably pulls more than 1000 cfm, which means not only will there be no boost, but it will actually reduce horsepower by restricting airflow.
This is something that's true of all superchargers by the way, but it's moreso prevalent with an electric model, which is going to produce a set amount of air, period. A belt driven blower will produce different airflow at different RPM's.
09/22/09
More air plus more fuel in the same space = bigger boom. THIS PARTICULAR supercharger will run an I4, but don't you think, maybe, just maybe it can be scaled, run in series or in parallel, or perhaps modified with a different compressor design?
09/22/09
09/22/09
09/22/09
no backpedalling. of course THE CONCEPT could be applied to any engine. the quote above referred to "that thing" specifically, implying the specific one mentioned above.
you're also not the only one with an engineering degree either. The one hanging over my fireplace does the same as the one over yours - absolutely nothing in the real world.
and SantaRita, of course you could change the speed via voltage adjustments, but it's still going to have a cap max airflow.
bottom line - there's been thousands of arguments on thousands of message boards thousands of times about this, and an electric supercharger is not good science. It takes energy to turn the fan, which is parasitic loss.
turbo-charging on the other hand, uses waste exhaust gases to create boost - it's actually efficient.
Maybe on a sub 2 liter engine running a 100+ amp alternator and a full sized battery, an electric charger might equate to some useful gains. But then again, the parasitic draw from a 100 amp alternator on a 2 liter engine is the same as it is on a 6 liter engine. Which percentage wise, is a much bigger loss.
09/22/09
IIRC, I figured it took about 300-350 steady state amps @ 12v to run the thing. A typical starter is sub-200A for less than ten seconds. It's going to take a big cable, big battery/ies (remember, typical lead acid batteries are graded on *max* CC amperage), and a big recharging system to run that thing. And a pretty sophisticated, high amperage controller which was beyond my grasp.
I didn't see the benefits after doing those calculations...
09/22/09
And BTW if you combine a low speed electric SC + a high speed TC = Much better system, both power and efficiency wise.
09/22/09
Turbodyne (of crazy rocket powered car fame) has made these for awhile now.
[www.turbodyne.com]
My favorite though is the Dynecharger system that they once made. Not sure if it's still available, but it sounds like a cool concept. An electric motor between the turbo and compressor helps the turbo to spool up quickly and can act as an alternator in overrun conditions.
[www.turbodyne.com] (scroll to the bottom)
[autospeed.com]
09/22/09
Um, where you do think the electrical power for the supercharger comes from? Unless you're flying a kite over the car in a thunderstorm, the engine has to generate it. The extra electrical load does sap engine power.
09/22/09
The idea behind this is that it wouldn't be running all the time, just when you stomp on the go-pedal.
09/22/09
I'm skeptical, but I like the exercise.
09/22/09
09/22/09
09/22/09
I do like the idea of being able to have a little more control over when that load occurs, though.
Now....somebody get to work on using an engine-heat-driven Stirling to drive accessories or recharge batteries. That's where some magic'll happen.
09/22/09
09/22/09
09/22/09
The clutch off a large truck or bus air compressor should be able to handle the power.
Bypassing it is an issue, but I'm working on that. I probably need to eat canned dog food while thinking about how it should work....
09/22/09
09/22/09
Thanks!
I was thinking larger clutch for a giant supercharger.
Gotta think overkill, y'know....
09/22/09
09/22/09
Ricky, all I did was hook a leaf blower to the corvair!
09/22/09
09/22/09
Why not just have an engine-powered unit with a clutch on it?
If the real benefit is at lower RPM and then it shuts down, why not put a very small pulley (effectively very tall gearing) on the unit, then decouple it as revs rise?
I have a hard time believing it's more efficient to use electric drive to get the same effect.
I recognize that an electric unit could have the advantage of more fine control over a range of speeds, but it seems that's not what they're advocating here.
09/22/09
I don't have an engineering degree but I could see an advantage if they coupled it with a regenerative braking system. Use the regenerative braking to charge a big capacitor, then use the capacitor to power the supercharger while getting back up to speed.
09/22/09
The real difference here is that the only way to truly have any kind of mechanically decoupled charger would be to have a transmission (probably CVT) between the pulley and the compressor, which would have it's own losses as well as incredible mechanical complexity. Also, the parasitic losses of this electric unit (claimed to be between about 3.5 - 5.2 HP) are fairly small compared to a traditional supercharger, although they are producing a relatively small amount of HP on a small engine, so it's difficult to compare to other supercharger setups I've seen
I think the biggest advantage of this electric system over a mechanical one is that the electric system allows better management. You don't have to draw that extra 3.5 - 5.2 HP from the engine / charging system while you're running the supercharger - you can reduce the charge on the battery during high load conditions, and then recharge it during low load conditions. with a mechanical system, you're putting extra load on the engine to run the supercharger when you want the most power out of the engine - not ideal.
09/22/09
That makes sense.
09/22/09
Plumb it in such a way as to be easily bypassed and and some interesting options arise for twincharging.
If I were more restrained and didn't pair it with a ginormous turbo, it would be fun to install just for the sake of having an electric supercharger. I'd put large "Hybrid" stickers all over the car and claim my eco-cred. Priuses, Insights, and their ilk have electric power adders too - they're just marketed as being warm and fuzzy, and slow.
09/22/09
Sure, you'd probably detonate an engine or two getting the setup right but it would be awesome.
09/22/09
Miata engines are cheap and my love for the environment is so great that I'd be willing to scatter engine parts on the pavement in my quest for more efficiency. I can't help it that a side effect of this efficiency is more power. Sometime we need to make sacrifices...