fan on intake

[mzdspd]

my friend recently put a ram air intake on his toyota celica. he put a 12 volt 3" fan on the end goin into the intake. this made it sound awsome but did it add any hp?

[TedLeeper]

it might have added a little but with wind drag while your driving youed be better off putting a scoop below the filter, it's pretty easy to make out of a big dust pan

[DJGypsy]

i don't think that the fan would be able to flow enough air to the engine say @ 5k rpm and wide open throttle. think: 1.6 liters (engine size example) of air are displaced in one revolution of the crank. so, 5000 rpm X 1.6 liters = 8000 liters of air per minute. airflow through a fan is usually measured in CFM, cubit feet per minute. 1.6 liters of air is equivalent to .0565 cubic feet of air. re-doing the math, we discover that @ 5000rpm wide open throttle, the engine will require 452 cubic feet of air per minute. these calculations do not take into account the volumetric efficiency of the engine, but still: if we assume 90% volumetric efficiency of a DOHC 4 valve motor @ 5000 rpm @ wide open throttle, the motor will still consume (0.9 X 452) about 400 cubic feet of air in one minute. if you can find a fan that will flow more air per minute than that, then you got something, you will be practically running boost! hence turbocharging. hope this sheds some light...good luck

[DJPRO]

Go Dan

[white94mx3]

Whoa! What Planet are you from Dan!? Holy ****

[DJGypsy]

...planet earth, believe it or not...i've read a lot of books and sport compact car magazine for a few years. you learn a few things ...forgive me, i'm an engineering major

[tk1138]

a couple of points: since the intake stroke is half of one revolution and there are four strokes to complete the cycle in one piston, the amount of air taken into the engine is about half of your estimate. But it's still a lot of air for a 3" fan, even after you take into acount the ineffeciencies.<P>1st & 2nd laws of thermodynamics: you can't win & you can't break even. While you might get more power at low RPM (where fan increases presure), it takes work to compress air into the intake, this work has to be supplied by the battery & ALT, which comes from the engine. It's the same parasitic effect as super chrging, but without the advantage of turning at a speed proportional to that of the crankshaft (boost at low RPM where you don't need it & drag at high RPM where you wan't more air). <P>Of course he might do better on a dyno in the low end, but he'll use more fuel to do it.<P>all the laws of nature are harsh 'mistresses', not just gravity,<BR>tk1138