Airbox modding

[VTRDark]

There's an email for him in this post Seb http://www.vtr1000.org/phpBB3/viewtopic ... 56#p154956



(:-})

[agentpineapple]

ouch!!!!! indeed, shame it was a nice looking storm, i reckon it might polish out, wheres me t-cut

[Eclectic]

Just purchased a Pipercross filter. Hoping its as Seb claims

[seb421]

Just purchased a Pipercross filter. Hoping its as Seb claims

wasn't me that claimed anything mate, tried mine but bike wont run using it with out rejetting at all, over 3k and its so lean it's unrideable when i get more jets i will get it put back in and report back

[tony.mon]

Here's a little update:

I bought a pair of SP1 stacks the other day, and thought I'd see how easy it was to graft them onto Storm ones.
The rounded profile is clearly going to be better: (this picture shows the finished ones; but you can see the rounded profile [the two in the centre} better than the picture I was going to use)


Sorry about the shadows, but you can see what I mean, I hope.
The SP1 stacks are larger diameter, so need to be grafted onto Storm bases.
In addition, the SP1 stacks mounting screws are in the wrong positions, and so I cut a pair of Storm stacks down to the point at which the side wings sprout from the body, and removed the small securing wings that poke upwards, and prevent the securing screws from coming out of the stack:
(left in this picture)


I then cut down the SP1 stack, so that the total height wouldn't be too tall to fit into the airbox (more on this later):


It doesn't fit neatly onto the Storm base:


But it's near enough to permit a smooth transition to be achieved. I first glued the parts together, using polystyrene plastic cement, which welds the plastic together. I then back filled the gaps from the outside with silicon sealer. Finally, I filled the inside transition with silicon sealer, achieving a smooth "ramp" all the way round. Ideally, it would have a single smooth angle all the way down, but I wanted to try this using silicon first, to see if it works and fits ok. I can always go to a plastic padding type filler later on and improve the design if I feel that it needs it.

The two completed stacks are in the centre.


As the outer rim is wider than the standard stack, I felt that it was too close to the lower edge of the K+N filter base.
So I cut the outer section from an old standard Storm air filter, to release the outer edge, which has a raised part all the way round, both upper and lower surfaces. These key into the airbox lid and base, holding everything into alignment.
I also cut off the top few mm from a spare airbox base, and sanded it flat.
These two components effectively lift the airbox lid up by 10mm, alternatively they can go under the filter, giving more room for the new stacks to breathe. This is the option I was after.
Pics in a while..........

[lloydie]

Very interesting work there .
Keep it up :-)

[VTRDark]

Are you making one short one long? I would suggest they need to be the height of the billet stacks. Would the circumference be to big for a standard airbox IIRC yours is empty of all the pipes/bottle.

Good work and it will be interesting to see how it behaves.

(:-})

[sirch345]

Very interesting Tony, keep up the good work

Chris.

[tony.mon]

Carl- Yes, the prop that pokes up in the airbox will interfere with these, and the long pipe that goes across will have to be moved to sit lower and run between them. Mine, as you say, has been gutted, and so it's clean and clear inside; no problems. And I've gone for one short one long, but both ended up slightly longer than the originals, the longer one by a few mm, and the shorter one longer by about 10mm.

So, I made a spacer by using the outer edge of a standard air filter, and the upper edge of an airbox box base:


Here the finished stacks are are when installed:

The shorter SP1 stack has an edge shaved off, which I just left for now but ideally would be built up to match the rest of the curved rim.

However, as you can see, the new stack is almost level with the top edge of the airbox:



So I added the new spacer:

Which as you can see now gives as much clearance above the stack as in the original airbox design.

So.
I installed these, and getting the spacer in and then lining up the airbox lid without disturbing the spacer is a real pain. The airbox lid is now lifted by about 10mm; this has the effect of lifting the snorkel as well, of course. The problem is that the upper curve of the snorkel in a normal airbox just about fits under the metal top edge of the frame. Lifting it means that the top surface of the snorkel interferes with the frame, and pushes it backwards whenever I tried to insert the spacer.

But I managed to force it into place with a bit of fiddling and pushing, and then found that (of course) the airbox screws are now too short.
So I fitted longer self-tappers, and they made a good seal with the lower edge of the K+N against the upper edge of my new spacer, so I didn't apply silicon sealer, as I'd originally planned.
Also I couldn't be bothered to pull it out again once it was in place....

The tank mounting bolts at the front of the tank needed extending; I fitted 20mm spacers and longer screws, which raises the tank off of the frame rails, but still allows use of the rear tank mounting bolt.

I started it, and it ran, with a noticeably more gruff intake noise.

Now for the test ride.

I am happy to report that the seat of the pants impression is of a noticeably stronger bottom end and midrange, second gear wheelies taking off from traffic lights are now not only easy, but to be frank, if you use the throttle past half-way, it's difficult not to.
And I usually sit forward; sit with my nuts on the tank and leant forward anyway, to keep the weight on the front wheel.
There is an occasional misfire, but I'm aware that this was happening before I did the stack work; so it's unrelated, and started after I carried out the snorkel mod.
I was planning anyway to rejet after the snorkel mods but wanted to wait until I'd done the stacks as well.
I anticipate that it's running quite lean around 5-6K, and probably fairly lean elsewhere, now that I've got more air flowing in, increased the airbox volume and made it easier for the engine to breathe in.

The raised tank actually feels better; it might just be the shape of my body and legs but climbing off the bike its easier to lock your outside leg against the tank than it was before, more comfortable as well.
I was considering lifting the rear tank mount by shimming under the mounting plate, only by a few mm as it also has the top shock mount running through it, which would mean that I wouldn't have to lift the front quite as much, but this would affect the fit of the seat against the tank, and I quite like it the way it is.

The tank might sit a little lower if I remove the sound deadening foam stuck to the bottom of the tank; next time it's off I'll inspect to see where it is squashed against the top of the airbox lid and shave it to get a little more clearance.

But before I do the jetting and carburation I want to reshim, as when I built this engine earlier this year I fitted shims and didn't have the exactly right sizes (within range, though, but only just); this needs correcting and I now have suitable shims to hand. I like mine in the middle of the range.
It could also do with an oil change, new filter, and plugs.

Would I recommend this mod?
Yes, definitely, but only to those who are prepared either gut the airbox and move the internal components to external, or alternatively can be creative with re-routing the piping inside the box to clear the new stacks.
And to get the carbs set up properly afterwards, on a dyno or by hand.

I'd like to dyno mine again to see what difference the latest series of airbox mods have made, but don't really have the cash at the moment, so that'll have to wait.
But very clearly the standard stack profiles are not very efficient, and a simple bolt-on, or a more complicated but cheaper mod such as mine can make a real difference.

Finally, thanks to Mikstr for the spacer info, I'm always up for nicking a good idea....drop by one evening after work, mate; I'll buy you a beer

[seb421]

Looks bloody good that Tony!

Hope its bagged you some more ponies too

[VTRDark]

Paint them silver and they will look just like billet ones.

That's some serious airbox modding. I've seen the airbox cut for spacer thing like that before http://www.ablett.jp/bikes/vtr/air_box_lid.htm it just goes to show how one thing effects another. Modify one thing and then have to modify something else to accommodate the first mod and so on.

Sounds like it's a made a serious difference then. I'm glad it worked out, it would have been a shame to go to all that bother only to find out it don't work. But then if you don't try, you will never know. So well done.

I would like to externalise my internals one day but I don't really wont to raise the box so will either have to settle for billets or try what you have done but make them shorter. Mmmm got me thinking now. Shall have to stick sp1 stacks on my ebay watch. Or I could make some out of P40. fibreglass stacks, that could work!

Good job

(:-})

[seb421]

Would the stack be better having a ruffed up surface or a smooth surface? was thinking along the lines of the 'golf ball' effect

i know the stacks are not moving but would it help aid more air flow if you textured them?

The "Porting and Polishing" myth

It is popularly held that enlarging the ports to the maximum possible size and applying a mirror finish is what porting is. However that is not so. Some ports may be enlarged to their maximum possible size (in keeping with the highest level of aerodynamic efficiency) but those engines are highly developed very high speed units where the actual size of the ports has become a restriction. Larger ports flow more fuel/air at higher RPM's but sacrifice torque at lower RPM's due to lower fuel/air velocity. A mirror finish of the port does not provide the increase that intuition suggests. In fact, within intake systems, the surface is usually deliberately textured to a degree of uniform roughness to encourage fuel deposited on the port walls to evaporate quickly. A rough surface on selected areas of the port may also alter flow by energizing the boundary layer, which can alter the flow path noticeably, possibly increasing flow. This is similar to what the dimples on a golf ball do. Flow bench testing shows that the difference between a mirror finished intake port and a rough textured port is typically less than 1%. The difference between a smooth to the touch port and an optically mirrored surface is not measurable by ordinary means. Exhaust ports may be smooth finished because of the dry gas flow and in the interest of minimizing exhaust by-product build-up. A 300 - 400 Grit finish followed by a light buff is generally accepted to be representative of a near optimal finish for exhaust gas ports.
The reason that polished ports are not advantageous from a flow standpoint is that at the interface between the metal wall and the air, the air speed is ZERO (see boundary layer and laminar flow). This is due to the wetting action of the air and indeed all fluids. The first layer of molecules adheres to the wall and does not move significantly. The rest of the flow field must shear past, which develops a velocity profile (or gradient) across the duct. For surface roughness to impact flow appreciably, the high spots must be high enough to protrude into the faster moving air toward the center. Only a very rough surface does this.

http://en.wikipedia.org/wiki/Cylinder_head_porting

http://www.scientificamerican.com/artic ... in-golf-ba

http://num.math.uni-goettingen.de/bail/ ... gs/tai.pdf

[agentpineapple]

very good work tony, but i can't help feeling it would be alot easier for the average storm owner to just go and buy the billet stacks and avoid alot of the issues you've had to overcome.
you are an innovator mr mon

[seb421]

Just wondering tony what would happen if some one was to remove the air filter inside the box and just have two filter socks placed over the trumpets?



http://www.demon-tweeks.co.uk/motorspor ... ilter-sock


also would / could any of these be made to fit instead of standard ones

http://www.demon-tweeks.co.uk/motorspor ... -ram-pipes

http://www.demon-tweeks.co.uk/motorspor ... -ram-pipes

http://www.demon-tweeks.co.uk/motorspor ... n-ram-pipe

[agentpineapple]

that bottom one looks pretty good, i'm not sure but aren't storm carbs 48mm, if only it was that easy