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]

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/0406tur_knight_turbo_electric_supercharger/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

[dkjones96]

Computer fans don't create much boost.

http://www.goldmine-elec-products.com/prodinfo.asp?number=G16216

That fan creates 235 cfm @ 0.768 static pressure. I'm using the fan for a flow bench i'm building and the cfm and pressure ratings are almost perfect for what I need. That, combined with a hot wire air flow sensor, will make for a pretty good bench when I start doing custom head work for fuel economy.

[flapdoodle]

I whipped up a plate with a barbed tubing fitting and measured two different 80mm computer fans with a manometer. Both read the same at 1/4 inch of water. That is about what I expected. I had been interested in this before (after I abandoned using an array of them for radiator cooling) and feel that gains could be made by reducing pumping losses rather than a "supercharger".

My car is very sensitive FE wise about intake restrictions. I had thought of a square box that replaced the original aircleaner housing and fit atop the carb. It would have 10 fans arranged around an inner box and two ram air hoses on the outer box. I can make a drawing if anyone is interested.

[ShadowWorks]

You can make a hood scoop to pressurise this intake, the bigger the scoop or mouth the greater the pressure will be, and its free, well almost, it will create drag if its making pressure.

I think the main goal is to reduce something called parasitic drag on the intake.

[Russ]

i also looked in to this for performance and i came across a product in the internet

http://images.google.co.uk/imgres?imgurl=http://www.autoaccessorystore.com/products/952-2_b.jpg&imgrefurl=http://www.autoaccessorystore.com/blowerinfo.asp&h=426&w=500&sz=85&hl=en&start=27&um=1&tbnid=EwVNVi9_PBBMPM:&tbnh=111&tbnw=130&prev=/images%3Fq%3Delectric%2Bsupercharger%26start%3D21% 26ndsp%3D21%26um%3D1%26hl%3Den%26safe%3Doff%26clie nt%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DN

maby this will be some help to you


Russ . .

[ShadowWorks]

That product claims on the dyno graph to give over 50hp, thats just to much of a claim, even the 10% is too much, if it could must 1 or 2% I would be happy with that.

[dosco]

You can make a hood scoop to pressurise this intake, the bigger the scoop or mouth the greater the pressure will be, and its free, well almost, it will create drag if its making pressure.

I think the main goal is to reduce something called parasitic drag on the intake.

You are referring to a ram air intake. It stops or "stagnates" the air, whose total pressure is the combination of static and dynamic pressures.

Not really worth it, IMO. I once calculated the difference in pressures, it was pretty low. I may revisit that calculation though, to refresh my memory.

[RoadWarrior]

I did some ram intake figuring a month or two ago and was figuring that at 60mph, it would only get about .1 PSI..... however, some performance sites claim that this is enough to nullify the pumping loss/restriction of the air filter.

I have the front bumper off a bonneville SSE and am thinking I might mount it on marvin and use the driving light holes for ram intakes.

Anyway, yes, computer fans = way too weak... they're even too weak to effectively cool CPU heatsinks, they don't push the air into the fins hard enough. I have a couple of relatively small heatsinks set up with 25cfm centrifugal blowers, and because they can push a couple of PSI, they work better than 80cfm axial "howlers" on huge heatsinks. (For the technically minded, this turns a .50 c/W heatsink/fan combo into a .25 c/W or better)

However, the power draw of that type of blower is about equivalent to an axial fan of 3x the CFM.

A thing to beware of while experimenting is that you might find something that appears to give you 10psi of boost at idle, but as soon as you crack the throttle this drops to nearly nothing.

For example, some of the most powerful centrifugal blowers you can get hold of at a consumer level are leaf blowers. A typical 350CFM leaf blower will give between about 1 and 2 PSI of boost at mid RPM. Try to go WOT and 6K and it prolly won't keep up still, figure about .5 PSI there.

[flapdoodle]

http://www.loewen.com/home.nsf/2/PLEE-67HL4V/$FILE/wind_force_chart.jpg

[ShadowWorks]

I have heard the Pressure is low even on a ram intake but those funny cars are doing 250mph, and because air gets hard to push the faster you go I guess at those speeds it must make some decent pressure and reduce pumping loses.

[RoadWarrior]

That's pounds per square foot isn't it, not square inch, 144 sqin to the sqft, = 0.03 PSI at 30mph...

[flapdoodle]

Things I have found that need to be taken into account...
The vacuum gage has been found to be the best indicator I have of FE. With the ram air hose installed it was good for a solid 1 MPG. But when the warm air intake from the exhaust manifold is activated there can be NO ram effect.
At the speeds I drive to and from town (45MPH) the vacuum runs about 15 inches of mercury. That translates to 7.367311 PSI. It takes energy to create that, and anything I can do the help means greater economy.

One thought is to use the air from the radiator fan to help. It is already nice and toasty (but less than the temperature setting on the intake heater which I measured at 133 F), and the energy to run the fan has already been accounted for, so I figure it might give a slight boost. All I would have to do is reroute hoses.

Every other form of intake uses power, be it hood scoop, or electric blower. Turbos are a different thing all together, but do create a little back pressure, hence the need for big exhaust pipes.

[almightybmw]

random thought from reading above. Ram air to air/water intercooler(warmer really) to manifold. Would be useless at low speeds, but at higher speeds down the Interstates or highways, the ram air pressure should negate the drop across the a/w IC while still providing hotter air that's pressurized more than what the motor pumps. Does that make sense?

[flapdoodle]

Yes, it does. I was hoping the cooling fan might give a little boost, and at speed the air would be forced through the radiator with a far greater area than the tiny amount going around the cowling. Insects and birds would be filtered out by the A/C condenser.

[almightybmw]

birds would be filtered out by the A/C condenser
....lol.. I use my radiator to filter small game! lol sorry, that made me laugh a lot.