Thoughts on Electric Turbo?

[jeremyc74]

so here's one thing a lot of you are overlooking, you are simply saying the power used to power the motor is just causing drag on the alternator. but at the same time, a supercharger causes drag on the engine. why does the supercharger work at all? because it allows the engine to burn fuel more quickly, and even more efficiently. its not all power in = power out, the engine isn't necessarily perfectly efficient, and you cant just consider what the output is only at one specific point.

the turbocharger on the other hand is much more efficient, using the wasted exhaust gas to compress the air. its conceivable that one could make an electric turbine generator that was driven by the exhaust, and have that in the rear of the truck, then have a second high power electric supercharger on the intake, and not one of these rinky dink ebay things, it would be based off of an actual turbo. whats the point you might ask, you can have a lot of boost whenever you want, not just in a certain rev range, because you can pull current from the battery, then when you are at wot, the electric turbine at the back can recharge the battery. in order to avoid alternator drag, a second battery could be used just for the supercharger, and it would recharge only via the turbine.

https://en.wikipedia.org/wiki/Electric_supercharger

You're ignoring all the electrical losses. That's why it won't work. By converting mechanical energy into electricity with the alternator you lose 10%. Then you lose another 10% when you run that through an inverter to control the speed of the electric motor, and then you lose another 10% converting it from electricity back to mechanical energy.

And then there's the MASSIVE current draw required to make any meaningful power with a 12V system. Superchargers consume upwards of 30Hp. To create 30Hp a 12V motor would draw roughly 2000 amps, and that's being conservative.

It's not that the whole thing is completely impossible to do, it's just that there's no reason to even attempt it! You're dealing with compounding electrical losses and gaining absolutely nothing in return. The system won't be lighter, it won't be cheaper (not even close!) and it won't solve any problems with existing systems. :smashputer:

 

[98OzarksRunner]

so here's one thing a lot of you are overlooking, you are simply saying the power used to power the motor is just causing drag on the alternator. but at the same time, a supercharger causes drag on the engine. why does the supercharger work at all? because it allows the engine to burn fuel more quickly, and even more efficiently. its not all power in = power out, the engine isn't necessarily perfectly efficient, and you cant just consider what the output is only at one specific point.

the turbocharger on the other hand is much more efficient, using the wasted exhaust gas to compress the air. its conceivable that one could make an electric turbine generator that was driven by the exhaust, and have that in the rear of the truck, then have a second high power electric supercharger on the intake, and not one of these rinky dink ebay things, it would be based off of an actual turbo. whats the point you might ask, you can have a lot of boost whenever you want, not just in a certain rev range, because you can pull current from the battery, then when you are at wot, the electric turbine at the back can recharge the battery. in order to avoid alternator drag, a second battery could be used just for the supercharger, and it would recharge only via the turbine.

https://en.wikipedia.org/wiki/Electric_supercharger

The problem is that you still need the same amount of electrical power to drive the centrifugal compressor - about 1000 amps @ 12 VDC (not counting the losses added by the turbo-generator and wiring). That means the wiring from the turbine generator in the back to the compressor motor needs to be huge! The largest wire I could find is 1000 ga and it's rated at 500 amps (aluminum - but it will be HOT at that current). It is over 1" in diameter, and costs about $4.50 a foot (and you'll probably need 60' at least [since you will have to double it up to get the current rating needed, and adding another run for 50% over capacity would be wise], and will have to run it both ways - positive and negative). You also need some kind of control circuitry for it, and fuse it so you aren't driving around in a 1000 amp arc welder (in case of an accident). I'm thinking an exhaust-driven turbo is a lot simpler, lighter (60' of 1" diameter wire will weight almost 200 lbs), cheaper, and SAFER!

It's not just drag on the alternator or battery that is the issue. It is that we're talking about electrical current requirements that are well beyond what one finds in a vehicle (unless that vehicle is a locomotive ). Out of the box thinking is good. But one must consider all the issues as well as the possibilities, and guys who design cars have probably considered all of them, and use turbos or belt-driven superchargers. If the goal is just to have a lot of power on demand for short periods of time, use nitrous oxide. It's the cheapest and easiest bang for the buck.

 

[98OzarksRunner]

I get it that the OP is sorta trying to cheat physics here, but dang guys. It would be better if we could deliver the bad news without beating on him so much, LOL. You never know, he might be tenacious enough to stumble onto something worthwhile.

I don't think anybody is beating on him. We're just telling him why it won't work, and what will. Maybe this discussion will lead to some new ideas.

 

[SpidermanGeek]

If it was efficient and cost effective, a lot more people would already be running some variation of an electric turbo setup.

Audi probably poured a ton of money into R&D for their electric turbo. Resources that most of us don't really have access to.

All I can say to OP is good luck on your venture, but I would be prepared for the possibility that it just won't work. Or.. by the time you do get around to a setup that aactually gives you the results you want, you probably would have spent more labor and money doing so that you could have turbo'd AND supercharged your rig for that amount.

Personally, if I was ever going to look into a mild boost setup, I'd seriously consider a remote/rear-mount setup similar to [MENTION=75824]Clownmeat[/MENTION] and [MENTION=76394]Yoterman87[/MENTION]

Seems fairly cheap and efficient save for finding someone locally that can do decent custom piping

 

[JeepKiller]

What everyone here is saying is that we wouldn't want to spend our money on trying to make it work. It's been discussed before and everyone's ideas have failed so far so it is deemed a "waste of money". The guys aren't bashing, they just really don't want you to spend money developing something that someone already found out doesn't work. But who knows, you may come up with something no one has ever thought of.

 

[jeremyc74]

Audi probably poured a ton of money into R&D for their electric turbo. Resources that most of us don't really have access to.

The setup Audi is using is only to fill in during the lag time of a traditional turbocharger, so it's only building boost for a few seconds at a time. That's not really in the same ballpark as using it full time, as the OP is talking about. Even in that limited application they had to add a 48V subsystem just to power the turbo.

 

[sjwelna]

I think you would get better results with direct exhaust injection...

 

[AZBub]

An electric turbo would work no doubt. brushless motors can generate insane power and rpm. But the cost to develop a functional system not made of PVC and duct tape would be pretty pricey. I would also thing it would need a stand alone electrical system.

 

[traffic61]

I'm holding out for Mr. Fusion.

 

[D Farms]

I never said anything about 12v, I never specified the amount of amps or voltage, or if it was a brushless motor. Transmitting that much power is easy, it's called alternating current, and high voltage. The circuit could be wired to.charge a battery, of an unspecified nature, and at the same time could simply be wired to the supercharger as well.

It seems like people just post an idea and instead of making suggestions, everyone just shoots them down.

 

[jeremyc74]

I never said anything about 12v, I never specified the amount of amps or voltage, or if it was a brushless motor. Transmitting that much power is easy, it's called alternating current, and high voltage. The circuit could be wired to.charge a battery, of an unspecified nature, and at the same time could simply be wired to the supercharger as well.

It seems like people just post an idea and instead of making suggestions, everyone just shoots them down.

The only suggestion that makes sense is: FORGET ABOUT IT. This idea won't work, and if it would you'd already see a manufacturer doing it.

Where is this high voltage going to come from?

I'm an electrical engineer. I work with this stuff on a daily basis. You don't just pull power out of thin air, be it 12VDC or 480VAC. Wattage (the measure of work) is wattage. A 30Hp motor is 22kW no matter what the input voltage is, and somehow you're going to have to supply that motor any time you want boost.

I guess maybe you could pull a trailer everywhere.....:lol:
This is what a 25kW generator looks like:

 

[D Farms]

The only suggestion that makes sense is: FORGET ABOUT IT. This idea won't work, and if it would you'd already see a manufacturer doing it.

Where is this high voltage going to come from?

I'm an electrical engineer. I work with this stuff on a daily basis. You don't just pull power out of thin air, be it 12VDC or 480VAC. Wattage (the measure of work) is wattage. A 30Hp motor is 22kW no matter what the input voltage is, and somehow you're going to have to supply that motor any time you want boost.

I guess maybe you could pull a trailer everywhere.....:lol:
This is what a 25kW generator looks like:

The rear turbine could easily provide the Nesesary voltage. Its not thin air, its unused energy from the exhaust. What kind of battery setup does the tesla have, you guessed it high voltage lithium polymer. Guess what you can pull a lot of wattage from those for a short period of time, then it gets recharged by the rear exhaust turbine. Also incase they didn't teach you this in school, you can get the same power from a high voltage low amp source, as you can get from a low voltage high current source. The difference is that you wouldn't loose as much energy with the high voltage setup and could use smaller cable, because of something called ohms law.

 

[jeremyc74]

The difference is that you wouldn't loose as much energy with the high voltage setup and could use smaller cable, because of something called ohms law.

Never heard of it. :nerd:

Carry on with your exhaust powered electric turbocharger.


Sometimes people just don't like to accept reality.............:rip:



I have just one question....why not do away with all the additional weight, cost, and complication of the battery, electric motor, generator, and wiring, and just power the compressor directly from the exhaust.....you know....like EVERY MAJOR MANUFACTURER DOES NOW?!

 

[Konkordmusk]

The rear turbine could easily provide the Nesesary voltage.

Easily? How easily are we talking about? I'd like to see data and info for an exhaust driven generator with enough output to recharge a LiPo battery.

Here's some data for the electric "turbo" used to pre-spool the turbo in the unreleased Audi's
The proposed 48-volt system will lower the required amperage to a workable 145 amps.
In a 12v system, the amp requirement is around 580. That's a lot of amps!

I would never install anything larger than a 50-60 volt battery in anything I require safety in, because that's a dangerous voltage to be shocked with, in case of an accident. The cost of a dual voltage system isn't fun to think about. Here, we're back to just using a conventional turbo or a supercharger, due to the cost vs yield.

Now let's talk about your exhaust driven generator again. The pressure required to keep an exhaust driven turbine happy is pretty insane. In order to keep the pressure consistent for your "rear mounted" assembly, you would have to throttle the pipe diameter in order to keep enough flow to even manage an output. Which means, reduced engine power because of too much backpressure, and that means a lot of losses that aren't being recovered by your proposed system. That, and I would never install anything electronic near something that gets as hot as exhaust gas. Which then means a belt pulley system, which means increased drag, and reduced output.

Lastly, how do you manage the speed of the generator? There IS such a thing as "too fast" for an alternator. Output doesn't 1:1 scale with speed.

 

[gamefreakgc]

I like how the OP hasn't even said anything for the last two pages opcorn:

 

[MTD]

Its been done...
New site - HOME

Proof.
http://www.ft86club.com/forums/showthread.php?t=39719
http://forum.miata.net/vb/showthread.php?t=537959

And being done again....
Electric turbos promise big performance and efficiency gains in the near future


:fish:

 

[Black798]

Its been done...
New site - HOME

Proof.
Full throttle Electric Supercharger Build Thread - Scion FR-S Forum | Subaru BRZ Forum | Toyota 86 GT 86 Forum | AS1 Forum - FT86CLUB
Openflash Electric Supercharger (Dyno & Pics) - MX-5 Miata Forum

And being done again....
Electric turbos promise big performance and efficiency gains in the near future


:fish:

I agree, this Phantom charger is definatly proof of concept. And its not just one or two out there, they sell quite a few. What I feel the majority of you are failing to look at is that the technology is there. It just needs to be refined. I mean hell we made a computer the size of a building fit into your pocket.

The reason why i continue to to ignore the posts regarding a normal system is I can not justify the cost of a turbo system, trd supercharger, or a procharger setup. So if someone finds a way for me to setup a turbo or a something for under $1,000 feel free to enlighten me.

And jeremyc74, as an electrical engineer isnt it your job to make the impossible possible. I mean Thats why im going for an engineering carrier.

 

[Konkordmusk]

Its been done...
New site - HOME

Proof.
Full throttle Electric Supercharger Build Thread - Scion FR-S Forum | Subaru BRZ Forum | Toyota 86 GT 86 Forum | AS1 Forum - FT86CLUB
Openflash Electric Supercharger (Dyno & Pics) - MX-5 Miata Forum

And being done again....
Electric turbos promise big performance and efficiency gains in the near future


:fish:

I've installed one of those kits before, on an FRS. Very awesome kit, decent price for what you get I suppose. I think the customer we installed it for bought everything for 2 grand.

However, the phantom system only works at WOT...
and here is the OP saying that he wants a system that works at variable speeds:

that would control the speed of the motor giving me entirely variable boost regardless of throttle position.

The mechanics behind achieving either are almost completely different.

 

[Black798]

The mechanics behind achieving either are almost completely different.

I feel like it would have to work similar to the vacuum actuated secondary "woompers" on a Rochester quadrajet.

 

[jeremyc74]

I agree, this Phantom charger is definatly proof of concept. And its not just one or two out there, they sell quite a few. What I feel the majority of you are failing to look at is that the technology is there. It just needs to be refined. I mean hell we made a computer the size of a building fit into your pocket.

The reason why i continue to to ignore the posts regarding a normal system is I can not justify the cost of a turbo system, trd supercharger, or a procharger setup. So if someone finds a way for me to setup a turbo or a something for under $1,000 feel free to enlighten me.

And jeremyc74, as an electrical engineer isnt it your job to make the impossible possible. I mean Thats why im going for an engineering carrier.

No one ever said it wasn't possible. It just doesn't make sense, and it never will.


That system in the links above is making 1.5psi on a 2.0L engine, costs over $2500 (without tuning) adds THREE batteries and only works at full throttle. It's like NO2 except much less effective and much more expensive. You've added weight, cost, and complexity, and you haven't accomplished anything. That's not engineering, it's a hack job!

There are laws of energy conservation at work here that simply can't be overcome.

Here are the options.

A) Traditional turbocharging - Take wasted exhaust gas energy, and use it to power a compressor to make boost.
B) Traditional supercharging - tie a compressor to the crankshaft and use it to make boost
C) Electric supercharging - tie a generator to the crankshaft, use it to charge a battery(10% loss), feed the energy from the battery through an inverter (10% loss) and then to power an electric motor (another 10% loss) and use that to power a compressor to make boost.

Now just step back from that for a second and realize that it will NEVER make sense. Even if you get the losses way down, it's NEVER going to be as good as having it directly coupled to either the crank or the exhaust flow.

Do you guys not realize that there are tens of thousands of automotive engineers around the world that would be all over something like this if it were feasible? It just isn't.