Variables in intake mods

[Dirtybill]

This thread is dealing with intake snorkels and ram air. The "Hans" is an aftermarket snorkel which is availabe for the ZX-12R.

 

Doug Meyer builds race engines for Muzzy.

 

http://www.bikeland.org/board/viewthread.p...=1829&set_time=

 

http://www.bikeland.org/board/viewthread.p...=8980&set_time=

[al_roethlisberger]

keeeee-rap, I have to login to get to those threads.... yet another login

 

Any chance you can summarize their findings/thoughts? I hate to dig through another thread on another board.... yeah, I'm lazy

 

al

[Dirtybill]

I'd have to have a degree in physics to understand half the stuff

 

I asked in the 2nd thread if Ram Air only works at high speed. According to Doug Meyer, it "works" (bad term, I know) at all speeds but how much it helps varies with speed.

 

The first thread I posted gets into 3 or 4 pages of very involved testing of the Hans snorkel compared to the stock snorkel on the first year ZX-12R. Apparently Kawasaki changed the snorkel shape, position and size for the 02 model.

[al_roethlisberger]

.....ahh, a "ram air" thread.... yeah we've "been there, done that"

 

"Ram Air" Thread

 

"Sewer Pipe" Ram Air Modification Thread

 

 

As I mentioned in the threads above, I had a couple fairly long-winded conversation with various engineering-types, and they were quite adamant about the "hype" of ram-air on a motorcycle, at the speeds any of us would normally ride, and considering the miniscule size of the inlets on these bikes.

 

Much of this is open to debate of course, because for some people the degree of performance gain, even if very small and at very high speeds, lends some credibility to their claims and endorsement of the solution. But specifically to Guzzis, Will Creedon, et al... have said that their experiments with Sport1100s and ram-air have proven no real benefit, and in some cases a detriment if airflow isn't well controlled.... and in many bikes, it isn't.

 

I think that in our case, with the V11 setup, the only real advantage.... and I think that this is a real one, is any extension that can get the air inlets away from the hot engine components. The OEM snorkels do a poor job of this, to put it kindly

 

So, extensions like Evoluzione's old(discontinued) kit that put the filters up in the fairing, or pods, do this quite well. Other mods like the "sewer pipe" extension probably help some, but they are still awfull close in proximity to the hot air around the cylinders and exhaust, to it's still not optimal.

 

Anyway, that's my opinion As always, YMMV, and in any case even under the best circumstances, the potential gains are small.... so do whatever you think is neat. It won't hurt You just won't get a 100RWHP out of any of these mods though

 

al

[gthyni]

There was a long discussion on ram air in the swedish sportbike forum -

www.sporthoj.com - no link since it all in swedish.

There was an actual calculation of the effect of a normal ramair

configuration. The result was ta-ta-damm:

 

2% at 200 km/h

4% at 300 km/h

 

If you get more the design of your airbox probably stinks

 

That is 7 hp at top speed on a Hayabusa

at that speed aerodynamics are more inportant than power.

[al_roethlisberger]

.... at that speed aerodynamics are more inportant than power.

 

...that was also an important point many had made in my conversations.

 

If one could get enough of a "ram air" effect, the trade-off in poor aerodynamics made it a losing proposition, or at best break-even...

 

al

[dlaing]

If one could get enough of a "ram air" effect, the trade-off in poor aerodynamics made it a losing proposition, or at best break-even...

What trade off?

The Guzzi is an excellent candidate for Ram Air.

The space between the cylinders is wasted space that aerodynamic design would be hard pressed to improve on.

When you take the lid off the air box, you immediately get some ram air effect.

I would like to build walls to funnel the hot air past the cylinder heads, to shield the wiring, fuel hoses, etc. from the heat, and yes, to raise the air pressure at the air filter intake.

If an air filter makes a difference to performance, so can ram air.

True sticking a pair of 1.5 inch diameter tubes into the head stream of air will not raise the pressure enough to increase HP significantly.

But Putting two 6 inch diameter tubes into the head stream will increase the pressure and HP, more significantly.

Put your hand out into the air stream at 70mph and tell me that that pressure will not negate the resistance of the air filter.

[gthyni]

> When you take the lid off the air box, you immediately get some ram air effect.

 

No, how could it be,

the "snorkles" is pointed forward/downward under the tank

an airbox without the lid is less ram air but more free flow of air.

 

ram air does increase HP

- a litte bit

- at very high speeds.

Most of us does not run over 200 km/h (= 125 mph)

and at that speed the increase should be 2% => 1.8 HP at peak power.

 

The air box of the V11 is not a good design as it restricts air,

the power gains people get by just remove the lid proves that.

My air box is in storage

[al_roethlisberger]

If one could get enough of a "ram air" effect, the trade-off in poor aerodynamics made it a losing proposition, or at best break-even...

What trade off?

The Guzzi is an excellent candidate for Ram Air.

The space between the cylinders is wasted space that aerodynamic design would be hard pressed to improve on.

When you take the lid off the air box, you immediately get some ram air effect.

I would like to build walls to funnel the hot air past the cylinder heads, to shield the wiring, fuel hoses, etc. from the heat, and yes, to raise the air pressure at the air filter intake.

If an air filter makes a difference to performance, so can ram air.

True sticking a pair of 1.5 inch diameter tubes into the head stream of air will not raise the pressure enough to increase HP significantly.

But Putting two 6 inch diameter tubes into the head stream will increase the pressure and HP, more significantly.

Put your hand out into the air stream at 70mph and tell me that that pressure will not negate the resistance of the air filter.

 

 

Dave,

 

...I'm no aeronautical engineer, but I did speak at length with several folks on a couple Guzzi lists that were, and as is apparently pointed out on the link to the ZX-12 forum... many there also concur that "ram-air"(note: not meaning, redirected plumbing to get colder air to the intake) really isn't noticeably effective at normal(sub ~200MPH+ speeds) unless one had a HUGE air scoop to gulp, then compress air, to make a true "ram air" effect. And at those low speeds, if one had a HUGE scoop.... the "trade off" in aerodynamic losses by having that huge scoop would more than offset any gains in HP... and probably actually slow one down enough to actually lose top-speed and any potential resultant HP gains. At the speeds we ride, the consensus was that it was a circular example of diminishing returns. HighSpeed->RamAir needs ->BigScoop=AeroDrag=SlowSpeed=LostPressure=LostHP... need HighSpeed... here we go again *whew*

 

At least that's what I've been told by several engineers.

 

Bottom line, we just don't travel at high enough velocities to make "ram-air" work, especially given the relatively small surface area of the front of our bikes. We'd need a "scoop" as big as our fairing to make any appreciable "ram-air" effect.

 

 

Now, again, there however is some advantage to be made by improving the efficiency of the flow we do have, and by rerouting the "plumbing" to get cooler air to the intake. But it's important to make the distinction between this, and "ram-air" which are different animals.

 

From most knowledgeable AE folks that are also motorcyclists that I've spoken to, "ram-air" even on race-rep production bikes... is all about marketing. More than anything, it's just a convenient place to route the air snorkel, in a cool and hyped fashion. It would be just as effective under the nose, hidden.

 

 

al

[dlaing]

I rode back from the prescott rally fighting a 30MPH head wind and I could not get the bike to go over 110 Veglia MPH which made it a bitch to catch up to my pack of riding buddies after I had to pull over to tighten up my tank bag.

I am sure that a not so HUGE scoop with maybe 50 square inches of frontal area placed between the cylinder heads would have boosted the air pressure enough to give me another 5 MPH or atleast get better MPG under the conditions compared to the stock scoops.

Yes, I would have to move the oil cooler to where is is on the Griso or the V1100Sports, where it might not be as aerodynamic.

But there is room for power gains, especially compared to the stock semi-ram air scoops.

The stock scoops on our bikes are a lousy design.

Putting pods behind the cylinders is a lousy design compared to ram air, but it has a beautiful simplicity and unless a dyno has air velocity compensation(a big variable speed fan) it will not show the comparative gains of ram air.

The Sportis had a lousy ram air design.

The angle at which the V1100 Sport intakes were placed probably creates about as much Venturi vacuum as it does positive pressure. Also the intakes were too small to see gains.

50 square inches (5x10 rectangle or two 5 inch diameter circles) of frontal area on a Hayabusa might restrict aerodynamics.

On my open faired bike it will not make a difference to the aerodynamics.

I am not an engineer, but I would predict about a 10% increase in HP compared to the stock setup at 150 MPH of wind. You may never hit that type of air speed, but if you did, you would want all the HP you can get.

And the beauty is that you could make the system out of $20 in plumbing supplies, although trashing the stock intake system and making a two into two, X crossover, carbon fiber system with large forward mounting pods, could produce the greatest gains.

[al_roethlisberger]

...well, YMMV

 

... and as you say, at 150MPH maybe you might see a little boost in peak HP under ideal circumstances I just don't know anyone who rides at that speed, except the Moto Guzzi LSR team and they only reached ~138MPH

 

Oh, and interestingly, those guys... whose sole goal is top speed, don't use "ram-air" at all. In fact, they rely on an enlarged airbox on the LeMans, and have removed the fairing on the Sport1100 they sometimes run, and simply extended hoses to get fresh-air to the air-box. At those high speeds, as you point out, it's actually quite difficult to design an airfoil and scoop design that doesn't actually increase turbulence and decrease effeciency. High HP, esp at high speeds, actually benefits more from a large volume of constant pressure, still air. So in reality, a larger air-box is generally a better benefit. But we all hate air-boxes, so

 

...but my opinion, and the engineers' I've spoken to on the subject, suggest it's unlikely one would ever normally reach nor ride consistently at those elevated speeds to make the "ram-air" excericise worth-while. As it is only at those ~150/200mph+ speeds one would note any measureable gain.

 

Feel free to experiment with it though, and I'm sure that if you have access to a wind-tunnel(which is what you would need in coordination with the dyno to truly evaluate the results) we would love to see the outcome.

 

I'd love to be proven incorrect, especially if one could show improved performance at the normal speeds (~70-90MPH) we all ride on a day-to-day basis.

 

Keep in mind, I'm only parroting what I was emphatically told by several folks with engineering backgrounds, after I was quite the proponent of "ram-air" myself a while back. You sound like me 18 months ago

 

Good luck

 

al

[Guest Jeff Kelland]

Oh hell, why not....Stop thinking pressure and start thinking resonance, intake resonance. I read an article in one of the major cycle magazines (sorry, can't remember which one) that dyno tested the effect of ram air on several bikes and found that the air stream through the air box gets all messed up when the intake valves close and send reverse pressure waves back through the box. The pressure in the air box spikes up and down dramatically, interupting smooth flow. One solution is a bigger air box, i.e. remove the lid, or even bigger remove the box and install pods. This can negate however the gains made in smooth air flow controlled by shaped intake systems that pull cool air from a nice high pressure source and shape it into a nice smooth stream of air that provides a big slug (think mass) of fresh breath to the cylinder. What the testing in that article seemed to find, was that ram air had a good effect on stabilizing the pressure in the air box thereby reducing the damage done to flow by intake resonance. Aerodynamics, part science, part black magic!

[Mike Stewart]

Bingo Jeff I couldn't of said it better!

 

Mike

[dlaing]

Aerodynamics, part science, part black magic!

Mostly black magic to me.

I think trial and error is a better technique than science.

I have little idea what resonance is.

But apparently the snorkels on this bike were part of the equation for 152MPH.

[Mike Stewart]

Better watch out for low flying sparrows!

 

Mike