Pneumatic MotoGP

[rwh]

Google is your friend

Interesting. I'm trying to figure out how that works. The in-car picture appears to show inlet and exhaust connecting to opposite ends of the head, but there's only one port in the head, so I guess the tube is split diagonally in the middle, with an inlet port on one side and exhaust on the other ... but not directly opposite, of course, since the inlet part of the cycle comes immediately after the exhaust - unless it doesn't rotate smoothly. I assume the sprocket visible in the vee of the block is geared down 2:1 from the crank as usual.

I'm assuming it's a 4-stroke, since otherwise the inlet and exhaust would have to overlap even more, and if the inlet doesn't go via the crankcase you'd need a supercharger or similar.

Sealing it sounds hard.

Richard

[cowpoos]

inlet port on one side and exhaust on the other ... but not directly opposite, of course, since the inlet part of the cycle comes immediately after the exhaust - unless it doesn't rotate smoothly.

turn the rotation of the valve the opposite way to your thinking in your head...the compression/firing stroke happens on the larger area of the valve that isn't ported...followed by exhaust....then inlet....comp...fire...

I assume the sprocket visible in the vee of the block is geared down 2:1 from the crank as usual.

I'm assuming it's a 4-stroke, since otherwise the inlet and exhaust would have to overlap even more, and if the inlet doesn't go via the crankcase you'd need a supercharger or similar.

its a 4 stroke...and it would have to be geared 2:1 other wise it wouldn't work...

Sealing it sounds hard.

have a closer look at the pic with the two rotary valves with heads shown away from the block...you can see three small ring like objects running the circumference of the valve....they are the seals....and they seal well...but I believe they are part of the lubrication isusse they had with them...and the wear placed on them was a lil high also I believe...

[cowpoos]

http://www.coatesengine.com/index.html

[FruitLooPs]

http://www.coatesengine.com/index.html

they do look the business!

This is also quite cool, looks like the whole 'keep it simple stupid' thing, hope they work well.
http://www.coatesengine.com/eGallery...aced-parts.htm

[Toaster]

Things are so techo nowdays, I dunno what to do with my spanner!

[slowpoke]

'Poos is onto a good thing.
I've seen simialr things done with fuel injection using rotary valves rather than throttle buttlerfly's and the flow potential is huge. If they can get rotary engine rotors to seal I don't see why this should be any more difficult.
I can't see it being any heavier than a camshaft/poppet valve set up, probably lighter as little strength is required unlike a camshaft which is hammering away at a spring actuated valve.
You'd think there would also be less maintenance involved as there wouldn't be any valve clearances to check/adjust.

[xwhatsit]

'Poos is onto a good thing.
I've seen simialr things done with fuel injection using rotary valves rather than throttle buttlerfly's and the flow potential is huge. If they can get rotary engine rotors to seal I don't see why this should be any more difficult.
I can't see it being any heavier than a camshaft/poppet valve set up, probably lighter as little strength is required unlike a camshaft which is hammering away at a spring actuated valve.
You'd think there would also be less maintenance involved as there wouldn't be any valve clearances to check/adjust.

I bet the seals would be a bitch, though -- in terms of maintenance. And that's something you'd have to take the cam cover off for (except you can't call it that any more ), instead of just poking a feeler gauge through the tappet covers.

[sAsLEX]

Things are so techo nowdays, I dunno what to do with my spanner!

Its in the biking culture that is predominating things as well these days.

Look at all the custom bike builders.......... all they do is use there spanners to bolt together parts. Was reading a magazine in America and the author was slating the new breed of "custom" bikes saying they were a cop out. He pointed at the Britten and the Indian saying they were true bike builders and that nothing these days compare.

Sure the knowledge needed to build a competitive engine/bike these days is a bit more but most of it can be learnt open source if you wanted, or just get a nerd friend to do the electrics?

[erik]

I thought one of the problems with rotary valves was that they can't open or close as suddently as normal valves can, so you can't get as much airflow?

[cowpoos]

I thought one of the problems with rotary valves was that they can't open or close as suddently as normal valves can, so you can't get as much airflow?

nope....would be interested to know where you heard that presumption??? rotary valves have a huge ability to flow air when compared to poppet valves...the timing/duration can have an effect on that...but you wouldn't design an engine to be low efficency for its design now would you??

[sAsLEX]

nope....would be interested to know where you heard that presumption??? rotary valves have a huge ability to flow air when compared to poppet valves...the timing/duration can have an effect on that...but you wouldn't design an engine to be low efficency for its design now would you??

One thing that seems rather obvious is you no longer have the valve head in the way of the airflow, or the associated turbulence past what is essentially a flat disc.

[Mental Trousers]

That's one of the major advantages of rotary valves - no obstructions in the airflow. Also, normal valves take up a certain amount of space inside the cylinder, space that could be better filled by the intake charge to give a bigger bang. The intake port and exhaust port volume's are also much larger for rotary valves. There's other advantages like less complexity, you'll never get the situation where valves contact the piston and handgrenade, piston crowns don't need cutouts for the valves so can be ideally shaped.
Some of the disadvantages are that the combustion chamber can never be an ideal shape as it has this large circular thing in the middle of it. Also, the spark plugs are no longer be in the middle so they usually need a twin plug arrangement, causing problems with merging flame fronts etc.
The single biggest hurdle for rotary valves is that the ordinary old poppet valve has been around forever, does the job required in 99.9% of cases, is proven technology and everybody knows the limitations. Nobody will risk multi million dollar racing budgets to develop a new (relatively) technology like rotary valves.

[Sanx]

<muppet mode> However, whilst a rotary valve can flow a large volume of air, isn't one of the advantages of the airflow passing over the head of a normal valve the turbulence it creates thus better mixing and distributing the fuel/air mixture?<muppet mode>

[Mental Trousers]

Yeah that's true. However, because the valve moves the turbulence isn't consistent over the length of a cycle so there's always a chance the mixture is uneven. Careful design usually sorts that problem out though. But the main thing is that the superior airflow of the rotary valves gives a significant advantage over the mixing from the turbulence that a poppet valve creates.
More air + fuel = more power.

[sAsLEX]

Yeah that's true. However, because the valve moves the turbulence isn't consistent over the length of a cycle so there's always a chance the mixture is uneven. Careful design usually sorts that problem out though. But the main thing is that the superior airflow of the rotary valves gives a significant advantage over the mixing from the turbulence that a poppet valve creates.
More air + fuel = more power.

And without the need for valve clearances on the top of the piston the piston top could be optimised to create a swirling/mixing what ever you want gas pattern