Looks too simple to be true.  One of those, why didn't anyone think of that before things.

I wonder how they seal without an oil film?

PKGB, try the search function

thread71-132613 for starters.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

I tried to correspond with George Coates about 5 years ago. I was interested in purchasing a head for a 4cyl I was working on at the time. Never responded to any emails and a woman that answered the phone told me they only sold complete engine assemblies. I think that the 5.0L ford was the only thing available. They wouldn't provide me with any information regarding leak down rates.(which I suspect is fairly high). I think the biggest problem is how to minimize the expansion on the exhaust valving. It would seem likely that the cold clearance would have to be fairly high in order to prevent the valve from galling or seizing during high throttle and load operation. I also wanted to ask him why he chose a ball configuration as opposed to a much easier to fabricate rotating cylinder. I think the arrangement has potential as intake valve on a 2 stroke diesel that would use bottom of the cylinder port as the exhaust. In that scenario you wouldn't have to contend with such a large range of operating temps.--------Phil

It might work well for the intakes but like so many others, the exhaust probably won't make it. There have been sleeve valves, rotary valves, and separate exhaust pistons (Puch-Sears Allstate, etc.) used to valve exhaust and they all suffered from heat. The only thing out of the ordinary that has really worked well is the exhaust valve on the 2-stroke Detroit and similar 2-stroke Diesels.

I heard a while back about this valve systm. Word is that they came up with this design back in the 70's. GM took them to court because they build the head for a small block with out chevy's permission, I believe it was something todo with the marketing of it all. Anyway, as it is told, GM bought the patent and let the design sit. When the patent was up, coates came down and renewed it. That's why it's starting to show up.

As for the exhaust valve, the valve is in constant contact with head. Unlike your stand valve used today that cools only on when it is seated. I believe this is why there is not an expansion problem with it.

 

The idea of rotary valves isn't new.

http://www.dself.dsl.pipex.com/MUSEUM/POWER/RotaryValveIC/RotaryValveIC.htm

It's always had the same advantage, no reciprocating parts, and the same disadvantage, sealing.

There is a whole book on rotary valve engines by someone named Hunter, if memory serves.

If the sealing is good, the things starve for lubrication.  If there is clearance for an oil film, they leak.