Coates Spherical Rotary Valve System – Let the Rivet Counting Begin!

Robert Farago
by Robert Farago

According to the official website, the Coates Spherical Rotary Valve System creates "a quieter engine with higher specific power output and longer life than conventional poppet valve engines due to better 'breathing' capability and higher speed capability." In fact, it's "the single most significant development in engine technology in the past thirty years." Not being the most mechanically-minded pistonhead on the planet, I asked Sajeev Mehta to check it out: "Its a logical extension of innovations like roller rockers: reduced friction, more power, efficiency etc. The general feel I got from people who know more than me: sealing a spherical valve isn't gonna work for a production car. Today's engines have to last over 100k miles without any trouble, and engine "blow by" will be even worse here… and don't even think about pressurizing these valves with a turbo/supercharger/ Good night! As for their claim of their valves not needing oil. Strap on an A/C compressor: sit in traffic in 100 degree weather on a heat-soaked hunk of tarmac and those valves will be begging for extra lubrication. The big red flag for me: their they compared it to a regular engine without an EGR valve. That's like challenging Carl Lewis to a 100m race and making him do it barefoot on hot asphalt. Everyone uses EGR valves for a good reason; they reduce NOx (the third row on their chart) emissions by something like 70% or more. "On the exhaust stroke the poppet exhaust valve stems allow "back" pressure through the valve guides into the engine casing. This pressure is then redirected through the fuel induction system and in turn is reburned in the engine creating yet more hydrocarbons, carbon dioxide and carbon monoxide." Except that happens on high mileage motors with worn valve guides/springs (valves snap shut plenty fine when new). It took 150k miles for my 5.0 Ford to get weaker/slower/dirtier from valvetrain age. Newer engines are even better at valvetrain durability for many reasons. I seriously question if the Coates engine will fare much better after that type of punishment. I'm skeptical, but would change my tune with better info. EPA-style tests that carmakers do wouldn't hurt."

Robert Farago
Robert Farago

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  • 50merc 50merc on Dec 18, 2007

    Naw, the "next big thing" will be the return of the Willys-Knight sleeve valve engine!

  • Kurtkoblitz Kurtkoblitz on Mar 05, 2009

    The latest "Coates HOT OF THE PRESS" China will require - if everything pans out - that all engines will be Coates engines. What next? This should happen in 2 weeks - ad infinitium.

  • The Oracle Well, we’re 3-4 years in with the Telluride and right around the time the long term durability issues start to really take hold. This is sad.
  • CoastieLenn No idea why, but nothing about a 4Runner excites me post-2004. To me, they're peak "try-hard", even above the Wrangler and Gladiator.
  • AZFelix A well earned anniversary.Can they also attend to the Mach-E?
  • Jalop1991 The intermediate shaft and right front driveshaft may not be fully engaged due to suspected improper assembly by the supplier. Over time, partial engagement can cause damage to the intermediate shaft splines. Damaged shaft splines may result in unintended vehicle movement while in Park if the parking brake is not engagedGee, my Chrysler van automatically engages the parking brake when we put it in Park. Do you mean to tell me that the idjits at Kia, and the idjit buyers, couldn't figure out wanting this in THEIR MOST EXPENSIVE VEHICLE????
  • Dukeisduke I've been waiting to see if they were going to do something special for the 60th Anniversary. I was four years old when the Mustang was introduced. I can remember that one of our neighbors bought a '65 coupe (they were all titled as '65 models, even the '64-1/2 cars), and it's the first one I can remember seeing. In the '90s I knew an older gentleman that owned a '64-1/2 model coupe with the 260 V8.
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