I went to target and bought a small squirrel cage blower for blowing up air mattresses and such. It's supposedly rated at 90 cfm. I only paid 17.00 for it and it runs on 12 volts. just a thought for you motorhead. They might even have one at walmart there in Lewiston, or is it Clarkston where walmart is?

 

Hey Motorhead, I hate to simplify things, but don't R/C car motors run on DC voltage? If this is the case, all you need is some form of potentiometer that will reduce voltage. I know audio potentiometers raise impedance to lower voltage therefore volume, hence should work. If you can get one that would work, it would solve most of your problems because you could mount it above or below your thumb throttle and attach an arm from it to the thumb throttle. Then as you push in the throttle (twisting the potentiometer), your resistance decreases supplying more voltage and more power for more rpms. Then as you let off throttle, you decrease voltage and your charging system is affected directly with RPM. This is like how the headlights get brighter with more RPM. Should solve all your problems except full throttle 25 amp draw, but how often are you wfo when riding?

If you can figure out the other stuff, wiring and everything else should be a breeze for you. In case you wonder, I have been in Car Audio for 14 years and build Demo cars for Xtant and Rockford Fosgate reps in the Midwest. Dammit, now you got me thinking... we used to make all sorts of stuff for cooling fans for car amps....

Your project should be easier now, I think I solved all your problems and made it much easier. Any questions, write me.

 

So, you need the R/C car motor, wire, the potentiometer, and a fuse at the battery to protect the quad from burning to the ground if one of the wires short out. That should be easy.

You can also change the angle of the potentiometer to reduce the voltage. I would guess that you will have about a 90 degree swing with the throttle. You will need to measure all that with a meter.
Pulse generator......you are thinking WAY too hard on this one dude... good luck.

 

Yes, simply using a potentiometer would be a very simple way to do it... but good luck finding a potentiometer that can handle even a 20 amp load... it'd be a very expensive, very big potentiometer . I am working on a simple circuit to generate the pulses, if it works it'll only require about $2.00 worth of components to build (I'm making it with an old electronic project lab thing I got from Radio Shack when I was a kid, hehe).

 

Woohoo. It's 4:00AM, and I've finally finished a circuit to drive the speed control. Uses 2 transistors, 2 capacitors, 4 resistors, and a potentiometer, and works great!

I didn't get around to mounting the fan today (er, I guess it was technically yesterday), but I'll do it tomorrow (today, Sunday). All I need is a 1.5"-2" long piece of 3" inside-diameter tubing (probly use some PVC pipe) to mount the fan inside, which will mount where the air cleaner now mounts, and the air cleaner will mount to the other side of it (basically a 1.5" air cleaner spacer with a fan inside). I found this is about the only way to fit the fan in the air box, and I don't think it will cause any problems being post-filter (in fact, it'll probly be more effective), and that should also keep the dirt and crap out of the fan. Well, time for bed, haha.

 

its 11:00 Sunday, where are the results.... I am still baffled by the fact that you claim a 25 amp draw from a R/C car motor. I would think it would be closer to 2.5 amp, but obviously you know what you are talking about. I will be anxious to have a list of stuff when it works. Seems overly complicated though. Good luck.

 

RC car motors are very high power, electric motors. They commonly use large diameter windings and are capable of pulling quite a load (over 100 amps @ 7.2v under full load (0 RPM), is common). That's why NiCad's are used, they are capable of letting go of that much current with very little internal resistance.

Maybe a free running motor under zero load conditions would only pull about 2.5 amps, but keep in mind that the more load you put on an electric motor, the less reverse voltage is generated, hence the more amperage used. A motor without reverse voltage is a dead short. 25 amps sounds quite reasonable to me for the load of a fan blade at the kind of RPMs that these motors turn.

Also a pulse generator will work better than straight DC as a power source, that's why RC cars and things like variable speed rechargable power tools use high frequency speed controls, they send high freq digital pulses to the motor which is more efficient than sending straight DC. I could quote the theory, but it's been a long time.....

 

You took the words right out of my mouth... very good explanation of the RC car motor.

Didn't get a WHOLE lot accomplished today.. had quite a few things going on other than my project. I got the ABS 3" 'air cleaner spacer/fan mount' built. Basically I'm waiting on two 2mm fine-thread metric screws, which I need to mount the RC motor (they use two tiny metric screws in the front of the motor to mount it, and I need some longer than I've got laying around). The specialized screw/bolt store was closed today (sunday), and I couldn't find some anywhere else. First thing tomorrow (Monday) I'll head out and pick up the screws, a few jets for the EX (like a 155, 160, and 165 main jet, just to get close to the necessary fuel mixture) and might as well get the parts for my circuit from Radio Shack while I'm out. Then I'll assemble it with it just hooked to the battery and do the test run. Man, I wasn't planning on spending this much time on making stuff just for the trial run, but it was somewhat unavoidable. Sorry to keep you guys hangin, but hey, this stuff takes time.

 

Motorhead,

Way to go with your creative efforts to squeeze a few more HP out of thin air :-) And I thought that I was going to become the "mad" professor by figuring out how to install an Edelbrock Nitrous System (made for a Harley)on my 400EX. Just think, with only a 10oz bottle of Nitrous, I could have serious horsepower available at the flip of a switch. Just a nice power burst for that occasional Banshee or Raptor that happens along. Check out the Nitrous system at: http://www.edelbrock.com/motorcycle/index.html

Anyone else ever thought about an aftermarket Nitrous system for a 400 EX? Might be big bucks in it.

 

Motorhead,

Keep up the work! This is whats cool about our sport, if you have an idea then go for it.

If you get it to work, you might wan't to patent the idea! You might make some bucks!