Valve Physics
The original Cyclone engine that garnered all the enthusiasm had some, shall we say, fascinating claims. For example:
On the Cyclone 13 May 2005 website, as accessed via the ‘Wayback Machine’ under “How it works”, under the heading “Heat Process”, it was said that:
Xxxxxxxxxxxxxxxxxx QUOTE XXXXXXXXXXXXX
“2. Water contained in the coils becomes super-heated steam (up to 1200°F) in as little as 5 seconds from start up which is (a) piped to the cylinders, (b) where it enters through a patent-pending valve system (not pictured). Note, valve timing mechanisms regulate how much steam enters the cylinders – the longer the cut-off the greater the torque and acceleration.”
AND it was also said:
“3. Steam enters the six radial-configured cylinders under pressures up to 3200 psi to push the pistons down in sequence.”
Xxxxxxxxxxxxxxxxxx END QUOTE XXXXXXXXXXXXX
I think we can all agree that was an admirably clear statement and that from it we can derive the information that the water is heated to 1200F at 3200 PSI and it then enters the engine through an unspecified valve having controllable opening duration to regulate the torque and acceleration.
Now, for a bit of a background, the average poppet valve car engine having overhead cams is designed to work with a maximum valve acceleration of about 750 gravities (gees); that’s about the most they can normally get while maintaining good operating characteristics and longevity.
Let’s assume we want to cut off the steam flow early so as to fully expand that 3200 psi so as to get the most work and the highest efficiency we can out of the steam. After all, isn’t efficiency what Cyclone keeps touting? If we assume a really small clearance volume of 1% (much less than they are getting with that rotary valve) and assume that the polynomial coefficient of expansion for supercritical steam is 1.333 and assume the cutoff is 4% of stroke….we will get an exhaust pressure leaving the cylinder of about 58.75 PSI. That’s still a fair amount of pressure left over, too much and it won’t be efficient
Having done all this we can now assume a rod to throw ratio of about 1.5 to 1 and we will find that the steam valve must open and close over about 12.75 degrees of rotation. If the engine is doing 3500 rpm, the valve is opening 3500/60 =58.333 times per second. It therefore follows that each revolution lasts about 1/58.333 or .0171 seconds. If the valve is open for 12.75 degrees per revolution that is 12.75/360 = .0354 or about 3.54% of the revolution ( .035417 x .0171 = 0.0006 seconds. )
If you think I am wrong, show your math.
The cam in the gasoline engine turns half as fast because it is a 4 stroke engine, so it turns over 58.333/2 or 29.1667 times per second. That comes out to .0343 seconds per revolution (1/29.1667). The average automobile cam lift duration is in the neighborhood of maybe 270 degrees, which is ¾ of a revolution. That makes the open duration about 0.026 seconds or about 42 times longer. Since the Cyclone engine recompressed the steam remaining in the cylinder to the admission pressure (they even have a special valve to store excess compression) it is certain that when the valve opens there isn’t much difference in pressure across the valve to push the steam. OK Pumpers, your two part question is, “Assuming Cyclone doesn’t have special metals from the planet Krypton, and given that the IC engine valves are already rated for maximum acceleration at 5500 rpm, just how high can the Cyclone valve open in the .0003 seconds before it reverses and closes in the same amount of time? Just how much steam can get through that pinhole?” Extra credit will be given if you can tie this phenomenon into why Cyclone spent so much time talking about how slowly their engines idle.
NOTE: Guess I was too nice to Cyclone. In their 8 FEB 2006 website they state:
Xxxxxxxxxxxxxxxxxx QUOTE XXXXXXXXXXXXX
“• The Cyclone Engine, of three or more cylinders, is self-starting. Pulling the throttle lever activates flow through individual needle valves situated at each cylinder. From a dead stop, the engine attains its highest torque within less than one crankshaft revolution and transitions to engine horsepower at 5,250 rpm giving the Cyclone a remarkably robust power band.”
Xxxxxxxxxxxxxxxxxx UNQUOTE XXXXXXXXXXXXX
WOW!!!! 5,250 RPM!!!! That cuts valve duration to .0004 seconds!!!!!!!!!!! Welcome to Fantasy Island!
