Author Topic: big gulp for the GT  (Read 148105 times)

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ace.cafe

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Reply #30 on: November 26, 2015, 03:09:53 am
On my bike, I routed the inlet duct over to the left side of the bike, and positioned the entry away from the engine fins so that cool air could enter. This allowed me to use the long length. I think that mine was around 17 inches.
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Otto_Ing

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Reply #31 on: November 26, 2015, 08:30:00 am
Well, 17" pipe should require a diameter of 1,77" which is about  the diameter of the intake valve in the GT head. The average airspeed in this kind of pipe does not seem to bee too dramatic with 0,045 mach, peak will be probably higher of course. It feels just little bit too small, maybe 2" will be the ideal compromise... and in reality the eigenfrequency goes always down due to damping effects so that the pipe can be somewhat shorter than calculated. So much to theory....  :-[


Ve =   0,000535   m^3         
               
V =   0,005   m^3      305,1187205   in^3
di =   0,045   m      1,771653543   in
Ai =   0,001590431   m^2      2,465173416   in^2
L =   0,45   m      17,71653543   in
air_d =   1,225   kg/m^3         
air_p =   101325   N/m^2         
                           
Freq. =   45,53450363   1/s   2732,070218   1/min   
               
Q_pipe =   1,461657567   m^3         
v_pipe =   15,31720341   m/s   0,045050598   mach   
« Last Edit: November 26, 2015, 03:41:27 pm by Otto »


ace.cafe

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Reply #32 on: November 26, 2015, 05:15:23 pm
Okay, you can try that out and see what it does.
I would make two of the ducts, and use one to cut down an inch at a time, to observe the changes that occur with the shorter lengths.
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Otto_Ing

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Reply #33 on: November 26, 2015, 05:28:27 pm
...this is the KTM RC 390 airbox...well it is a elefant trunk, that confirms the theory atleast, and that engine runs faster, so ours might need to be even somewhat longer.  ::)

...i look for the possibility of a practical solution at the weekend  ;D

...also the duct seems to be narrower than the intake side, could be oval however.
« Last Edit: November 26, 2015, 06:00:59 pm by Otto »


Otto_Ing

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Reply #34 on: November 28, 2015, 03:34:24 pm
This is how the intake looks, view from the airbox. Pretty sharp cornered? ...no room for any bellmouths, filter sits right in front of it.

...also the volume is about 2 to 2,5 liters...that means even longer duct.  :'(
« Last Edit: November 28, 2015, 03:39:27 pm by Otto »


ace.cafe

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Reply #35 on: November 28, 2015, 07:11:33 pm
Any rounding or smoothing the sharp edeges/corners will help. Re-profiling the transition into the airbox with any amount of bellmouth shape would help.
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Otto_Ing

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Reply #36 on: November 28, 2015, 08:10:08 pm
Any rounding or smoothing the sharp edeges/corners will help. Re-profiling the transition into the airbox with any amount of bellmouth shape would help.

The sharp edge is there due to the mold , so there might be some material on the outside to round it up at least. The inner edges might need some sort of silicon or epoxy i think.

This is what could fit in the side panel. It is 19" long, dia. 1,65".
Flow 0,056 mach counting every second revolution. It needs to be 5" longer in theory.

What I could do is make the cover in 3d print and than connect some sort of flexible??? (has to be stiff?) hose to it for testing and figure out the correct length.

« Last Edit: November 29, 2015, 08:26:12 pm by Otto »


Ice

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Reply #37 on: November 28, 2015, 09:00:19 pm

 This has been done before but not like you are doing it and not on the Conti !
You are the first. Keep up the good work Otto !


IIRC it was good for few "free" HP then.

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Otto_Ing

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Reply #38 on: November 28, 2015, 09:04:21 pm
Thanks Ice, but I will realise it only if i succeed making it invisible.  :P

The dimensions on the bullet seem to be as anticipated....
« Last Edit: November 29, 2015, 03:08:44 pm by Otto »


Otto_Ing

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Reply #39 on: November 29, 2015, 02:00:29 pm
Plan B: if packaging of Plan A fails due too many bends.


Farmer_John

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Reply #40 on: November 29, 2015, 02:18:18 pm
Doesn't the filter seal against the lid?
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Otto_Ing

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Reply #41 on: November 29, 2015, 02:33:51 pm
Doesn't the filter seal against the lid?

Yes it does, this is thought as 1:1 replacement. 3d print, ABS should be good. Filter stays in.
« Last Edit: November 30, 2015, 01:40:25 pm by Otto »


Aus.GT

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Reply #42 on: December 01, 2015, 07:46:52 am
Thought I'd ante in on this.
I dynoed my bike with K&N filter, Royal Enfield Sports Muffler and PCV from our host. Didn't make any real difference to horse power but made rideability much better.
I then fitted the Conti muffler to the bike, Didn't notice any appreciable difference to power however the sound was great.
On the 22nd of October I fitted a bell mouth to the entry of my air box and radiused the edge leading to the throttle body. First thing I noticed was the engine seemed to accelerate quicker so the following weekend I dynoed the bike to check the air/fuel wasn't too lean.(It wasn't) To my surprise the engine made greater Torque every where from 2500rpm onwards. The peak power previously was 22HP now it's 26HP

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Otto_Ing

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Reply #43 on: December 01, 2015, 07:50:35 am
Thanks for your report Aus.GT. I will publish the plan B, stl file as i come home for anybody to try. Can't test it as it is winter here for another 4-5 months...

Meanwhile i plan to look at plan A, my hope is that i find a way to put the intake duct under the tank so it becomes as straight as possible.

The airbox seems to be worse than it looked....

The sound will be best with the bellmouth i think, it should give a good "snore" like the old manxes.
« Last Edit: December 01, 2015, 09:42:13 am by Otto »


gizzo

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Reply #44 on: December 01, 2015, 10:40:04 am
4 HP is a good increase. Where did you source the bellmouth?
simon from south Australia
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