Fan-assisted air box: another home-made mod.
11-13-2007, 11:24 AM
#81
Member
Join Date: Mar 2004
Posts: 35
well i have 329cfm in my ~=`c~~ which boosts 506hp when it runs at wot for 5 mins and your back tires psi is 12 and your wipers are off, but after all that is done it ends up running at a load of dirt in a fan at 60mph at a great distance with an air filter bringing in 100cfm on the edge which if you add 5% window tint and a set of 26" rims on a 300zx skyline makes the computer go to maxima.org at which point your fan runs on lithium at 70cfm then you purge your wiper fluid and you can beat a fighter jet in a 100 mile race that runs at 10cfm...
now this is what i understand when i read this thread, am i right, is that what happens?????
now this is what i understand when i read this thread, am i right, is that what happens?????
11-13-2007, 03:04 PM
#83
Good Luck with that!!
With the cost of replacing your engine when the plastic blades of the bilge pump break off and get sucked into your intake and you have to replace the top half of your engine you might as well have spent all that money on a Supercharger.
Was he serious??!!!
With the cost of replacing your engine when the plastic blades of the bilge pump break off and get sucked into your intake and you have to replace the top half of your engine you might as well have spent all that money on a Supercharger.
Was he serious??!!!
I can make fun of this stuff too, y'know.
11-13-2007, 03:08 PM
#86
I'm not sure if anyone else has said this but do you realize this is a computer case fan? Most cpu fan's can't even handle 6+ years worth of dust before they stop spinning and lock up. This fan will have to deal with a lot more than what your standard computer will have to deal with sitting in a completely controlled environment. There's moisture, dirt, rocks, leaves, and extreme temperatures this fan will have to deal with.
Shh...not so loud. you'll give the fan an inferiority complex.
11-13-2007, 03:14 PM
#87
After six years of use, and putting on 100k in my I30, I found a total of 20 grains of sand sitting on the bottom of the stock box, and about 2 grams worth of dried-out, tiny bug parts inside my air filter when I opened it up.
Air has enough trouble making it through that narrow slot lying between the top of the radiator and the front of the hood.
Nah....not as funny as drilling holes in the bottom of a stock airbox. Nothing says "sucky performance" like a "hot air intake" or HAI for you acronuts.
Last edited by dr-rjp; 11-13-2007 at 03:44 PM.
11-13-2007, 03:16 PM
#88
Originally Posted by dr-rjp
Nah....not as funny as drilling holes in the bottom of a stock airbox. Nothing says "sucky performance" like a "hot air intake" or HAI for you acronuts.
Why, yes, it does create air flow....right out the FRONT OF THE INTAKE!!!
11-13-2007, 03:39 PM
#91
Oh know, what did you do!! 
I think the fan would only be a restriction buddy. In theory it adds more cfm and the specification numbers rock!! but in reality, its nothing. Try getting a 3in pipe thats 1.5-2 feet long, and put the fan on the other end, if you felt anything, its little to none.... now imagine that same pipe with ridges all around and mutiple bends on the pipe, its not happening. Atleast you tried, but this idea has been around as long as civics has been around. And all that improvement, I think its a placebo.. but everyone feels different so... nice try though! 
but if you are dynoing, definately interested to see what the changes are! (good or bad)
I think the fan would only be a restriction buddy. In theory it adds more cfm and the specification numbers rock!! but in reality, its nothing. Try getting a 3in pipe thats 1.5-2 feet long, and put the fan on the other end, if you felt anything, its little to none.... now imagine that same pipe with ridges all around and mutiple bends on the pipe, its not happening. Atleast you tried, but this idea has been around as long as civics has been around. And all that improvement, I think its a placebo.. but everyone feels different so... nice try though! but if you are dynoing, definately interested to see what the changes are! (good or bad)I plan on running some pressure tests on it, just to see what amount of pressure drops I'm getting across the fan.
11-13-2007, 03:47 PM
#96
Kids, whether this is true or not, it's mind-numbingly simple.
At low speeds, when you're just bumbling along and demanding less than 107 CFM, the fan is pressurizing the intake tract slightly. So, when you open the throttle, you don't have to wait for that entire column of air to start moving before you get power.
Once you start digging into the throttle and getting the revs up, your engine quickly starts demanding more than 107 CFM. At that point, the fan does nothing but generate turbulence and restrict airflow.
In other words, it makes the car faster when you want to drive it slow, and slower when you want to drive it fast.
See? Simple. Quit whining.
At low speeds, when you're just bumbling along and demanding less than 107 CFM, the fan is pressurizing the intake tract slightly. So, when you open the throttle, you don't have to wait for that entire column of air to start moving before you get power.
Once you start digging into the throttle and getting the revs up, your engine quickly starts demanding more than 107 CFM. At that point, the fan does nothing but generate turbulence and restrict airflow.
In other words, it makes the car faster when you want to drive it slow, and slower when you want to drive it fast.
See? Simple. Quit whining.
Last edited by d00df00d; 11-13-2007 at 03:49 PM.
11-13-2007, 03:51 PM
#99
...like the sharply angled stock air box and the MAF screens let the airflow through without any.
The worst thing that could happen is not my fan making things worse.
No. The worst thing is that the fan actually helps.
I'm out..
11-13-2007, 04:03 PM
#101
Do you have any idea what a fan does to an air stream that is trying to move at over twice the fan's output?
What do you expect that giant impeller to do to your flow rates when it almost completely covers the opening in the intake tract?
I'm being generous here. If you seriously think that tiny MAF screen (it can actually straighten air flow) and the angles in the stock air box (which holds a large volume of air and has a giant air filter in the middle to spread things out) are major points of restriction and sources of turbulence, you probably aren't equipped to continue this discussion, much less answer those questions. I'd just like to give you the benefit of the doubt...
What do you expect that giant impeller to do to your flow rates when it almost completely covers the opening in the intake tract?
I'm being generous here. If you seriously think that tiny MAF screen (it can actually straighten air flow) and the angles in the stock air box (which holds a large volume of air and has a giant air filter in the middle to spread things out) are major points of restriction and sources of turbulence, you probably aren't equipped to continue this discussion, much less answer those questions. I'd just like to give you the benefit of the doubt...
11-13-2007, 04:46 PM
#102
But the gain's aren't worth the losses you'll see from the restriction.
That is the sum up, make your own decision.
If you idle all day, this is a great idea,
if you move your car, its a waste of time and energy.
OH> STOP YELLING!!!
11-13-2007, 05:27 PM
#103
This is assuming there's a vacuum in the intake tract at low throttle angles. I don't really think this is the case. From what I know the giant earth supercharger @ 14.7 PSI does quite well for itself.
11-13-2007, 06:03 PM
#104
The earth doesn't run off your crank, therefore it is effectively a turbocharger.
11-13-2007, 06:20 PM
#108
agreed.
Originally Posted by MorpheusZero
The earth doesn't run off your crank, therefore it is effectively a turbocharger.
The earth doesn't run off your crank, therefore it is effectively a turbocharger.
Last edited by TunerMaxima3000; 11-13-2007 at 06:23 PM.
11-13-2007, 06:52 PM
#112
And either way, if the fan is generating enough pressure to move 107 CFM, and if the engine isn't generating enough vacuum to draw 107 CFM, doesn't that mean by definition that the fan will be adding pressure?
11-13-2007, 07:18 PM
#113
And either way, if the fan is generating enough pressure to move 107 CFM, and if the engine isn't generating enough vacuum to draw 107 CFM, doesn't that mean by definition that the fan will be adding pressure?
Atmoshperic pressure >>>>>> a fraction of a PSI that this fan could generate (which is probably completely negated by the filter itself) at idle just like drivetrain inertia >>>>> an UDP. The engine swallows all the air it can based on how much the throttle plate allows it to. Like I said, I don't think you give atmospheric pressure enough credit.
Last edited by nismology; 11-13-2007 at 07:38 PM.
11-13-2007, 07:24 PM
#114
Stop saying vacuum. I feel like we're in the Hoover appreciation thread at www.maidsofamerica.org.
11-13-2007, 08:32 PM
#117
Member
Join Date: Feb 2007
Location: Maryland
Posts: 94
Wait, what happened to the guy screaming about his leafblower turbocharger? I want to see some more of those sweet pics.
11-13-2007, 09:46 PM
#118
The engine is generating enough vacuum to draw 107 CFM but the throttle plate won't let it. A matter of semantics but just wanted to clear that up.
Atmoshperic pressure >>>>>> a fraction of a PSI that this fan could generate (which is probably completely negated by the filter itself) at idle just like drivetrain inertia >>>>> an UDP. The engine swallows all the air it can based on how much the throttle plate allows it to. Like I said, I don't think you give atmospheric pressure enough credit.
Atmoshperic pressure >>>>>> a fraction of a PSI that this fan could generate (which is probably completely negated by the filter itself) at idle just like drivetrain inertia >>>>> an UDP. The engine swallows all the air it can based on how much the throttle plate allows it to. Like I said, I don't think you give atmospheric pressure enough credit.
EDIT: And I guess I should have referred to the intake tract rather than "the engine" in my original post...
Last edited by d00df00d; 11-13-2007 at 09:48 PM.
11-13-2007, 09:50 PM
#119
Another thing: This might actually raise the idle a bit. I'm not sure how much of a buffer the IAC is.. probably enough to soak up the extra pressure, but it would be interesting to see.
11-13-2007, 09:58 PM
#120
I am saying there's no vaccum in the intake tract at low throttle angles. When you breathe in, the vacuum created in your lungs causes air to rush in. That does not mean there is vacuum present in the mouth/nasal passages. In these cases, moving air is just nature's response to the vacuum, not vacuum itself. If you read about PCV systems, air from the intake tract actually enters the crankcase via the breather tube to dilute the blow-by gases and oil vapors at idle and moderate throttle angles. This is the principle upon which modern PCV systems are based. Air isn't sucked out of the crankcase at the breather until very aggressive throttle angles are introduced.
I'm also saying that the fan generates very little pressure, if any. My opinion is that the pressure drop through the filter would invalidate any pressure it could put out and unless the air box is completely sealed ANY excess pressure would leak out of the holes anyway.
I'm also saying that the fan generates very little pressure, if any. My opinion is that the pressure drop through the filter would invalidate any pressure it could put out and unless the air box is completely sealed ANY excess pressure would leak out of the holes anyway.
Last edited by nismology; 11-13-2007 at 10:06 PM.