Leccy techie help needed for a little project....

[tony.mon]

I've been playing for a while with various lengths of intake trumpets, and have come to the conclusion (as Honda seem to as well) that there is no ideal length.
The long one's ok for torque, and ideally could be a bit longer, (clearance in the airbox being the limiting factor) and the short one's ok for top end HP, but loses torque.
So ideally you need both.

A few bikes have a two-part stack, which has a short section with another short section above.
There's a small stepper motor fitting to a linkage so that at certain engine conditions the top section lifts away, and air can flow in to the lower section alone.

Now that I've raised the top of the airbox lid I have a little more clearance to play with, and this idea seems possible. If more is needed I'm happy to buy a 2nd hand tank and chop or hammer more clearance out of the bottom, and doing away with the airbox lid entirely; sealing the tank against the airbox top edge.

I'll need one, possibly two (to make the linkages simpler) stepper motors, and a controller. Yamaha have this on the R1 cross plane crank version, and Aprilia have it on the V4's. There are probably more bikes that have it fitted already. But I can't merely buy those parts and make them fit, as the electronics are more sophisticated on those bikes; it's linked to the fuel injection systems and uses sensors we don't have.

To make things simple at first, I could rig a mechanical version using a twin pull throttle tube and merely attaching one cable to the throttle as normal, with the other operating the lifting mechanism at 3/4 throttle and above.
But I think that this will be a little crude, (and a heavier throttle action) and would prefer to use the TPS signal, and possibly the advance signal from the igniter box/ECU to manage the timing and degree of lift so as to make it smoother in use, with a stepless and quite quick transition between two stacks and one shorter stack.

So I'm after a little help, as my bike electrics knowledge is ok but my electronics isn't.

I've found a nice cheap controller unit:
http://www.ebay.co.uk/itm/Dual-H-Bridge ... 224wt_1397
but really don't know if it'll be sophisticated enough to cope with two variable inputs.

Anyone fancy a challenge? No time pressures; this will be a trial and error, when the money permits sort of a project. Obviously the ideal outcome would be a "how-to" for anyone to copy, assuming that the results are worth the outlay.

But my own experiments with different length stacks over the years leads me to think that there are reasonable gains to be had at both ends of the rev range, with no losses in the middle. Naturally, carburation would also need to be played with but a good compromise should be possible, probably with it running a little rich at the low end but spot on at high revs.

Game on?

[VTRDark]

Sounds complicated to me. Would using RC vehicle servo's be a good idea for the moving of the top half of the stack up and down. http://www.ebay.co.uk/sch/i.html?_from= ... +car+servo
Just a thought.

(:-})

[seb421]

tony you mad b8stard this is fantastic, looking forward to this one

[VTRDark]

He's been having dreams about this one. It's just when he has an oil leak it's a problem

(:-})

[tony.mon]

tony you mad b8stard this is fantastic, looking forward to this one

You wait until you see the project after this one......
Clue: it's exhaust related, but not cans or a full system

[VTRDark]

Clue: it's exhaust related, but not cans or a full system

I think that only leaves the cam/valves or ports. Unless you talking about the studs.

I've got mu eye on you.

(:-})

[lloydie]

V teck valves :-)

[Kev L]

An Exup valve to tune exhaust length?

[MacV2]

Clue: it's exhaust related, but not cans or a full system

I think that only leaves the cam/valves or ports. Unless you talking about the studs.

I've got mu eye on you.

(:-})

Ah a mu eye...that explains it.....

[Xenocide]

I've used an arduino before a few times. It can cope with your variable inputs easily. It's a programmable micro processor + controller really, you can then just put your stepper motor on.

Not sure if you know how steppers work? You give it 5v+ gnd then the controller sends a pulse to the motor ordering it to "step". The longer the pulse width, the longer it moves (like fuel injectors).

All the parts you can get from dealtime.com

Get a 4x small steppers (just incase you blow one up) and one arduino + one controller (With dual outputs).

The arduino can have 16 inputs or outputs, you can do logging over a serial connection or store the values in ram to look at later. IT can be powered off 12v (USB, so 5 really) or batteries.

What signal would you be going on? TPS?

I don't mind having a bash at making it all work but i'll have to wait until i've been paid to get a controller. I've got some stepper motors out of old cd rom drives which are quite small (they move the worm gear on the head which the laser sits on).

If you want some slightly bigger ones, rip open an inkjet printer, there's two of each in there .

[tony.mon]

AH, a volunteer steps forward.....

As you would expect, I threw away a perfectly good printer last week, as it didn't like Win7.

I'd think that the TPS signal would be the best, the likely trigger points would be between 75% and full throttle, we'd need to play about to see where worked best.
I know nothing about stepper motors, but I want better control than simply an up or down position; or do I?
Thinking about it, the air flowing into the lower section would be disrupted badly at the point of separation all the way to fully out of the way, I would think.
That's why Yamaha's version not only lifts the top section but also moves it sideways, which seems sensible.

So maybe an easier option would be to have the top section either lowered or lifted, open or closed, as two distinct positions, and not a smooth transition between the two positions depending on the TPS signal strength.

Hmmm, I'm going to have to do more homework....

Here's some interesting info from an Aprilia forum where a mech responsible for tuning the V4 for racing purposes has done a lot of development work (and 2-3000 dyno runs) trying to find the best solution.
Settle in with a mug of cocoa and see what you make of it:
http://www.apriliaforum.com/forums/show ... ake-system

Don't blame me if you get a headache, though.

[Xenocide]

That is a wee bit full on isn't it .

I'll carry on reading.

How were you planning on actually actuating the trumpets? Carl's right; you could use RC car servos. They're a bit jumpy and are susceptible to interference sometimes. But you could use a simple rocker/slider sort of arrangement.

A worm gear and a small stepper would be good but you'd need a runner at 180 degrees to the worm to make it stable i'd imagine.

Might be able to make a clever linkage to make both move off one device maybe?

[tony.mon]

For the mechanical version; I had in mind a pair of upright posts mounted from the base of the airbox, with a slider moving the stack up and down along them.
They'd be lifted up by a forked arm pivoting from a mounting on the base of the airbox, and a light spring would return them downwards when the throttle cable isn't opening them.
An alternative might be a forked wedge sliding in from the rear or front of each stack, and acting directly on the stack slider mounts, causing it to slide up and down on the posts.

The stepper motors seemed easier, as they not only lift but also lower, so there's no need for lowering springs.
But controlling them is the bit I don't have the knowledge to solve.

I'd be fairly happy to try a mark 1 electronic version where they lift the stacks at 75% throttle or above, and close them otherwise. That seems fairly easy to achieve, taking a signal from the TPS, mine's set at 500 at rest but I'd have to measure the value at 75% throttle to see what setting is needed as the trigger point for lifting.

It might lead to a bit of a "power band" situation, though, so a little experimentation would definitely be needed.

Perhaps a variable resistor (triac?) mounted on the bars would help to determine the bests witching point, and then the next stage would be to see whether on/off lifting or a slower, more gradual lift would be better.

[Xenocide]

Ok well this is what i was thinking of. I'm absolutely sh1t at CAD though but might let you get a rough idea.

The pole on the right is just a smooth slider

the one on the left is a tall worm gear (like something you'd get out a floppy drive.. if you have any of them lying about).

I'd also need two microswitches aswell i'd imagine so we can sense when it's at top and bottom of it's travel. When it powers on it'd set it's top and bottom of the travel and sense the resting position of the tps. It'll then know the rough range of the tps (they're all the same i'd hope/imagine) so it'll know where the 75% (or whatever) starts and ends.

then everything doubled.



When I get paid i'll do a mockup of some bogroll.

[tony.mon]

I did quite a lot of pneumatic design and testing years ago, and we had a similar problem.
We found that trying to raise one side up its post and the other one just being a dumb guide didn't work; the sideways leverage that was an inevitable result just jammed the slider in place.
Lubrication would be a problem in the airbox environment, as well.

So how about a fork, with arms actuating on the sticky-out ears as you have drawn, but with the pivot at the handle end of the fork and the actuator motor halfway along its "handle"?

The fork arms at the stack end would terminate in a slider rather than a fixed pivot, as the effective length would change as it slides.

To avoid taking up volume in the airbox the motor could be sited externally. Just a thought....

GL-S-R's come up with some very useful suggestions for the control mechanism, incorporating feedback into the controller so that it "knows" where it is after an input has been applied.
Thanks, guys, this is just the sort of thing I was after- without some sort of decent control mechanism and movement actuator, with sensors, I would have just built a simple on/off device, probably spring operated or via an extra throttle cable, and knew that that wouldn't be a good solution, really.

In one way it's a shame we haven't got sensors all over these bikes to use as inputs when developing technical devices such as this, but it don't half keep things (relatively) simple, doesn't it?
Looking at all of the inputs connected to Aprilia's, for example- I'd have given up by now.
KISS, eh?