ESE's works engine tuner

[husaberg]

I have my 3D printer up and running and am continuing on with my snowmobile drag racing cylinder development project. My hope is to design and build a cylinder using the best design features of proven high output engines, notably the Aprilia RSA and Wobbly's further development from there. There are some design parameters that have to be taken into account. My plan right now is to build a 508cc twin with a bore and stroke of 68 X 70mm. If this produces good results an inline four cylinder of 1016cc would follow. I have tentatively chosen a Honda CR250R flat top piston and would move the ring locating pin to the centre of the c port. The 70 mm stroke was chosen because it is stock in a couple of manufacturer variations and allows close to a square engine at the displacements I am interested in. This setup would target max HP at 9500 RPM and due to the use of a CVT belt drive system which will hold the engine at peak power RPM throughout the run requires no overrev power. Snowmobile engines are conventionally inline twin or triple cylinder designs with the intake on the back side of the engine and the exhaust exiting forward. I will be using stock crankcases and crankshafts and this limits the width of the cylinder. In my case the base of the cylinder is approximately 137.5mm wide. I have scaled up and printed an RSA cylinder at a 68 mm bore and unless I have screwed up, which is entirely possible, the base of this cylinder is approximately 173mm wide. Obviously, I do not have the room to include the large sweeping radii of the transfer passages of the Aprilia cylinder. I have attached a couple of pics to hopefully clarify the situation. I can design the exhaust port and ducting and transfer ports themselves inline with Frits' FOS calculations but am concerned that the transfer passages will be a limiting factor. What is the minimum radius that I can get away with? Or am I fighting a losing battle?

To get around the width problem make it a v4 or V2. they allow more room for tranfers at a narrower width.
either single or twin crank gives you extra room without excessive width.

[pete376403]

Seen this?---https://www.cycleworld.com/story/motorcycle-news/kawasaki-to-design-supercharged-two-stroke-hybrid/

[Frits Overmars]

Seen this?---https://www.cycleworld.com/story/motorcycle-news/kawasaki-to-design-supercharged-two-stroke-hybrid/

70% efficiency - yeah right. And what about those radical technologies?
A cross-plane crank? Helmut Fath used that in the '70s.
Direct fuel injection? Mercedes did it in the '40s and I wouldn't be surprised if it has been around for about a century.
Overhead inlet and exhaust valves for a two-stroke?
Toyota built a six-in-line DOHC two-stroke with this exact layout, right down to the deflector ridge # 25a between the valves, some 20-odd years ago.

This Kawasaki may become a wonderful machine yet. I just wish that marketing people in general would behave more like responsible historians and less like Donald Trump.

[jbiplane]

Sounds similar to a megasquirt. What control strategies are supported?

All existing fuel strategies are supported. Processor about 10 times more fast than MegaSquirt and it baced on open source project.

[lohring]

346339[/ATTACH]

Our great leader has sent his best general and faithful troopers to quell these outbreaks. May the floss be with you. You'll need it.

Lohring Miller

[Haufen]

70% efficiency - yeah right.

Come on Frits, it's 'experts' that 'believe' that, it must be true!

I can imagine such a concept achieving efficiencies in the high fourties, after some development, though. More than double of that of a typical chainsaw engine.

[wobbly]

Polecat - I had CPI make a special Sphynx cylinder with stock bore and stroke = 250cc.
On Avgas this made 68.5 Hp @ 10200 rear wheel on a Dynojet. I would opine that the 68 overbore cylinder on 110 Leaded would easily do 75 and more if using the CR500 rod
as even at 130 the so called "long rod " TRX250 is still way too short.
The Spynx casting has provision for a PV , but with CVT this may not be needed - thinking back to an Aprilia GP though, this made peak power at 13,000 but the PV wasnt fully up till 12,000
thus aiding the front side power all the way up very close to peak.
The gasket width is same as CR250 , I think I have one here , I will have a look.

[ceci]

(Herr Schneurle?) would turn in his grave if he saw that we were still using his system today - he would have moved on!

Although the Schnuerle scavenging is very nostalgically interesting as an iconic 2S model.
The current trend is that of the 3 models in the photo:

1st Kawasaki (https://www.cycleworld.com/story/mot...stroke-hybrid/).
2nd Renault, has spent years researching and developing.
3º This type of motor is the most advanced, is Flettner, its prototype is one of the best solutions for motorcycles

[WilDun]

OOH! this is good!! - I was beginning to think that I was pissing upwind with my beliefs! - now I'm noticing some of my thoughts being vindicated! - maybe it's a bit early for me to be suggesting all these things??

AND yes, I do realize I'll probably never achieve anything myself, but it's great to see all of this stuff coming up - the only way to save the two stroke !! (even if it means using poppets) - but poppets are probably perfectly good for most of the applications mentioned (except OP)! - the good old poppets have managed to survive for a very long time. ......

70%? - I dunno about that!

[ken seeber]

Kawasaki & 70% thermal efficiency.

I've always believed that huge marine externally scavenged 2 stroke diesels were the best in thermal efficiency of around 50%. The main reasons being a very low surface area/volume ratio (= less energy lost to cooling circuit). Supposedly Mercedes claim 50% for their F1 engine, but not sure if this is in conjunction with KERS (or some other regen function). Maybe they had to do it so they could save on fuel costs to be able to pay for Hamilton's totally moderate $72M salary demand.

So, as I understand it, it will:
1. Be comparatively small in capacity = unfavourable surface area/volume ratio
2. Have to drive an external blower = losses need to be accounted for
3. Have friction losses of running camshafts etc at crank speed.

Running at constant speed is in its favour or there is some other bottoming cycle feature that didn't come to light..

Got my doubts. Anyways, it's a wait and see thing. Hope it is true though.

[Flettner]

Isn't this a Toyota thing, didn't I read about this ten years ago?

[WilDun]

I don't think that there are many things today which haven't been tried or at least proposed! - big breakthroughs came in the last century.

As I said before somewhere, it's a matter of fishing them out of the great pool of failures, sifting through them and reassembling them into different configurations, then refining them to suit the times we are in.

All good fun for enthusiasts to try everything, but for manufacturers a very dicey business - the status quo is safer! - good practice to leave the ideas to the enthusiasts, then pick their brains and rob them when the time is right!

[Peter1962]

I don't think that there are many things today which haven't been tried or at least proposed! - big breakthroughs came in the last century.

As I said before somewhere, it's a matter of fishing them out of the great pool of failures, sifting through them and reassembling them into different configurations, then refining them to suit the times we are in.

Alll good fun for enthusiasts to try everything, but for manufacturers a very dicey business - the status quo is safer! - good practice to leave the ideas to the enthusiasts, then pick their brains and rob them when the time is right!

That sounds about like the tentative by KTM to patent Neil's TPI concept...

Good thing that there are open forums on the internet like Kiwibiker, twostrokemotocross.com, deraceheldenvanweleer.nl or pit-lane.biz or thumpertalk.com.

If idea's have been published there, maybe even with working proof of concept, it will be very hard for a manufacturer to take that idea and claim it theirs and file a patent request.

Now, TPI is for everybody.

Same thing with Frits idea of a variable tailpipe. It has been published, there is a timeline as proof. No manufacturer can claim the intellectual property of this concept.

[lohring]

http://strangedevelopment.com/ for more old ideas combined into a new package.

Lohring Miller

[WilDun]

That sounds about like the tentative by KTM to patent Neil's TPI concept...

Good thing that there are open forums on the internet like Kiwibiker, twostrokemotocross.com, deraceheldenvanweleer.nl or pit-lane.biz or thumpertalk.com.

Not really clued up on the details about the laws around it all, but I did know about a couple of small companies who were doing ok selling successful stuff who had to shut down when someone BIG in the world copied their design and called it something else! - Laws are only good against those agree to abide by them! - as they say, "padlocks only stop honest people".