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Discussion Starter #1
Has anyone modified the air snorkel that comes off the air box? It seems that if the front section of the snorkel was removed it would give a slightly larger opening to allow a bit more errand. For such a large engine it has a very small air intake
 

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Has anyone modified the air snorkel that comes off the air box? It seems that if the front section of the snorkel was removed it would give a slightly larger opening to allow a bit more errand. For such a large engine it has a very small air intake
I am not sure what part you mean. The part up inside the fairing? My concern would be that BMW has likely placed the intake in an area of high pressure to get a ram effect at higher speeds. Cutting it shorter might increase the cross section, but might move the intake out of the high pressure area.
 
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Discussion Starter #3
Yes thats the part im referring to....the long tube that extends to the front of the bike. I thought about removing the smaller part where there is a muffler like device and extending the larger diameter area with some larger diameter tubing
 

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Discussion Starter #4
Yes, the front tube that connects to the air box. Right before that muffler like part the tube is larger in diameter. I believe if that muffler heart is removed and a suitable extension is made there may be some improvement
 

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Yes, the front tube that connects to the air box. Right before that muffler like part the tube is larger in diameter. I believe if that muffler heart is removed and a suitable extension is made there may be some improvement
I would be surprised if there is any improvement given the level of engineering BMW invests in both engines and wind tunnel testing. However, if you have access to a dyno, give it a shot and let us know the results.
 

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If I had access to a dyno, I would first simply remove entire air box and do a test with and without to see if there is significant air restriction before I went trying to engineer something that as Voyager said, would very likely make no detectable real difference but I am not an engineer. If you do make changes, do document them especially of you find a significant improvement that can be demonstrated.
 
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I would be surprised if there is any improvement given the level of engineering BMW invests in both engines and wind tunnel testing. However, if you have access to a dyno, give it a shot and let us know the results.
I would not be surprised if there was an improvement. A standard upgrade for the K1200R is to add the second snorkle from a K1200S since the K1200R only come with one snorkle and the airbox is otherwise identical.
 

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Discussion Starter #8
So I remove the front section and measured the difference in diameter. The front section has a diameter inside of about 1.75 inches. The back part of the snorkel has a diameter of 2.25 inches.

That may not seem much to the non mathematical people. But the area of a circle is pi r squared. If you plug those numbers in that formula you will find that the smaller front part has an area of 9.62 square inches. The back part has 15.9 square inches which is 60% larger in area even though the diameter is only half an inch more.

I'm fabricating a tube out of carbon fiber that will be slightly larger then the back part. It will speed up at the front like the original part except it won't have that built-in Muffler and it will be much larger in diameter. I'm waiting for the resin to dry and I will keep you all posted
 

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If you don't do dino tests, how will you know if there is any significant gain? I remember turning the top of the breather on my 68 Plymouth 2 barrel upside down with the expectation it would allow better air flow. In actuality, the oval opening on the side of the breather was larger than the the 2 barrels venturi so all it did was make more noise. Sounded cool but did nothing. There is no shared manifold on the LT so it will pull individually from each TB and I suspect that the opening is larger than any one of the TB openings. Maybe you could do some vacuum tests if you have anything sensitive enough to measure the air box with both attachments one at a time. A crude measure of improvement but possibly measurable. Also, I suspect the only improvement may be realized only at full throttle and I rarely run my LT wide open for any length of time as it isn't a track bike. Still interested in your project though.
 

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Discussion Starter #11
The throttle bodies' combined opening cannot possible be smaller than the original snorkel opening size. Ill measure them tomorrow.

As indicated above, the K 1200 r came with one snorkel and the K 1200 S came with two and a common modification is to add the second snorkel on the r model. This means that the BMW Engineers didn't necessarily engineer the snorkels for maximum power.

My carbon fiber has dried some and I pulled it off the mold that I used which happened to be a bathroom cleaner spray can that was the right diameter that I needed and approximately the right length. Tomorrow I will put some resin on inside and out to make it more solid. It won't be pretty but it will definitely be functional I believe. Ill keep you posted.
 

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The throttle bodies' combined opening cannot possible be smaller than the original snorkel opening size. Ill measure them tomorrow.

As indicated above, the K 1200 r came with one snorkel and the K 1200 S came with two and a common modification is to add the second snorkel on the r model. This means that the BMW Engineers didn't necessarily engineer the snorkels for maximum power.

My carbon fiber has dried some and I pulled it off the mold that I used which happened to be a bathroom cleaner spray can that was the right diameter that I needed and approximately the right length. Tomorrow I will put some resin on inside and out to make it more solid. It won't be pretty but it will definitely be functional I believe. Ill keep you posted.
I wasn't talking about the combined in this case as each of the 4 TB opens onto its own cylinder port and each one draws at a different time so only one of the 4 will be applying vacuum to the air box at any one time unlike a shared manifold of a modern car. So the question is, is this really a significant restriction more so than the air filter itself? If the diameter of a single TB opening is the same as the opening on that piece of plastic, and you aren't changing the displacement of the air being drawn in, will there be any difference? Still hanging with something that can be measured indicating some positive gain for the effort. I know the front of the tube forms a venturi so let the engineers chime in. Does this venturi serve to cool the air being drawn in from the venturi effect and in changing that engineered opening, are you affecting the temperature of the air, possibly in a negative way?
 

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Discussion Starter #13
The inner diameter of each throttle body is one and seven eighths of an inch which is slightly larger then the inner diameter of the original snorkel. The new snorkel which I made out of carbon fiber is about two and a half inches in inner diameter and tapers down to two and a quarter inches to hopefully give a ram effect.





 

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If you don't do dino tests, how will you know if there is any significant gain? I remember turning the top of the breather on my 68 Plymouth 2 barrel upside down with the expectation it would allow better air flow. In actuality, the oval opening on the side of the breather was larger than the the 2 barrels venturi so all it did was make more noise. Sounded cool but did nothing. There is no shared manifold on the LT so it will pull individually from each TB and I suspect that the opening is larger than any one of the TB openings. Maybe you could do some vacuum tests if you have anything sensitive enough to measure the air box with both attachments one at a time. A crude measure of improvement but possibly measurable. Also, I suspect the only improvement may be realized only at full throttle and I rarely run my LT wide open for any length of time as it isn't a track bike. Still interested in your project though.
Because it will "feel" faster and probably be louder which most equate with higher performance.

If there is any benefit, it likely would be only at WOT at slower speeds when there is little ram effect. However, there will also very likely be a loss in low and mid RPM performance as the velocity of the air entering will be less. This velocity helps charge the cylinders as each intake opens. That is why it is common to see the same engine be fitted with smaller valves and throttle bodies when moved from a sporbike to a touring bike. Charge velocity matters at lower RPMs.

Without a dyno, the results will be imperceptible. And probably nearly imperceptible on a dyno, but I would bet a dyno would show broad low and mid-range loss in order to gain a little at high-rpm WOT operation.
 

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Each cylinder on the newer LT makes about 30 HP & that is what matters on the size of the intake snorkel. The size of the engine is irrelevant. 30 HP needs a certain amount of cubic feet per minute of air to achieve that. Anything over the size of the required snorkel size to make 30 HP per cylinder will do nothing to enhance horsepower.
 

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Each cylinder on the newer LT makes about 30 HP & that is what matters on the size of the intake snorkel. The size of the engine is irrelevant. 30 HP needs a certain amount of cubic feet per minute of air to achieve that. Anything over the size of the required snorkel size to make 30 HP per cylinder will do nothing to enhance horsepower.
And that only matters at WOT at one specific rpm. The rest of the time things like charge velocity and tuning for pressure pulses can have far more performance impact than cross sectional area of the intake.

People forget that dyno data is almost always taken at WOT, whereas in the real world we seldom ride at WOT.
 
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