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OMG! Airbox fan

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serious inconsistancies in the post still make we consider the validity.

the bike that was used was a new 07 yz250f that had no time on it at all ,

it still had the titty's on the tires and the chain had not been adjusted yet, and it is all stock -----everthing stock .

the new tires from bridgstone are really cool on this bike , also a bonus !

07's came with dunlops.

then you install a different pilot jet, leak jet, and a pump diafram -----all included in the kit-----.

this jetting won't improve anything above 1/4 throttle!

what is the cfm rating of this fan at 5000 rpm?

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the thing works better than i though it would , it felt like a big motor in the mid ----but it would still spin to the moon and made good overrev because you are still using a nice light stock size piston !

there are several really big long jumps right out of corners that were really hard to make on the stock bike ,-----with the fan installed the bike could easily carry 4th gear and clear them -----as when stock the bike had to stay in 3rd and you had one hell of a time getting the ft wheel over .

i have to say the thing is real , and it does help power no doubt.

i really feel that with a pipe, and a modded motor the thing would really work well there also .

i took and put the bike back to stock ( except i left the stator in )--and then i ran it again to see if i could tell if the stator would pull the motor down at all ,---( there was no difference from stock stator to mod stator )

the bike ran just the same stock ( it was easy to tell when you took it off and then road the thing that it was back to being week in the mid and top again .)

it took along time to get this test going , but i feel like Scott has really put a huge effort in getting the kit streemlined and doing away with the battery pack .

this alone is worth the weight.

I gotta say, I at first was against the product because it used to require batteries; with the stator powering it, that "undoes" that reservation. It still is not legal for AMA racing, as near as I can figure.

I hope that the people that were vicious to this guy and his idea apologize now. This guy was nothing but a professional under all the hating he received.

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I just saw this thread and checked out the website. As far as I can tell there's really no difference between this product and the Turbo-Zet for cars - which doesn't work because it can't make enough CFM at useful pressures. Yes, the product runs off a stator, so the fan RPM can vary, but there's really no way to get enough pressure into the intake to do much good. Plus, since the carb throat is being pressurized (if at all), that alone creates issues with fuel flow reversion in the carb passages.

Since the float bowl is vented to the atmosphere, intake vacuum is used to pull fuel through the jets and emulsion tube. But, if there is less vacuum in the carb throat, there's less force moving the fuel through the passages. Would rejetting help that? I suppose... to a point. If the carb throat pressure rises above atmospheric, then no fuel could possibly flow through the carb, so the "better" the product worked, the leaner the bike would get until the engine would stall due to an incombustible mixture.

At best, I can't see how this product would improve performance, at worst it's located on the wrong side of the carb. It's definitely not AMA legal if their definition includes all active means of raising intake pressure.

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serious inconsistancies in the post still make we consider the validity.

07's came with dunlops.

this jetting won't improve anything above 1/4 throttle!

what is the cfm rating of this fan at 5000 rpm?

i do not know why i said bridgstones ( i have been having troubble getting the 401 402 A bridgstone latley and they have gone to the 403 404 :cry: ----and i have had bridgstone on my brain :busted: )

but i should have said the new fresh 739 ft and the 756 worked well on the Motoland track on this little bike -------they really did work well .

the fan is a 200 cfm fan ,

the different jetting at the bottom of the carb just keeps the very bottom corrected for the slight fan force -----

and ofcourse different areas a guy will have to tweak the jetting some to really get it all cleaned up .

i also forgot that i raised the needle clip from the 4th to the 5th clip on the needle with the fan on :ride:

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I gotta say, I at first was against the product because it used to require batteries; with the stator powering it, that "undoes" that reservation. It still is not legal for AMA racing, as near as I can figure.

I hope that the people that were vicious to this guy and his idea apologize now. This guy was nothing but a professional under all the hating he received.

the batteries were a biggie for me also , the thing is nice and clean with no batteries :thumbsup:

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OK, that's nuts. Maybe it works...I don't know, but can someone explain to me how you can force more air into the engine than what the engine can suck?

in a normal motor your motor has to pull air into the motor on the intake stroke. once you add a supercharger or turbo. when your intake valve open the air is pushed in faster and puts more air into the cylinder. which equals more power.

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I may be new to WR's but I'm not new to the thermodynamics and fluid flow within internal combustion engines. The claim being made here is that this little fan is going to increase the airflow into your carburetor. This is exactly the same principle behind superchargers and turbochargers. Superchargers employ a belt running off the engine. Turbochargers scavenge the energy from the exhaust stream via a turbine. Both offer increases in pressure significantly above atmospheric. This pressure increase is called 'boost'.

Automotive pressure chargers typically use two types of air pumps: Roots type blowers which feature two rotors with interlaced grooves engineered to very high tolerances, and centrifugal blowers which use a squirrel-cage type blowers and take advantage of flow inertia. So why doesn't anyone in the automotive industry use an axial-type fan like this set up? Because you can't significantly raise the pressure of the down stream flow with an axial fan!

To prove this to yourself, put your hand over the end of a blow dryer. Does it raise the pressure and try to push your hand off? Or does it squeal, overspeed, and quickly burn up? And a hair dryer is running off of 120V A/C from a nuclear plant, a whole lot more power than you're going to get from a little battery pack or even the engine of a dirt bike. In fact, you can't spin an axial flow fan fast enough to raise the pressure on the downstream side. If you try, you just get stagnation and no air flows at all. The same effect is called stall in aerodyamics and it makes planes CRASH.

This is complete B.S. The fluid dynamics behind this product are about like those that support perpetual motion machines. The most likely situation is that the fan, housing, and associated hardware will actually significantly obstruct air flow. If it does anything beneficial, it might reduce turbulence and cause the air stream to swirl. Certain tests have shown in increase in efficience with a swirling air stream. But if you wanted that you'd be much better off with fixed system that not only would take up much less space, but cost about 10X less.

The final evidence: if it worked there would be dyno runs showing the measured increases in power. Where are they?

Keep Ridin',

John

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in a normal motor your motor has to pull air into the motor on the intake stroke. once you add a supercharger or turbo. when your intake valve open the air is pushed in faster and puts more air into the cylinder. which equals more power.

this is so true, its funny the guys that have never added a small turbo and blown through their small stock carb on their 1970 vw bug -------i built one thet blew through the stock pick 34 carb and it only made 1 lb of boost and the dam thing really came alive , ----when i finnally made some money i installed a turbo on my bug that made 10 psi boost on a blow through, and that dam thing would pull the ft wheels off the ground :crazy:

of course it hammered the clutch out shortly ----but it did run great :thumbsup:

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I may be new to WR's but I'm not new to the thermodynamics and fluid flow within internal combustion engines. The claim being made here is that this little fan is going to increase the airflow into your carburetor. This is exactly the same principle behind superchargers and turbochargers. Superchargers employ a belt running off the engine. Turbochargers scavenge the energy from the exhaust stream via a turbine. Both offer increases in pressure significantly above atmospheric. This pressure increase is called 'boost'.

Automotive pressure chargers typically use two types of air pumps: Roots type blowers which feature two rotors with interlaced grooves engineered to very high tolerances, and centrifugal blowers which use a squirrel-cage type blowers and take advantage of flow inertia. So why doesn't anyone in the automotive industry use an axial-type fan like this set up? Because you can't significantly raise the pressure of the down stream flow with an axial fan!

To prove this to yourself, put your hand over the end of a blow dryer. Does it raise the pressure and try to push your hand off? Or does it squeal, overspeed, and quickly burn up? And a hair dryer is running off of 120V A/C from a nuclear plant, a whole lot more power than you're going to get from a little battery pack or even the engine of a dirt bike. In fact, you can't spin an axial flow fan fast enough to raise the pressure on the downstream side. If you try, you just get stagnation and no air flows at all. The same effect is called stall in aerodyamics and it makes planes CRASH.

This is complete B.S. The fluid dynamics behind this product are about like those that support perpetual motion machines. The most likely situation is that the fan, housing, and associated hardware will actually significantly obstruct air flow. If it does anything beneficial, it might reduce turbulence and cause the air stream to swirl. Certain tests have shown in increase in efficience with a swirling air stream. But if you wanted that you'd be much better off with fixed system that not only would take up much less space, but cost about 10X less.

The final evidence: if it worked there would be dyno runs showing the measured increases in power. Where are they?

Keep Ridin',

John

i really see what you are saying, and you have very good points .

but the little system does work and can open the door for more thinking out side the box in the normal old school mx world :ride:

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I may be new to WR's but I'm not new to the thermodynamics and fluid flow within internal combustion engines. The claim being made here is that this little fan is going to increase the airflow into your carburetor. This is exactly the same principle behind superchargers and turbochargers. Superchargers employ a belt running off the engine. Turbochargers scavenge the energy from the exhaust stream via a turbine. Both offer increases in pressure significantly above atmospheric. This pressure increase is called 'boost'.

Automotive pressure chargers typically use two types of air pumps: Roots type blowers which feature two rotors with interlaced grooves engineered to very high tolerances, and centrifugal blowers which use a squirrel-cage type blowers and take advantage of flow inertia. So why doesn't anyone in the automotive industry use an axial-type fan like this set up? Because you can't significantly raise the pressure of the down stream flow with an axial fan!

To prove this to yourself, put your hand over the end of a blow dryer. Does it raise the pressure and try to push your hand off? Or does it squeal, overspeed, and quickly burn up? And a hair dryer is running off of 120V A/C from a nuclear plant, a whole lot more power than you're going to get from a little battery pack or even the engine of a dirt bike. In fact, you can't spin an axial flow fan fast enough to raise the pressure on the downstream side. If you try, you just get stagnation and no air flows at all. The same effect is called stall in aerodyamics and it makes planes CRASH.

This is complete B.S. The fluid dynamics behind this product are about like those that support perpetual motion machines. The most likely situation is that the fan, housing, and associated hardware will actually significantly obstruct air flow. If it does anything beneficial, it might reduce turbulence and cause the air stream to swirl. Certain tests have shown in increase in efficience with a swirling air stream. But if you wanted that you'd be much better off with fixed system that not only would take up much less space, but cost about 10X less.

The final evidence: if it worked there would be dyno runs showing the measured increases in power. Where are they?

Keep Ridin',

John

Well said.

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I installed a new front fender on my '07 YZ250F last week. I also installed a different pilot jet, leak jet, and a pump diaphram. The bike feels much more powerful now, which proves that the fender works and was worth every penny.

-B

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I may be new to WR's but I'm not new to the thermodynamics and fluid flow within internal combustion engines. The claim being made here is that this little fan is going to increase the airflow into your carburetor. This is exactly the same principle behind superchargers and turbochargers. Superchargers employ a belt running off the engine. Turbochargers scavenge the energy from the exhaust stream via a turbine. Both offer increases in pressure significantly above atmospheric. This pressure increase is called 'boost'.

Automotive pressure chargers typically use two types of air pumps: Roots type blowers which feature two rotors with interlaced grooves engineered to very high tolerances, and centrifugal blowers which use a squirrel-cage type blowers and take advantage of flow inertia. So why doesn't anyone in the automotive industry use an axial-type fan like this set up? Because you can't significantly raise the pressure of the down stream flow with an axial fan!

To prove this to yourself, put your hand over the end of a blow dryer. Does it raise the pressure and try to push your hand off? Or does it squeal, overspeed, and quickly burn up? And a hair dryer is running off of 120V A/C from a nuclear plant, a whole lot more power than you're going to get from a little battery pack or even the engine of a dirt bike. In fact, you can't spin an axial flow fan fast enough to raise the pressure on the downstream side. If you try, you just get stagnation and no air flows at all. The same effect is called stall in aerodyamics and it makes planes CRASH.

This is complete B.S. The fluid dynamics behind this product are about like those that support perpetual motion machines. The most likely situation is that the fan, housing, and associated hardware will actually significantly obstruct air flow. If it does anything beneficial, it might reduce turbulence and cause the air stream to swirl. Certain tests have shown in increase in efficience with a swirling air stream. But if you wanted that you'd be much better off with fixed system that not only would take up much less space, but cost about 10X less.

The final evidence: if it worked there would be dyno runs showing the measured increases in power. Where are they?

Keep Ridin',

John

Of all the stuff I've read on this thread (all of it), this makes the most sense.:thumbsup:

My take on the product is that it doesn't actually provide the boost a real turbo or supercharger would, but it makes it easier for the engine to inhale its fuel. Less power is lost as the engine sucks in the fuel, so more power can be put to the ground. It's not a massive gain, but it could definetly make the bike more responsive and pull a bit harder.

Is it worth $250? Not to me, but only because this thread is my only exposure to the product, and this thread has been a JOY to read, let me tell you :thumbsdn: . I agree with tranqwhl, some of you guys were total jerks to the dude who designed and built this thing. At least he's out there experimenting with different ideas and seeing what will work and what won't, rather than sitting on the couch waiting for someone else to do it. Based on the actual review of the product it seems to do some good things, so why doubt it now?

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...what is the cfm rating of this fan at 5000 rpm?

The website says 200 CFM (with no backpressure).

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Based on the actual review of the product it seems to do some good things, so why doubt it now?

With all due respect to kelstr, his review - assuming that's the review you're speaking of - is worthless for the simple fact that he made substantial changes to the carburetor at the same time that he mounted the fan. The jetting changes alone could easily, and probably did, account for the performance gains he felt.

I dunno.....I guess if people want to throw their money away on this thing it's their business. If after reading this thread and the excellent technical evaluations posted by grayracer513 and CRM114 (among others) they still think this thing is a worthwhile investment, there's not much more anyone can do for 'em, is there?

-B

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With all due respect to kelstr, his review - assuming that's the review you're speaking of - is worthless for the simple fact that he made substantial changes to the carburetor at the same time that he mounted the fan. The jetting changes alone could easily, and probably did, account for the performance gains he felt.

I dunno.....I guess if people want to throw their money away on this thing it's their business. If after reading this thread and the excellent technical evaluations posted by grayracer513 and CRM114 (among others) they still think this thing is a worthwhile investment, there's not much more anyone can do for 'em, is there?

-B

You would have to find the optimal jetting for stock and dyno it then find the optimal jetting for the fan and dyno it again, but by the time you do all this, the dyno may not be accurate anymore. :banghead:

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You would have to find the optimal jetting for stock and dyno it then find the optimal jetting for the fan and dyno it again, but by the time you do all this, the dyno may not be accurate anymore. :banghead:

Bingo... and that is the problem with this particular type of blow-through system. As has been noted before, the bowl vents are outside of the throttle bore, so any increase in pressure will lean out the mixture.

The mixture can be held somewhat stable IF the fan's "boost" can be held to a consistent level through the RPM range. Unfortunately, using the stator voltage to control the fan speed does not do this... at WOT low RPM the boost is going to be zilch, and at a high RPM shift point, partial throttle, it's going to max out the fan and stall the blades.

Turbos are load-based and are driven by exhaust temperature. Close the throttle even at redline and boost drops to zero. Firewall it at idle and the wastegate will open (unless it's VVT) and exhaust temps skyrocket.

From a standpoint of pure physics, this system can not work. There is a period at the end of that sentence.

If the fan were actually capable of producing even ONE HALF PSI of REAL BOOST under operating conditions, it would blow the fuel out of the bowl from the vents and the engine would not be able to draw fuel from the bowl.

The bowl vents in a carb'd system MUST be maintained at the same OR HIGHER relative pressure as the airbox, and must be higher than manifold vacuum. Positive pressure in the system cannot work on the stock carb configuration.

The swirling/smoothing of airflow COULD be beneficial at WOT, but at partial throttle settings, that nice smooth flow of air going into the carb throat will slam against the flat slide and once again become turbulent as it rolls under it. That is the whole idea of the PowerNow... it helps to smooth airflow at part-throttle openings by limiting the volume of air available to create turbulence, and it works.

Without publication of a dyno run from an independent and impartial source, this product remains snake oil.

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there is a video online where guys taped a leaf blower to the intake pipeing and it actualy made like 30 hp. lol im trying to find the video

hahahahahah

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there is a video online where guys taped a leaf blower to the intake pipeing and it actualy made like 30 hp. lol im trying to find the video

That's funny, but the only reason it worked is because the Civic is fuel injected... ambient pressure has no effect on jetting. The MAF tells the computer how much air is coming in and the ECU adjusts the amount of fuel to maintain the correct mixture.

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So you could install this on the new 08 RMZ450?

Suppose so, but that type of fan isn't going to work any better.

I'm not familiar with the Zuk injection system... if it doesn't have an airflow sensor, then it would not be very different from a carb with respect to a device like this.

On EFI streetbikes, a change of exhaust and intake requires the addition of an EFI computer to correct the mixture... the stock ECU is not programmed to operate outside of "normal" parameters.

My Vulcan 1600 is EFI and has neither MAF nor exhaust O2 sensors.

The Vulcan 2000 and some Honda VTX models have an O2 sensor... I doubt a dirtbike EFI system will be more complex than the system on a cruiser.

FWIW, a popular intake modification on cruisers uses a housing that looks like the scoop on a funny car. A common complaint is that it is difficult to get the mixture correct due to the inconsistencies in the "ram air" effect when moving forward. If the fan were capable of producing any usable pressure, the situation would be similar here.

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