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Location:
Sydney
Registered:
May 2004
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 Interesting idea, maybe
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Thu, 19 August 2004 12:21
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Ok,I want to know if it would be possible or at all usefull to somehow put a fan in the air inlet pipe? dont laugh yet, ive done a few calcs:
i have a 01' rolla, so its 1.8L which = 0.0018m sq.
so at 2000rpm it is sucking around 3.6m sq/min
and at 5000rpm its sucking around 9m sq/min
And a 120mm computer case fan can blow up to around 2.5m sq/min
so if i were to take 4 X fan it would blow - 10m sq/min
which is more than the engine requires (up to 5555.55rpm)
therefore for the engine to suck its required air volume at any given rpm it would be doing less 'work' therefore = more power!
there is also the issue of wiring the fans to a car battery, but i figure that's a minor detail.
now you can laugh...
Please let me know if you dont agree with the calculations
(or the idea at all)
sorry to get all 'maths' on you
thanks.
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Location:
Ipswich
Registered:
October 2003
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Location:
Sydney
Registered:
May 2004
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Re: Interesting idea, maybe
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Thu, 19 August 2004 13:41
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Thanks for the link, but the calculations on the page are a bit funny, i can get a 120mm fan to do 80cfm (2.3m sq./min)
(jaycar cat. YX-2516)
They use as their comparison the figue of ony 18cfm. they are also using a 3L v6 engine, where as mine is only 1.8L 4 pot.
i recalculated, and before i didn't take into concideration the fact the the intake stroke is only on 2 or 4 strokes, so that means i would get the same effect with only 2 fans & not 4.
does anybody know how to wire a 12v 380mA fan to a car battery?
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Location:
Ipswich
Registered:
October 2003
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Re: Interesting idea, maybe
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Thu, 19 August 2004 13:50
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I know its cynical, but I figure that the amount of money car companies put into engineering and research, would have determined if a few relatively cheap fans can increase volumetric efficiency.
But thats ust my 2 cents.
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Location:
Brisbane
Registered:
May 2002
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Re: Interesting idea, maybe
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Thu, 19 August 2004 22:36
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A pissy little computer fan might be able to push 2.5m sq/min into free air, but put the smallest restriction in front of it and watch that figure drop through the floor.
What it comes down to is this: it takes large amounts of power (we're talking kilowatts here) to get any noticeable increase in manifold pressure at high rpm, and no computer case fan can deliver that sort of power.
Believe me, you're not the first person to come up with this brilliant idea (I remember people discussing it on the aus.cars newsgroup in the mid 90's) but strangely enough you don't see a lot of cars getting around with computer case fans taped to the airbox? 
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Interesting idea, maybe
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Thu, 19 August 2004 23:37
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well, in the movie "metalskin" he put a vacuum cleaner on the intake 
i actually did do this.. got an old electrolux and attached it to the intake of my datto Stanza SSS... just for kicks (in blowing mode of course)
made it idle a little higher, but throttle response off idle was much faster.. i think the vac ran out of puff when holding throttle at a steady 2000rpm tho...
so anything more than a 2000rpm idle was already going past it's capability... and i think a 1200W vac will do more than a 6w fan.
what you want is a SUPERCHARGER 
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Location:
Terrigal
Registered:
May 2002
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Re: Interesting idea, maybe
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Thu, 19 August 2004 23:45
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Haha my mate put a vac on his 2tg ta22. Mounted it and everything, had a belt running it.. Was ok until 2000rpm or so when the bearings or bushes whatever is in a vac fell to pieces.
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Location:
Sydney
Registered:
May 2004
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Re: Interesting idea, maybe
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Fri, 20 August 2004 02:45
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thats a good point norbie, about the fan not having enough power to increase manifold pressure, which is true of course. that though is not the idea. the idea is to simply reduce the amount of work the engine needs to do to suck its required air, and not increase the pressure of the air going in.
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Location:
c'town, NSW
Registered:
May 2002
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I supported Toymods
Location:
Perth, Western Australia
Registered:
December 2002
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Re: Interesting idea, maybe
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Fri, 20 August 2004 04:01
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| oldcorollas wrote on Fri, 20 August 2004 07:37 |
well, in the movie "metalskin" he put a vacuum cleaner on the intake
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ROFLMAO, what memory, thanks for draggin it up Stew!!! The scary realisation is you tried it??? Bored that day hey?
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I Supported Toymods
Location:
south Melbourne/KL
Registered:
June 2004
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Re: Interesting idea, maybe
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Fri, 20 August 2004 05:32
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well, my basic opinion is that a fan to do that would require lots of energy to provide enough air. If that much energy is required for the fan, the engine would probably already lose some power somewhere. So basically u would be back to square one or end up losing more power in the fan.
Just my thoughts. No scientific proof or calculations to support my theory.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Interesting idea, maybe
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Fri, 20 August 2004 05:45
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| CLG wrote on Fri, 20 August 2004 14:01 |
| oldcorollas wrote on Fri, 20 August 2004 07:37 |
well, in the movie "metalskin" he put a vacuum cleaner on the intake
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ROFLMAO, what memory, thanks for draggin it up Stew!!! The scary realisation is you tried it??? Bored that day hey?
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yeah just a little.... 1st car.. vacuuming it... hmmmm "i wonder what would happen if..."
i was surprised it made any difference, and dissapointed it made little difference.
btw, i did it long before i watched metalskin... man thats one fucked up movie... good aussie flick tho
Cya, Stewart
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Location:
Brisbane
Registered:
May 2002
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Re: Interesting idea, maybe
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Fri, 20 August 2004 06:12
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| b1gb3n wrote on Fri, 20 August 2004 15:32 |
Just my thoughts. No scientific proof or calculations to support my theory.
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Except for the Law of Conservation of Energy. 
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Location:
Brisbane, QLD
Registered:
February 2003
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Re: Interesting idea, maybe
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Fri, 20 August 2004 08:41
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| Norbie wrote on Fri, 20 August 2004 16:12 |
| b1gb3n wrote on Fri, 20 August 2004 15:32 |
Just my thoughts. No scientific proof or calculations to support my theory.
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Except for the Law of Conservation of Energy.
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Laws are made to be broken... 
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: Interesting idea, maybe
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Fri, 20 August 2004 09:55
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as mentioned, a supercharger will push the kind of air you're after
electronically power forced induction, from all the reading I've done, blows goats.
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Location:
Adelaide
Registered:
May 2003
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Re: Interesting idea, maybe
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Fri, 20 August 2004 10:06
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Unless its like a 3phase blower which you trail around on a lead.
Would be good, till you got about 25m from home.
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Location:
Montrose, VIC
Registered:
May 2002
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Re: Interesting idea, maybe
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Fri, 20 August 2004 10:59
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Here's an even easier way to prove it to yourself; fire up your car, and stick your hand over the throttle while free revving to, say, 5000rpm. Do the same to a computer fan air intake. Notice a difference? Also, remember that your car engine is only able to generate a couple of KW while free revving like this...
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Location:
Brisbane
Registered:
May 2002
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Re: Interesting idea, maybe
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Fri, 20 August 2004 14:47
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| mrshin wrote on Fri, 20 August 2004 20:59 |
fire up your car, and stick your hand over the throttle while free revving to, say, 5000rpm.
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NOTE: not recommended if you want to keep your hand. 
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Location:
Adelaide
Registered:
January 2004
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Re: Interesting idea, maybe
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Sun, 22 August 2004 00:58
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| takai wrote on Fri, 20 August 2004 19:36 |
Unless its like a 3phase blower which you trail around on a lead.
Would be good, till you got about 25m from home.
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I like the idea of the 3phase blower.
What if you got a 400m long (have to be longer but anyway)exstenion cord and just used it down the quarter?
That would turn a few heads at the drags
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