My cousin bought a crappy electric supercharger the other day, and I must say it looks like a piece of crap. There is no way these things can work, right?[/align]

 

Work? as in add power to the vehicle... HA... you could get more power from hooking up a leaf blower to your car.

Tell him to return it and invest in something better.

 

+1 no offense to your cousin,but that was a stupid choice. They almost had me sucked in, might as well get a Tornado while your at it. [8D]

 

I like to do whitewater rafting
and long before I saw an 'electric supercharger' advertised
I bought a Metro brand name 12 volt raft inflator:

http://www.lonelyplanet.com/travel_s...ump_12volt.htm



You will see that the 'electric supercharger' is a re-packaged Metro raft inflator, which in turn was originally a modified 12 volt vacuum cleaner.
I think I paid $49 for mine several years ago.

There is a high profit on those electric superchargers being sold,
isn't there?

I have never measured the cfm of my Metro, but I do know it won't put out more than about 1 psi of pressure. I have to "top off" the rafts to about 3 psi to get them 'hard' and to keep the air inside them hard when they touch the cooling water.

Would a Metro give any horsepower increase?

On a cubic inch displacement small engine,
or a large engine at low rpm,
the boost from 'normal' 14.7 psi of air pressure
to 15.7 psi would give a small boost in torque
particularly in the 1500-2500 rpm range.

There would need to be a 'bypass flap valve' that would open when the cfm through the Metro could no longer supply the engine's air needs at high rpm.
The amp draw on the alternator should also be checked.

But a Metro electric supercharger,
or even better a pair of them,
would probably provide more 'real' gain than most aftermarket CAI kits, which have been found to give less than 1 hp gain:

http://www.lxforums.com/board/showthread.php?t=14140

The profits on the CAI kits,
which are in the 100-200% range,
are just as high as those on the electric supercharger.

Like my grandmother used to say:
"Figures never lie,
but Liars never stop figuring"

 

You do realize that the engine on it's own can PULL in more CFM than that pump can PUSH right?? There would be NO gain. In fact it would be a restriction. Andwhere did you get 14.7PSI? N/A engine don't haveANYpsi. The air is being sucked in (vacuum) not pushed (boost/PSI). If you had a turbo or S/C and were pushing 14.7PSI, even if the "electric supercharger" couldproduce 1PSI of pressureit isnt gonna make the overall pressure 15.7psi. For that to be possible the electric supercharger would have to be able to produce the 15.7psi on it's own. Otherwise, even at 1psi, it's a restriction for the real turbo or S/C and would more likely reduce boost, not increase it.

If you are refering to the 14.7PSI as atmospheric pressure, then O.K., but even if the ESC could produce 1PSI above AP, as soon as the throttle valves open, the vacuum created wouldsuperceed that 1PSI and it would still become a restriction.

 

One of the first things that they teach students in first year 'Fluid Dynamics' classes in Engineering School is that there is no such thing as 'suction'.

It is very common on the first quiz for the teacher to try to trick the students by giving them a problem where the answer is a 'negative' absolute pressure.

No engine can 'pull' air into it.

The pressure of the atmosphere always 'pushes' air into what lay people think of as suction.

Over the last 30 years I bet I have spent more than 20 hours explaining to coal miners why a water pump can't 'suck' water higher than about 27 feet below the pump inlet level.

Right now, there are two 'speed limits' to the Universe.

It would take all the energy in the Universe to accelerate any thing with mass to equal to the speed of light. That is the 'top end' speed limit.

It would also take all the energy in the Universe to drop anything to 0 absolute pressure. That is the 'bottom end' speed limit.

Most people have heard about the speed of light limit
but few understand the lower limit.

 

You're exactly right. It's all about displacement. A pump can't "suck" more than 27 feet because the pressure of the in the atmosphere can't push the water any higher than that. The pressure equilizes. (Thisvariesslightly with height above sea level though, correct?) But if the vehicle was at idle, and your pump was reading 1PSI (Above AP), thats with the throttle blades as a resitriction. As soon as the blades are open, the atmosphere would be able to displace the air faster than the pump could. Making that 1PSI go away. Right? For example, turn on a bicylce pump and read the pressure on the gauge. It would read 0 because the pressure is equal to atmospheric pressure, put a restriction on that by placing it on a tire (closing the throttle valves)and the pressure goes up, put a hole in the tire (Opening the throttle)and the pressure goes away again. Right?

I may be way wrong with this, I'm not arguiing I'm right. Just a theory. But I still agree, based on the CFM, that an electric supercharger is a complete waste. The pressure of the atmosphere can force more air into the motor all by itself, than the pump can at WOT.

 

I don't know, but I have found the idiots that sell these things www.electricchargers.com[/b]