Fan-assisted air box: another home-made mod.
11-06-2007, 07:03 PM
#45
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Posts: n/a
I didn't really care to read much of this thread because I didn't understand much of the vocabulary and mathematics you guys were using, but I do have one question. I would guess that this is actually what you are talking about though.
I would guess that the fan wouldn't be able to keep up with the air flow going into the intake and actually restrict air?
I would guess that the fan wouldn't be able to keep up with the air flow going into the intake and actually restrict air?
I wonder what it would be if I added this?
11-06-2007, 11:39 PM
#49
Junior Member
Join Date: Oct 2007
Posts: 25
Dj ,i think this is a waste ,well you know the amout of dirt that air stock pulls in ,your fan is mounted before the filter ....so your 100+ CFM fan will die in no time and will need replacement almost every week or may be earlier .So u use that fan money to fuel up instead
11-06-2007, 11:54 PM
#50
dj said his intake was flowing about 40CFM at a steady 60mph. I'm guesstimating that at 60mph a 4th gen is at about a 40hp load.
But the exact numbers are not really the important part. The important part is that when he's railing on his car his intake will be sucking in a lot more than 107CFM. Besides possibly adding a bit of low-end, the mod will do nothing to actually make the car faster (and will be a big bottleneck at redline). It will seem a bit zipper around town but that's about it, at partial throttle it's the equivalent of opening the throttle butterfly a little more.
But the exact numbers are not really the important part. The important part is that when he's railing on his car his intake will be sucking in a lot more than 107CFM. Besides possibly adding a bit of low-end, the mod will do nothing to actually make the car faster (and will be a big bottleneck at redline). It will seem a bit zipper around town but that's about it, at partial throttle it's the equivalent of opening the throttle butterfly a little more.
11-07-2007, 12:53 AM
#51
A cpu fan is rated @ static air pressure (ie. free-stream pressure) They aren't capable of producing cfms @ pressure. say thru a intake maifold.static wiki from the wiki "The pressure inside a ventilation duct is not the static pressure, unless the air inside the duct is still. CFM vol vs. flow wiki
ie. the pressure inside the intake isn't static unless it's off
under vacuum or WOT load the fan will produce butkiss. like a turbonator
If you want pure air intake on a budget I'd suggest this
mod. air box mod
I did it /w 1 scoop and dropped 300 rpms @ 65mph
And check the Infineon Traffic Battle! vid on pg.1
my .02 on this Im out
ie. the pressure inside the intake isn't static unless it's off
under vacuum or WOT load the fan will produce butkiss. like a turbonator
If you want pure air intake on a budget I'd suggest this
mod. air box mod
I did it /w 1 scoop and dropped 300 rpms @ 65mph
And check the Infineon Traffic Battle! vid on pg.1
my .02 on this Im out
Last edited by Buck96; 11-07-2007 at 01:10 AM.
11-07-2007, 09:30 AM
#53
A cpu fan is rated @ static air pressure (ie. free-stream pressure) They aren't capable of producing cfms @ pressure. say thru a intake maifold.static wiki from the wiki "The pressure inside a ventilation duct is not the static pressure, unless the air inside the duct is still. CFM vol vs. flow wiki
ie. the pressure inside the intake isn't static unless it's off
under vacuum or WOT load the fan will produce butkiss. like a turbonator
If you want pure air intake on a budget I'd suggest this
mod. air box mod
I did it /w 1 scoop and dropped 300 rpms @ 65mph
And check the Infineon Traffic Battle! vid on pg.1
my .02 on this Im out
ie. the pressure inside the intake isn't static unless it's off
under vacuum or WOT load the fan will produce butkiss. like a turbonator
If you want pure air intake on a budget I'd suggest this
mod. air box mod
I did it /w 1 scoop and dropped 300 rpms @ 65mph
And check the Infineon Traffic Battle! vid on pg.1
my .02 on this Im out
Nice mod, but nothing new. Adding another intake source has been around for a long time (at least nine years or more):
(http://www.autospeed.com/cms/article.html?&A=0009&P=1)
I've also tried what you did, but found it to be not that effective or practical in rainstorms. It's essentially the same as the old HACAI well-documented elsewhere in this forum)
The stock scoop on our A32's has an intentionally narrow opening so as to (1) reduce noise and (2) fit in the available space between the radiator and hood.
Any additional openings to the outside air will be an improvement, and one of Honda's airboxes does, indeed, have two openings, and much higher CFM ratings than Nissan boxes (*surprise*).
The problem is that, unless you put in a bypass switch, you are going to suck in water during rainstorms.
In short, they may be OK for the track, but not advisable for everyday driving.
If it weren't for the vacuum created by the engine, the engine would not run at idle. At a dead stop, and on a calm day, there is zero air coming into the air intake on its own power. It is drawn in by the vacuum.
I advise everyone to read the following article on stock air boxes that appeared in AutoSpeed:
http://www.autospeed.com/cms/A_0073/printArticle.html
They compare 14 different makes of stock air intakers (stock airboxes and snorkels). Although they did not test a 4th Gen airbox, they did test a Z31 300ZX and an R31 Skyline, and I don't see how our stock intakes could be much higher than those -- in fact, they may be lower.
The CFM readings they obtained for these two stock boxes were 85CFM for the 300ZX and 78CFM for the Skyline. They also tested the 300ZX without the snorkel and got a reading of 90CFM -- which tends to validates my statement regarding the restrictiveness of the snorkel.
I'df also like to point out -- and this will be my last comment on this subject -- that CFM's, measured as the static rate of air flow through a cylinder, are inversely proportional to the volume of that cylinder. Shrinking the size of the cylinder shrinks its volume and increases CFMs. Increasing the volume decreases CFM's.
It's the reason why vacuum cleaners draw air in through long, narrow cylinders, and the reason why putting a nozzle on -- which has an even smaller volume --- increases the rate of air flowing through it.
So, making direct comparisons in CFM between the very small, and uniformly shaped, cylindrical volume of an intake and the much larger, and more convoluted, volume of a stock air box is like comparing apples and lasagna.
When someone can prove to me that the static rate of air flow, measured in CFM's, two inches to the right of the opening inside the bottom half of a stock, 4th Gen air box, using a totally stock OEM 4th Gen setup, exceeds 107 CFM by at least 5% during normal driving, then I'll admit that the fan is an impediment under those conditions.
In fact, I would really like to know of any realistic driving scenario in which the incoming air is at least 5% more than 107CFM's in the bottom half of a totally stock 4th Gen. Given how easy it is to remove the fan, I can always pull it when needed.
(the 5% is to allow for measurement error)
11-07-2007, 09:59 AM
#55
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?????
Last edited by jvckustumz; 11-07-2007 at 10:02 AM.
11-07-2007, 08:46 PM
#56
In fact, I would really like to know of any realistic driving scenario in which the incoming air is at least 5% more than 107CFM's in the bottom half of a totally stock 4th Gen. Given how easy it is to remove the fan, I can always pull it when needed.
(the 5% is to allow for measurement error)
(the 5% is to allow for measurement error)
Last edited by MorpheusZero; 11-07-2007 at 08:56 PM.
11-07-2007, 08:55 PM
#57
I'df also like to point out -- and this will be my last comment on this subject -- that CFM's, measured as the static rate of air flow through a cylinder, are inversely proportional to the volume of that cylinder. Shrinking the size of the cylinder shrinks its volume and increases CFMs. Increasing the volume decreases CFM's.
It's the reason why vacuum cleaners draw air in through long, narrow cylinders, and the reason why putting a nozzle on -- which has an even smaller volume --- increases the rate of air flowing through it.
11-07-2007, 09:06 PM
#58
Just a heads up.
You said "if it does nothing else other than cool the air down it still helps" or something to that effect.
Fans dont cool the air down, they force more air over surfaces, and when that surface is your skin it causes more evaporation, which is a cooling process, so unless your car is powered by hampsters (hondas might benefit from this) its not cooling anything
You said "if it does nothing else other than cool the air down it still helps" or something to that effect.
Fans dont cool the air down, they force more air over surfaces, and when that surface is your skin it causes more evaporation, which is a cooling process, so unless your car is powered by hampsters (hondas might benefit from this) its not cooling anything
11-07-2007, 09:42 PM
#59
OMG I just realized the thread creator is the same person that came up with this one
http://forums.maxima.org/showthread.php?t=541186
bahahhahah
http://forums.maxima.org/showthread.php?t=541186
bahahhahah
11-08-2007, 01:01 AM
#60
^^^ I remember that
Dj, Putting aside fuel and spark....Just think of a motor as a big pump, the faster you get air to flow through the engine (Intake & Exhaust) the more HP you'll create once fuel and spark are added- this is why people port, do cams, pistons, exhaust, etc. Volume of air is also important....with this said, how do you expect that 100+ cfm fan to keep up with the broad range of air required by the motor in different rpm's?
Also bringing in vacuum cleaners isn't necessarily a good comparison, If you put a CAI on your car that has an ID of 1.5" will your car gain or loose HP? You said this increases flow....try walking around with only a straw to breath through-->no nose- no mouth- just the straw....your blood pressure will rise cause you heart will b working harder. That vacuum cleaners motor draws "x" amps Y? because it's being restricted. The fan can't keep up with the demands of the motor-so the motor will have to work harder, thus the bottle necking others have stated. I can understand some of ur logic but...... but application is off when it comes to pre-existing requirements.
Dj, Putting aside fuel and spark....Just think of a motor as a big pump, the faster you get air to flow through the engine (Intake & Exhaust) the more HP you'll create once fuel and spark are added- this is why people port, do cams, pistons, exhaust, etc. Volume of air is also important....with this said, how do you expect that 100+ cfm fan to keep up with the broad range of air required by the motor in different rpm's?
Also bringing in vacuum cleaners isn't necessarily a good comparison, If you put a CAI on your car that has an ID of 1.5" will your car gain or loose HP? You said this increases flow....try walking around with only a straw to breath through-->no nose- no mouth- just the straw....your blood pressure will rise cause you heart will b working harder. That vacuum cleaners motor draws "x" amps Y? because it's being restricted. The fan can't keep up with the demands of the motor-so the motor will have to work harder, thus the bottle necking others have stated. I can understand some of ur logic but...... but application is off when it comes to pre-existing requirements.
11-08-2007, 08:23 AM
#62
Guest
Posts: n/a
florida + 4th gen = this thread
i am not surprised but i am amused.
i am not surprised but i am amused.
11-08-2007, 02:21 PM
#65
Because I Can
Join Date: Nov 2007
Location: massachusetts son
Posts: 1,723
thats pretty cool...id never think to do nething like that...prly cuz im not on stock intake tho -_- props!!
11-08-2007, 02:40 PM
#66
Read up, buddy. CFM is short for "cubic feet per minute," or a rate of VOLUME flow, NOT linear flow. While smaller openings will restrict flow they will not increase maximum flow.
No, this is to increase the VELOCITY of the air traveling to the vac bag. The quicker the air travels (by using a smaller diameter tube and flowing the same CFM) the more it will suck up. Same deal for the small nozzle cross-sectional area--higher velocity of airflow = more force (or suction) acting on whatever it's close to.
No, this is to increase the VELOCITY of the air traveling to the vac bag. The quicker the air travels (by using a smaller diameter tube and flowing the same CFM) the more it will suck up. Same deal for the small nozzle cross-sectional area--higher velocity of airflow = more force (or suction) acting on whatever it's close to.
thank you
Originally Posted by dr-rjp
I'df also like to point out -- and this will be my last comment on this subject -- that CFM's, measured as the static rate of air flow through a cylinder, are inversely proportional to the volume of that cylinder. Shrinking the size of the cylinder shrinks its volume and increases CFMs. Increasing the volume decreases CFM's
I'df also like to point out -- and this will be my last comment on this subject -- that CFM's, measured as the static rate of air flow through a cylinder, are inversely proportional to the volume of that cylinder. Shrinking the size of the cylinder shrinks its volume and increases CFMs. Increasing the volume decreases CFM's
static means stationary, as in, NOT moving, how can you calculate CFM if the air isnt moving?
sorry dude but you are talking COMPLETELY OUT OF YOUR A$$
keep the computer fan in there though, its wickid!
I was waiting for that. 
11-09-2007, 02:56 AM
#71
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.
11-09-2007, 05:26 AM
#72
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Posts: n/a
I'd like to see a dyno and A/F readout over the entire RPM range vs. stock.
11-11-2007, 06:03 PM
#73
Senior Member
Join Date: Feb 2006
Posts: 127
Super chargers work because they create pressure and flow. This fan has some flow but pressure is almost zero. Thats great for ventilating air but is useless for forced-inducation. You may have felt some difference, but the difference was probably caused by the fan throwing the MAF out of calibration and making the computer dump extra fuel in. If you ran this fan, took out the spark plugs and felt for air coming out, there would be next to nothing there.
11-11-2007, 07:11 PM
#74
Junior Member
Join Date: Aug 2007
Posts: 39
I had to double check the date to make sure it's not April 1st
11-11-2007, 11:09 PM
#75
Licensed to Spell
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Join Date: Feb 2001
Location: Murrieta (southern California)
Posts: 4,521
:o)
dr, I don't think you mentioned what size fan you are using. 80mm I assume? I took a look in the bag of computer fans I have in the garage, and you are right, 107 CFM is very good. Here's what I have in my bag o' fans:
Link Depot, 50mm, 9.6 CFM ($6)
Link Depot, Z-Quiet fan, 80mm, 4 pack: 27.5 CFM ($15/4)
Link Depot, 80mm, 38.2 CFM ($8)
Link Depot, 92mm, 43.5 CFM ($8)
Vantec, Tornado, 80mm, 81.5 CFM ($15)
Link Depot, 120mm, 100.4 CFM ($12)
I am going to strategically place them throughout my engine bay for cooler engine temps and increased heat dissipation. I plan to put the 120mm fan directly in front of my water-to-air aftercooler's heat exchanger.
dr, what do you do with the yellow wire? I assume it can just be ignored and only the red and black need be hooked up?
Link Depot, 50mm, 9.6 CFM ($6)
Link Depot, Z-Quiet fan, 80mm, 4 pack: 27.5 CFM ($15/4)
Link Depot, 80mm, 38.2 CFM ($8)
Link Depot, 92mm, 43.5 CFM ($8)
Vantec, Tornado, 80mm, 81.5 CFM ($15)
Link Depot, 120mm, 100.4 CFM ($12)
I am going to strategically place them throughout my engine bay for cooler engine temps and increased heat dissipation. I plan to put the 120mm fan directly in front of my water-to-air aftercooler's heat exchanger.
dr, what do you do with the yellow wire? I assume it can just be ignored and only the red and black need be hooked up?
11-12-2007, 03:58 AM
#76
Senior Member
Join Date: Apr 2007
Posts: 143
there is good reason for people to make fun of a 100cfm fan when at redline your car is trying to pump through 300cfm.
However..
what if you where to place 4 of these 100cfm fans in series, or perhaps paralleling to each other. in paralleling they would be pushing through close to 350 CFM. and in series they may be able to generate some pressure at the lower rpm.
Also. how much do they cost?
However..
what if you where to place 4 of these 100cfm fans in series, or perhaps paralleling to each other. in paralleling they would be pushing through close to 350 CFM. and in series they may be able to generate some pressure at the lower rpm.
Also. how much do they cost?
11-12-2007, 09:46 AM
#77
Member
Join Date: Feb 2007
Location: Maryland
Posts: 94
CPU fan FTL
Leafblower FTW
http://videos.streetfire.net/Player....AD23CA9564&p=0
(music in the video FTL)
Leafblower FTW
http://videos.streetfire.net/Player....AD23CA9564&p=0
(music in the video FTL)
It's called forced induction and you should leave this to Turbo's and Superchargers.
Next thing we will hear is someone strapping a Leafblower to the rear of the car because it gives the car thrust.
11-13-2007, 06:33 AM
#79
there is good reason for people to make fun of a 100cfm fan when at redline your car is trying to pump through 300cfm.
However..
what if you where to place 4 of these 100cfm fans in series, or perhaps paralleling to each other. in paralleling they would be pushing through close to 350 CFM. and in series they may be able to generate some pressure at the lower rpm.
Also. how much do they cost?
However..
what if you where to place 4 of these 100cfm fans in series, or perhaps paralleling to each other. in paralleling they would be pushing through close to 350 CFM. and in series they may be able to generate some pressure at the lower rpm.
Also. how much do they cost?
If you are looking for more CFMs', you could try what will be my next project: hooking up a 4" cylindrical bilge blower fan (an axial fan with an output of 250CFM's) to a CAI. These blower fans cost about $25 shipped. You could also try running two of them in tandem, which would give you nearly 400CFM's.
I also bought a 3" bilge blower fan for $15 shipped. That has a 170CFM rating.
AutoSpeed did an article on Electric Boost (http://www.autospeed.com/cms/A_2063/article.html) that discussed what's currently available. My idea about the bilge blower fans is similar to the e-RAM reviewed there.
11-13-2007, 11:05 AM
#80
Member
Join Date: Feb 2007
Location: Maryland
Posts: 94
The fan is 80mm square, outputs 107CFM at static air pressure, and cost $12.00 shipped.
If you are looking for more CFMs', you could try what will be my next project: hooking up a 4" cylindrical bilge blower fan (an axial fan with an output of 250CFM's) to a CAI. These blower fans cost about $25 shipped. You could also try running two of them in tandem, which would give you nearly 400CFM's.
I also bought a 3" bilge blower fan for $15 shipped. That has a 170CFM rating.
AutoSpeed did an article on Electric Boost (http://www.autospeed.com/cms/A_2063/article.html) that discussed what's currently available. My idea about the bilge blower fans is similar to the e-RAM reviewed there.
If you are looking for more CFMs', you could try what will be my next project: hooking up a 4" cylindrical bilge blower fan (an axial fan with an output of 250CFM's) to a CAI. These blower fans cost about $25 shipped. You could also try running two of them in tandem, which would give you nearly 400CFM's.
I also bought a 3" bilge blower fan for $15 shipped. That has a 170CFM rating.
AutoSpeed did an article on Electric Boost (http://www.autospeed.com/cms/A_2063/article.html) that discussed what's currently available. My idea about the bilge blower fans is similar to the e-RAM reviewed there.
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??!!!