LOOK MOM, NO CAMSHAFT!

Revolutionary Spherical Rotary Valve Reinvents the Engine?

By Ray T. BohaczPOPULAR HOT RODDINGOctober 1999For an engine to produce power, it needs to breathe, plainand simple. The more air that it can pump with the properamount of fuel, the greater the specific output will be. The

quest for airflow is not a singular pursuit by the performance industry though: Detroit shares the samegoal. This has been represented by four-valve cylinder heads, forced induction, and variable-runnerintake manifolds in OEM applications. It's common with most things when you set out to improve them, again in one area is usually offset by a restriction in another. A efficient cylinder head can be diminished topoor flowing status by the installation of a low-capacity intake manifold, whereas an intake that is toolarge will not work with a restrictive cylinder head.It has been universally accepted that the current valve design is the largest offender in the quest forairflow in an engine. Identified as a poppet valve, this tulip shaped devise has been used in some formfrom the first engine up to the latest marvels from the Motor City. Earning its name from the reciprocatingmotion it travels in, it has been the standard bearer of airflow until now. Like many others before him,engineer George Coates recognized that the efficiency of an engine would always be limited if themindset of valve designed is not expanded. The idea of using a rotating motion to operate a reciprocatingvalve adds complexity, cost, and friction to an engine. The ideal arrangement would have the valvesshare the same motion as the crankshaft, eliminating all of the downfalls of the poppet valve.Over the years, this technology never developed due to a problem that until recently could not be solved:How to seal the valve when it was closed. Coates is the brainchild of a spinning valve, and he is thefather of sealing one and making it work, a four-year labor of love. Using a spherical assembly thatrotated in a timed sequence to expose the intake and exhaust ports, his design allows for an approximate18-percent gain in fuel efficiency along with a corresponding increase in power, while eliminating thecamshaft and its ancillary mechanisms.

Inherent Deficiencies

Before the benefits of the Coates Spherical Rotary Valve (CSRV) can be established, the deficiencies ofthe poppet valve need to be represented. By nature of its design, the necessary use of a camshaft toopen and close a poppet valve requires that the clearance between the cam, tappet, and valve must betaken up slowly, and the valve lifted slowly at first, to avoid unacceptable levels of noise and wear.Additionally, the valve can not be closed abruptly or it will bounce on its seat. Another concern is theshrouding of the poppet valve at low lifts and the undesirable effect it imparts to the port's flowcapabilities. Valve of this design, even with aggressive cam profiles, spend more time traversing their liftranges than dwelling at full lift. Herein lies the importance of examining low-lift flow numbers for a cylinderhead. The slow response time when measured in degrees of the crankshaft's arc of rotation createspumping losses, since the intake valve is not open far enough to take full advantage of the low pressurecreated in the bore as the piston sweeps downward toward bottom dead center. To compensate for this, itis customary to open the intake valve prior to the piston reaching TDC and the beginning of the intakestroke. Exhaust port concerns are aided by the high pressure in relation to the exhaust manifold duringblow down, share the same obstacles, and require early opening and late closing along with a period ofoverlap, when both valves are open. During this time, it is critical to have a defined amount of overlap toexhaust the bore while not overscavening and pulling any fresh charge out of the tailpipe. If there were a

means of exposing the intake and exhaust ports quicker to full flow, the efficiency of the engine would beincreased. The poppet valve is a greater liability to the engine beyond its flow limitations. The energy thatis used to expand against the piston and turn the crankshaft is wasted during overlap and the prerequisitetime that is required to open the valves prematurely and delay their closing. With the CSRV, this energyloss is eliminated.If opening the poppet valve is a problem, closing it is an even greater concern. Keeping the lifter incontact with the camshaft lobe mandates the use of valvesprings to close the valve and ensure the lifterstays on the lobe, especially when it rides over the nose of the cam and lifter changes direction. This isknown as the inflection point. The pressure requires energy to overcome and is identified as a frictionalloss to the engine. The power consumed internally by the engine accounts for frictional losses, and thepoppet valvetrain is a major offender. Additional internal friction is created by the water and oil pumpsalong with the crankshaft traveling through the oil pan. Friction is usually established by a motoring dynotest, where the engine is run by a large electric motor without any combustion, measuring the powerrequired to turn it. In a test performed by Coates Engineering, an early Ford Escort engine consumedover 20 lb.-ft of torque just to operate its valvetrain. Imagine the losses in a small-block Chevy with asolid-roller cam and high valvespring pressures! Pumping losses can be defined as the difference in thevalue of the work delivered to the piston during the compression and power strokes only; when subtractedfrom the total work delivered to the engine over the entire four strokes. The first internal combustionengine was approximately 20-percent thermally efficient, with the best designs today approaching only 24percent. This means that 76 percent of the energy from the fuel consumed is going either out the tailpipeor into the cooling system and is being wasted.Poppet valves also dictate the design of the combustion chamber by virtue of their placement in relationto the bore. Moving only up and down means that the valve heads themselves are sources of retainedheat and the stem needs to be lubricates as it slides through the guide in the head. This poses a distinctproblem. The retained heat creates a propensity for detonation, limiting the compression ratio of theengine. The first and second laws of thermodynamics dictate that any increase in compression ratio willyield a disproportionate gain in fuel efficiency over power generation. Raising the compression ratio from8:0:1 to 11:0:1 will add just over 5 percent to the engine's power but decrease fuel consumption by 20percent, if all other factors of the engine remain constant. This is the reason the cars of the mid-'70 wereso fuel thirsty, the mind set then was to lower the compression ratio to reduce oxides of nitrogen (NOx)emissions.The oil that is required to lubricate the valvetrain, even with the latest in valve seal design, allows somelosses into the combustion event. When oil is introduced into combustion, the likelihood for detonation isincreased. NOx is always present in all forms of combustion and requires pressure, heat, and exposuretime to be produced. When the engine detonates, or the leading edge flame front temperatures reach2,500 degrees F or greater, NOx production goes sky high. The poppet valve's retained head andnecessary lubrication contributes to this and requires other areas of engine design to be compromised.What is often overlooked is the heat transfer from the poppet valve to the intake port and the heating ofthe incoming charge. A law of physics states the for every 10 degrees F the air-charge temperature israised, a corresponding drop in engine power of one percent is experienced. Inefficient exhaust portsdesigned for poppet valves transfer exhaust heat into the water jacket of the cylinder head, loweringengine efficiency and reducing the effectiveness of blow down. In summation, the poppet valve has beenthe bane of the internal combustion engine, but the lack of a suitable replacement meant that it wasdeemed a necessary evil to be worked around.

The Coates Advantage

Not limited to working within the confines of a poppet valve, the CSRV design required a completerethinking of the cylinder head and port designs. Coming from a long line of inventors, George Coates'years of experience as an engineer for Rolls Royce, General Motors, Ford, and Mercedes-Benz affordedhim the skills to develop this new valve system. A conceptual mock-up of this design was first handmadeby Coates in 1961 and was attached to a European Ford four-cylinder engine. It took nearly fifteen more

years for the first running prototype to power a vehicle, and another five years to fully develop the sealingmechanism.When PHR arrived at the New Jersey based engineering and manufacturing facility, the ease ofadaptability of the CSRV system was quite apparent, with myriad of engines up and running with thistechnology. We witnessed four-cylinder helicopter engines, Harley-Davidson, Ford, Mercedes Benz alongwith a number of industrial engines, all functional. The elimination of the camshaft and its companionvalvetrain components not only drastically reduce the manufacturing costs, but would allow for anapplication-specific engine block to be designed, eliminating the space required to house the camshaft.This would allow for less total engine height and lower hood lines for better visibility and aerodynamics.This system is very simple, consisting of the Coates' cylinder head and intake and exhaust sphericalrotary valves for each bore. The valves are attached to a machined shaft that is supported on each endby a sealed roller bearing and utilize patented Coates' ceramic graphite bearings as center supports. Theuse of this material in conjunction with the end roller bearings allows for the elimination of any oil in thetop of the head.The only moving parts are the two shafts with the spherical rotary valves attached to them. The floatingceramic-carbon seals are two-piece units that respond to cylinder pressure to form a leak-free fit,containing the combustion gases. The shaft is driving from the crankshaft and counter rotates at the sameratio as a camshaft would, being one-half the crankshaft speed. As the shaft turns, the appropriate rotaryvalve will expose the intake port, allowing the cylinder to fill with charge. For the compression stroke, thevalve that is constantly turning will be rotated, closing off the combustion chamber to the intake port.During the exhaust stroke, the spent gases will travel through the passage in the rotary valve and exit thecylinder head. With this technology; the incoming charge assumes a tumbling motion that creates aquicker burn and increased octane tolerance while limiting heat transfer to the charge and the need forexcessive spark lead.Where the CSRV really shines is in its airflow potential compared to a poppet valve Bench-marking a 5.0L engine from a Lincoln, the stock Ford casting (when tested at 28 inches of H2O) flowed approximately180 cfm on the intake port at static. The rotary valve for the engine in comparison flowed a whopping319-cfm at the same test pressure. Equipped with the poppet valve head, the Lincoln engine dynoed at260 hp and 249 lb.-ft of torque. When equipped with the CSRV head at the same 5,500 rpm test protocol,it made 475 hp and 454 lb.-ft of torque, with no changes to the block or rotating assembly: The higherpower was a result of diminished frictional and pumping losses, but the inherent airflow benefit of thespherical valve was the major contributor. With a conventional poppet valve, it can take 34 degrees ofcrankshaft rotation or more to reach a fully open position, wasting energy and limiting volumetricefficiency. With the CSRV, a comparable port area is exposed in only 2 degrees of crank rotation. TheCSRV allows for superior surface flow coefficients from its spherical shape. With the standard 4-inch Fordbore, the factory poppet valve covers only 15.8 percent of the total bore area, while the rotary valve ismeasured at 20.5 percent.The design of the CSRV, which at first glance resembles an OHC cylinder head, allows for the centralplacement of the spark plug in the bore. By varying the spark plug location when referenced to the borecenterline, the most desirable position is in the center. This will allow the cylinder pressure build in theminimum amount of crank rotational degrees past TDC.Since horsepower is defined as work over time, the CSRV allows for an extremely high rpm potential.Test run at Coates' facility have seen a Ford 5.0 liter engine spin to 14,750 rpm! Though the CSRVremoves the valvetrain rpm limitations, the need to have a rotating assembly that can withstand theengine speed becomes the essential element. Another benefit of this design is the extended oil changeintervals, with the lubricating system not being exposed to the rigors and pollution from the poppet valve.

The End Result

The CSRV represents a technological breakthrough that has the potential to impact the internalcombustion engine in a manner not seen since its discovery. All of the engines we witnessed offeredexceptionally smooth performance with low levels of noise, vibration, and harshness. This was anextraordinary accomplishment since all of the test engines were based about production poppet valve

designs; one can only wonder the level of refinement that the CSRV will offer when integrated with ablock that is designed for it. To date, Coates offers complete engines based on a block of your choice forracing, street/strip, and industrial applications. The pricing starts at $ 15,000, and by the time you readthis, retrofit kits should be available for the popular Ford and Chevy V-8. So far, Detroit has shown theleast interest in further developing the CSRV technology, and disappointingly, Coates feels that the firstengines to use this will most likely be from foreign companies.© Popular Hot Rodding: October 1999