Airboxdeckel-neue Rohre implantiert

Zitat

Original von JCN
Was konstruktives fällt Dir aber auch nicht ein...

Wenn man bedenkt dass ich nur erklären wollte warum die Idee die dickeren Rohre auch länger zu machen so schlecht nicht ist...

Gruß, J-C

:D...man wird sehen

Da hat sich jemand aber richtig gedanken gemacht,und keine mühe gescheut(PLAGIAT aus Australien 8o)

RGV250 Forums: Airbox. Size Of Intakes On Aprilia - RGV250 Forums

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Airbox. Size Of Intakes On Aprilia mine are 30mm
#1 User is online Glennf Icon

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Posted 14 February 2010 - 08:19 PM
Been looking at modding a spare airbox lid I have. ( for the ape )
I was intending putting different size tubes in ( 36mm id ). I measured mine with a ruler and thought they were 32mm.
Got the verniers out today and got them right into the airfeed intake pipes.
result = they are 30mm. ( this is definately an aprilia box lid , as stickers/ numbers are all in place )

I was wondering why they are 30mm , when the carbs are 34mm??
Can someone in the know explain this? surely this restricts air intake??

Also has anyone done any testing with a std lid compared to modded as above? If so, care to share findings?

Thanks in advance.
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Posted 14 February 2010 - 08:43 PM
on my bike I've rebored carbs, and airbox ducts have been rebuild and rebored to the same size of the carbs..36mmPosted Image
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Posted 14 February 2010 - 08:52 PM
Airbox is a reservoir it has a full 360° of revolution to charge. A carb has to deliver its load in about 180° - therefore air intake doesn't have to be as big :)

Next question should be did Suzuki make the intake that size and length for a reason?
Followed by what am I going to change by altering it :uhm:
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Posted 14 February 2010 - 10:49 PM
don't forget that the air box has to be a muffler
the bigger the holes, the noisier the airbox
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Posted 15 February 2010 - 07:53 PM
Does the airbox lid have a divider? The RGV one doesn't. So 2 x ø30mm area.

As MJ says, it's a road bike, so noise is the issue, airflow is of no use if you can't homologate it.

And as MJ also says, flow is constant(ish) relative to the carb, as long as 250cc+/rev can flow then it's adequate.

I would also hazzard a guess that they are just the right area/volume to damp the noise out at whatever the loudest range is - usually low revs, big throttle openings.

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Posted 15 February 2010 - 08:00 PM

View PostGlennf, on 15 February 2010 - 06:19 AM, said:
Been looking at modding a spare airbox lid I have. ( for the ape )
I was intending putting different size tubes in ( 36mm id ). I measured mine with a ruler and thought they were 32mm.
Got the verniers out today and got them right into the airfeed intake pipes.
result = they are 30mm. ( this is definately an aprilia box lid , as stickers/ numbers are all in place )

I was wondering why they are 30mm , when the carbs are 34mm??
Can someone in the know explain this? surely this restricts air intake??

Also has anyone done any testing with a std lid compared to modded as above? If so, care to share findings?

Thanks in advance.

Excellent question. This has been asked many times before with most people saying standard lid is best.
I modified my airbox on my VJ21 with 34mm carbs, i just used pvc pipe with ID of 36mm. I cut off 2 lengths of pipe the same length as the standard pipes in the lid, bored out the old pipes with a hole saw with the same size outside diameter of the new pipes, then glued them in place with some urethane sealant.
Probably not ideal, i didn't make any bellmouth on the end of the new pipes.
The 30mm pipes in the standard airbox probably flow as well as a 36mm pipe with no bellmouth.
I noticed no change at all. No gains whatsoever.

Some people will talk about helmholtz resonator effect from the standard airbox. Load of crap if you ask me, the airbox has a drain hose attached to the bottom of it so any of that effect would be lost. Block that drain hole and it might work.

Only REAL way to find out if the airbox snorkels are too small is to test.

Check this article on how to make a manometer:
http://autospeed.com...25/article.html

I am going to test my airbox with 36mm intake pipes later on this week and I will post the results.
I have done lots of testing before on car intakes with the homemade manometer and the results you get usually blow your mind. What you think works usually doesnt. What looks good enough usually isn't. What looks like overkill isn't.

I'm going to keep modifying my airbox until I find out what size intake pipes are required to allow no restriction.
I think it's also balance between keeping the intake temperatures close to ambient as well. I think you could just cut the hole top off the airbox to let it as much air is needed but whats the point if it ends up drawing hot air from the radiator anyway?
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Posted 15 February 2010 - 08:10 PM

View Postluke111, on 15 February 2010 - 08:00 PM, said:
Excellent question. This has been asked many times before with most people saying standard lid is best.
I modified my airbox on my VJ21 with 34mm carbs, i just used pvc pipe with ID of 36mm. I cut off 2 lengths of pipe the same length as the standard pipes in the lid, bored out the old pipes with a hole saw with the same size outside diameter of the new pipes, then glued them in place with some urethane sealant.
Probably not ideal, i didn't make any bellmouth on the end of the new pipes.
The 30mm pipes in the standard airbox probably flow as well as a 36mm pipe with no bellmouth.
I noticed no change at all. No gains whatsoever.

Some people will talk about helmholtz resonator effect from the standard airbox. Load of crap if you ask me, the airbox has a drain hose attached to the bottom of it so any of that effect would be lost. Block that drain hole and it might work.

Only REAL way to find out if the airbox snorkels are too small is to test.

Check this article on how to make a manometer:
http://autospeed.com...25/article.html

I am going to test my airbox with 36mm intake pipes later on this week and I will post the results.
I have done lots of testing before on car intakes with the homemade manometer and the results you get usually blow your mind. What you think works usually doesnt. What looks good enough usually isn't. What looks like overkill isn't.

I'm going to keep modifying my airbox until I find out what size intake pipes are required to allow no restriction.
I think it's also balance between keeping the intake temperatures close to ambient as well. I think you could just cut the hole top off the airbox to let it as much air is needed but whats the point if it ends up drawing hot air from the radiator anyway?

I await your testing results.
My bike is track only / not bothered about noise, ( its only 98db's with tygas on! )
Thanks guys for all the input.
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Posted 15 February 2010 - 08:43 PM
Thumbs up for noise :spoton:
I'm so far away that looking behind i see..the future
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Posted 15 February 2010 - 09:00 PM

View Postluke111, on 15 February 2010 - 08:00 PM, said:
Some people will talk about helmholtz resonator effect from the standard airbox. Load of crap if you ask me, the airbox has a drain hose attached to the bottom of it so any of that effect would be lost. Block that drain hole and it might work.

Helmholtz principles work on relative volume, not pressure, within a vessel with a narrow opening, so drain holes etc don't have much effect on the whole. Helmholtz resonanse doesn't strictly apply to airboxes - unless they have damping plenums attached - as the flow is cyclic and through them rather than past them, though the equations will give you the resonant frequency.

A sharp cornered tube will restrict flow proportionally to the area of wall to tube area. Any radius is better than none. The airbox intakes are slightly tapered an all.

The big issue with the RGV/RS box is where it draws from, about the worst place really, tucked up in what becomes a low pressure region under the tank that gets a good flow of heated air from rad/motor. Not a bad thing for a road bike in winter I guess. It's other problem is it's just stuck where there was space for it, it's supprising how much extra volume you can gain by just making it fit the space available.

Make a front feed box (see Barry b's thread in the F250 forum) and see and feel the difference it makes. Don't think it helps the motor make any more power, just you don't lose any through low airflow/pressure into the airbox once air starts flowing over the bodywork/you. Barry's will blow the lid off under the pressure of a dyno fan, and my somewhat more amateur effort blows the drain hose blank of the bottom of the airbox at anything over 100ish if it's not clamped on.

HTH

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Posted 15 February 2010 - 10:36 PM
Just a couple of comments Jim.

The diameter of the opening does not have to be narrow, it depends on the relationship to it's volume and neck length.

What it does have to be is effectively sealed, so you can't have any drain tubes etc open to atmosphere.

Helmholtz principles apply equally to airboxes as much as they do to anything else.

The air doesn't have to flow past them.

For the entire duration of the reed being closed ie for about 50% of the cycle, the airbox acts as a sealed chamber as far as the reeds on the intake side. It is this effect that can be used to allow a pressure wave caused by the Helmholtz effect in the airbox to act as 'cheap supercharging' when the reed initially opens.

Don't know what damping plenums have to do with it, you don't want it damped.

Other than the above though, pretty accurate.

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Posted 16 February 2010 - 03:38 AM

View Postrgv250geoff, on 16 February 2010 - 08:36 AM, said:
Just a couple of comments Jim.

The diameter of the opening does not have to be narrow, it depends on the relationship to it's volume and neck length.

What it does have to be is effectively sealed, so you can't have any drain tubes etc open to atmosphere.

Helmholtz principles apply equally to airboxes as much as they do to anything else.

The air doesn't have to flow past them.

For the entire duration of the reed being closed ie for about 50% of the cycle, the airbox acts as a sealed chamber as far as the reeds on the intake side. It is this effect that can be used to allow a pressure wave caused by the Helmholtz effect in the airbox to act as 'cheap supercharging' when the reed initially opens.

Don't know what damping plenums have to do with it, you don't want it damped.

Other than the above though, pretty accurate.

Geoff (Slim) Posted Image

Geoff - what was the pressure of the pulse wave front in the Helmholtz box you made? (calculated or measured either will do)

Only asking because modern sportsbike RAM air will increase airbox pressure on average (across different brands) about 12 mbar.

*Note- This is not an attempt to rehash old debates, just interest.
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Posted 16 February 2010 - 08:28 AM
Was hoping to do some testing today but it looks like the rain has set in.
Im going to rig up a smaller manometer to measure the restriction inside the airbox. Im going to just make a small one that reads around 12" of water, i'd be surprised if there is anymore restriction than that. I'll just make an adapter and connect it to the airbox drain, this should give an average of both sides of the airbox.

The manometer I have made already reads up to 42" of water! Its about 1 metre high, it would look a bit weird riding around with that strapped to the petrol tank. I don't have the luxury of a dyno so Ive gotta do all my testing "out tha road".

I've got a digital temperature meter with 2 * thermocouples. I did some testing on the weekend to check the difference between intake air temperature in the top of the airbox versus ambient temperature.
I didn't know what to expect but I was very happy with the results.
I don't have the duct attached the the left fairing with the pipe running up the the back of the airbox on my bike (the one that directs cold air up there). Never got around to fitting it since rebuilding my bike.
It was 30deg C during testing, hottest air temperature I saw was 8 degree's above ambient. Remember this is with standard airbox sucking air from under the fuel tank.
Pretty impressive figures, most cars don't get any where near that.
It seemed that the faster the bike went, the hotter the air temperature got. When I slowed back down to a stand still, temps dropped immediately to 2 degrees above ambient and then 1 degree above. Cruising at 100km/h in top gear gave 4deg C above.
I figure the airbox is sucking air that has passed thru the radiator.
Going to fit the left ducting & pipework and re-test this week. Will return with results.
I think there would be very minimal - zero gained by reducing intake air temps by 8 degress, but i'll keep fiddling anyway.
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Posted 16 February 2010 - 08:52 AM
I've got 34 mm pipes in the airbox, same lenght as original. My bike has always made very healthy power with it but it's not the only mod so hard to say how much it contributed.

I know Guido Furster in Germany used this mod and he made race winning RS250's

I've never believed in drilling holes in the lid.

This post has been edited by redmer: 16 February 2010 - 08:54 AM
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Posted 16 February 2010 - 09:29 AM

View Postash33, on 16 February 2010 - 01:38 PM, said:
Geoff - what was the pressure of the pulse wave front in the Helmholtz box you made? (calculated or measured either will do)

Only asking because modern sportsbike RAM air will increase airbox pressure on average (across different brands) about 12 mbar.

*Note- This is not an attempt to rehash old debates, just interest.

12mbar = 4.8" of water & 0.17psi & also = 2 tenths of fug all

If suzuki wanted the airbox to work as a helmholtz chamber they wouldn't have put a drain (HUGE LEAK) in the bottom of it.

I'm also interested in finding out the pressure drop through the standard air filter. I bet its only 1" of water - maybe not even measurable.

I did notice induction noise did go up with bigger pipes in the airbox lid.
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Posted 16 February 2010 - 09:48 AM

View Postluke111, on 16 February 2010 - 10:29 AM, said:
12mbar = 4.8" of water & 0.17psi & also = 2 tenths of fug all

If suzuki wanted the airbox to work as a helmholtz chamber they wouldn't have put a drain (HUGE LEAK) in the bottom of it.

I'm also interested in finding out the pressure drop through the standard air filter. I bet its only 1" of water - maybe not even measurable.

I did notice induction noise did go up with bigger pipes in the airbox lid.

12 mbar is only 0.8" of water and 0.029 psi... still f all...
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Posted 16 February 2010 - 10:21 AM

View Postash33, on 16 February 2010 - 04:38 AM, said:
Geoff - what was the pressure of the pulse wave front in the Helmholtz box you made? (calculated or measured either will do)

Only asking because modern sportsbike RAM air will increase airbox pressure on average (across different brands) about 12 mbar.

*Note- This is not an attempt to rehash old debates, just interest.

Appreciate the interest Ash.

To be truthful I have neither measured nor calculated it ..... yet. But, it doesn't take a great pressure, only that it is above atmospheric to assist charging.

However, my main interest in exploring it is that it is dependent on rpm, not the relative speed of the bike. So, the resonator when tuned will produce positive pressure waves around a small range of revs in every gear. So, it should improve drive, not just top speed.

On the other hand, ram air only starts to work with increased speed and will have a variable effect on airbox pressure that may or may not be linear. I suppose the contra question to yours is 'at what speed did they measure the 12 mbar'?

Geoff (Slim) :)
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Posted 16 February 2010 - 07:42 PM
Slightly off topic, but does teh bottom end have a helmholtz resonance?

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Posted 16 February 2010 - 08:13 PM

View Postluke111, on 16 February 2010 - 09:29 AM, said:
If suzuki wanted the airbox to work as a helmholtz chamber they wouldn't have put a drain (HUGE LEAK) in the bottom of it.
the drain is also a part of the helmoltz
an helmoltz is only a simple weight/spring system. if you add a hose, it will add little bit of weight in the resonant system

some hoses have a kind of valve

if the hose is very little in diameter and very long, that will not modify the helmoltz frequency
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Posted 16 February 2010 - 10:29 PM

View Postrgv250geoff, on 16 February 2010 - 08:21 PM, said:
Appreciate the interest Ash.

To be truthful I have neither measured nor calculated it ..... yet. But, it doesn't take a great pressure, only that it is above atmospheric to assist charging.

However, my main interest in exploring it is that it is dependent on rpm, not the relative speed of the bike. So, the resonator when tuned will produce positive pressure waves around a small range of revs in every gear. So, it should improve drive, not just top speed.

On the other hand, ram air only starts to work with increased speed and will have a variable effect on airbox pressure that may or may not be linear. I suppose the contra question to yours is 'at what speed did they measure the 12 mbar'?

Geoff (Slim) Posted Image

This is a direct cut & paste from Sports rider mag. of the best and worst form of the

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KAWASAKI ZX-7R: Kawasaki was the pioneer of ram-air induction on sportbikes, and this graph shows why. Compare this graph (and the ZX-9R's) with all the others. Note that there are virtually no pressure spikes during shifts. And airbox pressure builds past ambient at approximately 60 mph, not 90 or 145 mph-just a smooth crescendo up to a peak of approximately 23mb. Kawasaki builds all sorts of aircraft, and that experience is obviously trickling down to the motorcycle division.

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YAMAHA YZF-R6: First up was Yamaha's 15,500 rpm YZF-R6. Note that the pressure drops below zero-that is, below ambient pressure-accelerating through second gear, and it finally builds once the bike gets past 85 mph. The spikes (present in all of the graphs) represent pressure buildup during shifts, since the throttle plates are closed momentarily. Pressure peaked at 17mb.

Finally here is the control run with a bike not using RAM air
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KAWASAKI ZRX1100: As a test control, we fitted the Pi System to a non-ram-air-equipped motorcycle. If you think figures like 17mb seem insignificant, take a look at how much vacuum is present in a regular airbox and you'll realize even that amount of positive pressure can make a huge difference. With a pressure of -27mb, it's obvious that power gains can be realized by converting that vacuum into positive pressure.

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#20 User is offline luke111 Icon

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Posted 17 February 2010 - 10:42 AM
I got motivated today after work & fitted the air duct that runs from the fairing up beside the airbox which vents fresh air up around the airbox intakes.
I used my digital thermometer QM1600 - not cheap just so you know my results are accurate.
same test route as before - very similar conditions, this time was 28deg C, this time got up to 10degrees above ambient!
Also noticed this time temps didn't drop at a standstill stayed at 8 or 9 deg C above, cruising at 100kmh stayed around 8 degrees above. 80kmh following some other cars gave 10 degrees above.
Even ran the bike up to about 170-180kmh and still 9 degrees above ambient.

I have proven that duct does nothing to reduce intake air temperature. I think that maybe it is actually there to cool the battery and not the intake air?
Most cars these days have air scoop directing cold air onto the battery.

Next I will test the pressure difference. Maybe it is there to increase the pressure in the low pressure area under the tank.
I will also test the pressure inside the duct to see how much pressure is actually produced. Probably very little.

Also found this website Bellmouths
they have a good selection and very reasonable price.

The other thing you may notice from the pics is that the bigger pipes are pretty close together and if bellmouths were used they would probably have to be cut on the inside edges and blended together or inserted pointing outwards so they didnt touch in the middle.
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