Air volume, Electric turbo???

[00dangerranger]

Ok Now I've seen these things on Ebay and utube. They seem to be pretty much crap. well I fly RC planes EDF electric ducted fan jets and some of these little motors turn a 70mm 6 blade fan 52000 RPM on a 100amp speed control and a 6cell lithium polymer batt. I've seen these in 2000+watt systems flying a 4 or 5 lb plane 150mph. My question is? is there a converstion from foot lbs of thrust to Bosst psi. Or does any one know the cfm intake of a OHV v6 at WOT. I was thinking if you know tottal intake of air at WOT and the out put of the EDF.I was thinking of running an inline set up maybe a big 120mm edf piped down to a 70mm. What are your thoughts?

 

[Yellowsplash]

Thoughts?

Look elsewhere if your looking for boost...

 

[88gt]

Thoughts?

Look elsewhere if your looking for boost...

+1 i think instead of spending the money on a electric fan big enough to boost a v6, you can get a turbo and fab it all up faster and cheaper

 

[Will]

I've never heard of those EDFs but they sound cool. What is the thrust of them? Can you get 5# of thrust and go vertical right off the ground?

I don't know anything at all so I'm just spitballing here--but a cubic foot of air weighs about 7.5#. A 4.0 with 80% VE engulfs 280cfms at 4900rpm with the throttle wide open--which is the rev limited speed. It's moving 2,100# of air through it every minute--which is work that the engine has to do, in addition to turning the wheels on the vehicle. A turbo or supercharger eases that load and frees up power. I have the feeling your airplane engine would be sucked through the intake and belched out the exhaust without noticing it.

 

[00dangerranger]

type fast or fastest RC edf in youtube. they produce a ton of thrust

 

[00dangerranger]

so at WOT if you were able to produce more than the 2,100# of air, thats boost? and if so how much more air does it take over that for each 1psi of boost?

 

[dangerranger83]

Not another "air dryer" turbo thread.....

They use more power then they can put out, laws of physics will tell you this.

Just do a normal turbo set-up.

 

[00dangerranger]

Ok I found a great thred about this on RC universe. it says in better detail, even though a little 2.75 inch EDF produces 700cfm and the motor takes 280cfm. That the motor stall the fan at 280cfm. Great thread to read some smart dudes. I googled it (Turbo RC EDF)
Thanks for all the input. looks like I'll just do a 50HP DRY shot.

 

[red85]

Buy a Holset HX351 That'll make some boost.

 

[Gotta_gofast]

Not another "air dryer" turbo thread.....

They use more power then they can put out, laws of physics will tell you this.

Just do a normal turbo set-up.

Not that the electric turbo is a great idea, but you do not understand the "laws of physics". It takes X-amount of energy to rotate the turbine and produce pressure (and volume for that matter).

Using an electric motor to spin a compressor requires electrical current. Electrical current needs to be generated by a magnetic field-a magnetic field that needs to be in motion to move the electrons. The alternator that moves those electrons needs to be powered by the engine (through a belt). This is why the electric turbo isn't as efficient (not to mention the amount of batteries to make it worth while). Every time the energy is converted into another form of energy there is a loss. So the friction from the belts and bearings, the electrical resistance, ect... all translates into a poor transfer of energy from the engine to the compressor. A turbo is most efficient because the "hot side" is being spun from expelled gasses that are pushed out from the piston. Although it isn't "free" like some say, it is more efficient to turn a compressor housing this way. A supercharger falls short to the turbo because the compressor must be spun via belt/gears which all sap up energy.

As for "they use more power than they put out"... I don't like when people say that either. The turbo (any type) is not driving the crankshaft. By that saying, an exhaust driven turbo or supercharger wouldn't be possible because you claim the power consumed to turn the compressor is more than the power it produces. But we are not harvesting the power from the compressor. We are harvesting the extra oxygen molecules that are now present in the combustion chamber. Now we can add more fuel and have a more intense explosion to drive the piston down. These are two entirely different forms of energy. Its hard to explain, I'm at a loss for words since its late and I'm tires... I'll explain later if you don't catch my drift

(oh, and to the OP... invest in a turbocharger and call it a day lol)

 

[00dangerranger]

Thank you. I like the informative answers like that. if every body that owned a vehicle was a motor head , I'm sure all these threads would be about how bad ass and fast our trucks were. Since were not replys like that break it down for us who still enjoy a good be n learned sesh. Thanks again.

 

[_BEYONDER_]

Gotta_gofast makes the best point here. I'm just gonna add a few things, Dont forget with a turbo setup, you need to rework your enine, different pistons,etc or you'll be goin to the scrap yard pretty fast. So there's a lot more that just 'slapping' on the equiptment and driving away.

In defence of the electric turbo though, the inefficiencies are only in the way you power it. Something to consider, electric motors are more efficient than gas. And yes it does take the ICE to power the alt to power the EM, however, it takes roughly 1.5HP ( ICE ) to generate enough electricity to run a 1HP EM. That same 1HP of Electric Motor is outputting the same torque,etc as what would take a 6HP ICE to produce. Proof of this can be found in electric vehicles, e.g. A ford Ranger when converted to electric only requires a 20 - 30HP EM to reach highway speeds.
That being said, if you were to compare the little amount of boost in each scenerio...say a 1LB boost in each, you would more than likely find the electric turbo to be more efficient.
Taking into consideration I dont know a lot about mechanical turbo's, I cant compare the how much power they actualy consume. But I can make an arguement for electric motors

All that being said, I'm not sure if personally I would waste my time with an electric turbo, BUT if you wanted to play with it just to see for yourself, I'd goto a hardware store and pickup a duct booster fan, they run around 10.00. I'd plum that into a toggle and go from there.

Something I just thaught of though, a turbo controls air flow via the rpm of the engine, where as an electric turbo w/o and electronics cannot do this, so you loose efficiency there.

To make an electric turbo more efficient, you could utilize one of those newer thermolectric generators that hookup to your exhaughst pipe, these produce significant amounts of power and dont draw anything from your engine...

Sorry if this is scattered, just trying to stay neutral and add onto what he said

 

[Will]

Something I just thaught of though, a turbo controls air flow via the rpm of the engine, where as an electric turbo w/o and electronics cannot do this, so you loose efficiency there.

No, a turbocharger is independent of rpms. I don't have a gasoline motor with a turbo, but I have an 18,000# diesel bus and a pickup that pulls up to 10,000#. When you head up a hill, the fuel governer tries to maintain the rpms by injecting more fuel. The extra fuel causes more gas expansion which leads to more exhaust gas being produced, which spools up the turbo faster, which makes more oxygen available for the fuel. And the engine rpms don't change at all. The turbo rpms change instead so you hear the thing singing more loudly on hills. That's all you notice.

An engine is only 20-40% efficient--gas to diesel spread there, with variation. A turbo is using waste heat to drive the compressor. A belt-driven or real electric turbo is using part of the non-waste heat to drive it.

A real electric supercharger would need to pump the same air as a a Paxton or Vortex unit and would be of the same quality and heavier, as the motor to drive it would be attached. If you don't have something like that, you have the wrong thing. A little 14oz bit of plastic isn't going to work.

 

[_BEYONDER_]

No, a turbocharger is independent of rpms. I don't have a gasoline motor with a turbo, but I have an 18,000# diesel bus and a pickup that pulls up to 10,000#. When you head up a hill, the fuel governer tries to maintain the rpms by injecting more fuel. The extra fuel causes more gas expansion which leads to more exhaust gas being produced, which spools up the turbo faster, which makes more oxygen available for the fuel. And the engine rpms don't change at all. The turbo rpms change instead so you hear the thing singing more loudly on hills. That's all you notice.

I drew the conclusion that the turbo was dependant on rpm's because the extra fuel increases the rpm's....wasn't thinking of on a hill, was thinking of when your sitting at an idle. lol. my mistake.

 

[dangerranger83]

Point being the electric turbo is a no-go.