Oddball engines and prototypes

[Frits Overmars]

If you want to supercharge an engine, you must blow through the port that closest last. In a four-stroke engine that's no problem, but supercharging a two-stroke tends to be less effective. You blow through the transfer ports, but when these close, the exhaust port is still open, so you cannot really create a high pressure in the cylinder.

Closing the exhaust port before the transfer ports was done in the pre-war blown DKW racers with their split-single layout and in the Jumo 205 uniflow engines
with a crankshaft at either end of the cylinders. But as supercharging was forbidden after the war, nobody seems to have given it much thought since then. Well, I did.

A two-stroke exhaust pipe is a supercharger, albeit without any moving parts, so it is not affected by the supercharger ban. And a good pipe can triple the power of a competition two-stroke, so you would think that it is quite effective. But it doesn't stand a chance against the power of a blown four-stroke.

Let's take a look at the engine I am most familiar with, the Aprilia RSA. At exhaust opening the pressure of the spent gases in the cylinder is about 12 bar abs.
At exhaust closure the pressure of the fresh mixture in the cylinder is about 2 bar abs. If we could raise that to say 4 bar, we would about double the power.
There is plenty energy in the spent gases, if only the exhaust pipe could deal with it more effectively.

Pondering about this, I ran into a forty-year old patent wherein the full pressure of one cylinder's exhaust pulse is used to charge the neighbour cylinder of a 180° parallel twin. It requires an exhaust timing of well over 180° but hey, if it works... And we could get away with a single exhaust pipe of modest dimensions. Think about it.

[WilDun]

If you want to supercharge an engine, you must blow through the port that closes last.........supercharging a two-stroke tends to be less effective. You blow through the transfer ports, but when these close, the exhaust port is still open, so you cannot really create a high pressure in the cylinder.

Closing the exhaust port before the transfer ports was done in the pre-war blown DKW racers with their split-single layout .............,but as supercharging was forbidden after the war, nobody seems to have given it much thought since .........

A two-stroke exhaust pipe is a supercharger, albeit without any moving parts, so it is not effected by the supercharger ban. And a good pipe can triple the power of a competition two-stroke, so you would think that it is quite effective. But it doesn't stand a chance against the power of a blown four-stroke.

................. At exhaust opening the pressure of the spent gases in the cylinder is about 12 bar abs. At exhaust closure the pressure of the fresh mixture in the cylinder is about 2 bar abs. If we could raise that to say 4 bar, we would about double the power.


I ran into a forty-year old patent wherein the full pressure of one cylinder's exhaust pulse is used to charge the neighbour cylinder of a 180° parallel twin. It requires an exhaust timing of well over 180° but hey, if it works we could get away with a single exhaust pipe of modest dimensions.

Now we're talking Frits!

I hadn't realized that DKW had exhausts which closed before the transfers, but I did wonder if that was feasible .... now I know it was.

So maybe the idea of using the "semi spent" exhaust gases for productive power, also by using direct forced induction to the "transfers" etc. we can get rid of bulky exhaust chambers, crankcase pumping and petroil lubrication - all in one go!
In fact a complete re-design of the two stroke! (last chance?).

This thread may be a good place to discuss all the possibilities (outside the rulebooks) of new experimental stuff, or ideas from the past abandoned for various reasons ........ all without treading on people's toes in other threads! but I'm sure there will always be an unavoidable overlap.

[tjbw]

No,No, God forbid! - if I could manage to get into that contraption I'd never be able to climb out of it! - I ran out of space in my garage to keep my little Honda Gyro tilting trike (and my main lathe also) but I do like tilting vehicles, motorcycle feel, but with less risk of falling off!

I have always loved two strokes (especially in bikes), but there are still one or two things about them which irritate me a lot - One is the amount of embarrassing smoke they continue to emit, two is the embarrassing size of their exhaust chambers, especially in larger cylinder sizes and in multi cylinder engines, and also fuel consumption - all this no doubt can be overcome (at a cost) and would leave four strokes for dead in just about every respect, but in order to achieve that everything would have to become complicated, - a far cry from the "simple" two stroke of the past. Trouble these days is, with motorcycles, people will accept expense and complication, ie if it's fashionable and will gain them a couple of horses, even if they can't use them - except for bragging rights!
I think the two stroke could survive in snowmobiles, karts and aircraft and ( thanks to the work already being done) are surviving, also the scales could just be starting to waver towards the two stroke in motocross!

So the criteria include:

No bevel gears
No big fat exhaust pipes
Easy to get into
Must have tilting motorcycle feel
...

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

[WilDun]

So the criteria include:

No bevel gears
No big fat exhaust pipes
Easy to get into
Must have tilting motorcycle feel
...

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

Well, I didn't mention bevel gears - anyway that contraption really takes the cake! and to be honest, the only "safe" braking method is exactly what the guy riding it used!
Another (albeit negative) thought is :- Imagine what would happen if a piece of gravel got caught on that bloody great bearing at 50mph!!!

Oh and I see why they used a lady on that machine on the old photo - a guy getting things caught on that sprocket just doesn't bear thinking about !

[Frits Overmars]

the only "safe" braking method is exactly what the guy riding it used!

Well, he used the gate he ran into at 2:32. But what if there's no gate at hand?

[tjbw]

...

Another (albeit negative) thought is :- Imagine what would happen if a piece of gravel got caught on that bloody great bearing at 50mph!!!
...

That was my first thought as well. It would give a new meaning to "going for a spin"

Also, vision is obscured by the wheel, imagine what would happen if two monowheels are on a collision course!

[WilDun]

That was my first thought as well. It would give a new meaning to "going for a spin"

Also, vision is obscured by the wheel, imagine what would happen if two monowheels are on a collision course!

I guess anything can be achieved if you chuck enough money at it - a camera on each side of the wheel and a monitor of course.!

How about using the "wheel rim" as giant rotor of a stepper motor, that stepper motor being controlled by a computer and using traction control type hardware as sensors, that way braking and acceleration will be be taken care of.
In theory a heavier pilot would be able to brake more heavily than a light one! but if there was a computer glitch and the "pilot" went for a "spin", think about the unbalanced forces!!
Could even be driverless! - hang on - then there would be thousands of the bloody things careering around the streets with no one aboard and nowhere in particular to go - what would be the point in that? - how about Pizza delivery?

I'm beginning to think that in reality bucket racers is as far as technology needs to go and anything further than that is a step too far - even that can sometimes get out of hand!

[tjbw]

I guess anything can be achieved if you chuck enough money at it - a camera on each side of the wheel and a monitor of course.!

How about using the "wheel rim" as giant rotor of a stepper motor, that stepper motor being controlled by a computer and using traction control type hardware as sensors, that way braking and acceleration will be be taken care of.
In theory a heavier pilot would be able to brake more heavily than a light one! but if there was a computer glitch and the "pilot" went for a "spin", think about the unbalanced forces!!
Could even be driverless! - hang on - then there would be thousands of the bloody things careering around the streets with no one aboard and nowhere in particular to go - what would be the point in that? - how about Pizza delivery?

I'm beginning to think that in reality bucket racers is as far as technology needs to go and anything further than that is a step too far - even that can sometimes get out of hand!

Yes, I was thinking of two cameras as well, didn't think about the stepper motor though, I like that idea. I was thinking there might be something in Segway technology that could be exploited.

You made me laugh re the pizza delivery, but what I think you should do is form a company, called Deliverwi, and do local deliveries using ncopters

[WilDun]

Yes, I was thinking of two cameras as well, didn't think about the stepper motor though, I like that idea. I was thinking there might be something in Segway technology that could be exploited.

You made me laugh re the pizza delivery, but what I think you should do is form a company, called Deliverwi, and do local deliveries using ncopters

Well ok, I'll do that but think I should call it "I Will Deliver" or maybe more appropriately " Will I Deliver"

"Segway" was the name I was trying to remember, - One thing to bear in mind is that Segway was killed by falling off one of his "safe" contraptions!!

FRITS,
The cost of gates and fences is prohibitive and if they were everywhere - then just think of the message that we would be sending to our aspiring but more timid monowheel riders!

Anyway no matter which way you look at that design, it is compromised by being completely dependent on electronic control and the only brake anchor available is dependent on the weight of the engine and the "rider/driver/pilot?" giving it severely limited stopping power (as in all monowheels). - to be serious you should have a brake anchor bearing somewhere on the ground, as far out as possible, ie if you want to sit inside the wheel.

[WilDun]

Talking of Oddball Engines, I see that the "everlasting" Ryger debate has erupted again over at ESE, with a lot of vicious stuff being spat out as well! - why is that? he may have been a little too premature with claims but hasn't really hurt anyone ( his own credibility has taken a knock though) but it's heartening to see that a certain well known and respected two stroke tuner from NZ has decided to retract some comments and give him a break! also a guy from Sweden gave some measured support.
Maybe Luc should just plod on, stop wasting time arguing and it might all eventually work out!

Regarding giving out ALL your info on the forum there are certain "gentlemen" in this world who will look at every idea seriously (credible or not), spend their days sifting through all this stuff, - next thing you know "whammo" a huge company suddenly comes up with a "brilliant" idea which they had "thought up" and proceed to sell it for a very competitive price! (no built in safety factor though, just a bare minimum of everything)!

I remember a couple of American guys managed to successfully come up with and sell lightweight electronic spark ignitions for the bigger model aircraft (petrol) engines and were trundling along fine, then a company from that big country we all know well, decided they were ripe for the picking and mass produced something almost identical and at a cheaper price than these small companies could manage - that's just how it is I guess!

[tjbw]

Talking of Oddball Engines, I see that the "everlasting" Ryger debate has erupted again over at ESE, with a lot of vicious stuff being spat out as well! - why is that? he may have been a little too premature with claims but hasn't really hurt anyone ( his own credibility has taken a knock though) but it's heartening to see that a certain well known and respected two stroke tuner from NZ has decided to retract some comments and give him a break! also a guy from Sweden who showed some measured support for the guy. Maybe Luc should just plod on and stop wasting time arguing and it might all eventually work out!
...

Luc's a great 2 stroke enthusiast, just like the rest of us. I think he could contribute a lot here, if he wasn't so busy with Ryger.

[WilDun]

Luc's a great 2 stroke enthusiast, just like the rest of us. I think he could contribute a lot here, if he wasn't so busy with Ryger.

Seems to me that in recent years the resurrection of the two stroke engine is not progressing as intended - and many (good) ideas just seem to evaporate and disappear (except in Buckets of course). The Bimota V Due, The Suter, the Ryger and others being the latest, but at least the outboard motors, snowmobiles and Karts are managing to keep a glimmer of hope going!

We have many little success stories with fuel injection (eg. Flettner's Kawasaki enduro efforts) but none of the big companies will take any notice, let alone pour money into something which for the future is probably more promising than the ever growing sophistication (read complication and cost) of the four stroke and all caused by legislators who only read the impressive graphs presented by certain domineering companies who produce four strokes (both cars and motorcycles) to guide them ......... except for one European company, with their fuel injected Two Stroke enduro model, but we will have to wait to see the results of their efforts this year,

Unfortunately the words "Two Stroke" have now become dirty words and the latest attempts at revival are further hampered by many people seeing this as fact.

[Frits Overmars]

... legislators who only read the impressive graphs presented by certain domineering companies who produce four strokes (both cars and motorcycles) to guide them...
Unfortunately the words "Two Stroke" have now become dirty words.

There's a private forum called the2strokes. If I write 'Honda' there, the forum software treats that name as a dirty word and automatically changes it into H***a

[WilDun]

There's a private forum called the2strokes. If I write 'Honda' there, the forum software treats that name as a dirty word and automatically changes it into H***a

Goes to show that artificial intelligence is not quite there yet - maybe we need to invent artificial commonsense! On the other hand ..... we have invented another artificial thing, called "PC", ...... hope it's still PC to say "Honda" here!

[YellowDog]

apparently alcohol is good for your engine: