Variable Valve Timing
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Variable Valve Timing
Anyone know what the first automotive application of Variable valve timing was?
According to this site
http://www.nationmaster.com/encyclop...mplementations
I don't think they would be incorrect.
Also, when did BMW first introduce their own variable valve timing (VANOS). Co-worker is claiming tha BMW invented variable valve timing and had it in production cars in the late 80's before Honda did VTEC. I was certain Honda used it in F1 back when supplying engines to McLaren and the first production car with VTEC was the 91 NSX.
According to this site
http://www.nationmaster.com/encyclop...mplementations
The first experimentation with variable valve timing and lift was performed by General Motors. GM was actually interested in throttling the intake valves in order to reduce emissions. This was done by minimizing the amount of lift at low load to keep the intake velocity higher, thereby atomizing the intake charge. GM encountered problems running at very low lift, and abandoned the project. General Motors Corporation (NYSE: GM), also known as GM, is a United States-based automobile maker with worldwide operations and brands including Buick, Cadillac, Chevrolet, Daewoo, GMC, Holden, Hummer, Opel, Pontiac, Saturn, Saab, and Vauxhall. ...
The first functional variable valve timing system, including variable lift, was developed at Fiat. Developed by Giovanni Torazza in the 1970s, the system used hydraulic pressure to vary the fulcrum of the cam followers. The hydraulic pressure changed according to engine speed and intake pressure. The typical opening variation was 37%. Fiat S.p. ... This article provides extensive lists of events and significant personalities of the 1970s. ...
The next big step was taken by Honda in the late 1980s and 90s, where Honda began by experimenting with variable valve lift. Pleased with the results, engineers took the knowledge and applied it to the B16A engine, fitted to the 1989 EF9 Honda Civic. From there it has been used in a variety of applications, from sport to utility, by many different auto makers.
The first functional variable valve timing system, including variable lift, was developed at Fiat. Developed by Giovanni Torazza in the 1970s, the system used hydraulic pressure to vary the fulcrum of the cam followers. The hydraulic pressure changed according to engine speed and intake pressure. The typical opening variation was 37%. Fiat S.p. ... This article provides extensive lists of events and significant personalities of the 1970s. ...
The next big step was taken by Honda in the late 1980s and 90s, where Honda began by experimenting with variable valve lift. Pleased with the results, engineers took the knowledge and applied it to the B16A engine, fitted to the 1989 EF9 Honda Civic. From there it has been used in a variety of applications, from sport to utility, by many different auto makers.
Also, when did BMW first introduce their own variable valve timing (VANOS). Co-worker is claiming tha BMW invented variable valve timing and had it in production cars in the late 80's before Honda did VTEC. I was certain Honda used it in F1 back when supplying engines to McLaren and the first production car with VTEC was the 91 NSX.
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From: Austin, TX
Originally Posted by F23A4
The 91 Acura NSX had the first commercial use of variable valve timing
I am certain that the NSX was the first production car to use variable valve timing. I think that Dom is trying to make the point that other compeditors were testing it in concepts a long time before. He's not saying that it was a production item.
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The Porsche 968 had variocam in 1991... (production car). German Model years begin in August, so a 1991 MY 968 would have been available in August 1990 IIRC (at least that the way model years worked for the old aircooled vws and pcars).
http://www22.porsche.com/uk/aboutpor...novations/90s/
http://www22.porsche.com/uk/aboutpor...novations/90s/
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Originally Posted by kurt_bradley
I am certain that the NSX was the first production car to use variable valve timing. I think that Dom is trying to make the point that other compeditors were testing it in concepts a long time before. He's not saying that it was a production item.
Originally Posted by DOM
Also, when did BMW first introduce their own variable valve timing (VANOS). Co-worker is claiming tha BMW invented variable valve timing and had it in production cars in the late 80's before Honda did VTEC. I was certain Honda used it in F1 back when supplying engines to McLaren and the first production car with VTEC was the 91 NSX.
Burning Brakes
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From: USA
Originally Posted by dom
Also, when did BMW first introduce their own variable valve timing (VANOS). Co-worker is claiming tha BMW invented variable valve timing and had it in production cars in the late 80's before Honda did VTEC. I was certain Honda used it in F1 back when supplying engines to McLaren and the first production car with VTEC was the 91 NSX.
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From: Toronto
Originally Posted by importtuner
VTEC is utilized to give a balance of performance and fuel economy; hence the 2-lobe profile.
Not neccesarily. VTEC is used to "optimize" at any given rpm. That can mean optimize for fuel economy, or performance alone. However, I would also question its usefulness in f1 because they are pretty much always running at high rpm. Unless those vtec systems are more "granular".
Ferrari has a really neat way of doing this. The camshafts on some Ferrari engines are cut with a three-dimensional profile that varies along the length of the cam lobe. At one end of the cam lobe is the least aggressive cam profile, and at the other end is the most aggressive. The shape of the cam smoothly blends these two profiles together. A mechanism can slide the whole camshaft laterally so that the valve engages different parts of the cam. The shaft still spins just like a regular camshaft -- but by gradually sliding the camshaft laterally as the engine speed and load increase, the valve timing can be optimized
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