Valve overlap

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
manchild
manchild
12
Joined: 03 Jun 2005, 10:54

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When I first saw this topic it reminded me on one article I read ages ago about cams in Porsche 917. Fortunately, today I've found that magazine again (printed in 1977 :lol:) and it mentions 917 as an extreme - intake valve on Porsche 917 is open 388 degrees! It opens 108 degrees before... how do you say it in English... top dead point? and closes 108 degrees after bottom dead point?

DaveKillens
DaveKillens
34
Joined: 20 Jan 2005, 04:02

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TDC = Top Dead Center
BDC = Bottom Dead Center

manchild
manchild
12
Joined: 03 Jun 2005, 10:54

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Thanks, I was close :)

riff_raff
riff_raff
132
Joined: 24 Dec 2004, 10:18

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Of course, the most extreme example of intake/exhaust overlap is the loop scavenged two stroke engine. The exhaust both opens before the intake/transfer and closes after it. That's 100% overlap!

Belatti
Belatti
33
Joined: 10 Jul 2007, 21:48
Location: Argentina

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This is what too much valve overlap cause!
http://farm1.static.flickr.com/197/4999 ... 08.jpg?v=0

PS: Argentine TC champion, former F1 driver Norberto Fontana, with a 1400kg Dodge behemoth: 3 litres, six cyl. in line, 9500 RPM, almost 380HP.

EDIT: no electronic inyection, just the good and old webbers!
"You need great passion, because everything you do with great pleasure, you do well." -Juan Manuel Fangio

"I have no idols. I admire work, dedication and competence." -Ayrton Senna