ESE's works engine tuner

[Leed]

I congratulate you on YOUR invention

maybe you could call it Boost Bottle 2k10

[TZ350]

As we know, a torque curve like the Matterhorn, however high, makes for a peaky engine and difficult to ride and that a flater wider torque curve makes for a more drivable engine and of course, flat, wide and higher is better still.

Looking at buckets graph showing the back to back trace of a conventionally mounted 24mm carb vis the plenum with its 34mm internal inlet.

You can see that if both torque curves could be combined in some way the power spread could be nearly 3,000 rpm wide, an extra 50%, making for a much more drivable engine.

As the only real difference between the curves is, that one is of a 24mm inlet tract and the other a 34mm one.

Now we are not talking about changing the length here for some resonant gain, but varying the effective diameter of the inlet as the rev's change.

This works, because reducing the inlet diameter as the rev's drop keeps the kinetic energy of the gas stream up for better crankcase stuffing at lower rpm and the larger inlet tract allows better crankcase filling at higher rpm.

So logic would tell us, that if we could have an inlet that varies in diameter from 24 to 34mm as the rpm increases then we would get the combined benefit of both curves.

But how to do that...........

[richban]

So logic would tell us, that if we could have an inlet that varies in diameter from 24 to 34mm as the rpm increases then we would get the combined benefit of both curves.

But how to do that...........

You could rob the aperture ring out of a camera lense for resting on the dyno. Some very old lenses had very manual aperture controls. You would need maybe an 85 mm lens then just rig a cable to the aperture and throttle job done. Easy you may need a swiss army knife in your tool kit for this job.

[Yow Ling]

You could rob the aperture ring out of a camera lense for resting on the dyno. Some very old lenses had very manual aperture controls. You would need maybe an 85 mm lens then just rig a cable to the aperture and throttle job done. Easy you may need a swiss army knife in your tool kit for this job.

that might cause alot of turbulence when maybe you want laminar flow.
maybe a piece of rubberish tube with ally ends if you wound up one end the rubber tube could constrict, could use a ypvs servo to do the twisting , they start coming on at 6 or 7 k, all in by 9500

[bucketracer]

You could rob the aperture ring out of a camera lense......

That looks good.......

.......maybe a piece of rubberish tube with ally ends if you wound up one end the rubber tube could constrict, could use a ypvs servo to do the twisting.....

Hadn't thought of that........ but it looks very good too........



I dug around in Dad's junk box and found a tuning capacitor. I had in mind that if he made a whole lot of leaves like the capacitor has and put a 34mm hole through them, then when the leaves are rotated, the hole that forms the inlet would be opened or closed and when fully open it could be quite smooth inside.

[bucketracer]

......maybe a piece of rubberish tube with ally ends if you wound up one end the rubber tube could constrict, could use a ypvs servo to do the twisting , they start coming on at 6 or 7 k, all in by 9500

Actually what about just flattening the tube, reducing its cross sectional area for lower rpm and opening it again for high rpm........

[Buckets4Me]

So logic would tell us, that if we could have an inlet that varies in diameter from 24 to 34mm as the rpm increases then we would get the combined benefit of both curves.

So logic should tell you this is going to be long and costly and you had better put it out of your mind till after Taupo

[bucketracer]

I congratulate you on YOUR invention

maybe you could call it Boost Bottle 2k10

Actually that's a good idea, a snappy name for TeeZee's plenum, but Boost-Bottle is not right as a boost bottle is a resonant chamber and TeeZee's plenum is a space where fuel/air mixture is stored waiting for the engine to snap it up.............

Maybe it should be called 2K10-Red-Shed where every engine gets a bargain.........

[SS90]

Actually that's a good idea, a snappy name for TeeZee's plenum, but Boost-Bottle is not right as a boost bottle is a resonant chamber and TeeZee's plenum is a space where fuel/air mixture is stored waiting for the engine to snap it up.............

Maybe it should be called 2K10-Red-Shed where every engine gets a bargain.........

Huh?

Its the same thing, a boost bottle is a resonant chamber, and so is the plenum.

[Leed]

So logic would tell us, that if we could have an inlet that varies in diameter from 24 to 34mm as the rpm increases then we would get the combined benefit of both curves.

yep... its call a carburetor

the works teams only used inlet tracts as short as possible... but you want to add volume...
...but they had the choice to run as bigger carbs as they liked.

the ideal lengths for inlet and exhaust are way longer than practical on a motorcycle hence tuning to lower orders of resonance.
what about upstream of the carb that also affects its flow... variable length trumpets (as done on the R1), stacks with proper/full return radius's
controlled by a powervalve servo
...but not that practical if the carb is at the front of the engine

[bucketracer]

Huh?

Its the same thing, a boost bottle is a resonant chamber, and so is the plenum.

And TeeZee would call it a resonant chamber too, if that was the primary reason it is there .......

But unlike the resonant boost bottle, the plenum has a bigger purpose ......

[F5 Dave]

I have to pop in to say making that sort of power at such pedestrian revs is pretty impressive. Now presumably the restrictions of poxy scooter parts, 4 gears & perhaps fixed gearing mean keeping to those sort of revs. Give that sucker some revs & I don't think the 'shape' of the torque curve would be a discussion point.

[bucketracer]

I have to pop in to say making that sort of power at such pedestrian revs is pretty impressive. Now presumably the restrictions of poxy scooter parts, 4 gears & perhaps fixed gearing mean keeping to those sort of revs. Give that sucker some revs & I don't think the 'shape' of the torque curve would be a discussion point.

I do have to agree, and it's pretty impressive hp at such low rpm..........

[SS90]

Just roll back a years worth of posts, you will see several other curves, all revving to 10,000 or so, some quite impressive, some a little more amateur.

For us, it come down to rideability.

I like my road engines to be like that, and my favorite race engine actually only makes 18 ps, but is so easy to ride fast, particularly on the karts tracks in Europe (although, generally speaking, they are somewhat more open than NZ Kart tracks)

Just to reaffirm where scooter engines are at, remember, we have been getting more tha 27 ps and 22 NM for some years now, it is nothing new (34mm carbs).

But the trend for many of us now is to have the most torque at the least RPM.

Its easier than you think to achieve


Plenty of us are getting 22 to 23 ps with 24 mm carbs, 4 speed gearboxes, and so on.

The 24 mm carb is more about "how much can I get" rather than being a rule like buckets (no carb size limit it most of the classes), although there is a "control class" for certain a model of cylinder, certain manifold, and certain carb, but the top 3 bikes are dyno tested at the end of the days racing, and anyone with more than 13ps is disqualified (unless theybare wiling to have their engine pulled down to check..... No one ever has been willing, funnily enough)

The rules are different though, in the class you now can run up to 140cc, but not that many people do, the reality is, in a short wheel based oddball set up as these things, you only really need, like I say 20 ps and 20 nm, and you have a good chance of getting on the podium. That and the fact that you don't need to rebuild you engine every 3 meetings.

the guys running the maximum capacity, easily break 30ps and 24nm (at about 11,500 rpm)

There is a guy in Saarbruken that has recently achieved 38ps, but it is water cooled,and 140cc.

It will be for quarter miles, of that I am certain.
It appears a Small frame Vespa crank can only handle more than 25 ps for only so long.... New ones are only €34, so not a big worry, unless of course you had cut them like me, then you have some hoers prep work.

[TZ350]

Just roll back a years worth of posts, you will see several other curves, all revving to 10,000 or so, some quite impressive, some a little more amateur.

Plenty of us are getting 22 to 23 ps with 24 mm carbs, 4 speed gearboxes, and so on.

Thank you for the wright up, yes your right, it's not always about hp, and we think, being easy to ride is where the FXR's have got it over us at Mt Welly.

Looking at the shape of the curves is where we are getting to now ourselves. The last year has turned out being more about building new chassis than engine development.

Building up new bikes takes longer than anyone would think and we feel we are runing out of time (again) to be ready for Taupo.

I will see if I can find the earlier graphs, and I am trying to get some graphs of different FXR's for comparison.

Because they relate to our own work any graphs of your 22 to 23 ps engines with 24 mm carbs would be most welcome.