Rotary Valves (if That's What They're Called)

[M3Evo 0]

I've been wondering for years now why engine manufacturers don't use rotary valves so here's a post about them

 

For anyone who doesn't know what I'm on about (not even sure they're called rotary valves!) It's a valving system which does away with the classic inverted 'T' shaped valve, and uses a rotating bar with holes drillings through it which line up with drillings in the head (forming the ports) and when in line provide no restriction to flow.......I think.

 

I know they're supposed to be very difficult to seal reliably, but as a plus they'd eliminate out of balance forces caused by the valve gear, reduce the number of components and also remove any danger from belts and the like snapping, plus it seems that they'd increase flow ability for a given port size.

 

It occrurs to me that they could be driven at 1/4 crank speed, although that might leave the port open for quite some time in each cycle I guess.

 

Anyway, lots of issues and reasons why they're not used, just wondered what people think?

[Cameron 16]

I think the 2 reasons you described in there are going to be the main factors in why it hasnt been done, that coupled with development costs.

The valves would surely be very difficult to seal and i imagine the edges will be especially prone to burning and heat damage, meaning they will have to be made of more exotic materials. And driving them at 1/4 speed would be very tricky, as youd either have to have them open for a very long time, or have multiple small holes in the valves.

I think it would be a bloody good idea if someone ever managed to sort out a system that works reliably

[pugrallye 0]

an american tuning company devoped a V8 using this method, god knows what became of it, or if it was only a one off

[Pugnut 9 1 Cars]

wouldnt the shaft need to be awfully close to the face of the cylinder head?

[jackherer 543]

something like this?

 

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

 

 

http://www.dself.dsl.pipex.com/MUSEUM/POWE...taryValveIC.htm

[Rippthrough 98]

Just too difficult to get sealing properly over the long term. On a car that got stripped every few thousand miles or so they would probably be OK I suppose.

Edited June 28, 2006 by Rippthrough

[Rob Thomson 6]

I remember my Dad raving about an aero engine that Rolls Royce and Ricaro developed towards the end of WW2. That had rotary valves and was ludicrously powerful - far in excess of any poppet valved competitor. Unfortunately the jet came along and rendered it obsoltete...

 

Think the main advantages are the ability to run higher revs and higher compression ratios. Obviously there are a few problems too...

[M3Evo 0]

I know it's not the same in many respects, but if they can control the leakage in a rotary engine to acceptable levels, surely similar principals could be applied to the rotary valve.

 

Hadn't realised there were so many permutations of the idea as those sites above show.

 

Interesting the thing about the 70hp/litre on crappy low octane fuel

 

Would've thought the powers that be in the world of F1 would be able to use the system given the life span of their engines.

[jackherer 543]

its my understanding that only the latest RX-8 rotary engines have properly acceptable reliabilty compared to conventional designs.

 

I agree that it would be used in motorsport such as F1 if it was effective with only long term reliability as a concern so there must be other probems preventing its uptake.

[Rippthrough 98]

its my understanding that only the latest RX-8 rotary engines have properly acceptable reliabilty compared to conventional designs.

 

I agree that it would be used in motorsport such as F1 if it was effective with only long term reliability as a concern so there must be other probems preventing its uptake.

 

And even then it's only through use of modern materials for sealing. Saying that, materials tech. has a come a long way in the past 30 years, so maybe you could get one to seal properly for use as a track car etc, something that get stripped down every 6/12 months anyway.

 

Can't use it in f1 as they are restricted as to what engine tech they can use.

 

 

Only way to find out is to make one, off you go Evo

Edited June 28, 2006 by Rippthrough

[M3Evo 0]

did have a play with rotary throttles on CAD but got bored pretty quickly.

 

Think cylinder head design is a tiny bit beyond me!

[Rippthrough 98]

did have a play with rotary throttles on CAD but got bored pretty quickly.

 

Think cylinder head design is a tiny bit beyond me!

 

 

Not too difficult with rotary valves. Pair of big barrels across the head, the ports can be virtually any angle you like, you could basically do what ever you thought would work best provided there's enough room in the engine bay. No camshafts or valve gear in the way.

 

Might want to use CAD for the shape and size of the holes in the barrel though.

[Cameron 16]

That coates rotary valve system looks bloody clever!

[M3Evo 0]

Seems to be one of those things whose genius lies in it's simplicity!

 

Well, if I ever win the lottery (perhaps twice in a row) we can all have a go at making an Mizero

[Cameron 16]

Shame its really not that simple though

The system looks massively complicated!

[M3Evo 0]

Looks like the machining of the bobbins might be a bit involved, but can't be any more time consuming than all the bits that go into a poppet valve system!