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Alex C
Level 6 User
Joined: 20 Jun 2004
Posts: 155
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Fri Jul 30, 2004 2:21 pm |
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Hey all
This isn't technically a question, but to the technically minded it might be quite interesting. I found this website while rummaging for R19 info - http://www.pattakon.com - on which some crazy guys in greece seem to have invented something they call VVA. I'm not an engineer but this looked quite interesting, especially since they prototyped it on a '89 19 GTS which is nearly the same as my car. They seem to have had some fairly spectacular results (if they're true  ) by actuating the valves by a variable amount instead of varying the valve timings like in VVT, VTEC, Variocam et all at different engine loads.
Anyway have a look if you're into that stuff - feel free to tell me their claims are bullshit if they are. I gotta say I'm still kinda suspicious about it since it looks so simple but claims such amazing results, and no car I've ever heard of uses it - I can't quite imagine my engine idling at 350rpm! 
Hope I don't piss anyone off by posting this here - sorry if I do!
Cheers
Alex
PS The R19 prototype is under the "Rod Version" of the VVA section of the site. |
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stan
Gay Rights Activist
Joined: 07 Apr 2004
Posts: 1268
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Fri Jul 30, 2004 2:49 pm |
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havnt read it but Mercedes (iirc) have already done this. basically throttle is controlled by inlet valve lift. therefore gets rid of the whole butterfly effort, which in turn reduces pumping losses dramatically, and so reduces fuel consumption by a fair whack.
benefits would also include better throttle response, increased peak power and smoother delivery |
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Chris H
Forum Moderator
Joined: 02 Mar 2004
Posts: 19978
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Sat Jul 31, 2004 4:43 am |
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the link is on this site and has been for ages. The site itself has been around for a few years.
BMW use it as well.
The simple things are always better and more efficient this means everythin ggets better.
Like Stan says response, power, torque, smoothness and fuel economy are all improved by the simple fact efficiency has increased. |
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Alex C
Level 6 User
Joined: 20 Jun 2004
Posts: 155
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Sun Aug 01, 2004 4:42 pm |
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Hey guys
Thanks for the replies - sorry if it's already posted here, I did do a quick forum search and nothing came up so I assumed it hadn't been mentioned here before. I think my favourite bit from that website is the video clip of them revving the modified 1.4 R19 lol - I bet you could give people a shock on the road with one of those! Would be even better on a valver
Just outta curiousity, would having constantly variable valve timing give the same results as this kind of vva technology, or is the vva technique inherently more efficient? Are BMW and Mercedes the only people known to use vva type technology? All the BMW stuff I found about Valvetronic says that BMW invented the idea itself - I can't believe they would allow that greek site to exist if that were true tho, knowing how big companies work!
Cheers
Alex |
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Chris H
Forum Moderator
Joined: 02 Mar 2004
Posts: 19978
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Mon Aug 02, 2004 4:19 am |
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VVT is different from VVA. The results are also different.
VVT is a cam which alters its position in relation to the bottom end, thus advancing or retarding the vale timing. The lift remains the same all thats changed is the overlap of the cams essentially.
Its better than a fixed cam because it allows a wider power band.
VVA is constantly variable lift, which does away with the throttle plate as Stan said, the air flow into and out of the cylinders is catered for by the valves themselves and their respective lifts. Less losses and more accurate mixture control for the load/speed of the engine. |
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