ESE's works engine tuner

[Frits Overmars]

Frits, I don't think Rob's computer will " fly by wire " the throttle.

Agreed; that is why I wrote 'by bowden wire' , controlled by the computer in the saddle. We can't call him dumb, can we?

Best to just copy the F9 for the minute, it works.

So do four-strokes, I'm told; not a reason to copy them though, eh?

I'm fitting this fly by wire throttle / variable valve cover to my new engine

I am looking forward to it.
By the way, the 990 cc three-cylinder Aprilia (with a little help and a stiff bill from Cosworth) was the first MotoGP bike with computer-controlled throttle operation which caused the riders 'some problems'. As one of them said fly-by-wire, the technical director corrected him: 'It is not a plane so you should call it ride-by-wire'.
Rider reply: 'you ride it, then you'll see how high you fly!'

[Forgi]

I havnt tested variations like yours - only reducing the duct as far back as it is possible to weld, and having the 75% at the manifold face.
Then expansion out to 100%.
A CNC transition from oval to round made more power than the stepped face into a round spigot did.
Only point I would add is that you should also look into grinding the aux ducts all the way along the length to the pipe.
This helps promote the blowdown flow when the piston has only partially opened the top 1/2 of the Exhaust.
Edit - once you have done the nozzle test have a go at modernising the ports as well.

Yes, I made such a nozzle which is on your drawing. This is the same as the third variation of mine, where the area of the nozzle is 75% only at the end of the duct.




Regretfully I can't do the subsequent modernization of the cylinder.
It's true that the bottom of the main exhaust port became too wide.
Concerning the aux ports' shape I make them rectangular, cos it is easier to calculate with them and it is also easier to prepare them as they are handmade. The latest version is the same as you draw. The ports of the Gp KTM 125 are also rectangular, aren't they?

Concerning the A transfer ports we can't modify them because of the pharameters of the cylinder and the block. The best you can do is this:



This way although the TA of the ports decreases, the scavenging will be better.

[wobbly]

If you can reshape the A transfer as you have drawn, then this will allow you to drop the main port, as well as the Aux, with more timing difference between them.
This will then give more blowdown capability, with less timing, bumping up mid power and overev.
A win, win.
The Aux ports flow the most when just opening, thus need to be the widest at the top. This is due to there being the greatest pressure delta across them as they crack open.
Transfers are the opposite, thus reducing the interaction of the Aux and transfers by reducing the Aux width at the bottom helps power everywhere.

[Flettner]

I am looking forward to it.
By the way, the 990 cc three-cylinder Aprilia (with a little help and a stiff bill from Cosworth) was the first MotoGP bike with computer-controlled throttle operation which caused the riders 'some problems'. As one of them said fly-by-wire, the technical director corrected him: 'It is not a plane so you should call it ride-by-wire'.
Rider reply: 'you ride it, then you'll see how high you fly!'

Perhaps. Yes the 360 may end up computer "assisted" rather than full fly by wire but I want to have a go at it. Yes the "timing throttle" could be run by cable just another thing to concentrate on when riding, not too much throttle too early. I'm interested in this technology to help control wheel spin / hookup on a dirt bike. Try and get the twostroke a little more like the fourstrokes on corner exit. There is even the possibility if injecting straight into the cylinder to miss an injection every cycle or other cycle ( no wasted fuel ) at low rpm say up to 1/3 throttle to get better bite, fire every second or third shot ( like a fourstroke ).
The issue will be blending this back to full injection with out a lump in the power?
I too am looking forward to it.

[Frits Overmars]

...the "timing throttle" could be run by cable just another thing to concentrate on when riding

I did not intend to say that this should be your approach; only a way for TZ350 to get going. Of course if you have a computer capable of handling ignition, injection, disc timing and throttle opening, you should free the rider from these tasks.

... not too much throttle too early. I'm interested in this technology to help control wheel spin / hookup on a dirt bike. Try and get the twostroke a little more like the fourstrokes on corner exit.

Making throttle response linear can be a big improvement. In the Aprilias it was done by linking ignition timing and power valve and power jet settings to rpm, throttle position and gear selector position, striving for a linear relation between throttle opening and rear wheel torque.

There is even the possibility if injecting straight into the cylinder to miss an injection every cycle or other cycle ( no wasted fuel ) at low rpm say up to 1/3 throttle to get better bite, fire every second or third shot ( like a fourstroke ).

That may be an insurmountable enterprise. If you cut one in two combustions in a two-stroke, the gas dynamics in the pipe will collapse and you will lose far more than 50% of engine power.

The issue will be blending this back to full injection with out a lump in the power?

That will be issue number two then.

[husaberg]

That may be an insurmountable enterprise. If you cut one in two combustions in a two-stroke, the gas dynamics in the pipe will collapse and you will lose far more than 50% of engine power.
.

When i seen Neil's response, (we had discussed it before) My take is to skip far less ignition cycles and fueling cyles. Say 6000rpm is 100 times per second. I think skipping only just a few would be enough, Maybe even just having a few wrongly timed where they make little contribution to the output.
My diesel (Husaberg) has a simple Duel ignition curve, (Maybe just the base advance and the limiter i don't know what it does actually) the results of changing between the curves are never the less quite dramatic.

But i take you point re the dynamics. But where i guess Neil intends to alter the Gas Dynamics, are well...... Not to.... Dnyamic anyway.

On another subject Frits your 50cc project what layout do you intend to use regarding the primary and the reductions. I are trying to get my head arround one with a CVT but there must be a simpler solution, Than what i have schemed which is basically a scooter setup.
To fit in a disc, i are also either mounting the ignition outboard (which i hate) or driving it off a counterbalancer, neither which i like.
I see advantages in driving the CVT after an initial primary reduction as i think i can get away with less modification to a std CVT setup

Lastly the RSW125 side profile drawing in the Frits files. Is it acculturate enough to scale crankcase dimensions off? or is it a illustration?
I have collected an number of Pictures but intriguingly there no drawings of the Crankcase yet plenty of the Cylinders available.
I recall you saying 1mm (or was it 2mm) was the miniumun to run to counter drag for the Crankwheel-crankcase clearance i assume this is what the Aprilias ran?

[Frits Overmars]

My take is to skip far less ignition cycles and fueling cyles. Say 6000rpm is 100 times per second. I think skipping only just a few would be enough, Maybe even just having a few wrongly timed where they make little contribution to the output.

In theory Neils plan to skip injection events instead of sparks is better for fuel consumption and for the environment. But as I said above, it's not gonna be simple.
Your take may be the way to go: skipping for example 1 in 10 cycles, then going to 1 in 12, then to 1 in 14, 1 in 16, etc. That is fairly easy to program.
Honda's quickshifter used to cut engine power not by omitting sparks but by heavily retarding them; by 50° if I remember correctly. But I would not recommend that as a means of reducing normal riding power, as it would heat up the engine real quick.

On another subject Frits your 50cc project what layout do you intend to use regarding the primary and the reductions. I are trying to get my head arround one with a CVT but there must be a simpler solution, Than what i have schemed which is basically a scooter setup.

I think you can't get much simpler than a scooter setup. But I would add an outrigger bearing to the CVT side of the crankshaft. Seeing how much that shaft bends when you just push at the V-belt, will make you shiver.

To fit in a disc, i are also either mounting the ignition outboard (which i hate) or driving it off a counterbalancer, neither which i like.

You should get the ignition signal directly from the crankshaft; you could use the RSA125-setup with a sensor looking at a notch in the circumference of one of the crank webs. You can then run the generator from any place that is convenient.


BTW: that crankshaft is not from an RSA125 but from a Rotax Max kart engine; they use the same setup.

I see advantages in driving the CVT after an initial primary reduction as i think i can get away with less modification to a std CVT setup.

Maybe, but remember that running the CVT slower will increase the torque upon it, requiring more clamping force on the V-belt.

Lastly the RSW125 side profile drawing in the Frits files. Is it acculturate enough to scale crankcase dimensions off? or is it a illustration?

Did I post an RSW side profile drawing showing the crankcase? I can't remember that for the life of me.
EDIT: I think I found what you meant. It is accurate all right, but you can hardly take dimensions from so tiny a picture, can you?

I recall you saying 1mm (or was it 2mm) was the miniumun to run to counter drag for the Crankwheel-crankcase clearance i assume this is what the Aprilias ran?

1 mm is correct, irrespective of engine size.

[husaberg]

Thanks Frits
The drawing was this one.(below)

These were other good side profile pics i had found (below)

Re the Primary drive yes you are of course right.
Its just with the scooter set up to stay with a conventional Japanese left side drive set up (for a rs1125 frame)it pushes everythink out the left a lot to line up the sprocket. Maybe i should do a frame with right side drive.(Cross over shaft for the counder shaft)

I think Wob showed a pic of the trigger long long ago or at least maybe the Pulse Swisauto one?

Makes me wonder why was the Works NSR250 Right side drive?

Re the drawing i haven't yet tried but how acturate is this

I assume it is a attempt at a RSV250 but i haven't got around to translating it yet.

I know the crank wheels are 49mm wide on the rsw125.

[Frits Overmars]

Re the drawing i haven't yet tried but how acturate is this

I can't say; I am on tour.

... i haven't got around to translating it yet.

Don't bother; there's nothing in there that you don't already know. Translating it will only show how good the italians are at using a lot of beautiful long words to say next to nothing.

[Forgi]

If you can reshape the A transfer as you have drawn, then this will allow you to drop the main port, as well as the Aux, with more timing difference between them.
This will then give more blowdown capability, with less timing, bumping up mid power and overev.
A win, win.
The Aux ports flow the most when just opening, thus need to be the widest at the top. This is due to there being the greatest pressure delta across them as they crack open.
Transfers are the opposite, thus reducing the interaction of the Aux and transfers by reducing the Aux width at the bottom helps power everywhere.

@Wobbly: I think I can understand what you are writing, but is it a good idea to decrease the timing of the exhaust port, even if the TA and the blowdown stay the same or because of the modifications it will be bigger? I think that Frits is right when he says that the best exhaust degree is about 190 degrees due to the resonance. If we could rely on engmod, 195 degrees would be even better, cos the peak of the blowdown is at 15 degrees after the opening of the port. What do you think?



Because of the abovementioned reasons I didn't want to decrease the exhaust's timing. This way the TA and the blowdown are convenient meanwhile if I modify them according to your drawing the two values would be too high for certain rmp.
I don't know if I'm right or not, so feel free to correct me!

Dear Frits! By any chance do you have your article titled "De Expansie-uitlaat" in english? I'd read it!

[Frits Overmars]

Dear Frits! By any chance do you have your article titled "De Expansie-uitlaat" in english? I'd read it!

Dear Forgi, sorry, no. But remember: that article may be older than you are; it's from 1978.

[wobbly]

It all depends upon the power you are wanting - or the power that the weakest link in the engine is capable of.
Yes, the best power bandwidth is to be had down at 190 Ex duration, but this is rarely used as no matter how you jig the ports, you are always looking for more blowdown when after good peak power.
But if the engine has shortcomings in other areas, and will never generate a bmep over say 150psi, then you dont need high timings with a 3 port, as its easy to
get the required blowdown STA.
Thus my comment about dropping the main port, and dropping the Aux even more.
With a radius on the A port top front corner, its then easy to get plenty of Aux blowdown STA.
But , if cutting the ports this way gives an excess of Blow STA, then simply drop the ports some more and get an even better powerband width.

When you drop the main port you get a wider rpm band of superposition wave reinforcement, and when you have plenty of separation between the main and aux timings,the mid power comes up even more.
Its the old story told 1000 times, low and wide is best, with the one caveat that the best combination with 3 ports is a 68% main, with the biggest Aux you can fit to get the blow STA needed.

Edit - the Pulse/SwissAoto design had two round magnets embedded at 180* in a crank wheel.
Each one had reverse polarity, ie one was S the other N facing out.
The trigger saw this as two distinct signals and the ECU was able to determine LH and RH cylinder pairs for correct ignition sequencing.

[Flettner]

Frits, intake length, how short is too short?

[wobbly]

The very short intake length is needed on a RV to reduce the effects of multiple fuel signals affecting the carburation.
With no such issues affecting injectors then the intake length can be tuned in EngMod to improve cylinder filling at any rpm you want.
But you are still faced with the problem of trying to fit any sort of normal length bellmouthed intake on the side, without compromising either flow, with a tight bend,or overall width
with a straight tube - hello Mr rear RV.

[husaberg]

The very short intake length is needed on a RV to reduce the effects of multiple fuel signals affecting the carburation.
With no such issues affecting injectors then the intake length can be tuned in EngMod to improve cylinder filling at any rpm you want.
But you are still faced with the problem of trying to fit any sort of normal length bellmouthed intake on the side, without compromising either flow, with a tight bend,or overall width
with a straight tube - hello Mr rear RV.

The tuned intake length testing I did with the reed engine was based on Dynamation sim results and as I have shown here before,involves combining the
case pressure ratio dropping below atma,at the same time as the intake length resonates with a + ratio at the reeds.
This opens them real quick,and fast,initiating intake flow early in the cycle.
Having around 135mm from bell to reed tips gives a good result centred around 12,000 rpm so works well on alot of 125s.
This tunes the intake to the 2rd harmonic from memory as it gives the best energy recovery over the widest range.
Using this approach on a 250 power unit gives really good gains ( making the length around 50% longer again ) and proves that the only reason the factories use 125 size carbs and manifolds
on these MX bikes ,is simply that there is no room.
Another pointer is that for example on the old TZ250 piston port.
If you are silly enough to remove the 20mm phenolic spacer fitted by the factory to "get some more top end ", all that happens is the the tuning range moves up past 12,000
and it is impossible to jet the thing at lower rpm.
Same with the tossers selling shortened carbs for the TZ350, simply throwing away a bunch of free mid power with no addition of any top end at all - the factory chose the big/long body Mikuni for a reason..

The RV scenario probably is working on the short 3rd harmonic, with less energy recovery, but also the very short length is mechanically desirable and reduces the deleterious effect
of the standing waves on the fuel delivery from the jets.

Thanks for the flowers, RAW.
You can have an intake length that is too short in combination with intake diameter, intake timing, crankcase volume and desired rpm, in which case the engine will express its displeasure by blowing back some of the inhaled mixture. I prefer to shorten the intake length as much as possible and shorten the intake timing accordingly.
By varying intake length, intake timing or crankcase volume you can adapt the induction system to different rpms. I think the best way to adapt to low revs is to advance the intake closing; it will make for a docile engine with a clean, easy to set carburation.

Varying exhaust pipe length seems to be a far better way of increasing overrev than retarding the ignition or leaning out the mixture; it would be a waste not to utilize all inhaled oxygen. Varying the pipe length can also markedly lower the beginning of the power band.

One Frits and Wob prepared earlier.

I was thinking about the rear disk the other day i seem to remember Wobs and Frits and Jan saying the Conrod was in the way and disrupting the flow a lot i guess a heck of a lot near or near bdc and likely more at TDC. But if the cylinder was on more of a forward angle like say a Rumi or even the classic Aermacchi layout wouldn't that lessen the issue? OK not as good as the rear disk but helpful? ....likely not i guess as the fatter part is still disruption maybe a Alpha or Ariel Arrow like hollow section rod shape

So, Jan Thiel gave his ok. A few pics I found interesting:




"Jamathi cilinder 1967"



Derbi ignition trigger



Cylinder inspecting - with Giovanni Sartorato e Matteo Marini



"Brno 1969, our best win! On the right is my Czech friend Olda Fiser."



"With my friend GJ Rigter at the Aprilia flowbench. The tool in my hand is for flowing the transfers. We flowed them with the piston in 4 different positions."



"The front half of an Aprilia crankcase. The crankshaft could be fixed in various positions by a springloaded ball. We used this for flowbench testing. We could see that the conrod disturbed the flow very much, so the idea of the rear inlet RSA was born!

I can't see dinamiks pic's here wish i could