eletric soopachargah...not just an ebay scam

[fred79]

i don't know what you are talking about from my understanding electric motors have a constant torque capability.
also there are many electric motors running in excess of 15,000 rpm since they have almost no friction they can turn at very high speed.
now this non the less doesn't dispute the fact that the electrical demand would probably require atleast 2 200amp alternators and multiple batterys/capacititors to increase the voltage and drop the amperage requirments.
I think that were it may be possible is in the new hybrid motors that use a generator as the starter and its high voltage charging capabilities to use electric supercharger so maybe in the next year when chevy brings out its full size hybrid truck some one may use thatengine motor combination to make Esupercharging possible and productive.

 

[Chris Benvie]

holy old post!

 

[Lance Cheney]

James Downing:
As of now, the electric motors cannot reach the speeds needed with a centrifugal supercharger while maintaining power to turn it effectively. Would an electric motor be more-likely to work with a roots or whipple s/c? especially since they require less rpm (yet more power I assume)?

Nah, you just use a belt or gear-driven step-up, just like they do when they run a centrifigual on your engine (but it wouldn't require as much gearing).

The cool thing about this is you get rid of the crappy torque curve you get with a centrifugal, since the speed is no longer directly coupled to the speed of the engine.

And yes, Thomas Knight is using a roots-type. It makes it easier to drive directly (most of the roots-type run up to ~14k RPM max), but it has a poorer efficiency curve than a centrifugal.

-Lance

 

[munkee]

I've been doing some research lately on this and I think the Thomas Knight product is pretty decent. Bear in mind though that it's purpose is a replacement for nitrous and the moderate hp gains(75-100) at short (15 second) bursts that are associated with it. It isn't necessarily supposed to compete with the high hp turbo and supercharger applications. I have found all the parts to completely install and tune this setup at 5psi without an intercooler for 2700 dollars. That is the lowest prices I could find for new products and would include a tweecer RT. This also doesn't include a 200 amp alternator. Does anyone know where to get one for the sho? You don't have to charge it with the alternator either, you can charge it with a battery charger instead.

 

[jelloslug]

As some of you guy and gals may know I design DC electric motors for a living. Here are a few things to think about:

Not all electric motors have the same type of speed torque curve, i.e.: a DC permanent magnet (PMDC) motor has a liner torque curve where as a DC wound field motors torque curve starts off climbing fast then tapers off. The only way to get constant torque is with a motor controller and the correct motor for the job. Electric motor have quiet a bit of friction in them, it’s not just the bearings but add the brushes (unless it's brushless) and add what is called windage. Windage is a combination of the resistant to turning that the field does to the armature (rotor). It also includes turbulence from the uneven surface of the armature and the cooling fan.

IMO the ideal motor would be a PMDC brush motor with neodymium magnets. The neo magnets let you have high torque in a smaller package with high effiencies (close to 95%). Neo magnet motors are expensive though. The cost-effective choice would be a well designed PMDC using ferrite ceramic magnets. It request a larger motor to get the same torque but is cost much less and can withstand much higher temperatures. Brushless motors are not a good choice for this application, the required motor controller will not easily (or cheaply) let you run more than a few HP since the entire current draw of the motor has to run through the controllers electronics.

A good setup would be a moderate speed motor (4000-6000 RPM) belt driving a small supercharger. A motor rated at 5 HP or so would be around the limit of what you could easily hope to fit under the hood (even that would be very tight)

One last thing: when looking at DC electric motors ignore the "Peak HP" rating. Look for a motor rated for a continuous HP at some speed.

 

[Lance Cheney]

jelloslug:
As some of you guy and gals may know I design DC electric motors for a living. Here are a few things to think about:

IMO the ideal motor would be a PMDC brush motor with neodymium magnets. The neo magnets let you have high torque in a smaller package with high effiencies (close to 95%). Neo magnet motors are expensive though. The cost-effective choice would be a well designed PMDC using ferrite ceramic magnets. It request a larger motor to get the same torque but is cost much less and can withstand much higher temperatures. Brushless motors are not a good choice for this application, the required motor controller will not easily (or cheaply) let you run more than a few HP since the entire current draw of the motor has to run through the controllers electronics.

A good setup would be a moderate speed motor (4000-6000 RPM) belt driving a small supercharger. A motor rated at 5 HP or so would be around the limit of what you could easily hope to fit under the hood (even that would be very tight)

One last thing: when looking at DC electric motors ignore the "Peak HP" rating. Look for a motor rated for a continuous HP at some speed.

A good controller (for the brushless motor) definitely adds cost, but if you're going the route of being able to control the thing anyway (eg. for boost control) you're going to have a PWM solution that can support the full current, so at that point you might as well go brushless and get the weight and torque advantages. That was my thinking anyway. My motors theory EE class was 6 years ago, so ...

5HP won't produce jack for boost, unfortunately. I think that's why he has three motors and he's likely overdriving them A LOT, counting on the fact that you can only do 15-second bursts anyway. The continuous rating really is irrelevant for an application like this. You want the 15-second burst rating ;-) (derated for underhood temps).

And yeah, getting it under the hood would be hard.

-Lance

 

[jelloslug]

A good controller (for the brushless motor) definitely adds cost, but if you're going the route of being able to control the thing anyway (eg. for boost control) you're going to have a PWM solution that can support the full current, so at that point you might as well go brushless and get the weight and torque advantages. That was my thinking anyway. My motors theory EE class was 6 years ago, so ...

You would have a hard time fitting the controller for a 300 AMP motor in you trunk. Even if it's a very short duty the electronics still have to be rated for the load. A 20HP motor in any form is going to be huge no matter the duty. The biggest problem is the fact that the electrical system is 12 volts. Most high HP motors are 220AC or 440AC. I really don't have enough information to do a proper motor design to see if a small motor would be able to work. I need to know more than the HP the compressor needs, I need to konw the RPM at that HP or the torque or both.

 

[Lance Cheney]

jelloslug:

A good controller (for the brushless motor) definitely adds cost, but if you're going the route of being able to control the thing anyway (eg. for boost control) you're going to have a PWM solution that can support the full current, so at that point you might as well go brushless and get the weight and torque advantages. That was my thinking anyway. My motors theory EE class was 6 years ago, so ...

You would have a hard time fitting the controller for a 300 AMP motor in you trunk. Even if it's a very short duty the electronics still have to be rated for the load. A 20HP motor in any form is going to be huge no matter the duty. The biggest problem is the fact that the electrical system is 12 volts. Most high HP motors are 220AC or 440AC. I really don't have enough information to do a proper motor design to see if a small motor would be able to work. I need to know more than the HP the compressor needs, I need to konw the RPM at that HP or the torque or both.

No 12-volt system here. It would have to be higher. The TK system is 42+ volts. I would probably push for 48-60 (4-5 batteries). HP is ~25 (for stock SHO). Requirements would be lower at lower RPMs. Assuming no gearing changes, the motor would need to be able to spin 12-14k RPM at the 25HP peak, with HP requirements vs. RPM being somewhat linear (eg. 12HP @ 6k). (This is why the thing should have a speed controller -- otherwise it will just spin up to 12k and then you'll have 15psi of boost at 3000 RPM and 8psi at 6000 RPM -- and you can see that is what the TK one does from their charts). The other thing is that you would likely have a few smaller motors rather than one huge one -- which means you could have one smaller controller for each one.

A 300A full-featured brushless motor controller isn't *that* big. They're just expensive.

No idea how much this one costs

Fitting it in the trunk would be cake though. You could probably fit it behind the dash (eg. where the glovebox is).

Anyway, I think it's moot because the controllers look to be >$1500 and that's more than just the blower by itself. A straight PWM controller for a DC brushed motor would definitely be cheaper (and for a Centrifugal blower, where it's either OFF or at 50% or higher of the max RPM, it's not as big a deal since the DC motor can be designed to be very efficient from 50-100% of peak RPM).

-Lance

 

[jelloslug]

Duh ... I feel kinda silly now. I completely forgot about using an electric vehicle controller. A 48 200amp unit in quantity is only around $100 or so. I worked closely with an outdoor equipment manufacturer on a small electric vehicle that never took off. I made a 5500 RPM 3 HP motor and they had a 200 amp PWM controller for it. It was 12"x8"x2" or so, not that big. I was thinking brushless controller, some of those things are huge.

The torque at 25 HP and 14k RPM is 9.378 ft/lbs. Getting that kind of torque out of a small motor is no problem, the speed on the other hand is. After 5k RPM or so friction and windage kills the efficiency, so keeping the motor speed down is a must. Now that I think about it some more the application really need a motor with lots of low end torque that can be pushed through a belt drive or gearbox to get the speed. The proper motor for that would be a wound field motor. The torque of a motor is based on the magnetic power (flux) in the stator and armature. The flux is based on the current flowing through the windings. PM motors have a liner curve because the flux in the stator never changes but the flux in the armature does as the load increases. A wound field motor can generate much more low end torque because both the armature and the field can change in strength. You can get much higher peak torque numbers with this type of motor; the trade off is lower efficiency. I can see a 6" diameter 12" long would field motor being able to do 3500 RPM @ 36 ft/lbs (24 HP). It will most likely draw close to 600 amps at 48 volts though. I think I can get my hands on a motor like that.

<small>[ March 12, 2004, 01:22 PM: Message edited by: jelloslug ]</small>

 

[fred79]

if it is electric why would it neccessarily have to fit under the hood?

also the thomas knight e supercharger looks like it is gear rather than belt driven, I would think a belt drive would take up much more space is there any advantage to using a belt drive.

also I think HP is completely inadecuate to describe what we are talking about here does any one know what rpm and torque need are of a super charger. also wouldn't that be a measurement in KW or work or something like that.

i just figured out that at 600 amps and 48 volts that would be a 28,800 watts of power. also to get teh amperage down would require a adjustment to 120v which would be 240amps. so all we would need is 10 12 volt batteries or 17 16v batteries.

<small>[ March 12, 2004, 02:34 PM: Message edited by: fred79 ]</small>

 

[jelloslug]

fred79:
if it is electric why would it neccessarily have to fit under the hood?

also the thomas knight e supercharger looks like it is gear rather than belt driven, I would think a belt drive would take up much more space is there any advantage to using a belt drive.

also I think HP is completely inadecuate to describe what we are talking about here does any one know what rpm and torque need are of a super charger. also wouldn't that be a measurement in KW or work or something like that.

i just figured out that at 600 amps and 48 volts that would be a 28,800 watts of power. also to get teh amperage down would require a adjustment to 120v which would be 240amps. so all we would need is 10 12 volt batteries or 17 16v batteries.

You want to keep the piping runs as short as possable, you get more flexabilty with the electric setup though.

Belt drives are more efficient than gears.

HP is just a way to measure power, just like watts. 1 HP=746 watts. If you look up a few replys the 25hp works out to 14000RPM @ 9.378ft/lbs or torque. The formula is for HP is:

RPM X FT/LB
----------- = HP
5252

Yes the higher the voltage the lower the amps but the watts (power) required stays the same. You also have charge all those batteries. Having a higher voltage motor does not change how big of a motor you will need, just the specifications of it.

 

[fred79]

yes but a lower amperage current wouldn't need as large of a wire to prevent resistance. also since the best option here seems to be a setup like nitrous so I think that it should be figured on charging seperatly from the vehicle. maybe a higher voltage battery could be found to reduce the size and weight of the batterys needed.
i thought that if some one really wanted this they could build the supre charger on the passenger side of the firewall so that the airconditioning heat exchanger could be used as a intercooler.

 

[Frankiek3]

Is there a 25hp engine out there thats very small, like could fit somewhere on the SHO.
All it would need is to be hooked up to Power to start it, gas, Exhaust, and Intake/air flow, to cool it and for air.

BTW I dont think anyone will do this, just poped into my head.

 

[olympic]

Is there a 25hp engine out there thats very small, like could fit somewhere on the SHO.

A snowmobile engine comes to mind.

Here's an idea: instead of trying to feed an extra 50% more power to your front wheels which have traction problems already, just mount two 100 hp snowmobile engines in your trunk and rig up a way for each one to drive a rear wheel. Snowmobiles have centrifugal clutches instead of transmissions so that would be fairly simple. And these engines are super light for the HP they put out.

Then all you'd need is a couple switches to start/stop them, a couple linear actuators to open the throttle on each engine and the actuators could be controlled by a manual switch or by a WOT switch.

So there you have it:
-200hp on demand
-4 wheel drive
-no forced induction tuning issues
-stock reliability, etc

And no I'm not joking..lol! I've been tossing this idea around for quite some time. Imagine pulling up to a light, the guy next to you revs, then you start the rear engines and rev back with 3 Yamahas! hail

 

[munkee]

How many hp does it take to drive an alternator? I was thinking about leaving the stock alternator alone and adding a 200 amp alternator just for charging the esc batteries. Just don't want too much parasitic loss. Maybe I could rig up a system that drops a wheel down from the trunk to drive an alt until the batteries are recharged, then pull it back up.... naughty laugh_ti

 

[Chris Benvie]

olympic:

Is there a 25hp engine out there thats very small, like could fit somewhere on the SHO.

A snowmobile engine comes to mind.

Here's an idea: instead of trying to feed an extra 50% more power to your front wheels which have traction problems already, just mount two 100 hp snowmobile engines in your trunk and rig up a way for each one to drive a rear wheel. Snowmobiles have centrifugal clutches instead of transmissions so that would be fairly simple. And these engines are super light for the HP they put out.

Then all you'd need is a couple switches to start/stop them, a couple linear actuators to open the throttle on each engine and the actuators could be controlled by a manual switch or by a WOT switch.

So there you have it:
-200hp on demand
-4 wheel drive
-no forced induction tuning issues
-stock reliability, etc

And no I'm not joking..lol! I've been tossing this idea around for quite some time. Imagine pulling up to a light, the guy next to you revs, then you start the rear engines and rev back with 3 Yamahas! hail

LMAO!

 

[92turboshoprobe]

I have quite a bit of knowledge of the TK ESC,
And off of a full battery charge there is about 15 mins of runtime (with decent drycells, maybe more ). Thats 17 runs, I don't know much about Naaaawws (couldn't help my self ) so how many runs to you get out of a 10lb bottle on say a 75hp shot?

 

[olympic]

92turboshoprobe:
so how many runs to you get out of a 10lb bottle on say a 75hp shot?

About 2.5 minutes of spray time, so around 10 runs down the 1/4.

 

[munkee]

92turboshoprobe, how many and what kind of batteries were used? How were they charged? Which kit was used at what psi on what car? Don't mean to be like a kid in a candy store, just trying to get all the info I can before I bite the bullet. Thanks.

 

[TimboSHO]

olympic:

Is there a 25hp engine out there thats very small, like could fit somewhere on the SHO.

A snowmobile engine comes to mind.

Here's an idea: instead of trying to feed an extra 50% more power to your front wheels which have traction problems already, just mount two 100 hp snowmobile engines in your trunk and rig up a way for each one to drive a rear wheel. Snowmobiles have centrifugal clutches instead of transmissions so that would be fairly simple. And these engines are super light for the HP they put out.

Then all you'd need is a couple switches to start/stop them, a couple linear actuators to open the throttle on each engine and the actuators could be controlled by a manual switch or by a WOT switch.

So there you have it:
-200hp on demand
-4 wheel drive
-no forced induction tuning issues
-stock reliability, etc

And no I'm not joking..lol! I've been tossing this idea around for quite some time. Imagine pulling up to a light, the guy next to you revs, then you start the rear engines and rev back with 3 Yamahas! hail

That has got to be the coolest idea ever. I'm sure it's very do-able, but i sure won't be the one doing it until i get out of school! This could be a revolution for the SHOs..... 'have you had the 4 wheel drive mod yet?' eek! naughty