I heard about this from my instructor at UTI today. This is brilliant engineering and I cannot figure out why it's not more common. It would seem Formula 1 cars or MotoGP teams may want to try it. ???
(http://www.coatesengine.com/eGallery/images/pic06.jpg)
- 18% increase in fuel efficiency
- much improved airflow through the head
- much improved torque and horsepower
- lower emissions
http://www.coatesengine.com/index.html (http://www.coatesengine.com/index.html)
I never looked into it....but back when I went to college...we had a spherical rotary valve just hanging out in a display case. It had been these for some time, and this was '98. It's not new technology.
Cost of manufacturing?
Quote from: someguy on June 18, 2008, 10:36:32 PM
I never looked into it....but back when I went to college...we had a spherical rotary valve just hanging out in a display case. It had been these for some time, and this was '98. It's not new technology.
I know it's not new. There was an article in Popular Hot Rodding magazine (Oct. 1999) and the first mock up of this was in the 1960's. I'm just curious why it hasn't been used.
Quote from: monsterduc on June 18, 2008, 10:45:51 PM
I know it's not new. There was an article in Popular Hot Rodding magazine (Oct. 1999) and the first mock up of this was in the 1960's. I'm just curious why it hasn't been used.
It'd be terribly expensive. Really...terribly expensive.
Reminds me of the wankle.
Quote from: someguy on June 18, 2008, 10:48:25 PM
It'd be terribly expensive. Really...terribly expensive.
Reminds me of the wankle.
Yet Mazda still produces that...
maintenance?
if that thing is exposed to the combustion chamber as it spins around
the deposits on the face of the valve will create issues in long term applications on production vehicles
clearance issues
balance issues
oil contamination issues
Quote from: NAKID on June 18, 2008, 10:54:52 PM
Yet Mazda still produces that...
Sorry....I didn't mean to imply the wankle was expensive.....just that it's different and goes roundy-round.
Quote from: Mother on June 18, 2008, 10:57:50 PM
maintenance?
if that thing is exposed to the combustion chamber and it spins around
the deposits on the face of the valve will create issues in long term applications on production vehicles
clearance issues
balance issues
oil contamination issues
That doesn't explain why it wouldn't be viable in a racing application though.
Quote from: Rameses on June 18, 2008, 11:03:48 PM
That doesn't explain why it wouldn't be viable in a racing application though.
das why I said "long term applications on production vehicles"
Quote from: Mother on June 18, 2008, 11:27:13 PM
das why I said "long term applications on production vehicles"
I know.
I was just pointing out that nobody had come up with anything relative to why it hadn't been tried in race engines. (Which is what was mentioned in the OP.)
Well, it could never be an interference engine, so you'd have that going for you...
In the video on their website they reckon oil contamination is not an issue as it is completely sealed(?)
I love seeing engineering solutions like this. I hate moving parts, and I like the idea of the rotary engine. Rotary: Two moving parts? in an engine? Awesome. 8)
And think how fast you could rev that thing without worrying about the valves bouncing open! [evil]
A single rotor would have 2, but Mazda typically builds 2 or 3 rotor Wankels. The rotor (2 or 3 of them) and a crank..
Quote from: NAKID on June 19, 2008, 12:49:37 AM
A single rotor would have 2, but Mazda typically builds 2 or 3 rotor Wankels. The rotor (2 or 3 of them) and a crank..
I knew someone would call me out on this! [cheeky]
;D
Quote from: BWClark on June 19, 2008, 12:46:34 AM
In the video on their website they reckon oil contamination is not an issue as it is completely sealed(?)
really?
just looking at that thing makes me think otherwise
but
if you were burning ethenol...
Quote from: NAKID on June 19, 2008, 12:49:37 AM
A single rotor would have 2, but Mazda typically builds 2 or 3 rotor Wankels. The rotor (2 or 3 of them) and a crank..
And then there's those 3 tip seals per rotor, and 6 side seals... Worse than bloody piston rings in my experience.
big
I don't see a port for water injection to further boost engine efficiency, so unless it runs on the power of my farts, what we have now for gas engines is perfectly fine.
Its neat, but in a 'gas crunch' I don't think slight boosts in fuel efficiency are where engineering time should be spent by the major manufacturers for production vehicles.
For racing applications, it looks nifty, but also really difficult to rebuild if something goes bad, etc....
Quote from: NAKID on June 19, 2008, 12:00:05 AM
Well, it could never be an interference engine, so you'd have that going for you...
i think that's the key...
compression ratio would be limited, or piston dome shape would be limited, or both (more likely).
kind of not what you want in a racing engine...
Quote from: bigiain on June 19, 2008, 02:29:08 AM
And then there's those 3 tip seals per rotor, and 6 side seals... Worse than bloody piston rings in my experience.
big
muhahaha, the dreaded 80k apex seal replacement.............
Quote from: Ash on June 19, 2008, 06:52:54 AM
i think that's the key...
compression ratio would be limited, or piston dome shape would be limited, or both (more likely).
kind of not what you want in a racing engine...
From their website:
"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"
and
"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 only thing that strikes me as questionable is that last sentence where they say they revved a 5 liter engine to 14,850 rpm. I thought one of the factors limiting rpm, besides valve float, is piston speed. Assuming that engine was a V8 (mentioned earlier in the article was a Lincoln engine), it seems hard to imagine the large pistons in a 5 liter V8 moving that fast.
I call BS, the rods and crank would obliterate themselves at those RPMs on a large displacement motor. Hell, Ducati 996s had trouble with the con rods at sustain high revs, and those hit about 10500.
Dave said "wankle"
tee hee [laugh]
Quote from: NeufUnSix on June 19, 2008, 07:20:08 AM
I call BS, the rods and crank would obliterate themselves at those RPMs on a large displacement motor. Hell, Ducati 996s had trouble with the con rods at sustain high revs, and those hit about 10500.
why?
Indy cars can hit 20,000 rpm
Quote
Coates stated, "The spherical rotary valve system provides such substantial benefits that this system has the potential to integrate within and revolutionize engine manufacturing and design. The Company's facility has already been visited by and hosted tours to the major manufacturers, and dialogue regarding the use of the technology is ongoing. Coates went on to say, "The major advantages of the Coates design include: Substantially lower CO carbon monoxide, HC hydrocarbon and NOX oxides of nitrogen emissions, Increased engine efficiency, Use of lower octane fuel, Elimination of oil from engine valves, Reduced lubrication and maintenance requirements, Reduced manufacturing costs, Reduced fuel consumption"
[laugh] [laugh] [laugh]
none of this makes sense in any possible way. Fuel trim and cyl head flow are two different things..
cyl head looks cool, but if it worked, don't you think some one would be using it. I've honestly never seen one running and I read about this years ago when I went to UTI...
they also read a bit on desmodromic valves.. since I read that, I had to own something with them [evil]
Probably the same reason engineers at honda/ford/gm/vw/nissan don't use these:
(http://ecx.images-amazon.com/images/I/61CTMC93JFL._SS400_.jpg) [roll]
;D
mitt
Quote from: Ash on June 19, 2008, 06:52:54 AM
i think that's the key...
compression ratio would be limited, or piston dome shape would be limited, or both (more likely).
kind of not what you want in a racing engine...
No, he was saying that it wouldn't be possible to build an interference engine since there would never be any valves protruding into the combustion chamber.
It would still be possible to design ultra-high compression ratios.
Quote from: monsterduc on June 19, 2008, 07:15:28 AM
...
The only thing that strikes me as questionable is that last sentence where they say they revved a 5 liter engine to 14,850 rpm. I thought one of the factors limiting rpm, besides valve float, is piston speed. Assuming that engine was a V8 (mentioned earlier in the article was a Lincoln engine), it seems hard to imagine the large pistons in a 5 liter V8 moving that fast.
Large bore / short stroke. Shorter the stroke, lower the piston speed. Increase the bore to counteract the loss of displacement. Just a hunch.
As for why the system wouldn't be used... Those valves are constantly spinning and have interruptions (see hole) on the surface that contacts the seals. Biggest problem I see with the valve design is seal life.
Quote from: Mother on June 18, 2008, 10:57:50 PM
if that thing is exposed to the combustion chamber as it spins around
the deposits on the face of the valve will create issues in long term applications on production vehicles
+1
Seems to me this issue is the key as far as it not being used widely in normal passenger vehicles. I remember (barely) reading an SAE paper a long time ago on them.
Quote from: Mother on June 19, 2008, 08:05:26 AM
why?
Indy cars can hit 20,000 rpm
An indy motor isn't a street Lincoln V8. They simply aren't designed to handle that kind of stress and piston speed. Most I've heard is about 8000 from a pushrod V8 in a top fuel dragster, and those things are designed to go down the quarter once without blowing (and many don't make it that far). Obviously they have a fair bit of tuning work to achieve that.
and super light unobtainium internals.
Quote from: NeufUnSix on June 20, 2008, 08:21:55 AM
An indy motor isn't a street Lincoln V8. They simply aren't designed to handle that kind of stress and piston speed. Most I've heard is about 8000 from a pushrod V8 in a top fuel dragster, and those things are designed to go down the quarter once without blowing (and many don't make it that far). Obviously they have a fair bit of tuning work to achieve that.
true
however
My pops used to spin his 4.3 ltr Chevy V-6 in his sprint car at 12,500
so it is possible for a modified motor
a Lincon V-8 in stock trim is questionable unless they were doing it via the crank with a secondary power source
and not with combustion
Seems to me Rotax messed with a rotary valve engine a while back and it didn't go so well.....
http://finance.google.com/finance?q=COTE&ie=UTF-8&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&sa=N&tab=we
I'm not buying a lot of what they are selling. If they really had something good they would be in production with someone. If you have a truly radical idea (that actually works) then you don't need the cheesy PR they have.
just the name of it makes my brain hurt. [bang]
Another rotary valve system different than this one is a system (I don't remember the name) where the bore sleeve spins, and there are side ports like a 2 stroke almost that open and close.
Quote from: mitt on June 22, 2008, 10:18:33 AM
Another rotary valve system different than this one is a system (I don't remember the name) where the bore sleeve spins, and there are side ports like a 2 stroke almost that open and close.
That almost sounds like the thing I mentioned above.....