Coates Rotary Valves

I've mentioned these in a thread in this forum already titled too many cylinders. (http://www.automotiveforums.com/vbulletin/t7397.html), but it seems that there has been no other mention of them here from what I can tell I couldn't find anything about them (except for my one post about them, which I located using the quick search function).

Does anybody have any impressions of them that they'd like to share? If you are not familiar with them, here's the web site:

http://www.coatesengine.com

I personally think they're a better direction for cylinder head design than the one that BMW is taking. BMW is researching and building prototype cylinder heads without cams, that control valve movements and timing electronically. The Coates rotary valve design does basically the opposite, keeping the cams, and pretty much only the cams, while eliminating all the other moving parts from the head (along with motor oil!!).

Imagine a smaller, lighter cylinder head, that needed no motor oil for lubrication (the system uses very low friction parts), made great power, and offered high rpm endurance (your first enemy of high rpm use is the threat of "valve float," where the valve cannot snap itself back into the valve seat fast enough to avoid contact with the piston, often due to mechanical limitations of the system at certain high rpms - this limiting factor commonly establishes a given engine's redline). Sounds like a dream too good to be true to me :)

But please, I'm curious for your thoughts. Thanks-

-JD

I believe Texan described them as "Death" in another post here some time ago. (as I havnt seen him since, but if you talk about him enough he does seem to show up).
:cool:

Oh man, I'll have to see if I can reach him on email and find out more. He was so excited about them about a year or so ago... hmmm.

Well anyway, thanks for the tip, Moppie.

Actually I think the Coates system is great, providing they can really demonstrate it's effectiveness on a production type engine. They claim to have done just that, but I'd just be super excited to see them develop an aftermarket cylinder head for say, a B series Honda motor, and let that do their talking. The concept itself certainly seems more simple than poppet valves though, you almost have to wonder why it wasn't thought of and worked out long before now (prolly just a status qou thing).

wow. speak of the devil and he shall appear!!!


Making the coates system varialbe lift would have its problems, leaving you back were started with a popet vavle.

This would have been a great idea had it made it into production 10 or 20 years ago (and I know the idea's been around for quite some time) but camless valves will be an even greater improvement when they arrive in a few years. As soon as 42-volt electrical systems are made available in cars (about two years away in some cars), camless valves will follow shortly. BMW's not the only one planning this.

As far as not needing oil in the head, are you sure about his? I don't care how "low friction" the parts are, those cams are moving quite fast and will be rubbing against other parts (or else there would be no seal and no compression) which will cause friction. Oil will be necessary in the head. Teflon on teflon (the lowest friction combination possible) would still need lubrication at 2,500 rpm.

Originally posted by Hudson
As far as not needing oil in the head, are you sure about his? I don't care how "low friction" the parts are, those cams are moving quite fast and will be rubbing against other parts (or else there would be no seal and no compression) which will cause friction. Oil will be necessary in the head. Teflon on teflon (the lowest friction combination possible) would still need lubrication at 2,500 rpm.

Originally posted by http://www.coatesengine.com/Body.htm
Absence of poppet valves and other operating accessories normally housed under the valve cover has permitted elimination of both oil lubrication and cooling water flow in the upper portion of the cylinder head. This reduces the overall engine height by as much as 20 cm from that of its conventional counter part, and maintains a clean engine.

The new, patented simple valve-train unit has minimized the area of contact for fluid flow through the gas exchange ports by making use of wide-open circular cross-sections. This significantly cuts down the pumping loss and unmatchably increases the volumetric efficiency to achieve a high torque/power-density engine.

The new dynamically balanced rotating spherical port valve eliminates entirely mechanical noise produced by current poppet-valve components. Hissing sound generated as gas flow squeaks through the narrow annulus valve opening in the conventional cylinder head is no longer audible. At the same time, the new unit cuts down, by an order of magnitude, the need for power out of the crankshaft. Normally a big parasitic power drain is required in conventional engines to drive the valve train.

Without quoting the entire web site, poke around, and they have some info on the materials used to lubricate the valves. In fact, I think they even went so far as to say that their heads coul operate without needing a valve cover in place!

As for the 10 to 20 years ago thing, I think you're only half right. Valves themselves still represent disruptions in airflow as the air/fuel mixture enters the combustion chamber. This disruption can be used to help aid air/fuel mixing, but in general, I like the idea of eliminating valves altogether. Besides that, do you think that eliminating the cams will be sufficient to prevent valve float at high rpm use? I think that this will continue to represent a challenge for engine designers married to poppet valves.

Valve float is eliminated with electro-magnetic valves. Formula 1 engines have used them and they run speeds much higher than you'll find in street cars. If you want to eliminate the traditional "valve" itself, that, too, can be done with an electro-magnetic system, again taking up less space than the system you're discussing.

This idea has been tossed around for decades. I know I've seen the design atleast ten years ago...and if I saw it then, it had to be around well before that time.

Nowhere on the site does it go into how the valves are lubricated. My money's on this engine either a) needing a lubrication system to work properly over the long haul or b) having such a gap (or wearing one away) that you would lose compression well before 50k miles. I know the site says that one prototype engine went over 150,000 miles, but until someone properly explains how you can have a low-tolerance moving part without any lubrication, I will not believe it.

Besides, since this idea's been around for over ten years, why hasn't it been put into production? Engineers are not "married" to the idea of the traditional engine design. They will, and have, taken dramatic steps in new directions when a better idea comes along. I don't think this is all you believe it to be.

Late response to this thread. I had meant to say that I was very impressed with your rebuttal, and you kind of took the wind out of the rotary valves' sail in contrast with advanced electro-magnetic technology being used in the cylinder head to control air and fuel entering and exiting the combustion chambers. As much as I still like the idea of rotary valves (part of me is still very fundamentally old-fashioned, and therefore I admire the simplicity of the overall design), they seem to just not cut it ultimately as competition for electro-magnetic applications. http://www.automotiveforums.com/vbulletin/images/icons/icon14.gif Nice job!!

Hudson, here is the info about the lubrication issue. Also, electromagnetic or not, conventional poppet valves restrict airflow when open which the Coates system does not.

Among the primary engineering challenges in the
development of the Coates head was implementing a reliable
seal between the combustion chamber and the valve, while
keeping friction at a minimum. The rubbing of metal against
metal, which results from a rotating surface moving over a
fixed one, usually causes substantial wear and lessens the
ability to form an effective seal.
Coates said that he has solved these problems using a
unique sealing mechanism with each valve. Although the seal
is fixed in the cylinder head, part of it moves in a linear
motion in response to cylinder pressure generated during
compression. As a result, the seal surface is pushed solidly
against the periphery of the rotating valve. The sealing
surfaces are, therefore, in contact for one piston stroke, or
one quarter revolution of the crankshaft.
The Coates rotary valves are fashioned from Nitralloy, and
the face of the seal is made from a proprietary carbon-
ceramic alloy. Both materials are highly resistant to wear,
and neither requires lubrication in the engine. "The seal
wears only 0.0001 inch every 25,000 vehicle miles," Coates
said. Indeed, the seal compensates automatically for wear
during engine compression by means of its linear motion.
A similar, but not identical, carbon-ceramic composition
is used in the bearings that support the shaft on each side
of the valves. Meanwhile, conventional steel ball bearings
provide support at opposite ends of the shaft.

:cool: NOW THAT IS SOME GOOD SHIT!!!

wow..he smarT

No Steel, I just good use of a search engine and cut & paste.
"Work smart, not hard"

It all sounds good but what kinda money does it cost to make heads like this over the good old heads we been using for decades? My only question

I read the post on the Coates (CSRV) engine with some interest as my company is currently bringing it to market as part of an advanced power generation system (*Well to Wire Energy Inc.) The units are in production at this time and a diesel version of the system has been licensed to a company called McLean England & Associates of Little Rock Arkansas.

Originally posted by Hudson
Valve float is eliminated with electro-magnetic valves. Formula 1 engines have used them and they run speeds much higher than you'll find in street cars. If you want to eliminate the traditional "valve" itself, that, too, can be done with an electro-magnetic system, again taking up less space than the system you're discussing.

This idea has been tossed around for decades. I know I've seen the design atleast ten years ago...and if I saw it then, it had to be around well before that time.

Nowhere on the site does it go into how the valves are lubricated. My money's on this engine either a) needing a lubrication system to work properly over the long haul or b) having such a gap (or wearing one away) that you would lose compression well before 50k miles. I know the site says that one prototype engine went over 150,000 miles, but until someone properly explains how you can have a low-tolerance moving part without any lubrication, I will not believe it.

Besides, since this idea's been around for over ten years, why hasn't it been put into production? Engineers are not "married" to the idea of the traditional engine design. They will, and have, taken dramatic steps in new directions when a better idea comes along. I don't think this is all you believe it to be.

F1 engines doesn't have electro-magnetic valves, they have a pneumatic valve train and they use camshafts (the pneumatics replace the valve springs since springs are too slow).
Electro-magnetic valves are today way too slow and takes too much power.

I read a lot of the Well to Wire press releases, sounds like some very cool stuff.

I also wrote to Coates about developing their cylinder head for my Mazda KL engine (2.5L V6) and they said they had no applications available at this time (September 2001) and developing an initial prototype would cost around a half million dollars. And they said if I had the interest and financial backing to proceed further, they would be happy to talk about it. Sadly, as I haven't won the SuperLotto yet, I have not corresponded any further with them.

Teflon on teflon (the lowest friction combination possible)
Nope. Molybdenum disulfide, a solid lubricant, has a lower coefficient of friction than any Teflon. NFC or Near Frictionless Carbon, a film coating, is currently the lowest-friction material in the world.

And, IIRC, it can handle temps higher than 700C. So, if what I remember is true, NFC could very well replace motor oil as the main lubricant in engines in the future.

Sounds incredibly slick. (sorry for the pun, couldn't resist.)

I wonder what else they can make with this stuff... It's a shoe-in for a Wankel rotary engine too if it can handle the combustion temperatures.

Yup, the seals on a rotary would benefit from this.

And the kicker is, it's superhard, abrasion-wise. A coating of this on a sapphire (!) substrate survived 17.5 million passes against a steel ball, after which the testing machine failed. Upon inspection of the coating, the ball had left a barely visible track.

More? After coating, the stuff doesn't need secondary machining.

All of the test results are for a pure nitrogen atmosphere, they mention that the friction increases in the presence of oxygen, water, etc. but they don't say by how much. Seems to be a critical omission.

Originally posted by 454Casull
And, IIRC, it can handle temps higher than 700C. So, if what I remember is true, NFC could very well replace motor oil as the main lubricant in engines in the future.

It seems more likely to me that NFC will augment motor oil, and perhaps allow a reduction in the viscosity used.

I read your notes about Molybdenum disulfide and I think it is something that our organization should be looking at. We are already producing the CSRV natural gas engine and if there are any ways of improving the performance, we would certainly be interested.

Just wondering if any of you have seen the news release on the Coates engine & Porsche.??

Take a look:

http://www.finanznachrichten.de/nachrichten/artikel-868301.asp

Forward progress is always a good thing. :)

Its just a long shot but i was wondering if any of you guys new of any engineering papers which have been released on the topic or spherical rotary valve engines such as the cross and the coates design.

if not are there any interesting, articles or reports i could follow up to find out more. i am particularly interested in the sealing design for the combustion chamber and how the advances in new materials have helped.

thanks alot for any help, great forum keep up the good work. Rich-h

..Hello,i ran across this sight,doing a search on Coates Rotary Valve,and thought id give it a bump and see whats new?..

These post are all pretty old. I don't think much has come of it. I don't think you could get must flow through since a 4-cycle valve is closed most of the time, most of the rotating valve would need to be solid. Even when open it would spend a large part of the time only partially open??? What kind of flow would this allow?

These post are all pretty old. I don't think much has come of it. I don't think you could get must flow through since a 4-cycle valve is closed most of the time, most of the rotating valve would need to be solid. Even when open it would spend a large part of the time only partially open??? What kind of flow would this allow?
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."

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.

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.

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.

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.

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.

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.

...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..

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.

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.

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.