Coates Rotary Valves

[curtis73]

The thing that bugged me about the site is the were quick to mention increased flow, increased HP, and increased VE... but at no point do they discuss torque, nor do they discuss the effects of the massive flow increases. They pointed out that on a test engine they increased flow from someting like 130 CFM to 319 CFMs. Great for HP, but what does that do to the RPMs and torque. Airflow is great, but at what velocity cost???

I must admit its exciting technology and it certainly removes many moving parts, but the website is shady. They withhold a lot of critical information while stroking their own egos whenever they can.

[JD@af]

Originally Posted by curtis73

The thing that bugged me about the site is the were quick to mention increased flow, increased HP, and increased VE... but at no point do they discuss torque, nor do they discuss the effects of the massive flow increases. They pointed out that on a test engine they increased flow from someting like 130 CFM to 319 CFMs. Great for HP, but what does that do to the RPMs and torque. Airflow is great, but at what velocity cost???

I must admit its exciting technology and it certainly removes many moving parts, but the website is shady. They withhold a lot of critical information while stroking their own egos whenever they can.

This is true too. There has to be a downside to this technology somewhere, and they certainly don't give you that on their web site. Like you, I like well-rounded information, as easy as it is to get caught up in the accolades of their valvetrains.

[SaabJohan]

Originally Posted by JD@af

The following is directly taken from http://www.coatesengine.com/engine_of_the_future.html:

"The breathing capabilities of the system are almost double that of a poppet valve. For instance: a static test of a five-litre poppet valve engine on an airflow machine produced a reading of 133 cubic feet per minute (CFM) with valve fully opened. The five-litre Coates Spherical Rotary Valve Engine on the same machine, however, produced a reading of 319 CFMs fully opened; a colossal advantage in airflow comparison. A five-litre poppet vavle engine tested on a dynomometer under the same loads and conditions at 5500 produced 480 BHP and 454 foot pounds of torque. The maximum RPMs on the poppet valve engine were 5700 RPMs; the Spherical Rotary Valve Engine in comparison reached 14,850 RPM's, The Coates Spherical Rotary Valve comprises two spherical rotary valves assembled on two separate shafts - one for inlet and one for exhaust. They rotate on ceramic carbon bearing with no oil lubrication, the spheres do not make contact with any part of the housing. The seals are a floating type and are also made of a ceramic material. They have two piston rings and are floating in a small cylinder-type chamber, they are activated by the compression and the combustion strokes of the engine which allows 100 percent sealing effectiveness, when compressed.

Because the valves rotate away from the combustion chamber and are vented and charged on the opposite side of each sphere, this creates a lower combustion chamber temperature, allowing for higher compression ratios to be used thus creating an extremely efficient engine. Some of the Coates Spherical Rotary Combustion Engines are at 12 to 1, 13 to 1, 14 to 1 and 15 to 1 compression ratios depending on the application."

If you print that out on paper at least you will have some good use of that info, you can make a paper aircraft out of it or even burn it for the energy. But that's it, the rest of it is just bullshit.

[public]

Originally Posted by SaabJohan

If you print that out on paper at least you will have some good use of that info, you can make a paper aircraft out of it or even burn it for the energy. But that's it, the rest of it is just bullshit.

Thanks, We have all been waiting for you to weigh in on this one. I think this is what a bunch of us felt.

[SaabJohan]

I have read an article (not on the internet but in a magizine with focus of automotive engineering for racing purposes) on some what seemed to be serious work with a rotary valve setup, and they had serious problems with leaks. They had made some system using combustion pressure to seal it (like poppet valves do) but the engine couldn't operate at speeds as high as the poppet valve version of the engine. But this article also contained some strange claims that seemed to go against the laws of physics, but I also have never heard of them since I read that article. The website they had is also gone now.

Also, it should be noted that engine speed is basicly limited by the bottom end of the engine. There are poppet valve systems that can operate at speeds above 20,000 rpm so the valvetrains isn't the problem. So if anyone says that their valve system can increase the rpm limit by three times they obviously aren't serious, more like sci-fi fans.

Another thing that should be noted is that when a poppet valve lifts more than 40% of its inner seat diameter it isn't the valve that limits the flow, it's the port size. And since poppet valves can be used to fill the cylinder up to 140% a static flow test isn't simply the answer.

So unless the problems with leakage I don't see any future for rotary valves.

[Alunani]

I suspect that anything went really wrong with Mr. Coates and/or his marvelous SRV concept because there are absolutely no news on his site nor the sites of both "Mc Lean, England & Associates" and "Well to Wire Energy" since about a year or more. In fact, it seemed that both firms were virtually nonexistant.

Sadly I begin to think seriously about other more classic ways to replace poppet valves, such opposed pistons or so.

[claas900]

...When i was reading the sight I thought it was a perty good set up,at least a good idea? I remeber reading about them years ago in a mag...I really like not haveing oil in the head,but you guys also bring up some good points,just more things to think about..it would be nice to have an update from them,or even seen one run in person would been cool..

[SaabJohan]

One of the advantages with poppet valves is that they doesn't require oil, it's only the actuating of the valves that needs oil.

[roton]

is anyone interested in picking up this thread again. i have built my own rotary valve engine andit works using quite old techology for our seals but we are moving on a bit now to get 50k miles at least before replacement. the discusion about coatings and low friction carbon i find interesting.

[curtis73]

No. Reviving old threads is a poopy thing to do People get confused since the technology that started the thread is from 2001. A lot has happened since that thread started.

Feel free to post your data from your engine in a new thread, though. I'm interested in seeing what the numbers have to say.