Anyone modified the airbox? Suggestions?

OK the first step is done. Here is the intake runner modified.
Next step is the velocity stacks.

The common rule of thumb is that experienced and skillful operation of a dyno (= rare...) covers about 60% of tuning work, the rest is done on the road. Dyno results don't show the feel and rideability of a bike.

But power, torque and air-fuel graphs DO show changes in the engine's performance. Regardless of how the feel on the road. So in that sense a dyno is essential for any serious tuning. If I had followed all the "seat of pants dyno's" through the years I would have a 1000HP LC4 single running 50mls on one litre of fuel now...

I know the people from Sommer KTM very well. The are the biggest KTM specialist in Europe and as close to the factory as you can get. They do a lot of research and testing in their own dyno-center to develop setups, mods and tuning stages to improve KTM bikes. As we speak they are working on the SD airbox for months. This work will be finished in January. As it looks now, the 'only' result will be a slightly modified side door of the airbox giving a small but worthwhile performance improvement throughout the rev range and a better throttle response. Just like on the carbed 950s BTW. I know how these guy work and believe me, they have tried everything...

Hence my curiosity for the results with your mods...

Richard.

Sounds good Richard... I agree with you 100%

Give them the link to my pics and have them reference the Yoshi site for the dual velocity stacks. Here is a list of some of my reference infromation.


Dual Intake Stacks:
http://www.superbike.co.uk/products/exh ... 85453.html

http://www.webike.net/ca/11983/boKG60R4ibD7oCCxj49Y/

http://www.yoshimura-jp.com/info/images/dual.jpg


Intake/Airbox/Resonator Formulas:
http://www.calsci.com/motorcycleinfo/Airboxes.html

http://www.team-integra.net/sections/ar ... icleID=471

Velocity Stacks:
http://www.superduke.net/forum/album_pic.php?pic_id=212

http://autospeed.drive.com.au/cms/A_2154/article.html


PowerNow:
http://www.cyclebuy.com/shopping/powern ... w_dyno.htm


Internal Tube intake (by weapon R):
http://www.prostreetonline.com/buy/weap ... n_intakes/

Autospeed Articles:
http://autospeed.drive.com.au/cms/article.html?&A=0629

http://autospeed.drive.com.au/cms/A_0542/article.html

http://autospeed.drive.com.au/cms/A_2154/article.html

Example of a very well designed car airbox:
http://www.outlawpower.com/system_technology.php?part=7

My Favorite innovation atm - the new R1:
http://www.mcnews.com.au/2007_bikes/spo ... aha_r1.htm

(Just like the old mazda rotories have been using for years)

Anyway.... Dyno graph will be provided when I get it done. GregZ

For the Dual Velocity stacks use the following:



These ports are flared to minimize air turbulence.
Inner Dia 58mm
Length 120mm
AU$4.95

They seem to work well but with my other mods it is hard to tell.
I will need to look at the power curve once I have done the dyno run.

In theory - the bottom end with be better and top end will not be affected.

Cheers Guys,

OK here are your answers:

1) all mods are done and the bike rides schmick! I am not happy with the bottom end but I am comparing it to a geared down, highly worked M900 with +70 ft-lbs at 2500rpm! Not a fair comparison really.

2) My Dyno guys is booked out until the 15th Jan.. I am booked in after that at the first possible date - don't fret I will post it ASAP.

3) I really dont feel like testing each mod...I know it would be good as I can 'fix' them individually... but I am not sure if I want to spend the cashola...I may change my mind if I get the day off and flywheels has the Dyno free for that day.

4) Dr F... I understand... but the dual stacks have a gap. They do not directly increase the full lenght as they will draw air between the stacks.

Theory.. The flow of air around a round tube is good in the middle and poor on the walls. This setup forces air onto the side and increases length as well - suposedly with increases and no detriment. Have a look at the Yoshimura links I have provided. BUT.. only dyno will show reality.


5) I am still considering modifying the intake runner on the airbox further... but I will need to work out:
a) resonance frequencies to work out the runner sizes/lenghts
b) how do do it.. this airbox is S#*T! no idea how to fit it, make it or mod it! HELP!

We'll see Gregz... We'll see...

BTW, with all your contributions and work on this forum and all the fiddling with your bike, lack of time isn't a believable issue.

Cheers.... yeah...

actaully all the mods took me only a few hrs.... the bike was off the road for about 1 week waiting for the seat and powdercoating. The rest of the bits were done very quicly.

Doing the airbox intake burnt my fingers LOL
Deburing the headers took a while... they are stainless!
The Velocity stacks fit like a glove.. and took no time
The db killer were an angle grinder job
The heat wrapping was shit on the nose.. I should have worn a breather
Everything else was a peice of cake

I have done all the mods previously on a few bikes... except the dual stacks. I have done the powernow on the R1 and I was hoping to do the same to the KTM... but no joy it does not use slides

Hey KTMax & Dr F.. here is some interesting reading regarding the Dual Velocity Stacks:

"Whenever air flows past something, like the walls of the inlet snorkel, the air touching the walls will stick to the walls and not flow. The air very close to the stuck air will flow, but sluggishly because the nearby air isn't moving. Thus there will be a region of air right next to the tube walls which does not flow easily. This area is called the Poisson stagnation region, named after the French physicist who first described it mathematically. The faster you try to flow air through the tube, the thicker the stagnation region gets. In a narrow tube at extremely high flow rates, the stagnation regions can grow to pretty much fill the tube and the flow through the tube can get slowed quite dramatically."

With this in mind - the dual velocity stacks may assist decreasing the Poisson stagnation area.... hmmmmm.

Hi Plipton, Dr F,

Only if you are interested.... have a read. I ahve done a few years of research on this topic.
(I will exclude my results from searches of the patent registration sites)

Tech note:
The daul velocity stack ends just above the 1st throttle butterfly.
This means that the intake air joins very quickly and then has the full runner length to run.

\------------
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/------ |
/------------

The theory is the the air on the edge of the runner will have an accellerated velocity as it entering from a smaller surface area blocked by the upper stack.
This should theoretically increase the external velocity, as well as increase the internal velocity as it is alo moving through a smaller venturi.
This is a clean method that is fixed position with daul effects... without electronics or movement.

Other methods:

My favorite is the tuned secondary airbox opening using computer controlled vaccumm actuated flap on the CBR1000RR
This is possible to implement on the SD... but I am not sure how to accutate it and if it would spoil the resonance - to complicated mathematically for me to work out.

The best simple design is the PowerNow or Powerblabe, which splits the venturi in half - and give extreme acceleration to the intake.
Unfortunately it only works with slide intakes not butterflys. I have fitted to EVERY bike I have owned with a slide since it came out.
See my airbox thread for links. Unfortunately not for the SD

The R1 that WA Duke pointed out is great but complicated and needs a lot of room (YCC-I)


Interestingly this is years old and has been used successfully, but cannot be implement in the space and size the SD has availble.
Here is the 26B rotary method
http://cp_www.tripod.com/rotary/pg03.htm

One cool design working with the Poisson stagnation theory is the Secret Weapon R intake system. Check out the link this is very cool and sort of on the dual intake velocity stack theory:


The other theory used by cars is an internally adjusting intake plenum, which changes flow between differnet length runners.
The simplest but most controllable is Porshes version - an excellent and simple design. Again this cannot be fitted into the SD.


Another method similar in concept (but not design) to the one Plipton mentioned is the dual runner with butterfly design - used by car like
This saves the closing vortext complexity and is similar to the PowerNow idea but is variable. Toyota call it T-VIS


Otherwise a very cool idea, which is completely irrelevant for us but sort of like plipton's imagination



Summary:
For the moment I have added more air... approx the same amount and the Sommer door/s give and improved teh intake trumpet design to flow better.
The dual velocity stacks by design do improve velocity without sacrificing (much) top end - which I do not use.
Theoretically if I get dips in the torque curve, tuning should be done with airbox resonance and worst case PC or RB.

Now for $10 bucks and about 1hrs simple work... I think this is a great bang for buck to gain a little more bottom end.

Come on Guys!

Bring it on..... conflict generates innovation!

The more you 'argue' with me the more you think about it the more idea's you will come to you. Who knows one of us might come up with a cracker solution and become a millionaire!

There is one simple theory of combustion that works and has not changed for years.

What is changing is how to get more mixture in and exahust gasses out.
(Obviously excluding super and turbo charging - which is in my opinion the way to go)

What is new is mathematics and resonances, and velocities etc.

The static engine is usless across a broad range (unlike electric motors which are brilliant - but that is another story). To increase the range we compromise, but that makes other parts worse - so we thing of new ways to fix these 'boken' areas.

So hence the recent answer is to make everything variable:
intakes, valves, exhausts. This moves the resonances and makes the engine 'retune' to differnt circumstances. Computers have allowed this to happen.

This is well out of the reach of mortals without mathematical skills and a lab with motoring equipment. ie.. me! and if you are actaully reading my dribble - you too!.

But once in a while there comes genius in simplicity that astounds us. The latest is the powernow... brilliant, cheap and easily done at home.

This is what I am looking for the holy grail of cheap, easy but effective mods. My mission is to find something that 1000's of highly skilled, full time employed mathematician's and engineers and mechanics with full access to formula's, history, design and technical information and labs and testing fascilities in every country cannot find.

Easy huh?

How to do this? Gather as much info and distribute this info to as many home mechanics as we can reach! who you ask?...You!

Will you take up this challenge?

Vortex Generation



Now this is interesting... I have looked into these years ago and even made an item and fitted it to my Ducati M900. (It didnt last long as the ducati coughed it out one day pulling a wheelie in Windsor - Australia LOL)

This is actaully the best design I have seen yet... I winder if it can be applied anywhere on the SD. Thought's running wild - possibly on both intake runners and both Akro mufflers..hmmm.... also these would be removable....



I have used Aerons on my YZ400F for a little while with great sound deadening effect.... this is the base concept for my DB killer mod... but I am sure it could be used for the exhaust as well as a vortex.

Link with detailed info on the Toyota T-VIS and ACIS Systems:

Here is a pic of the Airbox airflow, I have also attatched it in the gallery.

The bad news is that the picture shows what looks like the intake funnel going into the start of the airbox... this is unfortunately incorrect. There is just the square edges of the airbox.

Hence my previous design suggestion in the gallery.



Wow - this is a very lonely thread! Apart from throwing good money into an exhaust... this is the cheapest way to improve a bikes performance. I am surprised no one is intereted. Ah well....your loss.

I have a cone cutter ready and waiting to attack the airbox side covers if its worhwhile to do so




other KTM's seem to benefit from airbox mods but on carbed bikes where the jetting can be adjusted to suit.... efi self compensating needs to be evaluated first

Easy solution - and it's NOT to increase power, airflow, etc.......

Keep the motor at the RPM where max torque occurs for as long as possible to increase performance....

How????

Dr Ferdinand Porsche had the answer back in the 30s but the technology in those days was not up to it. So what did he do.......

The motor drove an electric generator which in turn powered motors at each corner (or end in our case).

Leccy motors nowadays are about 96% efficient (compared to 80 - 85% for gearboxes, chains etc) and allow the engine to be kept revving where it makes to most of the petrol it's burning.

Therefore, 10%+ more efficient drive system, plus more torque for longer. It has to be the way forward (Plipton now runs and takes cover awaiting the barrage of "buts")

OK, it's not a DIY solution, but think about it for a minute.

I'm amazed some of the racing teams haven't done this, but then, they're the ones who ditched ideas even though that bike trounced the competition on its first outing.

Comments? anyone fancy trying this??? (I'll get me coat)

Proof that it isn't just money and BHP that win races - innovation and thinking outside the box are just as important.



Isn't that why we aren't the ordinary "flock of sheep" riding UJMs??

OK Gents, the aibox is modofied..but not like I expected.

The Grand Plan:
I planned to fit a tuned runner and if possible fit a Hemoltz resonator on the intake runner. I have already opened the existing intake runner with a rounded stack curve (see gallery)... and I spent many hours pondering how to fit a tuned length of runner. EIther inside or ouside the aibox (see my previous thoughts in the gallery).

Tuned intake:
There is no room for any length of runner in the airbox. This includes extentions, seperate pipes, custom bends or anything. Hence why I expect Sommer KTM decided on intakes elsewhere to the current intake runner system. This means that we will leave resonance to the KTM engineers.

Additional intake sources:
Again - congrates to the lads at Sommer - ditto again. There is no other source that is cold air. Plenty of spots below tha box to fit velocity stacks... but all hot. Hence this option is really best using the Sommer KTM door (see gallery)

The Modification:
Really the only option I cound find it to fit a flapper plate in the inside of the airbox. It is controlled directly by the secondary butterflies controlled by the ECU.

The flapper closes half the intake variablly using the same position as the butterflies. Leaving just over 50% of the runner open. At full throttle the flapper is also fully open and is curved to improve the airflow slghtly for 50% of the runner.

Photo's and dimentions tomorrow. Ride impressions also tomorrow. I am booked in for the Dyno on Wed so we will see the results of my delicate mods thereafter.

I know your aiming for midrange, but I seem to remember Fast Bikes mag dynoing an SD with the old style oval akra's and it making about 118 rwbhp. Don't know if it had a filter, I'd guess at no, it was a while ago and probably before filters were available. Has anyone else with just akra slip-on's dyno'd their bike yet?

jim620scot,

That is awsome!.... I totally agree. Also, if you see my a/f ratio it shows I need more air at least at full throttle.

I am looking at more air by temporarily removing a airbox door. I expect that this will ruin any resonance tuning and I will not keep this - but it will show if more air improves anything.

I prefer your method with tubes but I chose the other way to be able to accommodate the intake flapper valve...although I can change that easily.
BTW - make sure you have belmouths fitted on your intake runners - this is a must for any intake see this table:


Personally I recommend fitting the dual intake runners - that I believe gives that bulky low rpm torque and no top end loss.

I am also waiting for the Tuneboy... I mainly wish to gain the smoothness and reduce my fuel consumption. I will keep you posted.

Cheers, now I am hanging for your dyno graph

Hey jim620scot,

AWSOME! Let me know how you go with your testing... esp dyno.
I think the long narrow runner will be a good match for the SD.


Another 'secret' that is not published you may wish to use.
This is a ramjet jet engine technology that could be useful.

When:
if you find that you have a large dip in the torque curve at a certain engine speed, but dont want to change the intake length.

What to do:
Cut the intake runner/s with a >45deg angle so the tops look like this:


What it does:
the Hermoltz theory shows that you have a fixed resonance in any tube where air moves. this bounce of the air shockwave is from one closed end of the tube to the open end.
When you slash the opening... the shockwave does not have a fixed point at one end. Effectively the slash disapates reverberations to some extent minimizing the effect of the resonance.
If you have tuned the intake well, you want the full effect of this shockwave - so don't slash.
If you have an unwanted resonance, you can use a resonance chamber for better effect... but they are hard to fit - so you can try and minimise that bad resonance with this slash.

Conclusion:
If you don't have a bad resonance in your intake, dont slash as it can cause a problem.

OK Lads,

Here are the pics of the flapper valve:





Open & Closed:


Fitted:



It seems to work well and is not noise..well at least not above the intake and exhaust - LOL. It is hard to tell the performance gains on the road and they are all subjective. Plus it would need a back to back test riding with it on then immediately off to see.

Looks impressive though!

Keep in mind though... that I still need more air. the plan is a long intake tube fitted into once of the airbox doors fitted with a belmouth. This should give more air without gicing the dip I felt without the door fitted.

I am now looking fir a tiny velocity stack!... good luck to me! More news on that soon.

Oh.. for you UK lads... here are some awsome ports and cheap!
Perfect for dual stacks, intake rams, or anything else to do with intakes.

nw jim620scot,

Yes and no...

On the surface.. the ones fitted to OEM are just that, noise restrictions.
The difference is that I have split the intake in two - leaving one runner open.
The other is opened/closed but the butterflies.
(I am about to fit a third open intake in the side door).

What this does is changes the frequency but adding/removing 1 extra intake to 'tune' extra air when the ECU believes it needs it. Also that means that if the ECU wants the butterflies closed... that means the 2nd runner is not needed... and when closed - speeds up the flow of the open runner.

The theory is to tune the length... so:

What could I have done better?:
1 - I should have done full calculations of the Hermoltz effect on the airbox

2 - I should have calculated the exact runner length needed for my chosen rpm range (done for 2 intake tubes)

3 - I should have fitted 2 individual tubes (they may be different lengths) with velocity stacks

4 - fitted the actuator to the 2nd intake runner as I did to my current setup

5 - if I felt adventurous.. calculated and fitted a Hermoltz resonator onto each of the runners

Why I didn't do that:
1 - it is exceptionally difficult to remove the cubic area of the throttle bodies from the capacity, and the measurements are a pain in the but.
without an exact measurement the runner lengths and Hermoltz resonator size will be out.

2 - actually from all my calculations > the longer the better in any road car, bike, etc... most importantly there is no room to fit anything under that SD tank. This means that we will be splitting wave lengths in 8ths, 16ths, or more! which means that mm's start mattering rather than cm's. Refer above and it is an approximate that will prob not pay off

3 - 2 tubes from what I calculate is not enough... at least not for my SD (as per my dyno results) Also, fitting velocity stacks is on the verge of impossible, as jim620scot has found.

4 - even tougher with round tubes.

5 - Now this is pushing anyones luck... the resonators need to be very close to the runners to work. This is a tough ask at the tight end of the tank.


Finally:
So why did KTM not do this.... personally, I think bang for buck it is not worth the technical design and manufacture. Especially with dual butterflies. I have not had any revelation on how to improve the airbox flow and keep the bike compact. The design is as good as I could muster.

Can the air intake system be improved - yes from my results it can... but it needs a lot of fiddle design and work for the flapper plus further injection tuning. I also need a third intake - as I have not the faintest clue of how to increase the size of the intake runner and/or straighten the flow - without custom moulding a completely new one & modifying the front of the airbox.

My summary - credit to the KTM engine designers for creating a useful and effective airbox under 'artists' specifications!

Sorry - I forgot to mention.... there is ONE other way!
(thanks lockers for reminding me!)

1) Replace the standard filter with Pods
2) remove the intake runner and weld closed the std hole
3) do the calculations I mentioned for resonance and fit new intake runner/s

I approximate fitting two 60mm ID x 150mm 'Speaker Ports' as intakes in appropriate spots in the top of the airbox should work well. This would also allow the fitting of a Hermoltz resonator in the position of the original intake runner spot - made as large as will fit under the tank.


Now if someone has the time, dollars (for a spare airbox) and means and actually does this... I would actually explode with joy!

I have done some measurements - there is only about 1cm of space from the tops of the v/s to the top of the airbox.

The only option for tuning is the inlet path into the airbox. I am still working on this - but not too much time to put into it,

Greg