ESE's works engine tuner

[nitro2tfx]

There are lots of interesting aspects to this engine, from an operational performance perspective. Looking at this further I get the feeling that in addition to what has been mentioned by many as possible construction scenarios for emissions, engine speeds etc., there may also be some "never before published" flow scenarios through the "crankcase" that have not been mentioned on here, something even GP engine designers might have possibly thought of, but dismissed without trying it because on the surface it doesn't seem to make sense. The engine has to be able to move a lot more air to make 70 HP than it does to make 54 HP, irregardless of crankcase/combustion tricks to clean up emissions and so forth. I won't say what I have in mind, but it will be interesting to see what does, or does not, come out in the wash when the full design is made public.

[peewee]

i think im not far from completing the exh portion of this project. the roof exit angle is 34* now but ill flaten it a bit closer to 30* which will put it at the red line. then make the aux back walls a bit deeper and do allittle more work on the small dividers.

frits i dont know the first thing about cnc machines but i bet wobbly does. ill get with him about the necesarry parts needed

[wobbly]

That Ex duct exit looks good.
But I think the best deal would be to get the first 1/2 of the duct at 25*, then curve it down slowly to achieve the exit area
you need.
The 25* angle would be more important close to the piston timing edge, than down at the duct end.

[jonny quest]

It would be interesting for someone with enginmod, on a known engine in their files.... to just change crankcase volume to around 25% (in other words... very small volume) of what you currently have setup as. What does that do to sim?

[husaberg]

It would be interesting for someone with enginmod, on a known engine in their files.... to just change crankcase volume to around 25% (in other words... very small volume) of what you currently have setup as. What does that do to sim?

not really sure it would work the sim relies on known principles. and the crankcase being of normal size I suspect is one of the fundementals

What would happen is the power band would narrow and the rpm at which it delivery efficiency would rise at something like a square of the reduction in Crankcase volume.

Thanks Frits


One last bit (I realise you are busy) is the crankcase volume most texts quote the peak speed at which the peak delivery ratio occurs as being inversely proportional to the square root of the crankcase volume (Ie higher revs need lower volume) yet seemingly the modern thinking doesn't follow this, is it about needing a certain reservoir volume available or just better duct flows and directional control nowadays?

Kinda hard to decipher that sentence. Are you sure you cannot write in Dutch, Husa? Anyways, square roots of volumes make me think of Helmholtz resonance. And if memory serves, I posted my 'Helmholtz blues' here not too long ago; you might want to take a look.
Nowadays an engine needs a large crankcase volume (the Aprilia RSA125's is 675 cc at TDC), all the port area you can cram into the cylinder circumference, good ducts for efficient flow and directional control, an exhaust that sucks and blows hard at the appropriate moments, and cooling, cooling, cooling.

It is nearly word for word from Robinson.
I think he was an Editor as well.
What it was saying was the last bit (Ie higher revs need lower volume)
Out of respect for you and some others i tend to post in Engerishish.

I havnt read that book - so I just ordered it in case there is some small golden piece of info, you never know.

Re Blowdown STA numbers and the effect they have.
Firstly get out of your head completely the lawnmower engines view of the world that the piston dropping increases the pressure in the case, and it is this that forces the flow thru the transfers.
Mr Villiers creations may have operated this way - not any modern 2T.
When the transfers open, there is more pressure above the piston than there is case pressure in the transfer duct.
This gives rise to the alarming notion that when using staggered ports, the one to open first has so much backflow that it takes ages to recover, thus it has inflow last.
The area available in the Ex from the time the port cracks, down to where the transfers open, sets the amount of combustion pressure that is lost down the duct, and thus the amount of
positive pressure ratio across the open transfers ( and for how long this lasts ).
We can have NO FLOW until that positive pressure ratio is reduced to the point where we have more case pressure than cylinder pressure.
There are two ways to do this - lift the case pressure and or lower the cylinder pressure.
In a modern engine the case pressure is only rising very slowly due to the piston dropping, but what we do have is the pipe diffuser action, that started with the high pressure front ripping
out the opening Ex port - then entering the expanding pipes front section.
As the piston approaches BDC the Ex port is starting to suck the chrome off the proverbial towball,dropping the cylinder pressure ratio dramatically, and it is this that forces the bulk flow into the cylinder.
If the blowdown is set correctly for the power needed within the rpm band we want, then the recovery time from the unavoidable transfer backflow at the opening point, is such that we get the correct
amount of inflow to be trapped above the piston, thus creating the conditions for the correct amount of combustion pressure after the spark event.
It is this set of conditions - all revolving around the blowdown pressure,that ultimately creates how much combustion psi is developed - this creates torque, and it is this combined with rpm that creates POWER.

I just read my origional post that Frits responded to and i see it had a rather crude spelling mistake that may have confused as it would not have translated so well to Dutch the French word "reservoir" pardon my engerishThis is a neat word to describe what bucket is saying above.

Does that make more sense Frits.
The bit i was quoting from Robinson was referring to when a engine was tuned to a higher rev range than it was original to maintain the original pumping efficiency you reduce the volume by an amount specified (inversely proportional to the square root of the original crankcase volume) to match the new higher rev range.
assuming say you don't want to modify the angles and shapes of the transfers or if you have say downsized or upsized an engine?

however Robinson does a couple of chapters later say

1)high stream velocity

:High crankcase compression
:Narrow port windows
:Late timing (Long blow down period)

2)Low(er) stream velocity

:earlier timing,larger ports
: Direction(s) of streams become critical.

So i guess he had a ball in both courts as it were. but the 2nd option is the modern approach?or slightly different again?

It already made (some) sense the first time; as a former technical editor I am used to reading what people try to write instead of what they are actually writing.
And I do not translate anything to and from Dutch; In my mind I stick with the language that is being used.

Crankcase pumping only serves to start the engine; once it is running in the power band you can forget all about pumping efficiency.

Why don't we then close the port windows completely? That should give us infinite stream velocity, right? Yeah, right.... If you want velocity, you need a pressure differential. But we do not want velocity per sé; we want mass transportation (no, I'm not talking about public transport) so that means ample time.areas.

Supercharging by definition is a method to increase the efficiency of an engine by using an external device that creates a higher delivery ratio,than that able to be achieved by the swept volume alone.
This can use energy within the Exhaust gas flow as is done by a Turbocharger.
It can use crank power to drive a pump, that creates more power at the crank than it consumes - a Supercharger.
Or - you can use sonic wave action in a divergent/convergent pipe,that uses that energy to evacuate and then refill the cylinder to a higher level than the swept volume alone could achieve - a Sonic Supercharger.
Next is Chemical Supercharging - where the fuel contains excess oxygen than that contained in the swept volume of air.

[karter444]

That Ex duct exit looks good.
But I think the best deal would be to get the first 1/2 of the duct at 25*, then curve it down slowly to achieve the exit area
you need.
The 25* angle would be more important close to the piston timing edge, than down at the duct end.

Wobbly what would happen if you took this concept one step further and made the exhaust duct exit really wide ie maybe wider than the bore size [it would require external welding to barrel to allow widening of aux ducts ]and then reduced the height of the duct exit so you could end up with say an exhaust duct exit dimension of 55mm x 15 mm

[adegnes]

i think im not far from completing the exh portion of this project. the roof exit angle is 34* now but ill flaten it a bit closer to 30* which will put it at the red line. then make the aux back walls a bit deeper and do allittle more work on the small dividers.

frits i dont know the first thing about cnc machines but i bet wobbly does. ill get with him about the necesarry parts needed

Lookin' good!

.... I won't say what I have in mind....

That's the spirit!

[gravmax88]

https://www.youtube.com/watch?v=AF9nBjgcX3E

[wobbly]

The super wide Ex duct idea suffers from one fatal flaw.
Trying to get any sort of reasonable shaped transition from 55X15 out to say 45 round at the header would be a flow detaching nightmare.
I have heard but not seen, that Aprilia had tested keeping the outflow flow biased toward helping the blowdown action of the Aux ducts
by oval shaping the beginning of the header as well.
Thus the transition was even smoother within the short slip fit spigot length.
Sounds good in theory, but I have never had a go at the idea.

[F5 Dave]

[QUOTE=gravmax88;1130906784]https://www.youtube.com/watch?v=AF9nBj/QUOTE]
So the karting was just a red herring. That was feckn funny. And impressive.

[TZ350]

https://www.youtube.com/watch?v=AF9nBj

So the karting was just a red herring. That was feckn funny. And impressive.

Pretty impressive alright.

[jonny quest]

Husaberg, that was going to be my point later on... sims are based off of known values.

So does anyweird anomaly still work in the sims?

I have a feeling one of the tricks of the Ryger is a tiny tiny "crankcase" volume (which will probably be called under piston volume from now on, or primary compression, because crankcase is now separate)

[seattle smitty]

(EDIT)-- post deleted

[adegnes]

Frits, I know of no way to get this to your friend other than to ask you to pass it along:

Mr. Ryger,

I am taking it upon myself to put this to you on behalf of the tiny sport of outboard hydroplane racing. Ours is an almost entirely amateur, in-crowd activity (despite its ironically humorous name in the USA of Professional Outboard Racing). In contrast with other forms of powerboat racing that use big V-6 engines built by big corporations, we use motorcycle-sized engines, currently from 125cc to 1100cc, burning alcohol and possibly other exotic fuels, and with few limitations as compared with motorcycle or kart racing. This has always been a sport that appeals to hands-on amateur tuners and modifiers. Although most of us have run highly modified engines from Mercury and OMC, or racing engines from such companies as Konig, Anzani, Quincy, Crescent, and Yamato, many have converted motorcycle and snowmobile engines into outboards. Currently, our manufactured engines are coming from Giuseppe Rossi and Carlo Verona in Italy, both of whom do high-quality work, and Konny in eastern Europe who bought the Konig operation.

With that introduction (our sport is so small that I am guessing you have little knowledge of it), I would like you to consider a request. Your new engine, by all we are hearing, is likely to immediately make all of our existing motors obsolete, and require any racer who intends to be competitive to either attempt to build an engine of your design in his own shop, or to wait for a small manufacturer such as Rossi or Verona to start building Ryger-design outboards with a license from you. I would be surprised if one or both of these individuals hasn't contacted you already.

Please consider that it would surely be best for us amateur outboard racers if no single outboard builder were awarded an exclusive license to build your engine . . . for all the reasons that will immediately occur to you.

Remember, this is a very small sport, and whether you license one or more than one manufacturer, the royalties won't amount to much in any case. Your design appears to be such a breakthrough, with great potential beyond the little world of motor-racing, that big corporations will soon come calling and all of your years of work will ultimately be well-repaid. All of us 2-stroke fans are hoping this will happen.

Thank you for considering this,

--Phil Smith,
Seattle, Washington State, USA

Word. (too short)

[Frits Overmars]

Frits, I know of no way to get this to your friend other than to ask you to pass it along

It would be my pleasure Smitty. But I don't wish to be the middleman in your correspondence, so it would be better if you mail him directly.
EDIT I see you've got his email now.