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Old 06-16-2005, 01:57 AM   #1
Masuk
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Fancy Valve Timing and what not

Hey guys-
It seems like today all I hear about are these new fancy valve timing componets found on some of newer cars. Now the only one that I am firmiliar with is the Honda VTEC. I hear about the Mercedes and BMW advanced set up on the valves and cam, but are these the same princable idea of the VTEC in that they have basically two different functioning camshafts for upper RPM's and lower RPM's? Whats the deal with this kind of stuff. I can understand the benefits of these, especially the VTEC, that being the only one I really know any thing about. Can some one please clear up this new valve timing idea for me.
Thanks.
-Justin
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Old 06-16-2005, 02:05 AM   #2
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Basically, it's a change in the valve's lift and retardation/advancement as compared to the other camshaft/stock lift.

http://auto.howstuffworks.com/camshaft6.htm
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Old 06-16-2005, 02:19 AM   #3
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no, I understand what happens, and how it happens, what I am wondering is....Does any other car company make a valve timing set up like the VTEC....Ive heard of Mercedes and BMW mainly, are these the same things as the VTEC?
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Old 06-16-2005, 02:26 AM   #4
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Quote:
Originally Posted by Masuk
no, I understand what happens, and how it happens, what I am wondering is....Does any other car company make a valve timing set up like the VTEC....Ive heard of Mercedes and BMW mainly, are these the same things as the VTEC?

yes, pretty much every company employs it nowadays. It's all the same, changing the valve's lift, duration and retardation/advancement across the RPM range.

The only company I can think of that doesn't employ it is Ford. (American-wise, anyway)
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Old 06-16-2005, 04:58 AM   #5
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BMW is currently using a system called Valvetronic. Now I believe, (and please god correct me if I'm wrong because I don't want to mislead anyone), that with this system, pressing the throttle actually controls the valve lift, by moving the intake camshaft up and down, or possibly a second shaft. All of which is done by wire.
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Old 06-16-2005, 10:23 AM   #6
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Quote:
Originally Posted by Godlaus
yes, pretty much every company employs it nowadays. It's all the same, changing the valve's lift, duration and retardation/advancement across the RPM range.

The only company I can think of that doesn't employ it is Ford. (American-wise, anyway)

an old article, but worth a read

http://autospeed.drive.com.au/cms/A_1523/article.html
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Old 06-16-2005, 11:49 AM   #7
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Quote:
Originally Posted by Godlaus
The only company I can think of that doesn't employ it is Ford. (American-wise, anyway)

they don't need it - they've alway been retarded...
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Old 06-16-2005, 01:46 PM   #8
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Quote:
Originally Posted by dodger65
they don't need it - they've alway been retarded...
here we go again......
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Old 06-16-2005, 02:48 PM   #9
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The main thing to understand is howthe average engine makes power, and how important the camshaft profile is to that. Before Honda invented VTEC, you eith er swapped cams for more power, at the expense of low rpm driveability (big engines could absorb the los of low end power as they had mroe of it to begin with, but small engines could become very undriveable in a hurry), or you advanced/retarded the stock cam timing in relation to the crank (which gave a very small change). A few companies managed to do that last trick internally on the fly. Porsche's VarioCam, BMWs Vanos, and Alfa's system. But it wasn't the same as actually swapping the cam.

VTEC set up more than one cam profile on the cam, and swapped back and forth where teh cam profiles started to become inefficient. This gave low end driveability like the old stock cams, and higher rpm pwer like older perfomance cams. Due to patent restrictions, everyone else has to find their own way fo doing the same thing, and it took most other manufactures most of a decade to do it. Newer systems are adding computer controlled, continuously variable cam profiles, but now they are adding complexity and the added chance for expensive failures to produce ever smaller benefits at ever increasing costs.
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Old 06-16-2005, 06:13 PM   #10
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toyota has VVT, VVTI VVTLI.... variable valve timing, variable valve timing with intelligence. (i think) and variable valve timing and lift with intellegence
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Old 06-16-2005, 11:06 PM   #11
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Quote:
Originally Posted by Inygknok
here we go again......

...just playful banter...
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Old 06-16-2005, 11:24 PM   #12
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Quote:
Originally Posted by mazda6man
toyota has VVT, VVTI VVTLI.... variable valve timing, variable valve timing with intelligence. (i think) and variable valve timing and lift with intellegence

How does the VVT-i systems work? Are they like the i-vtecs in the new Civic Sis hatchback?
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