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Ran the bike on the dyno, both static and with a bit of ram air.

Without snorkels and without ram air, down about 2.5 hp With ram air the results you see.

With snorkels in place, more consistant power and slightly higher. Did not matter if you had ram air.

Biggest difference is running without snorkels hurts low power greatly. From 3-5k rpm, snorkels helped. (second chart).

Air/fuel ratio change was negligible.

So, my snorkels are back in.
 

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Thanks John...interesting. So, overall, are the results in line with your expectations? It seems about right for the R (136hp) plus the mods we may never see (8hp). But I was thinking the Ti system would help even more.
 

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yea, rode again yesterday and could feel it wasnt quite right no matter how much more beefy the sound on load, thanks for confirming..
 

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I think the snorkels are constructed the way they are, to create a certain airflow. Good we have a dyno now to compaire.

This forum rocks!
 

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MVorBMW said:
Thanks John...interesting. So, overall, are the results in line with your expectations? It seems about right for the R (136hp) plus the mods we may never see (8hp). But I was thinking the Ti system would help even more.

I think things are just where they are suppose to be. I just ran another bone stock 910R yesterday and it put out 115 hp. (just what mine did stock)

So, the Ti system is just a little shy (by 1hp) to what the factory states. No complaints here!!! :yo:
 

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airfuel - that's freakin' awesome that you did this work.

i don't know how many times i've seen a debate like this rage on a forum. and here on this great site, we get someone who does the experiment and gathers the REAL data.

nice job.

now, all you east coasters - go out to his shop and let him tune up your bikes!

alex
 

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I'm trying to take my R into John for the pc but I need my exhaust....have their been any threads here about the delivery of exhausts?! :silly: :crazyeyes :jsm: :banghead: :ahhh:
 

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:yo: Thanks John , job well done:king:
 

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Great work Airfuel & thanks. I wen't back and forth on this mod just before having my power commander mapped. Luckily I left them in. :D
 

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Peet said:
I think the snorkels are constructed the way they are, to create a certain airflow. Good we have a dyno now to compaire.

This forum rocks!
Airflow is important, but also is resonance, as torque depends a lot on length of the intake. See variable lenght solution on TAMBO. Short length for high rev perfomance, long tubes for low down torque. Is due to air wave ending in a knot or open end of frequency curve
 

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hb88xx said:
Airflow is important, but also is resonance, as torque depends a lot on length of the intake. See variable lenght solution on TAMBO. Short length for high rev perfomance, long tubes for low down torque. Is due to air wave ending in a knot or open end of frequency curve
Length of the intake tract is very important. Peak torque occurs at peak volumetric efficiency (which is a measure of the % cylinder fill compared to the theoretical volume of charge in the chamber at 1ATM).

The reason short length runners are better for high RPM operation has to do with the "bounce" of the intake charge when the valve snaps shut. When the intake valve closes, the incoming a wave in the intake charge "bounces" back up the intake tract. At the plenum, it turns around and goes back down. Now, if we're real clever, we get the timing right and get the valve to open right when that downward wave arrives and it helps boost VE by acting as an enhancement to cylinder fill.(actually, ideally the wave will have "bounced twice, and it'll be the third time down) VERY highly engineered engines (think F1, or other well developed race stuff)can actually get a bit over 100% VE in narrow RPM bands. Sytems like the variable trumpets, or variable cam timing, allow the designer to open this RPM range a bit.

Because at high RPM there is less time between valve events, you want shorter trumpets so you can get your three waves.

Clear?
 

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Thanks! :)

What I forgot to say, as I got wrapped up in my explanation, was that the snorkels have nothing to do with the power curve from an "intake manifold perspective" here. The reason they help is related to something else, which I will only guess is turbulence related. (At higher RPM the pressure signal from the engine gets much stronger and can more easily overcome funkiness in the box.)

The snorkels could be 10 feet long and still be feeding an engine with a peak VE at 15,000RPM provided they were in front of the plenum as in this case.
 

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luvtolean said:
Thanks! :)

What I forgot to say, as I got wrapped up in my explanation, was that the snorkels have nothing to do with the power curve from an "intake manifold perspective" here. The reason they help is related to something else, which I will only guess is turbulence related. (At higher RPM the pressure signal from the engine gets much stronger and can more easily overcome funkiness in the box.)

The snorkels could be 10 feet long and still be feeding an engine with a peak VE at 15,000RPM provided they were in front of the plenum as in this case.
Turbulence, resonance, whatever. Yep.

It doesn't surprise me that this is the case. Those things are there for 1 of probably 2 reasons:

1. To reduce noise to meet noise emissions requirements.
2. To optimize airflow
(if you're lucky, both)

It's funny how you can't always use "common sense" when you're extracting more and more performance from an engine. Gets more and more "scientific" as more power comes out.

I had someone tell me I'm going to lose power if I use an "over the stack" air filter on my Ducati race bike because it changes the flow characteristics of the airbox.

I have no doubt that's true, but he failed to account for the fact that I'm likely going to be crashing in lots of dirt and rocks :) I'll give up a few horsepower to keep from putting rocks through my engine, which the stock filters don't do a good job of protecting against if the tank lifts a little and exposes the airbox.
 
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