Why don't rotary valve engines work???

[Gareth]

Hi all,

there seems to be a bit of renewed interest in this topic with a couple of people in oz playing with various types of this valve action, was wondering why it doesn't work...
Im sure if it did work we would be driving around in rotary valve Commodores

It seems like a great idea with valve bounce not an issue, no parts that need to accelerate in different directions, no harmonics, etc..

Is heat the problem? speed of opening and closing?

Cheers.

[vlad01]

what rotary valve? never heard of it.

[Gareth]

Check this out for an old grey motor

http://forum.fefcholden.club/index.php?topic=19105.0

also check out youtube 'V8 rotary valve'

[jenko]

They do work I believe Bruce Mclaren expiremented with them in some formula one engines and found unworkable harmonics which virtually blocked the ports at high revs

[slewinson]

If I recall correctly it is more likely that you can't get the "area under the curve" with regard to port duration and "lift".

Rotary valve will always have a sinusoidal profile of lift vs duration where a cam and valve train setup can have steeper sides, hence more area which equates to filling time for the cylinder. Add this to mad turbulence at low flows where the air is squeezed diagonally across the passage.

Simon

[Gareth]

Thanks for the replies guys, I understand the responses but not yet sold on why it doesn't work

for those who still don't know what I'm on about, check out this video of a V8 in Australia

http://youtu.be/FeMODpnkDLA

[Gareth]

or this one that shows in more detail how it works

http://youtu.be/QWb70X0xELA

[slewinson]

Also, looking at the cross section of the W12, the combustion chamber geometry does not look great - too much surface area and also nooks and crannies for unburnt gases. Longevity of the rotary valve exposed to combustion temperatures and deposits would be a problem in my opinion.

Great idea that does not quite make it in production terms.

Simon

[Jayme]

I reckon camless free valve systems are going to take off for the reciprocating engine soon.
http://www.cargine.com/technology/free- ... echnology/

[vlad01]

I reckon camless free valve systems are going to take off for the reciprocating engine soon.
http://www.cargine.com/technology/free- ... echnology/

I been thinking about that sort of concept for years but never saw anyone really attempt to overcome the problems.
This looks like the first to do so.