Administrators BRAAP Posted December 20, 2007 Administrators Share Posted December 20, 2007 Tony, All that high tech wizardry and still using poppet valves? One barrel maybe would use a linear response. If you have multiple barrels, then you want a dead tip-in for drivability. Why put anything at all in there or worry about designing the 'correct cam' for the application, and simply control the intake and exhaust valves via electrohydraulic actuators driven off an engine-based pump and accumulator setup? Variable valve lift, timing, and duration will give you EXACTLY the same response as a throttle valve without anything there to muck up the flow. And you can bet the advantages of variable valve events will make more power everywhere along the powerband as lift/duration/rpm is all optimized for each point on the curve, infinately recalculated realtime as the engine is being driven! Twin 140MHz ECU processors will do that easily on a 12Cylinder engine to 12K rpms I believe. "DEVAS" (Since we're throwing the stuff out there...) Quote Link to comment Share on other sites More sharing options...
BobbyZ Posted December 21, 2007 Share Posted December 21, 2007 I think i found this on here but this thing is a visual orgasm of perfection. Who needs poppet valves!!! Quote Link to comment Share on other sites More sharing options...
Careless Posted December 21, 2007 Share Posted December 21, 2007 That's the Coates Spherical Valve design. I remember bringing it up in a thread and BRAAP mentioned that he or TonyD or someone else had asked Coates to design an L series head utilizing the Coates system, but they turned it down due to "niche" market and production/R&D costs not adding up. Tony D, Wouldn't then DEVAS System require a custom head, just like the Coates design? It is the digital hydraulic valve system right? I remember reading up on it through some obscure website back when I posted the Coates head design, but they don't have any pictures or anything... It sounds like an amazing piece. 2 stroke or 4 stroke option, individual valve activation, speed burst accumulator assitance, valve clap dampening, VALVE CONTROLLED throttle input... SIGN ME UP! Quote Link to comment Share on other sites More sharing options...
BobbyZ Posted December 21, 2007 Share Posted December 21, 2007 I dont think it would require a custom head, you could probably rig the actuators directly to the valves or rockers of a normal L engine head. The speed of the actuators would have to be extremely fast though. Quote Link to comment Share on other sites More sharing options...
Careless Posted December 21, 2007 Share Posted December 21, 2007 I dont think it would require a custom head, you could probably rig the actuators directly to the valves or rockers of a normal L engine head. The speed of the actuators would have to be extremely fast though. it's fast enough for 20,000 rpm + on 16 cylinder engines as far as I remember. and there is an accumulator that has constant pressure that is capable of four or five times that which is required (in reference to a constant valve size), and it has a dedicated sump to send everything to. The website I went to was old as hell and didn't have more than just text info. Not sure if its been used or on what car/application and what the resultant numbers were in comparison to a fully mechanical valve train. Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 21, 2007 Share Posted December 21, 2007 The Coates spherical valve will require a new head for optimization, and JeffP called and they weren't interested in anything other than conversions of diesels in city busses, regardless of who paid development costs. Coates spherical valve conversions of Diesels to CNG in busses has been done for years. As I said then, working for the company that was supplying the CNG for the Busses and having an onsite Cat Rep fulltime in our corporate offices held no sway with the Coates People. The DEVAS system would use the stock head, remove the valve cover and all drive components (unless you wanted to drive the pump from the camshaft gear...but I would think retrofitting the Diesel front cover and driving the pump in the same way the diesel injection pump is driven would be an easy swap and use a lot of stock components.) bolt a plate on with your hydraulic actuators, and go from there. The DEVAS system could fit on just about any engine head, the actuators are not that big. But yeah, from a practical standpoint, a poppett valve is far more practical than the spherical valve. I would love to have the spherical valve...BUT the timing is not variable, and duration is not variable, etc etc etc... The spherical valve would be great for a FIXED camshaft profile. But the DEVAS allows infinitely adjustable cam profile and timing. Think VTEC with variable lift... It really ends up being far superior in regards to drivability and versatility when you think about the Coates design in that it's really nothing more than a fixed cam profile. It's just flowing so much more because of less restriction. But it's not adjustable, so for fuel economy AND power, it will suffer the same as a conventional camshaft. I had a rotary valve on my 360CC Suzuki Jeep from 1976............ Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted January 2, 2008 Share Posted January 2, 2008 I guess that's true from a racing standpoint, but my thoughts were that gas mileage would benefit from less turbulent airflow. (daily driver mentality, sorry!) How turbulant can you make air flow in a vacuum environment? At anything less than WOT, any less than perfect flow pathes for the air will not make a differnce in cylinder fill, because well, the cylinders are not being filled as it is. That is that are not taking in as many oxygen molecules as they do at WOT (or fuel, but that's not exactly a function of the throttle plate, for this discussion). Quote Link to comment Share on other sites More sharing options...
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