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-   -   Why is forced induction always mechanical? (https://www.rx8club.com/series-i-major-horsepower-upgrades-93/why-forced-induction-always-mechanical-202904/)

alnielsen 08-15-2010 12:31 PM


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.

That is more of what I see as how a electric supercharger would work. It wouldn't power up until you put your foot to the floor. Kinda like using nitrous or the supercharger in the Mad Max/The Road Warrior movie.

FazdaRX_8 08-15-2010 12:40 PM


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.

thats called a clutched supercharger, Mercedes did this in the slk kompressor. it only turned on at WOT. I put one of these in my ford probe, still switched. so I flip a switch and get instant boost, recently a protege adapted the kit too. it doesn't make gobbs of power but the idea has been done before....2.0 I4 160whp, @ 4.5psi. stock is 110whp....

zoom44 08-15-2010 12:55 PM

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#

isays 08-15-2010 01:11 PM


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.

well im am interested in arguing, you're right... I like to argue, its fun.
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?

Draining the battery after a few seconds is a problem, though. How much does a battery that holds more charge cost? What are the available car battery technologies?



Originally Posted by Triangle Man
as you could easily switch the blower on and off at your leisure.

Thats what i imagine too. I have a dream where amount of boost is tied to throttle position rather than engine rpm.



Originally Posted by jasonrxeight
you need metal rods to handle that current.

Hahaha, that could be a problem for safety :p


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.

Brettus 08-15-2010 03:53 PM


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.

That little turbine is spinning at 100,000 rpm and needs anywhere between 5-10hp to drive it.

Spin9k 08-15-2010 04:38 PM

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.

8upbad 08-15-2010 04:42 PM

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.

jasonrxeight 08-15-2010 05:09 PM


Originally Posted by DarkBrew (Post 3674674)
You'd have to be running the system at hundreds of volts to be practical

yea, but then your car will be dangerous driving in the rain with hundreds of volts under the hood.

jasonrxeight 08-15-2010 05:11 PM


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.

the problem with electricity is that its not mechanic, to get it working you need wires. its not like a belt or highpresure exhaust gas.

zenrx8 08-15-2010 05:43 PM

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.

zoom44 08-15-2010 05:58 PM


Originally Posted by Brettus (Post 3674816)
That little turbine is spinning at 100,000 rpm and needs anywhere between 5-10hp to drive it.

6 according to the thomas knight folk

paulmasoner 08-15-2010 06:34 PM


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#

i did, a long time ago. thus my previous comment

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.
thats a a pretty penny in batteries, and an ass-ton of weight to fill your trunk with. no better than NOS, except that you get to be different.(by different, i mean alone when it comes to troubleshooting)

zoom44 08-15-2010 06:54 PM

yeah but its way cheaper to refill those batteries than it is to refill the NOS

isays 08-16-2010 12:38 AM


Originally Posted by paulmasoner (Post 3674945)
no better than NOS, except that you get to be different

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.


Originally Posted by Brettus (Post 3674816)
That little turbine is spinning at 100,000 rpm and needs anywhere between 5-10hp to drive it.

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?

Brettus 08-16-2010 12:42 AM


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?

who said it would take 50hp ? It would take a lot more than 5hp though due to mechanical gearing losses......

Mawnee 08-16-2010 01:12 AM

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.

lyndsielee 08-16-2010 01:24 AM

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. :)

Brettus 08-16-2010 01:57 AM


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. :)

Go to the forum that best fits your question and click on the 'new thread' button at the upper left had corner .
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 .

jaymzs66 08-16-2010 02:39 AM

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?

zenrx8 08-16-2010 05:25 AM


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.

I was thinking the same thing during a fit of insomnia last night. Paul, the alternator load would have to at least equal if not exceed mechanical losses from a turbo or S/C, not to mention the alternator would have to be beefed up from stock considerably.

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.

isays 08-16-2010 06:51 AM


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......

Mawnee mentioned it, but i also got it from looking up the thomas knight system. He tried various motors up to 90hp (apperently).


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.

I'm not looking to make it more efficient. I know that won't happen. But because you'd be using stored energy, being less efficient wouldn't be a performance hit. Your overall gas milage would be worse, but there'd be other advantages... it it could be made to work :p. Doesn't seem to be possible, but I still cant wrap my head around why a turbo could power a compressor but you'd need a big-ass electric motor to do the same thing.


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

does the compressor in a turbo also spin at 150000 rmp or has it been geared down? You dont need that kind of speed in a supercharger, so i cant imagine that the speed is the key. Rather than have a supercharger driven from the engine, you could have it driven from an electric motor. Why wouldn't that be able to provide enough air?

Like, i get the idea that this just wouldn't work. but i still dont get what makes it so un-doable.

Spin9k 08-16-2010 07:08 AM

(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.

paulmasoner 08-16-2010 07:22 AM


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.

bingo. congratulations, you've won a heaping serving of common sense! now share some with the other boys and girls since they obviously need it and you dont

oh and a brand new car:rolleyes:

Spin9k 08-16-2010 07:32 AM

^ I won a car ??? :anger: just don't make it a damn electric anything please :rofl:

paulmasoner 08-16-2010 07:34 AM


Originally Posted by Spin9k (Post 3675527)
^ I won a car ??? :anger: just don't make it a damn electric anything please :rofl:

aw:tear:

http://static.cargurus.com/images/si...pic-29741.jpeg


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