150plusZ Posted January 18, 2009 Share Posted January 18, 2009 Does anybody know when the Decuir springless valvetrain is out on the market or is it already out? also any ideas or experience. sounds great for sbc as the valvetrain is the limiting factor for rpm. Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted January 18, 2009 Share Posted January 18, 2009 Seems like they are in the same situation as these guys: http://www.coatesengine.com/ where they have an idea, but since nobody big is using them OEM, they don't really have traction. The Decuir system though I don't get, is it still a reciprocating assembly? Quote Link to comment Share on other sites More sharing options...
150plusZ Posted January 19, 2009 Author Share Posted January 19, 2009 i dont fully understand the decuir system either. the video really doesnt explain much about what goes on with the camshaft. i know the system has been used on ducati bikes for awhile. everything ive found on the internet about the desmodromic system is on 4 cylinder bikes and looks nothing like the one on the video for push rod engines. anbody have a better understanding of this? Quote Link to comment Share on other sites More sharing options...
hoov100 Posted January 19, 2009 Share Posted January 19, 2009 just research "rotary valve" in general on google and you find everything you need, the concept is VERY simple, but requires alot of attention in the timing aspect of it. Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted January 19, 2009 Share Posted January 19, 2009 The point is though that it doesn't appear that these are circular valves. Quote Link to comment Share on other sites More sharing options...
Guest Widebodys30 Posted January 19, 2009 Share Posted January 19, 2009 I hear eliminating the poppet valve makes it safe to run as high as 14-1 c/r on STREET gas. You think that's wild, I read in a hot rod mag about '94, where this guy made what was like a small radial engine(like what is on really old aircraft), but didn't use the antique steam engine technology crankshaft. The pistons rode on something similar to a CAM LOBE, like overgrown roller rockers. What does it do to have all of the combustion energy focused on your motor's centerline? How about his preliminary test model displacing 40 CI, and putting out nearly 400HP. I'm sure the auto or oil companies must have bought the rights, and quickly scuttled it away, as I only heard of it the one time... Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted January 19, 2009 Share Posted January 19, 2009 What, pray tell, do the valves have to do with how much you can compress the intake charge? And something tells me that this 40CI radial probably was spinning to the moon or something. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 19, 2009 Share Posted January 19, 2009 I believe it has to do with combustion chamber shape, elimination of hot valves, diluted intake charge, etc. Quote Link to comment Share on other sites More sharing options...
JimConner Posted February 3, 2009 Share Posted February 3, 2009 The Decuir springless valve doesn't change the valves at all. It just connects the cam to the lifter, to the pushrod, to the rocker, to the spring. So the cam can pull the valve closed, thus no spring necessary. I think there is a light spring just to make sure the valve guide seal doesn't pop out. I read somewhere it gains power mostly from friction reduction between the cam and lifter face. Well, a roller cam would do the same thing.. Decuir posted a gain of 15 HP or so on a Chevy 350, that is about in line with gains from a roller cam. It doesn't gain any huge amount of power, just frees up some due to friction reduction. My guess is he wants a fortune for it, just like the Coates guy, so no one is willing to pony up the $$$ for such a small gain. Quote Link to comment Share on other sites More sharing options...
ZZZeee Posted February 3, 2009 Share Posted February 3, 2009 If they're going to have independently digitally controlled valves they should do away with springs and as much reciprocating mass and friction as is possible. They should go with rotary valves. This eliminates the need for excessive torque needed to open and close typical reciprocating spring-loaded valves and promotes nearly immediate accuracy. Yes... if I could develop this technology I would be a millionaire. Story of my life... Quote Link to comment Share on other sites More sharing options...
ZZZeee Posted February 3, 2009 Share Posted February 3, 2009 Holy cripes... I'm no longer a Nerf Herder. I'm now HZ member of the frickin' week. I guess I must be one bad-a$$ SOB. Damm I must be really good!! In fact, I'm practically a HZ God. I'm almost... lump in my throat... I'm almost... eyes welling up... I'm almost... tears streaming now... I'm ALMOST... a BRAAP!!! Quote Link to comment Share on other sites More sharing options...
150plusZ Posted February 4, 2009 Author Share Posted February 4, 2009 haha, i got the phone number to decuir and im going to call them in the next few days to ask a few questions like when is it available? and im very interested in how much they are going to sell thesefor. interesting they are trying to apply different technology to engines that honestly need it. im suprised there hasnt been more aftermarket for things like this and even possibly a system for overhead cams on chevys?/ i know there would be a huge market Quote Link to comment Share on other sites More sharing options...
olie05 Posted February 4, 2009 Share Posted February 4, 2009 The Decuir springless valve doesn't change the valves at all. It just connects the cam to the lifter, to the pushrod, to the rocker, to the spring. So the cam can pull the valve closed, thus no spring necessary. I think there is a light spring just to make sure the valve guide seal doesn't pop out. I read somewhere it gains power mostly from friction reduction between the cam and lifter face. Well, a roller cam would do the same thing.. Decuir posted a gain of 15 HP or so on a Chevy 350, that is about in line with gains from a roller cam. It doesn't gain any huge amount of power, just frees up some due to friction reduction. My guess is he wants a fortune for it, just like the Coates guy, so no one is willing to pony up the $$$ for such a small gain. There are two advantages to having a "springless" or "positive valve actuation" system (as decuir calls it). 1. elimination of a high rate spring from the valve train - leads to the friction reduction mentioned above. 2. the valve following the exact* movements of the cam all the way to the point where normal valve springs would float. In those regards it is not too closely comparable to a roller rocker setup. BUT you can't eliminate the spring altogether. Even in the Ducati system you see a spring mounted on the follower pivots to help keep the followers close to the cam. Also, by using 2 cam lobes instead of one to open and close the valve, the ducati system is far superior to the Decuir system because valve movements are not constrained by the movement of an offset circle (basically a sine wave). This allows you to take advantage of optimizing the velocity of the valve at open and closing points. *within tolerance. Quote Link to comment Share on other sites More sharing options...
JimConner Posted February 20, 2009 Share Posted February 20, 2009 haha, i got the phone number to decuir and im going to call them in the next few days to ask a few questions like when is it available? So what was the result? Quote Link to comment Share on other sites More sharing options...
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