More airbox experiments
 

Ever true to myself (with an idle brain in this winter season to make things worse.... lol), I started thinking about ways to help my engine to breath better. Since my tuner did not have success in getting it to run properly with a lid-less airbox, I am looking to improve the breathing while keeping the lid. This had led me to two ideas:

i) I will be fitting a spacer to the underside of the (BMC) air filter. I carved up a used OEM Honda filter by cutting out the inside section and just keeping the outer ring. THis will raise the filter (and hence the lid) by about 9mm and, by my calculation, increase the volume by about 0.6 L (will also help the filter to clear the stacks completely as it now rests directly on them; hopefully increase flow a bit). To address the issue of the moulded block-offs now sitting too high, I cut up the OEM filter to retreive the block-offs from it and will install them directly on the lower section (replicating the set-up one uses with a K&N filter and its two rubber block-offs). I will cut out the block-off protrusions from the BVMC filter as they will no longer be needed.

ii) I started looking at ways to let more air in. While easy to do in principle, the issue is dong so without creating excess turbulence in the box and actually harming airflow. So, here is what I have come up with: I picked up an airbox snorkle from an 83 Nighthawk 550 and will be piggybacking it directly on top of the existing snorkel (same width). I will simply enlarge the cut-out in the lid, thereby increasing the area by 50%. My hope is that the incoming airstreams will blend without excess turbulence. As I will have to raise the front of the tank slightly to make room for the spacer, it will create an opening at the front (under the tank) to allow air to enter the upper snorkle.

It if doesn't work out, no problem, I tape it all up or pull out the second (pristine) lid I have.....

Pics? Please...... Sounds interesting. Was thinking of a way to make the air box more of a true ram air system, like on most sport bike of today. Possibly picking up another snorkel and tying it in with the existing one. May need a little more thought on this.

Moriwaki built a ram-air airbox for VTRs they built for BSB racing. The problem with such set-ups is that they only truly become effective at high speeds, much higher than what is permitted on the street. If you plan to race your bike, or do track days, it could be worth looking into but for street riding, I personally think it's not worth the effort (at least for me).....

True you have a good point. Was just thinking of a way to reroute or add to the snorkel to allow for cooler air. Since the stock snorkel opening sits right above the front valve cover. Your idea sounds doable.

mikstr got any updates?

Ive been toying with the idea for a while of putting some cold air feeds into that space infront of the snorkel through the space where the fairings dump cold air ontop of the radiators...

havent actually looked in detail on how they would mount up but still an idea...

Nothing yet for a few reasons:
i) am still waiting on a spare airbox lid to experiment on
ii) it's still winter here and my schedule of late has been quite busy
iii) am waiting on the results of the MWR air filter prototype (which may make all of this a moot point)...


I will keep this post updated as things develop...

i am thinking to made one myself.....foam, some cutting and i think it will work:D

Upping the ante
 

My mk 3 parts have mostly arrived, and here's what I plan to do.
Firstly, I want to increase the airbox volume as much as is possible. This means making a new airbox by using a dummy frame, engine, carbs set I have, and laying carbon fibre matting into the void, keeping the movable carb links and front cct out of the way, but going right up to the front heat shield area.
I plan to introduce fabricated ram air tubes in through the triangular gaps in the frame, the RH one has the throttle cables running through it and so I'll need to modify those a re-route using longer cables, or change the routing one way or another to leave those triangular holes clear.
The LH one is clear, as I have stick coils fitted.
Once I have a carbon tub I can arrange to seal it against the underside of the tank.
So far so easy.....
I have one side of a fairing so far, and need a LH side to cut up. If you look at a pic of the bike side-on, you'll see where the leading edge of the fairing has a sort of bulge, the line directly from the section underneath the headlight section doesn't follow a straight line down to where the winglet pokes out. If you cut along that imaginary straight line, you end up with a hole, just forward of the rads. I have to move the rads back a few mm to clear the usd forks anyway....
That's fine for cooling the rads, with a bit of mesh in, and frees up the triangular air intakes near the headlight for ram air.
Sealing those ducts up won't take a lot of doing, and then routing it to feed smoothly in through those triangular holes in the frame is the last thing to do there.
Once we have cold high pressure air flowing into the airbox, it needs to be filtered. I plan to use the triangular section behind the headstock, usually above the heat shield, and that's going to be the new pre-filter section. Fitting a rectangular filter vertically across the rear of what was the triangular heatshield area should now be possible.

OK, I now have ram air, and a filter, with a larger volume of airbox. I removed the catch bottle and pipework from the airbox ages ago.

I'll be fitting variable stacks, and so with ram air I'll need to keep rejetting- it'll be a lot of faffing around, and generally dynos aren't good at duplicating ram air effects.
So I've bought a main air jet version of the Flo Commander, which gives me a chance to adjust main jet size on the fly, and if mounted up externally to the air box, next to the clocks, I can adjust it on the go. Well, that was the plan, but I spoke to the Flo Commander guys and they said that more than a couple of inches extension on the tubes they supply would detrimentally affect the performance of the unit, so I'm now looking at making a remote adjuster for it instead end leaving it inside the airbox, but leaving it adjustable from the outside.
This should enable me to tune to "stack up, lots of ram air" situations just as easily as "stacks down stationary" on the dyno tuning.

Stacks, by the way, will be controlled by a thumb rear brake setup on the LH bar, initially, anyway, I might yet get them motorised and automatic, once I've decided at what revs they should operate.

That might be enough to be getting on with for now, although I might add the pilot circuit Flo Commander if it looks like the gains are worth the cost.

So far I have some of the parts, and need to get on with ordering the carbon weave sheets and resin. It probably won't be pretty, but I hope it will be functional.

The last part of the jigsaw, once all of that's sorted and running cleanly, will be a custom exhaust, with a sump modification, the downpipes having individual Lambda wide-range sensors fitted which, with two gauges on the dash area, will help to let me tune the flo commander to each rev range/ load/stack position setting.

Apart from that, the engine mods, and I've now got most of the 929 front end bought, just wheel, mudguard and 3 1/2" rise clip-ons to go.

That should do for this winter's activities, may take me through to the spring as well..... :thumbup:

Ram air has been done before. If I remember right, the holes that you are planning to run your ram air through, they aren't big enough.
Have you looked at other examples? Like this?
Or this awesome bike?
Check out all the pictures in the above link. There are awesome pictures to help you out with your project.

There is also a couple other bikes that have ram air. Just use a search engine and look at what they did to get some ideas.

Edit: I found some more detailed pictures for ya here.

I also am messing with the airbox. I purchased an airbox & used filter for five bucks last week. Making the airbox volume larger and installing a K&N filter almost as big as the airbox itself and then kind of arching the filter to gain even more volume and distance above the carb inlets. Fun project.

Dyno before and after, preferably on the same day and hour, so we can see the changes.

James

Yes, I know those bikes, and as it happens, I know the edit link you posted quite well.....
(I use tony.mon on the VTR site.:cool:)
I think the triangular fairing cutouts will be big enough. The total area is bigger than the snorkel cross-sectional area, so whatever happens I'll have an increase.
I'll be running scoops as well, just to add to the air pressure when travelling over 70 or so.
As you can see from my thread on the vtr site I have been playing with the MWR filter with a larger area for a while, and it's that game that set me off down the Flo-Commander route, after I noticed that although these bikes run like shit with the airbox lid and filter off. SO an open airbox just doesn't work without major jetting changes.
But if you cover the two main airjet holes with your fingers, they rev fine, I discovered. Messing about while balancing carbs was what got me playing. Mains and pilot jets are ok, they would needs an adjustment but they're not going to be miles out, however the bike won't rev out properly, and that seems to be related to the airjet.
There's something going on here....

btw I can't dyno back-to-back, as there will be too much going on, but I always keep my dyno runs and set-up info, for comparison purposes.
Ram air, adding the flo commander, larger airbox volume over what I currently run, etc, etc- the like-for-like comparison isn't going to be much help, and anyway, it won't work perfectly until the exhaust and engine work is done.

I'll be doing something interesting with the heads as well.....keep an eye out, I'll post it as it happens.

Mikstr

Are you trying to attain massive 2d gear throttle wheelies like some others on here have reported? That should require about 100lb ft of torque so a perfect airbox configuration is necessary. Good luck at finding perfection but it seems others have achieved this. :cool:

zxbud, check mikstr's other thread here. He has more pictures and some follow ups to the mods as well.

VTaRse a.k.a. tony.mon Yeah, you would be familiar haha
I'll be watching this thread to see what you come up with. Take and post lots of pictures.

There as been some mention about adjusting the stacks and running a taller stack in the front. What does that get you in performance?

a little bit more bottom and mid range with less top end .

Thanks for the input on the stacks. Low am mid is what I use crusing around backroads. A follow up I have also heard suggestions on shimming the rear needle up a little more than the front (0.04 in front, 0.06" in rear) will putting the taller stack in the front have any effect on setting the carbs up like that?