Poor man's supercharger :)
#31
06-12-2000, 10:46 PM
#32
06-12-2000, 11:57 PM
Motorhead,
Your DC current measurement is probably in error. The power supply duty cycle is pulse width modulated, so peak current is much higher. Be sure to use a reasonable sized capacitor on your V+ power supply line to ground, with as short a length of wire to the controller as possible. You might consider your RMS power requirement also, don’t want to smoke the alternator.
Your DC current measurement is probably in error. The power supply duty cycle is pulse width modulated, so peak current is much higher. Be sure to use a reasonable sized capacitor on your V+ power supply line to ground, with as short a length of wire to the controller as possible. You might consider your RMS power requirement also, don’t want to smoke the alternator.
#33
06-13-2000, 12:18 AM
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I already have a couple big caps on the charger, I wanted to make sure it was putting out relatively clean power, and it also makes it capable of a little more amperage. I'm usign a digital clamp-on AC/DC multimeter to measure the current, so I'm sure it's pretty accurate.
Think of it this way: the RC battery packs are 1800mAH, meaning they can sustaing a 1.8 amp load for one hour before they're drained. Afeter a full peak charge, the car will run 7-10 minutes of racing before the battery is drained. That's around 15 amps average drain, which includes times that you are cruising (not using much power), so under a good load it's pretty easy for the motor to pull 20-30 amps.
Think of it this way: the RC battery packs are 1800mAH, meaning they can sustaing a 1.8 amp load for one hour before they're drained. Afeter a full peak charge, the car will run 7-10 minutes of racing before the battery is drained. That's around 15 amps average drain, which includes times that you are cruising (not using much power), so under a good load it's pretty easy for the motor to pull 20-30 amps.
#34
06-13-2000, 12:53 AM
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Well, I got to make some test runs today (with the fan running of a RC battery pack and an on/off switch), and the results were not too awesome 
.
I was able to make some full-throttle acceleration runs with someone timing me. With and without the fan, the run times were roughly the same with stock carburetor jetting. Even after swapping in a 155 and 165 main jet, there was still no improvement. What made the test not-so-accurate was the fact that I had to let the clutch out, then quickly reach down and hit the switch while I was trying to accelerate, so that alone could have thrown my test off a few tenths of a second. The whole run only lasted 5.5 seconds, which is not really long enough time to get a precise measurement. Also, this acceleration test is purely a top-end test, it's not really a good way to test overall power. But, the simple fact is that it didn't feel much faster or seem to lift the front tires any easier, so it couldn't have been much of an improvement.
One interesting point is that when I was running less than 1/2 throttle and turn the fan on, it would lean out so bad that the engine would stall. This tells me it was making a difference, and maybe if I changed the needle position or swapped in a bigger pilot jet, I'd be seeing some midrange power improvement. It makes sense that the fan, which was running at a constant rate, would make more difference at lower RPMs than higher. I might play with the carburetion a bit more, since the fact that the engine leaned out at part throttle tells me the fan is actually doing something, but I'm not nearly as optimistic now.
Conceptually, an electric blower is capable of greatly increasing power, having the same effect as a turbocharger or supercharger. However,it appears as though the electric blower I made isn't powerful enough to get the job done. I believe this blower is as powerful as can be used given the charging system on the ATV. So unless a much more efficient blower can be made, it appears as though this project is a bust.
Sorry I couldn't deliver better news for you guys. I feel bad that I spent all this time working on it to get these results... but I had to prove to myself whether or not it could be done. Maybe one of you will be able to take my idea and improve on it. Oh well, at least I didn't break anything.
Ride on.
.I was able to make some full-throttle acceleration runs with someone timing me. With and without the fan, the run times were roughly the same with stock carburetor jetting. Even after swapping in a 155 and 165 main jet, there was still no improvement. What made the test not-so-accurate was the fact that I had to let the clutch out, then quickly reach down and hit the switch while I was trying to accelerate, so that alone could have thrown my test off a few tenths of a second. The whole run only lasted 5.5 seconds, which is not really long enough time to get a precise measurement. Also, this acceleration test is purely a top-end test, it's not really a good way to test overall power. But, the simple fact is that it didn't feel much faster or seem to lift the front tires any easier, so it couldn't have been much of an improvement.
One interesting point is that when I was running less than 1/2 throttle and turn the fan on, it would lean out so bad that the engine would stall. This tells me it was making a difference, and maybe if I changed the needle position or swapped in a bigger pilot jet, I'd be seeing some midrange power improvement. It makes sense that the fan, which was running at a constant rate, would make more difference at lower RPMs than higher. I might play with the carburetion a bit more, since the fact that the engine leaned out at part throttle tells me the fan is actually doing something, but I'm not nearly as optimistic now.
Conceptually, an electric blower is capable of greatly increasing power, having the same effect as a turbocharger or supercharger. However,it appears as though the electric blower I made isn't powerful enough to get the job done. I believe this blower is as powerful as can be used given the charging system on the ATV. So unless a much more efficient blower can be made, it appears as though this project is a bust.
Sorry I couldn't deliver better news for you guys. I feel bad that I spent all this time working on it to get these results... but I had to prove to myself whether or not it could be done. Maybe one of you will be able to take my idea and improve on it. Oh well, at least I didn't break anything.
Ride on.
#35
06-13-2000, 01:00 AM
#36
06-13-2000, 02:00 AM
#37
06-13-2000, 09:56 AM
#39
06-13-2000, 06:05 PM
Heres something i found interesteting on a motorcycle forum bout using a smog pump as a supercharger:
"OK, here it is. Please don't laugh until you've triedthis, it really works. We've used these things for manydifferent jobs where we needed a lot of volume at low- tomoderate pressure levels, and they almost always work outvery well. All you need is a "smog pump"! I assume everyone knowswhat I am referring to. In the USA, at least, almost everynew car has been required to have one of these since around1970, (by government regulations) to pump air into theexhaust manifolds, which supposedly facilitates moreefficient conversion of the unburned hydrocarbons as themixture passes through the catalytic converter. If we build them into a machine, we by them new, butthere are piles of them in junk yards which you can actuallyget for as little as $5.00 each. People don't realize justhow efficient these little pumps are. At 8,000 rpm you canfeel a strong air blast from a one inch pipe attached to oneof these standing over twenty five feet away, they willactually produce up to sixty pounds or more (for a VERYshort time), and if you block the air flow completely thepump will stop a five horsepower electric motor. Most of them take in air though an impeller right behindthe drive pulley, which is fine for most purposes, but someare equipped with a separate inlet port complete with asmall air filtering device,- which can prove useful incertain circumstances. You can even hook these things up "back to back", andthe first one will drive the second,- with amazingefficiency. If you get the kind equipped with both inletand outlet ports, you can the make a closed loop and eitherone will drive the other,- in either direction. There's anovel way to transmit power! If you do try this, be sure toinclude an intercooler in the plumbing,- the only thing I'vefound that will ruin these pumps, is heat! Some of the pumps I'm describing have more capacity thanothers. I like to play with the ones from 350 cid Chevroletpolice cars, or 454 cid trucks. It takes four to six ofthese to provide ample boost for the average V8, but one ortwo should suffice for most motorcycle engines. I built asetup using these on a small V8 once, and used a automotiveair conditioner pump, electric clutch & pulley, so that itwas not necessary to wast fuel driving the arrangement untilit was needed. 90% of the pump body is aluminum, so they are relativelylight, and it's not difficult to polish them up andradically alter their appearance. By the time you've donethat, and added a aluminum timing pulley,- no one will everguess what it is/was, or how little you have invested.Be careful how much intake pressure you apply to a highcompression engine. You probably shoudn't try to go over 8- 10 pounds on any engine with a 9 :1 compression ratio orhigher. We attached one of these to a friend's son's go-cart engine (Briggs & Stratton) and the power increasewas very impressive,-- the kid decided he'd like even morepower, and changed to a larger primary pulley. I'm not sureif it was the extra compression or detonation, but itdidn't run very long after that before the complete cylinderassembly separated and exploded off the engine block (nokidding!),-- kind of reminded me of pictures I've seen ofBlown(up) top fuel drag engines. If anyone is not familiar with these types of pumps, orhas any trouble understanding how they can be attached,-driven, etc..., let me know, and I'll post a photograph ofone mounted on a prototyping test setup."
"OK, here it is. Please don't laugh until you've triedthis, it really works. We've used these things for manydifferent jobs where we needed a lot of volume at low- tomoderate pressure levels, and they almost always work outvery well. All you need is a "smog pump"! I assume everyone knowswhat I am referring to. In the USA, at least, almost everynew car has been required to have one of these since around1970, (by government regulations) to pump air into theexhaust manifolds, which supposedly facilitates moreefficient conversion of the unburned hydrocarbons as themixture passes through the catalytic converter. If we build them into a machine, we by them new, butthere are piles of them in junk yards which you can actuallyget for as little as $5.00 each. People don't realize justhow efficient these little pumps are. At 8,000 rpm you canfeel a strong air blast from a one inch pipe attached to oneof these standing over twenty five feet away, they willactually produce up to sixty pounds or more (for a VERYshort time), and if you block the air flow completely thepump will stop a five horsepower electric motor. Most of them take in air though an impeller right behindthe drive pulley, which is fine for most purposes, but someare equipped with a separate inlet port complete with asmall air filtering device,- which can prove useful incertain circumstances. You can even hook these things up "back to back", andthe first one will drive the second,- with amazingefficiency. If you get the kind equipped with both inletand outlet ports, you can the make a closed loop and eitherone will drive the other,- in either direction. There's anovel way to transmit power! If you do try this, be sure toinclude an intercooler in the plumbing,- the only thing I'vefound that will ruin these pumps, is heat! Some of the pumps I'm describing have more capacity thanothers. I like to play with the ones from 350 cid Chevroletpolice cars, or 454 cid trucks. It takes four to six ofthese to provide ample boost for the average V8, but one ortwo should suffice for most motorcycle engines. I built asetup using these on a small V8 once, and used a automotiveair conditioner pump, electric clutch & pulley, so that itwas not necessary to wast fuel driving the arrangement untilit was needed. 90% of the pump body is aluminum, so they are relativelylight, and it's not difficult to polish them up andradically alter their appearance. By the time you've donethat, and added a aluminum timing pulley,- no one will everguess what it is/was, or how little you have invested.Be careful how much intake pressure you apply to a highcompression engine. You probably shoudn't try to go over 8- 10 pounds on any engine with a 9 :1 compression ratio orhigher. We attached one of these to a friend's son's go-cart engine (Briggs & Stratton) and the power increasewas very impressive,-- the kid decided he'd like even morepower, and changed to a larger primary pulley. I'm not sureif it was the extra compression or detonation, but itdidn't run very long after that before the complete cylinderassembly separated and exploded off the engine block (nokidding!),-- kind of reminded me of pictures I've seen ofBlown(up) top fuel drag engines. If anyone is not familiar with these types of pumps, orhas any trouble understanding how they can be attached,-driven, etc..., let me know, and I'll post a photograph ofone mounted on a prototyping test setup."
