inspyral

If different companies have differant names for essentially the same technology, I don't see why one has to be better than the other.

MrFatbooty

Oh lord, let's get this straight.

There are two main types of variable valve timing out there. One of them is a "cam phasing" system which makes use of adjustable cam gear(s) controlled by the ECU. The computer is able to vary the timing of the cams up to a certian degree. This can either be done with infinitely adjustable gear(s) or with just a couple of settings.

The other type is a "cam switching" system in which the motor is able to switch between different cam profiles. There are generally either two or three profiles. Now, the various options out there are basically a combination of one or both of these options, and either on one or both cam or on a single-cam motor. In a couple of instances, the systems are able to deactivate one intake valve per cylinder to save fuel. I'll call this "valve deactivation" on my guide. A thorough although by no means absolutely correct rundown:

Audi 3.0 V6 and V8 = DOHC. Continous intake cam phasing , 2-stage exhaust.
BMW VANOS = DOHC. 2-stage intake cam phasing.
BMW Dual VANOS = DOHC. Continuous intake and exhaust cam phasing
Ferrari 360 Modena = DOHC. 2-stage exhaust cam phasing.
Ford VCT = DOHC. 2-stage intake cam phasing.
Honda DOHC VTEC = DOHC. 2-stage intake and exhaust cam switching.
Honda SOHC VTEC = SOHC. 2-stage intake cam switching.
Honda SOHC VTEC-E = SOHC. 2-stage intake cam switching. Valve deactivation.
Honda 2-rocker DOHC i-VTEC = DOHC. Continous intake cam phasing. 2-stage intake cam switching.
Honda 3-rocker DOHC i-VTEC = DOHC. Continous intake cam phasing. 3-stage intake and exhuast cam switching.
Honda SOHC i-VTEC = SOHC. Continuous cam phasing. 2-stage intake lobe switching.
Jaguar AJ-V8 = DOHC. Continous intake cam phasing.
Mazda VVT = DOHC. Continous intake cam phasing.
Mercedes-Benz V6 and V8 = 2-stage intake cam phasing.
Mitsubishi MIVEC = DOHC. 3-stage intake and exhaust cam switching.
Mitsubishi MIVEC-MD = DOHC. 3-stage intake and exhaust cam switching. Valve deactivation.
Nissan VVT = Continuous intake cam phasing.
Nissan Neo-VVL = DOHC. 3-stage intake and exhaust cam switching.
Porsche VarioCam = 3-stage intake cam phasing.
Porsche VarioCam Plus = Continuous intake cam phasing. 2-stage intake cam switching.
Renault V6 = 2-stage intake cam phasing.
Subaru AVCS = 2-stage intake cam phasing.
Toyota VVT-i = DOHC. Continous intake cam phasing.
Toyota VVTL-i = DOHC. Continous intake cam-phasing on intake, 2-stage intake and exhaust cam switching.
Volvo = Continuous intake cam phasing.

BMW has a new system called Valvetronic which does away with cams. Instead the valves are pneumatically (or maybe hydraulically) actuated and their lift, duration and timing is all computer controlled. It's infinitely variable so much so that the motor no longer has a throttle body.

So yeah I didn't really pay attention to what you guys are arguing about, but this should probably settle any sort of comparisons that are being made.

VtecApprentice

:bowdown: MrFatBooty You really know all the stuff :bigok:

From your explaination of Cam switching and Cam Phasing, is it that cam switching play around with the valve lift degree and duration and cam phasing only touch on when to open and close the valve ? ? ? So am i correct to assume that Cam switching will be more effective then Cam phasing in power potential ? ? ?

Stock to Stock Mitsubishi 1.6l Mivec had more BHP (on paper) compare to 1.6l DOHC Vtec . . but on the road . . Honda on seems to be faster. If MIVEC have a better technology then DOHC Vtec why issit appeared to be slower ? ? ? :dunno:

Does the new EP series honda civic have technology ? ? ?

-KangaRod-

I was under the impression that "valvetronic" (If I'm thinking of the same thing) still used a cam, but had a moveable rocker arm, and that is how the cams were indefinitely variable.

MrFatbooty

That could be...I haven't really read up on it. I always confuse it with the pneumatically-actuated valves on the old BMW V12 in the McLaren F1.

Cam switching is in effect having 2 or more cam profiles. Change the cam and you change lift, duration and timing. Cam phasing just changes the timing of a fixed cam profile.

On the MIVEC, it's actually a "quasi" 3-stage. There are only 2 stages on each cam, but rather than switch both cams at the same time like VTEC, it switches the intake and exhaust cams separately. I don't know much about the cars the motor came in although I believe the MIVEC-MD motor was only a 1.6 liters and there was also a V6 of some sort in the FTO which had MIVEC.

VtecApprentice

Oh then is a DOHC i-VTEC also a "quasi" 3-stage ? ? ? or it has 3 cam profile that change the intake and exhaust together for 3 times ? ? ?

MrFatbooty

Yet another mistake on my part. i-VTEC in all its forms still uses 2-stage cam switching.

-KangaRod-

but has VTC which allows advance or retard (phasing) of the intake cam. On the A2 at least....

terryt

BMW is currently using an infinitely variable variable valve timing system on the M3.
I think the M3's is the best by far in operation, being able to adjust infinitely versus being in on or off position.
VTEC is basically on or off for the valves, and variable cam timing.
Toyotas is a similar concept to hondas with the wedge activated higher lift/longer duration instead of a 3rd cam profile.

Just my $0.05 worth.

93Integra

Just to let you know the GT-S has VVTL-i which stands for variable valve timing and lift with intelligence. Which is Toyota's off-breed of VTEC