Which Variable Valve Timing is better ? ?

[VtecApprentice]

I realise that many other brands also did play around with the Variable Vale Timing technology like Honda Vtec . . and my question is . . what made Honda's Vtec stands out amoung all ? ? Subaru : Active Valve Control System (variable valve timing) Toyota : Variable Valve timing with intelligence (VVT-i) technology Mitsubishi : Mivec stands for Mitsubishi Innovative Valve timing with lift Electronic Control These are a few Variable Valve Timing Technology other then Vtec i know . . I think i've missed out some other brands technology Can someone convince me that Vtec is the best amoung all ? ? and can expert here comment on the different rechnology please. ThankzZ

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[Doofnoil]

I think that they are all the same, vtec is just an extra set of lobes on the cams with a more agressive lift and duration to provide more power whenever the engine hits a certain rpm.
hence VARIABLE valve timing, i don't think any one company is better because to my knowledge(which is very limited) they all use the same basic principles as honda, however most people chose honda A: because of hidden performance and overall integrity that the engines possess and B: Honda has been at the vtec technology for awhile now and has the kinks worked out of it for the most part....who need vtec anyway?

[forcedinduction]

I believe that Honda has the jump on everyone else because they were the first to get it on the market and patent it, which restricted other auto makers from coming out with it for X number of years. Even though they all do 'basically' the same thing many manufactures have a different way of going about it.

Porsche has their own too.

[taylormadem5]

You forgot the best "vtec" application, BMW's double Vanos system, its awsome.

[jclau00]

http://www.edmunds.com/news/innovati...9/article.html

brief description of variable valve timing systems from honda, toyota, and bimmer.

[jclau00]

along the same lines, saab developed variable compression. it's not as widely known as vtec yet, but perhaps someday.

http://www.edmunds.com/news/innovati...7/article.html

[v4lu3s]

vtec was around long before the others...the BMW system looks like the most advanced right now though.

[-KangaRod-]

Of the three you listed there, the Toyota system is probably the most advanced simply because it was the last one designed. VTEC was so widely "popular" because it was the first out, and came in some pretty potent sport compacts. You may think that VTEC is bar none the most popular, but that is because VTEC is the one people brag about most. All of Lexus' line has featured VVt-i for a few years now, but they don't have the huge stickers on the side because 45-something father's of 3 don't want stickers on their ES300. The GT-S on the other hand screams of its VVt-i system. Not many people know this, but not many companies have actual variable valve timing, the majority, including BMW's VANOS system is variable cam timing. There is a slight difference. The VTC part of i-VTEC is simliar to VANOS. To my knowledge, there is only 3 (4 if you count i-VTEC) kinds of variable valve timing on the market right now. VTEC, VVti-, and MIVEC. Of those 3 VVt-i is probably the best because the variation is done in the head, not in the cam as is the case with VTEC and MIVEC reducding paracidic loss to wight in the valve train. BMW is comming out with a system to match to its double VANOS system which consists of rocker arms situatuated on a movable fulcurum, allowing for infinite VTEC (not two stage anymore). That system will be the best once it comes out. The way I remember I tell the difference between variable cam timing and varible valve timing, is that vvt changes the actual lift and duration of the valves (as can be seen by the fatter lobes on a vtec cam). vct only changes the advance or retard of the cam relative to the speed of the engine, in essence only allowing a longer duration. A vvt system is a little more complicated, but allows for more power potential, as we all know because VTEC kicks ass!

PS I don't know much about MIVEC. I don't think it was ever offered in USDM. Does anyone know more about it?

[SmOkIneLf]

i remember there being Variable Valve timing on the 911TT or maybe the new one maybe i'm wrong but anyway there is an issue of Super Street i think that explains basically most Variable Valve timing from most companies

[VtecApprentice]

Thanks for all the reply . . but from all the post . . it seems like VVTi and the BMW technology were better then Vtec huh We are big fan of Vtec ~! how can this happens

1stGenCRXer ? ? Inspyral ? ? qtiger ? ? MrFatBooty ? ? any comments and opinion ? ? ? ? ?

[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]

MrFatBooty You really know all the stuff

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 ? ? ?

Mitsubishi MIVEC = DOHC. 3-stage intake and exhaust cam switching.

Honda DOHC VTEC = DOHC. 2-stage intake and exhaust cam switching.

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 ? ? ?

Does the new EP series honda civic have

Honda 3-rocker DOHC i-VTEC = DOHC. Continous intake cam phasing. 3-stage intake and exhuast cam switching.

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]

Honda 3-rocker DOHC i-VTEC = DOHC. Continous intake cam phasing. 3-stage intake and exhuast cam switching.

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]

Originally posted by -KangaRod-
The GT-S on the other hand screams of its VVt-i system.

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

[MrFatbooty]

Read the list above and quit trying to out-wit each other. If you think anything up there is wrong that hasn't already been corrected, say so. Otherwise there's not really much left to discuss.