Why is forced induction always mechanical?
The only popular forms of FI are superchargers and turbochargers. Why (besides some crappy bogus stuff on ebay) aren't there any electric compressors that run off the battery (or some other electrical supply)?
With an electric compressor you're not tied to engine RPM or exhust flow / turbine size. Also it doesn't put extra load on the engine (powering the super or reducing exhust flow). If you're eating from the battery, then it'll cause the alternator to kick into overdrive, but there are other ways to get power (ie. charge battery over time with regeneritive brakeing / exhust turbine like a turbo, rather than alternator). Seems to me that getting variable level of boost on demand (without the worry over overboost) would make an electric forced induction system popular... so why aren't there any? There must be an electric compressor out there that has enoguh airflow / pressure for the cost of a good turbo/super. |
It's simply a matter of the power requirement to run an electric SC at anything like the boost you would need to compete with a turbo or SC . You would need either a huge alternator or a big ass battery (or both)- just not practical .
I do think there would be a place for an electric SC that can flow enough to boost low end to mid range torque on the Renesis - but it would do nothing at the top end which is where most of us want the extra. |
I did a little more looking around at the electric super-charger scams (some im prepared for some flames)... and yes... they're shit... but i dont see why someone couldnt make a GOOD one.
It wouldnt work if you were constantly at full boost, but considering that you usually aren't... you store up energy in the battery gradually as you drive, and you use all that energy in bursts when you run the compressor. you can assist the alternator with regeneritive breaking (or if you're worried because there probably aren't any performance brakes that have regen braking out there), put a small turbine in the exust, like a turbo, that generates electricity. That way you dont need some monster alternator. regeneritive breaking especially. just curious, at sealevel with no boost, how much airflow does the renesis need? |
There was a local company here in San Antonio that had a Electric Supercharged Civic and it was fairly fast but their kit was like $10,000 estimated and sort of unreliable and added a ton of weight to the car. It ended up being a one off thing and the idea failed. I tried to search for it right now could not find any info on it.
|
It's called NAAAWZ
|
Originally Posted by mysql101
(Post 3674274)
It's called NAAAWZ
|
For electric boost they go from mechanical to electrical and back to mechanical...
It involves two losses so it can't match the efficiency of the direct mechanical link. Maybe once we can directly move air using electricity we'll get a non mechanical FI... with no moving parts ;) The big advantage of electric boost would be the decoupling of the boost pressure from the engine RPM... |
Its all about the losses associated with converting energy. Both superchargers and turbos us energy already created by the engine to spin a turbine or blower. With an electric solution you would have to convert that energy to electricity, store it, then convert it back to a physical motion to turn a turbine. Everytime you convert it you lose energy and as such lose effeciency.
And then there is weight. To store that energy would require a battery(s). Also a supercharger uses a fair amount of HP to get turning. An electric motor capable of producing the 30-60hp needed to spin a gearbox and turbine would be heavy as hell! |
I would like to see a hydraulically powered supercharger. Either have exhaust gas or an electric motor turn the hydraulic pump. Draw from a small reservoir of oil which supplies oil through oil lines that in turn power a small hydraulic motor that turns the compressor wheel. I think it would eliminate some packaging restraints. It's all a fluid power link. The only thing is hydraulic pumps don't like variable speed so an electric motor would be more conducive to turning the hydraulic pump unless you have the electric motor cut-out once a certain RPM is reached once appropriate exhaust pressure builds. But that might make an overly complex system as compared to a plain ol' turbo charger.
|
Originally Posted by DarkBrew
(Post 3674327)
For electric boost they go from mechanical to electrical and back to mechanical...
It involves two losses so it can't match the efficiency of the direct mechanical link. .. |
Originally Posted by DarkBrew
(Post 3674327)
For electric boost they go from mechanical to electrical and back to mechanical...
It involves two losses so it can't match the efficiency of the direct mechanical link. However, if you're using regeneritive breaking... you're using energy that would have been lost anyways. And if you're using a turbine in the exhust, and it is variable geometry, you can make it spin at the most efficient speed, rather than the speed that will produce the most boost. but the biggest thing is, you're building potential energy in the battery over time, to be used quickly in bursts. Sure, its a bit less efficient... but because you're using stored energy you're going to have more than enough. over-all you'll get worse gas milage, but the inefficiency isn't going to hurt performance (which is what matters here).
Originally Posted by Mawnee
(Post 3674350)
And then there is weight. To store that energy would require a battery(s). Also a supercharger uses a fair amount of HP to get turning. An electric motor capable of producing the 30-60hp needed to spin a gearbox and turbine would be heavy as hell!
You're right, it would be heavy... but people who run nitrous don't seem to mind a big-ass tank in their car, so i didn't think it'd make that much of a diff. I don't think it'd be hundreds of pounds worth of heavy. |
Originally Posted by DarkBrew
(Post 3674327)
Maybe once we can directly move air using electricity we'll get a non mechanical FI... with no moving parts ;)
The big advantage of electric boost would be the decoupling of the boost pressure from the engine RPM... |
running an alternator needed to power such a device would be just as parasitic as a supercharger
|
Remember, You need energy to create energy!
|
Originally Posted by WingleBeast
(Post 3674409)
running an alternator needed to power such a device would be just as parasitic as a supercharger
You aren't running the compressor directly off the alternator. Sure, in the grand scheme, you lose a bit of gas milage... but since when do people who mod for power really care about that? With an electric compressor, you'll get boost that isn't tied to exhust flow, turbo size or engine RMP, and you'll get it immediatly, whenever you want. is this really not do-able? I can't believe that an electric engine couldn't drive a turbo's compressor. How much power does it take to drive one of em, and how much airflow does the renesis need? |
There are good electrical superchargers out there. The Thomas Knight company is one of them. The best way to find them is to google and look for the review articles. There are just too many of the bogus ebay type ones out there.
|
you have to take into effect the bigger (read: more parasitic) alternator you will have to run and you will run more of it, you would be suprised how much more amps you would be pulling with an electric compressor
its not like turbos or superchargers are always at full boost either, most super kits have a bypass while the engine is in vacuum. say you want to turn on your compressor at low rpm's for a kick in the pants, you are going to drain your battery and overstress your alternator at low engine speeds, so you would need a bigger one. Im not sure you understand the limits of electrical storage and how much stress your stock alternator is under with just your headlights, a/c, and stereo on. is it doable? absolutely, is it going to work like you want it to? kinda. will it give mechanical FI a run for its money? in your dreams |
the problem with electric compressors(legitimate ones) is that you cant generally run them for more than a few seconds at a time. Essentially you'll spend 2-3 times the money to end up with the same result as a much cheaper and less intrusive NOS setup
|
Originally Posted by WingleBeast
(Post 3674458)
you have to take into effect the bigger (read: more parasitic) alternator you will have to run and you will run more of it, you would be suprised how much more amps you would be pulling with an electric compressor
Originally Posted by WingleBeast
(Post 3674458)
its not like turbos or superchargers are always at full boost either, most super kits have a bypass while the engine is in vacuum.
You're not powering the compressor directly from the alternator, so the alternator doesn't have to be powerful enoguh to run the compressor. Pair it up with regeneritive breaking (which is powerful and has the added benefit never locking your breaks), and i think you'd probably take much of the load off the alternator. Not that i've ever heard of regen braking kits for cars lol. of course, there are variable geometry turbos that also reduce lag and are better across a wide RPM range, but those dont seem popular either. Or atleast aren't advertized as such. but thats a whole other topic :p |
It would make the RX-8 sound like 2 hairdryer instead of 1.
|
Originally Posted by isays
(Post 3674474)
You're not powering the compressor directly from the alternator, so the alternator doesn't have to be powerful enoguh to run the compressor.
the main argument I am boiling down to here is that the alternator you would need to run, would suck up more horsepower at a constant speed, than any benefit you would get from on demand FI; however it seems to me that you refuse to listen to anyone on this board trying to describe logic in automotive and electrical engineering, and are more interested in arguing any point with the same old sentence about store power in a battery and use brakes to charge it. |
Originally Posted by WingleBeast
(Post 3674604)
..... it seems to me that you refuse to listen to anyone on this board trying to describe logic in automotive and electrical engineering, and are more interested in arguing any point with the same old sentence about store power in a battery and use brakes to charge it.
|
Originally Posted by isays
(Post 3674225)
The only popular forms of FI are superchargers and turbochargers. Why (besides some crappy bogus stuff on ebay) aren't there any electric compressors that run off the battery (or some other electrical supply)?
With an electric compressor you're not tied to engine RPM or exhust flow / turbine size. Also it doesn't put extra load on the engine (powering the super or reducing exhust flow). If you're eating from the battery, then it'll cause the alternator to kick into overdrive, but there are other ways to get power (ie. charge battery over time with regeneritive brakeing / exhust turbine like a turbo, rather than alternator). Seems to me that getting variable level of boost on demand (without the worry over overboost) would make an electric forced induction system popular... so why aren't there any? There must be an electric compressor out there that has enoguh airflow / pressure for the cost of a good turbo/super. |
Originally Posted by jasonrxeight
(Post 3674654)
you need at least something around 50kw just to run a supercharger. do you think your small battery and alternator can do that? can you imagine how thick the wire is gonna be just to handle 30kw at 12V? 2500 freaking amps, you need metal rods to handle that current. :bowdown::bowdown:
|
I think one of the biggest problems that hasn't been addressed is the rechargeability of the battery. You can't just keep dumping in charge and pulling it back out as that'll massively shorten the lifespan of the battery. You'd need a special kind of battery (meaning expensive) to deal with memory issues and to hold enough charge. Perhaps a bank of the Tesla or Tango ones?
That said, if an electric-driven supercharger could be made to work, it would be pretty neat, as you could easily switch the blower on and off at your leisure. Picture your RX-8 whirring down the road when some schmuck in a 350Z or Mustang tries to race you. You reach up, flip a switch Speed Racer-style, and leave him eating your dust. |
Originally Posted by Triangle Man
(Post 3674676)
That said, if an electric-driven supercharger could be made to work, it would be pretty neat, as you could easily switch the blower on and off at your leisure. Picture your RX-8 whirring down the road when some schmuck in a 350Z or Mustang tries to race you. You reach up, flip a switch Speed Racer-style, and leave him eating your dust.
|
Originally Posted by Triangle Man
(Post 3674676)
I think one of the biggest problems that hasn't been addressed is the rechargeability of the battery. You can't just keep dumping in charge and pulling it back out as that'll massively shorten the lifespan of the battery. You'd need a special kind of battery (meaning expensive) to deal with memory issues and to hold enough charge. Perhaps a bank of the Tesla or Tango ones?
That said, if an electric-driven supercharger could be made to work, it would be pretty neat, as you could easily switch the blower on and off at your leisure. Picture your RX-8 whirring down the road when some schmuck in a 350Z or Mustang tries to race you. You reach up, flip a switch Speed Racer-style, and leave him eating your dust. |
any of you naysayers or yeahsayers actually run the numbers? its possible that running the SC electrical is actually less parasitic than running it off a belt. until someone runs the numbers you are all talking out of your ass.
its like the fuel cell at your home arguement. people say "oh its non sense to reform the NG into H2 to run through a fuel cell. you could just burn the NG for electricity. reforming it is 2 conversions so its more loss yadddyadda yadda" well every study actually done now shows that its actually more efficient to reform it ,use the waste heat to heat your water and use the resultant electricity for fueling your electric car etc. than it is to burn the gas for heating the water and making electricity. so somebody run the numbers ill give you a hint though- thomas knight esuperchargers run off of separate batteries http://www.boosthead.com/product.php# |
Originally Posted by WingleBeast
(Post 3674604)
however it seems to me that you refuse to listen to anyone on this board trying to describe logic in automotive and electrical engineering, and are more interested in arguing any point with the same old sentence about store power in a battery and use brakes to charge it.
but i use the same old sentence because nobody has explained why it is wrong... people keep on saying it wont work... so i have to assume that they didn't read that sentence or i didn't explain it right. The whole reason I made this thread is because i'm curious and I wan't to understand... So i'm going to keep asking until I do. yes the alternator is on the same system as the compressor would be, but because the compressor isnt always running, it doesnt have to produce enough electricity to keep the compressor running indefinatly. maybe you'd need to replace your alternator, but the new alternator you'd use wouldnt need to put as much drain on the engine as a stock alternator + supercharger because it isn't always running the compressor. its like a well. it fills up very slowly, but thats ok because you only take water out periodically.
Originally Posted by WingleBeast
(Post 3674604)
you can only crank the rx-8 engine over about 15-20 seconds before your battery is gone, how many seconds you think you can spin your compressor with that little juice?
Originally Posted by Triangle Man
as you could easily switch the blower on and off at your leisure.
Originally Posted by jasonrxeight
you need metal rods to handle that current.
It just baffles my mind that a little turbine sitting in your exhust can generate enough power to run the compressor (and still allow enough flow), but you need an enormus electric motor that drains your battery to run it electrically. |
Originally Posted by isays
(Post 3674717)
It just baffles my mind that a little turbine sitting in your exhust can generate enough power to run the compressor (and still allow enough flow), but you need an enormus electric motor that drains your battery to run it electrically.
|
I see reading this thread so much frustration with reality. However, the universe and its rules are rather unbending. Now consider how frustrated those engineers that are trying to develop useful and practical electric electric/hybrid vehicles must be...because they know the difficulties involved!
Gasoline (aka dead dinosours and ancient swamp ferns) has so much energy stored in it it really is unbelievably amazing. Even sucking just a little bit of that energy to power a vehicle provides power beyond most any fuel available, plus....in the form of gasoline's poop (exhaust gas) we can reaps loads more energy and more than enough to power turbos, for example! On the other hand transporting and /or transfering the raw form of energy (electricity or really moving electrons) takes massive everything...batteries, heavy wires, then there's real problems switching and controlling them little electron devils traveling around inside everything. Perhaps a plasma drive has possibilities, if we could only contain it one day, but until we come up with a cheaper and more long lasting way to store the stuff (like some form of hugely effiecient large capacity super-capacitors - they don't wear out with repeated charge cycles like chemical storage) the purely electric anything is going to remain a engineering paradox for long distance transportation - or for powering superchargers, turbos, or anything else. |
I say take the car and turbo or supercharge it. Then make the body of the car a 100% solar pannel. Have a seperate computer, fuel system and electrocharger that you can use like NAAAWWWZZZ when you're racing or showing off. I'm assuming that my personal design would allow the renisis to go from 345 rwhp turbo to 1333 rwhp with the turbo/electrocharger both engauged. Just a thought.
|
Originally Posted by DarkBrew
(Post 3674674)
You'd have to be running the system at hundreds of volts to be practical
|
Originally Posted by isays
(Post 3674717)
It just baffles my mind that a little turbine sitting in your exhust can generate enough power to run the compressor (and still allow enough flow), but you need an enormus electric motor that drains your battery to run it electrically.
|
I think the Prius Fanbois are using some sort of electrical forced induction...or maybe it's conduction...anyway, they're claiming soemthing like 500 whp, but they have to run Optima Yellow Tops..everything has a tradeoff.
|
Originally Posted by Brettus
(Post 3674816)
That little turbine is spinning at 100,000 rpm and needs anywhere between 5-10hp to drive it.
|
Originally Posted by zoom44
(Post 3674714)
so somebody run the numbers ill give you a hint though- thomas knight esuperchargers run off of separate batteries http://www.boosthead.com/product.php# you typically cant run such a contraption for more than a few seconds, this is from Thomas Knight website: You can expect 10 runs of 15 seconds from two fully charged car batteries like yellow tops. |
yeah but its way cheaper to refill those batteries than it is to refill the NOS
|
Originally Posted by paulmasoner
(Post 3674945)
no better than NOS, except that you get to be different
Originally Posted by Brettus
(Post 3674816)
That little turbine is spinning at 100,000 rpm and needs anywhere between 5-10hp to drive it.
|
Originally Posted by isays
(Post 3675355)
lol, it looks like the tomas knight system is like the nitrous that you find in video games that recharges when you go fast for a while :p.
How fast it is spinning doesn't really make a difference unless its acting like a flywheel, would it? If it is only drawing 5-10 hp from the engine, then it has at most 5-10 hp worth of power. Thats if it wasn't wasting any of the energy. so why can 5hp in a turbo power a compressor, but it'd take 50hp if it was electric? |
I threw out the 30-60hp number to drive a supercharger. It depends on the type of blower, but typically it takes 15-20% of your engines power to actually drive the supercharger. This would obviously vary depending ont he gear ratio and engine airflow needs.
I remember with the procharger on the LS1 application and P1SC its something like 50hp to spin the impeller up to the 65k rpm with the resistance of average boost pressure. |
hi
This is completely irrelevant to your post but I'm a new member and I joined because I had a few questions regarding my rx8. Embarrassing as is it to say, I don't know how to start a post to ask a question. I would really appreciate it if someone can help me by just pointing me into the right direction. Thanks a lot. :)
|
Originally Posted by lyndsielee
(Post 3675370)
This is completely irrelevant to your post but I'm a new member and I joined because I had a few questions regarding my rx8. Embarrassing as is it to say, I don't know how to start a post to ask a question. I would really appreciate it if someone can help me by just pointing me into the right direction. Thanks a lot. :)
Make sure you use the search button in the tool bar and see if your question has already been asked before you start a new thread . |
Not that I'm a really hands-on kind of guy, but it doesn't take a genius to figure out simple laws of physics. If you're converting from mechanical to electrical there is always a loss ( no conversion is 100% efficient). Now converting back is the same thing would be even more lossy. There is simply no way that you can make it more efficient than mechanical. Not to contradict anyone here, but you don't have to run numbers to prove a fundamental concept.
Also, I guess I have to take a look at the Mercedes thing someone mentioned here, because I can't possible imagine a turbine spinning up to even 50k from 0 with any reasonable kind of lag, the motor would have to be immense. Ever see a electric go-kart engine that lies around 10hp or so? Would you stack that on top of your existing engine? |
Originally Posted by jaymzs66
(Post 3675416)
Not that I'm a really hands-on kind of guy, but it doesn't take a genius to figure out simple laws of physics. If you're converting from mechanical to electrical there is always a loss ( no conversion is 100% efficient). Now converting back is the same thing would be even more lossy. There is simply no way that you can make it more efficient than mechanical.
Years ago I was struck by the "electric supercharger" idea until I realized that stick a fan in the middle of the intake, no matter how fast it turned, presented an obstruction. It might provide some increased intake at idle, but once intake velocity speeds up I don't know of any 3" fan than can move enough air to pressurize the intake. As has been mentioned, turbos spin in excess of 150000 rpm. To get this from an electrical system would require a drive ration increase off the motor and a large enough motor to spool it up fast enough. Could probably be done, but it has to suffer more loss than a mechanically driven system. |
Originally Posted by Brettus
(Post 3675360)
who said it would take 50hp ? It would take a lot more than 5hp though due to mechanical gearing losses......
Originally Posted by jaymzs66
(Post 3675416)
There is simply no way that you can make it more efficient than mechanical. Not to contradict anyone here, but you don't have to run numbers to prove a fundamental concept.
Originally Posted by zenrx8
(Post 3675485)
I realized that stick a fan in the middle of the intake, no matter how fast it turned, presented an obstruction. It might provide some increased intake at idle, but once intake velocity speeds up I don't know of any 3" fan than can move enough air to pressurize the intake. As has been mentioned, turbos spin in excess of 150000 rpm. To get this from an electrical system would require a drive ration increase off the motor and a large enough motor to spool it up fast enough
Like, i get the idea that this just wouldn't work. but i still dont get what makes it so un-doable. |
(from howstuff works)
A gallon of gasoline contains about 132x106 joules of energy, which is equivalent to 125,000 BTU or 36,650 watt-hours, so... •If you took a 1,500-watt space heater and left it on full blast for a full 24-hour day, that's about how much heat (electrical energy) is in a gallon of gas. .... Think how much battery mass to even get a fraction of that power stored! That's the problem with battery energy - it's impossible yet to store enough to do much useful for any length of time. What is needed is superior storage technology that doesn't yet exist. |
Originally Posted by Spin9k
(Post 3675508)
(from howstuff works)
A gallon of gasoline contains about 132x106 joules of energy, which is equivalent to 125,000 BTU or 36,650 watt-hours, so... •If you took a 1,500-watt space heater and left it on full blast for a full 24-hour day, that's about how much heat (electrical energy) is in a gallon of gas. .... Think how much battery mass to even get a fraction of that power stored! That's the problem with battery energy - it's impossible yet get store enough to do much useful for any length of time. What is needed is superior storage technology that doesn't yet exist. oh and a brand new car:rolleyes: |
^ I won a car ??? :anger: just don't make it a damn electric anything please :rofl:
|
Originally Posted by Spin9k
(Post 3675527)
^ I won a car ??? :anger: just don't make it a damn electric anything please :rofl:
http://static.cargurus.com/images/si...pic-29741.jpeg |
All times are GMT -5. The time now is 12:51 PM. |
© 2024 MH Sub I, LLC dba Internet Brands