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Guest nevarmore
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Guest visualpoet
I'd have to see it in action first. The motor looks like it could spin the turbine fast enough, the design would create pressure, but how much boost could it really create? Not to mention the hassles of getting it to spool up with your rpms, unless you just went WOT and flipped it on.
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Guest nevarmore

This will not work and is a bad idea.

 

This requires electricity to run. To make electricity the car has to turn the alternator. The car turns the alternator with a belt. This device then converts the electricity back to a physical force that turns the compressor. At the very least you have efficiency losses. Every time you convert one form of energy to another you lose some of the overall power.

 

How is it any easier to turn an alternator than to jsut turn the compressor? It isn't. It gets worse when you consider the strain on the electrical system.

 

Before anyone asks, no turning an alternator isn't easier than turning a blower. The alternator will have to make more power, you'll have to have a bigger alternator which is going to be harder to turn.

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Originally posted by Rotary Jihad:

This will not work and is a bad idea.

 

This requires electricity to run. To make electricity the car has to turn the alternator. The car turns the alternator with a belt. This device then converts the electricity back to a physical force that turns the compressor. At the very least you have efficiency losses. Every time you convert one form of energy to another you lose some of the overall power.

 

How is it any easier to turn an alternator than to jsut turn the compressor? It isn't. It gets worse when you consider the strain on the electrical system.

 

Before anyone asks, no turning an alternator isn't easier than turning a blower. The alternator will have to make more power, you'll have to have a bigger alternator which is going to be harder to turn.

I disagree. That is how your electric fan works, and it does save power. I would imagine there would be a microswitch on the throttle (like with nitrous kits) to keep it out of boost when the throttle is closed. I think it could work, especially since it is made by KKK. They make good stuff.
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What Jon is saying would be valid if there were no storage medium for electricity in the system (ie. a battery). The battery can allow an electric supercharger to consume MORE energy than the alternator can put out, albeit for a limited period of time (say while you are at WOT).

 

Jon is also missing the loss inside the gear case of a centrifugal supercharger, which is needed since the compressor wheel spins at a much higher RPM than the engine.

 

The real question is power demand. If you are compressing air with a supercharger that has a parasitic loss of 50hp (just using a number for illustration) at a particular airflow and boost level, the electric motor would need to pull (are you ready?) 37.28 kilowatts, neglecting the power loss of the supercharger gearcase (I neglected it because I can't find any real data on it. We could use 10% as a WAG - wild ass guess). On a 12 volt system, that power means a current flow of 3100 amps.

 

I don't know about any of you guys, but my alternator isn't pumping out that kind of juice, and neither is my battery.

 

Even if you cut that 50hp number in half, AND take out the wild ass guess 10%, you are still looking at over 1300 amps. Again, my battery and alternator aren't going to cut it.

 

So, how much power could our electrical systems use to drive an electric supercharger? Let's say that we can do a short term draw of 500 amps using the battery. Stereo guys can tell us if that can be done -- I know that some high torque starters can pull over 300 amps at full load.

On a 12v system (operating at 13.8v), that's going to get us to just under 7000 watts, or 7 kilowatts. That's 9.4hp driving our compressor, which isn't going to do much. As an example, a very efficient compressor is going to take somewhere around twice that much to get close to 300cfm at a modest boost pressure, and that's nothing. A decent NA Ford 5.0 is going to suck in twice that airflow at redline.

 

I have completely neglected power loss in the motor windings or in the very thick power lines going to the motor also, but even then, a conclusion is becoming clear: it is very unlikely that the modern 12v electrical system is going to put out enough juice to boost a motor of any significant airflow.

 

Now, when the much-awaited 42 volt systems arrive, the current requirement will drop to around 30%. So the 3100 amp compressor would become a little over 900 amp compressor. Still a healthy pull, but possible with a dual battery system and a big ass alternator, presuming 42v charging systems will have similar current capacities to 12v.

 

So, that auction is graemlins/bsflag.gif . Clearly that KKK compressor unit is meant for low airflow, low pressure and probably a stationary application. It's certainly not automotive.

 

Edit for Eli: Look! I showed my work. tongue.gif

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Guest visualpoet
Originally posted by Dave Sigman:

the housimg would work fine it looks like a regular automotive blower I would just switch out the lectric motor for a shaft drive and run it like normal.

I'm thinking you'd need a pulley the size of a quarter to spin fast enough for a noticable boost level.
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Originally posted by WWJKD?:

presuming 42v charging systems will have similar current capacities to 12v.

But that's highly unlikely, as the big reason behind the 42V systems is that there isn't the high current demand (thinner gauge wiring, alternators outputting less current, etc.).

 

Simply put; this just won't work.

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Guest Tony_K

Instead of an *electric* motor to drive the turbo, how about a small *gasoline* engine under the hood (separate from the car's engine) that exists for the sole purpose of driving forced induction?

 

graemlins/popcorn.gif

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the V8 guys can by a underhood generator kit. that would get you 110v or 220v power supplies. I have no clue how much HP is lost in turning this type of generator, but for the size of it it must be pretty good.

Oh and if that won't work you can install a second alternator and set its regulator to put out alot higher voltage. some of my 4x4 truck buddies have stock alternators putting out around 100volts and using them as welders out on the trails.

 

Evan

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Originally posted by Tony K:

Instead of an *electric* motor to drive the turbo, how about a small *gasoline* engine under the hood (separate from the car's engine) that exists for the sole purpose of driving forced induction?

 

graemlins/popcorn.gif

bwahahahahaha
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Originally posted by BiG BeN:

that is some homemade hooptie junk there...the motor would disintegrate trying to spin to effective RPMs without a geardrive for gearing increase.

I guess that you have never screwed with RC electric cars. I have had several of the high end kits. Motor RPM's range from 19.kK to 105K for the drag motors. ANd for their size they are very high torque.

 

That being said. When you spin ANY electric motor, or anything else that fast the forces are ungodly on it. THe one drag motor I had for the 1/10 scale drag car I had went back to be rewound 3 times. The windings would litterally fly out of the armature. So the reliability of a motor this size turning this speed would not hold together for long. Yes, there are centrifical electric superchargers, most are geared up for speed.

 

As far as the load required, and curent requirements, yes they would be quite high. But you need to remember that a 1/2 house motor will blow 2100 CFM of air without problems, hell furnaces blowers do that with 1/3 HP motors or less, granted that there is not the backpressure on them that there is here but it's not going to take 50 HP to spin the thing either.

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Originally posted by Desperado:

I guess that you have never screwed with RC electric cars. I have had several of the high end kits. Motor RPM's range from 19.kK to 105K for the drag motors. ANd for their size they are very high torque.

 

That being said. When you spin ANY electric motor, or anything else that fast the forces are ungodly on it. THe one drag motor I had for the 1/10 scale drag car I had went back to be rewound 3 times. The windings would litterally fly out of the armature. So the reliability of a motor this size turning this speed would not hold together for long. Yes, there are centrifical electric superchargers, most are geared up for speed.

 

As far as the load required, and curent requirements, yes they would be quite high. But you need to remember that a 1/2 house motor will blow 2100 CFM of air without problems, hell furnaces blowers do that with 1/3 HP motors or less, granted that there is not the backpressure on them that there is here but it's not going to take 50 HP to spin the thing either.

sure i have,the best motors i ever had in my old losi xxt or whatever (10 years ago) always burned through brushes after about 10 good runs. wich would equate to what...40-60 minutes of runtime? not to mention the size/load difference of a tiny rc motor and a compressor wheel.if you could turn the shaft on that thing to 100krpms it might make some boost.
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Guest visualpoet
Originally posted by HIgh Risk:

I paid 22.99 for my new bilge blower this afternoon.

This is the second reference to a bilge blower I've seen in three days. WTF? The highest flow rate I've seen is only about 300 CFM. Is that really going to help? I understand that to a point you'll benefit, but how much power is it really going to give you? 5 hp? 10? Can you guys toss a little bilge blower knowledge my way?
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Guest nevarmore
Originally posted by visualpoet:

.. how much power is it really going to give you? 5 hp? 10? Can you guys toss a little bilge blower knowledge my way?

Its a joke. They were being relabeled and sold as 'electric superchargers' for a few hundred dollars. Thats a hell of a markup considering it costs about $20.
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