computer fan turbo?

[lunarhighway]

i was thinking about useing a computer fan as some sort of cheap small electric turbo.

while i was looking for information i found this reader response on autospeed.com

"Airflow Fan

I stumbled across your article on the Turbo Zet and, while your power draw claim is accurate, it doesn't make electric supercharging completely unpractical. Your conclusion is that it would take over a thousand amps to power a 'real' supercharger electrically. However, a high-powered 12V computer ball-bearing cooling fan will run 131.5 cfm while drawing only .66 amps - only 7.92W in total. At that rate, you could run several computer fans in parallel and not even impact the alternator. These fans are designed for continuous use, as PCs usually stay switched on for years straight. Your thoughts?

Steve
USA

Computer fans are designed to run in a virtually 'free-air' environment - in other words, they operate with barely any airflow restriction on their inlet and outlet sides.

The output air volume of a computer fan - or any electric fan with such a small current draw for that matter - falls off dramatically when it's being 'loaded' due to a flow restriction.
"


this would sugest it's not possible, but than i was thinking, what would happen if a few small fans where set up inline with eachother?

wouldn't this produce a multi stage effect where each successive fan would both help accelerate the air and deliver it to the next fan? this might not increase their total air-ouput, but it might distribute the load over several fans makeing it possible for these little fans to get the job done


i might get my hand one some used fans for free so that's why i'd be interested in useing them as an economy boost... i'm not looking for a real turbo conversion though

[lunarhighway]

owkay i just looked up the original article on autospeed that inspired the reader, it would seem that a normal supercharger would require much more power than any computer fan could deliver, still , i can't help but think there might be a small benefit to computer fans, for example delever cooler more dense air the the airbox perhaps?

[flapdoodle]

The load on the fans(s) would be dynamic in an automotive application. Assuming a carbureted engine, the greatest load would be when the throttle plate is closed, and the least at full throttle. In addition, the volume the engine requires varies with RPM.

At the greater load the amperage rises. A sealed test box could be made the current measured. I would use clear plastic tubing to make a manometer to measure the pressure inside the box.

I have made tests on various makes of fans and found that few have accurate current ratings, and the amount of air flow varies greatly. I.E, efficiency. The best was a Magic model MGA8012MS and was the most tolerant to drop in voltage.

It may be a worthwhile project since pumping losses in a naturally aspirated engine is the biggest robber of efficiency.

BTW, the 1000 amps quoted above would be 16 HP.

[dosco]

Originally Posted by lunarhighway

this would sugest it's not possible, but than i was thinking, what would happen if a few small fans where set up inline with eachother?

wouldn't this produce a multi stage effect where each successive fan would both help accelerate the air and deliver it to the next fan? this might not increase their total air-ouput, but it might distribute the load over several fans makeing it possible for these little fans to get the job done

I wouldn't expect much.

1. These fans are not designed for this application.
2. The power the fans put into the air is negligible.
3. The pressure ratio of the fan is nearly nil.
4. There are no stator sections. Turbine compressors first increase the velocity of the air then pass the air through a diffuser which "trade" the velocity for pressure.

With all that said, try it and report your findings.

[BBsGarage]

IMO you would be blocking more air from getting thru the intake then you would be pushing.

[theholycow]

There are purpose-designed electric turbochargers that are known among performance folks to be pretty useless. Perhaps they'd be more worthwhile in a FE application.

There's no way that computer fans will help. Maybe if you lined the whole front end of the car with them and brought it down to your intake, they could help during idle, but that would be all.

[lunarhighway]

ok i suppose this in one of these seemingly great ideas that eventualy turn to nothing.

i might look if i can get some free fans to play with, but the facts are not favourable to spend to much time on it.

[ShadowWorks]

If you want to look into fans then size is important, the sweep of the blade has to be large, a radiator cooling fan in a car takes something like 8 to 20 amperes, yet it provides a lot of CFM, more than a big turbo, but its low pressure because of its size, but if we had a 4 foot fan blade it would provide even more CM with the right blades, in the 10,000 CFM but its even lower pressure unless you tunnel it into narrow vent, look up how wind tunnels are made for inspiration.

[DrivenByNothing]

I think this is one of the first things everyone thinks of. haha. I guess because the fans are so small.

Anyway, the electric s/c idea has been toyed around with and employed by a guy named Thomas Knight.

http://www.turbomagazine.com/tech/04...ger/index.html

[bobc455]

As you probably know, turbos/superchargers give some sort of PSI boost - maybe 8 - 15 PSI or higher. What kind of pressure increase do you suppose these fans would generate?

The engine can already suck plenty of CFM, but with more pressure the cylinders can ingest more CFM. It's the pressure, combined with airflow, that gives this pressure increase. Knowing CFM without PSI is useless.

Food for thought.

-BC