variable valve timing on 2007 V10
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Champion
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variable valve timing on 2007 V10
http://www.nytimes.com/2007/01/14/au...s/14VIPER.html
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To coax their pushrod designs to rev higher without running out of breath, engineers have designed lighter, stiffer, lower-friction valvetrains. Pushrod V-8 engines racing in Nascar routinely rev to 9,000 rpm. Thanks to natural trickle-down, the lightweight valves, low-friction lifters and high-tension valve springs made of exotic steels have filtered into production pushrod engines, giving them the speed and stamina to compete with Ferrari’s V-8. While the F-430’s screaming 8,500 r.p.m. maximum speed is still out of reach, the 7,000-r.p.m. redline of the Corvette outdoes the 6,600-r.p.m. maximum of the Porsche 911 Turbo. The new Viper engine revs to 6,200 r.p.m., 200 more than before.
To fill the cylinders with the air and fuel needed to sustain high-speed operation, Detroit engine designers have packed larger intake ports into the space available between the pushrods. Lacking the room to go wider, engineers increased the capacity of the intake passages by making them taller.
Variable valve timing is another emerging technology that engineers employ to minimize emissions, improve smoothness and enhance power. Changing the timing of specific operations — when valves open and close in relation to each other and to the position of the pistons — is not difficult in a dual-cam engine, which controls the intake and exhaust valves independently.
Accomplishing variable valve timing with a single camshaft is a different matter entirely, because the lobes that lift the valves are locked in relation to each other.
Engineers at Dodge, working with the British firm Mechadyne, redesigned the camshaft to create two concentric shafts, one inside the other. The hollow outer tube holds the exhaust lobes while an inner shaft drives the intake lobes.
This allows continual adjustment of valve operation, according to the needs of the engine at different speeds.
The cam-within-a-cam concept has existed for decades, but perfecting it for production might just add another decade to the life of the pushrod engine.
picture
http://graphics8.nytimes.com/images/...viper_span.jpg
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or use of bugmenot.com
sample quote
To coax their pushrod designs to rev higher without running out of breath, engineers have designed lighter, stiffer, lower-friction valvetrains. Pushrod V-8 engines racing in Nascar routinely rev to 9,000 rpm. Thanks to natural trickle-down, the lightweight valves, low-friction lifters and high-tension valve springs made of exotic steels have filtered into production pushrod engines, giving them the speed and stamina to compete with Ferrari’s V-8. While the F-430’s screaming 8,500 r.p.m. maximum speed is still out of reach, the 7,000-r.p.m. redline of the Corvette outdoes the 6,600-r.p.m. maximum of the Porsche 911 Turbo. The new Viper engine revs to 6,200 r.p.m., 200 more than before.
To fill the cylinders with the air and fuel needed to sustain high-speed operation, Detroit engine designers have packed larger intake ports into the space available between the pushrods. Lacking the room to go wider, engineers increased the capacity of the intake passages by making them taller.
Variable valve timing is another emerging technology that engineers employ to minimize emissions, improve smoothness and enhance power. Changing the timing of specific operations — when valves open and close in relation to each other and to the position of the pistons — is not difficult in a dual-cam engine, which controls the intake and exhaust valves independently.
Accomplishing variable valve timing with a single camshaft is a different matter entirely, because the lobes that lift the valves are locked in relation to each other.
Engineers at Dodge, working with the British firm Mechadyne, redesigned the camshaft to create two concentric shafts, one inside the other. The hollow outer tube holds the exhaust lobes while an inner shaft drives the intake lobes.
This allows continual adjustment of valve operation, according to the needs of the engine at different speeds.
The cam-within-a-cam concept has existed for decades, but perfecting it for production might just add another decade to the life of the pushrod engine.
picture
http://graphics8.nytimes.com/images/...viper_span.jpg
Veteran
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From: TBK Enterprises
RE: variable valve timing on 2007 V10
Chryslerhas pioneered just about 90% of the racing technology in America for the past 90 years.They love doing everything first and they will decide if its a keeper or not. I am glad they did it no matter what way they go in the future. 
Record Breaker
Joined: Sep 2005
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From:
RE: variable valve timing on 2007 V10
How similar was this to the GM High Feature V6's (3.5L & 3.9L)and the Cadillac 6.2L V8's addition of VVT? GM was the first to add VVT to a pushrod (Cadillac Escalade, Pontiac G6/Saturn Aura/Chevrolet Malibu and Impala/Monte Carlo), but Chrysler was the first to add it to a performance car.
