Dual Ram air intakes for H2? - Page 2 - Kawasaki Ninja H2 Forum
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post #11 of 21 Old 03-30-2019, 12:19 PM
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Originally Posted by Richarddps19 View Post
So do you recommend sealing those holes and removing charcoal box?
The charcoal box is only for evpaporative emissions and does not effect HP in the slightest. Just adds a bit of weight. They were a problem on carburated bikes because if they got fouled with fuel the carbs couldn't vent properly. But on FI it is less of a problem.

After thinking about it, the holes in the intake tube probably don't effect the ram air too much at high speeds. The air flow would build pressure in the tube behind the holes and only excess would be allowed to escape. And I have a feeling with the SC there is no excess.
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post #12 of 21 Old 03-30-2019, 12:21 PM Thread Starter
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Bob with all due respect that's wrong. A centrifugal blower is very affected by restrictions on the suction side of its intake. A positive displacement pump or roots type blower is less so. You want the air going to the blower to have the least amount of restriction as possible. A little ram effect or positive pressure is even desirable! Also, keep in mind that more boost (Pressure) does not necessarily equal more power. It could even result in less power.
I do agree charge cooling would be of benefit.
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Because this bike uses forced induction uncovering the second air intake, even if it were possible, would make little difference to the boost level and resulting peak power of the H2.

Charge cooling is probably the best thing to do. Also raising the engine rpm limit and installing higher gearing for the supercharger, if you want to take the risk.
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post #13 of 21 Old 03-30-2019, 05:06 PM
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From the service manual.

The nets [A] (stainless steel) positioned over intake fun- nels.
Top injectors spray onto nets.
- Ordering effect >> intakes air-fuel mixture uniformly
- Promotesfuelmisting>>coolsintakeair,increasingfill ing
efficiency
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post #14 of 21 Old 03-30-2019, 10:32 PM Thread Starter
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I wonder why there are holes in the ram air intake tube? Could it be that the sealed tube doesn't flow enough air and is a restriction? Are the holes like a secondary intake? Seems strange....
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post #15 of 21 Old 03-31-2019, 02:49 PM
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Re the holes in the air intake tube:


1. They won't significantly affect ram-air pressure. At high wind speed, there is more air volume trying to be rammed into the single ram-air inlet than the engine can draw in. A little bit of overflowing through those holes won't matter. Do the following experiment: Take a paper cup, poke a hole a few millimeters diameter in the bottom of it, hold it in a stream of water from a faucet so that the cup is overflowing by 2 or 3 times as much water as is going out the hole in the bottom. Now poke a pinhole in the side of it. What happens? A bit of water comes out the pinhole, a bit less overflows, what comes out the bottom stays the same.


2. They provide an alternate air intake path in the event that the front ram-air inlet gets blocked (e.g. you strike a wayward plastic bag or some such thing while riding.)


It's entirely possible that there is some other more esoteric purpose to them ... acoustic/noise control, damping out some critical resonance frequency, etc.
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post #16 of 21 Old 03-31-2019, 03:00 PM
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cooling the under tank area
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post #17 of 21 Old 03-31-2019, 09:19 PM
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GoFaster, the cup/water analogy is not quite right for a few reasons. The six holes holes in the air tube are each 3/4" or about 19mm if you add up all that area you get just over 17 square centimeters (2.65 square inches). So in the cup analogy if you have a hole in the bottom of the cup then you would put a relatively gigantic hole in the side almost the same size as the top of the cup itself. ...all your Ram Air Pressure is leaked out path of least resistance to atmospheric pressure. The math for discovering pressure in a tube is the same for water in a pipe and electricity in a wire. In electrical terms this is called a shunt or short to ground. Air pressure us shunted to atmospheric pressure by the very large holes and downstream air tube pressure can never be higher than the pressure at the holes.

I do believe the holes are there in case a plastic bag finds its way onto your air duct inlet at full power. which if you think about it could be quite dangerous. And maybe for noise or cooling under the cowl etc...

If you are racing or just trying to split every hair and squeeze every last drop of power then yes seal up those holes and even if it is a tiny fraction of a PSI positive pressure it would be positive gain. Keep in mind though that the ram air boost would introduce additional air volume and fueling for it should be considered. The bike already runs really rich so maybe the fueling would actually be better? Logging would get you there.

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post #18 of 21 Old 03-31-2019, 10:10 PM
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Holes could aso be to let water drain out when riding in the rain.

2018 H2 SX/SE
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post #19 of 21 Old 04-01-2019, 02:52 AM
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Today this conversation inspired me to check my air filter and supercharger axial play and in doing so removed the ram air tube. The holes, they are strategically place at the boundary of velocity change and provide sufficient air when the H2 is under high rev but little forward velocity and when the forward motion is sufficient the holes do nothing until the pressure difference changes at the point where the holes are and then excess air is bleed off. The shape of the tube is well thought out. Such a long intake at low speed could be restrictive if they had not shaped it this way. It's nothing more than a cunning way to get around pressure drop at low speed and excessive pressure at high speed. The H2R has other requirements being a track bike.
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post #20 of 21 Old 04-01-2019, 01:46 PM
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Holes could aso be to let water drain out when riding in the rain.
There is a proper drain downstream of the holes.
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