VTEC vs. S-VT & VTCS

[bRANDO]

So when i bought my m3 last spring, i recall the dealer trying to sell me with all the under the hood stuff, when in fact \" you had me at hello\" (only analogy i could come up with!). Now he discussed things like the timing chain instead of the belt, etc. I also remember him comparing our variable valve timing to hondas vtech, giving us more power at higher rpm. Now i love the 3, and its growl at higher rpm, but its no vtech. I love my car stock the way it is, which is why modding this spring will bring me ever so closer to my baby (despite discussions with the wife!). So heres the question for you engine tech\'s. How siimilar is our VVT to the vtech? Ive also decided that mazda shold offically assign the following name to there motors, not unlike vtech is to honda!



i give you 3TECH

comments?

EDIT by majic: changed the subject so people don\'t think we\'re talking about phones in the USA ;) (vtech vs US)

[majic]

VVT (http://en.wikipedia.org/wiki/VVT)



Most simple VVT systems (like Mazda\'s S-VT) advance or retard the timing of the intake or exhaust valves. Others (like Honda\'s VTEC) switch between two sets of cams at a certain engine rpm. Still others can alter duration and lift continuously.


honda\'s VTEC (http://en.wikipedia.org/wiki/VTEC)
mazda\'s S-VT (http://en.wikipedia.org/wiki/S-VT) and VTCS (http://en.wikipedia.org/wiki/VTCS)

there\'s an excellent article here (http://www.mazda6tech.com/Articles/Drivetrain/) but the site is down for maintenance now

[FLIPDADY]

Nothing out there beats the sound of a high revving VTEC motor!;)

[TheProfessor]

Different Honda engines reacted differently to VTEC.....on some of them (B18C1, B18C5 and B16A for instance) it was very noticable and quite enjoyable. On some of the smaller and older engines however I could barely notice it. Mazda\'s version of variable valve timing doesn\'t come close to Honda\'s IMO. I personally haven\'t driven any of the new Honda\'s/Acura\'s with the K series motors, but I can\'t imagine them not having the same effect.

[SABIO]

at the end of this video... you can hear the difference

http://www.putfile.com/media.php?n=M3Movie

[MajesticBlueNTO]

i have a vtech phone :sarc :p

in any case, the MAIN difference between honda\'s VTEC (Variable Valve Timing and Lift Electronic Control) and the 3\'s VVT is the fact that there is a 3rd camshaft lobe (activated by oil pressure \"pushing\" a pin in place) that increases the LIFT of the valves; meaning, it opens the valves more at high rpm.

The DOCH B18C1/C5, B17A, B16A had the Lift on both the intake and exhaust cams. This was done for more power.

Certain variants of the SOHC VTEC had the different lobe for the exhaust valves only for emissions and fuel economy.

Toyota owners with the 1.8L VVTi-L motor refer to \"hitting Lift\" which is the same thing -- the engagement point of the more aggressive cam lobe profile.

[MAZDA Kitten]

Originally posted by FLIPSPEED


Nothing out there beats the sound of a high revving VTEC motor!;)

Yes there is; its called VR6 :D

[SIM SIMMA]

^^ Agreed.

As much as I had a love/hate relationship with my VR6... that engine was sweet.

[Nolat]

Vtec, 2 distinct cam lobes, low and high, that the ECU switches between to give more lift and change the timing. Low and high cams differ in valve timing, duration, overlap and lift. However its a one time thing. At a certian RPM (5500 on b16\'s) the ecu activates a solenoid to pass oil to pusht a pin to activate the other lobes. Vid of how vtec works (http://www.hondaclubcr.com/mult/V-TecSystem.mpg)

i-vtec has the same system but also has full varriable valve timing on the intake cam.

vvt-i - Toyotas Varriable valve timing with intellegence. A duty cycled oil solenoid valve hydrolically moves the intake cam with a maximum range af 43 crank degrees to increase or decrease valve overlap.

VVTL-i Toyota 2zzge specific. Basically vvt-i with vtec.... very similar to i-vtec. Uses full vvt-i on the intake cam, and switches between high and low cams at certian rpms. The cam switchover is the most audible change. Example here... on dyno (http://videos.streetfire.net/search/matrix/0/4EAFFB17-F817-47FF-B952-0F237452C6B7.htm) you can hear the vvt-i playing around too.

Im not too sure how your s-vt or vtcs work, but I would assume its more like vvt-i. Not nearly like vtec.

[SABIO]

I think your lying;)

[dredd2099]

hey mr nolat
welcome to the site
nice first post

:)

[MZ3_GS]

You guys forgot i-VTEC, probably the best one out there, well maybe behind BMWs system.

Anyways, does anyone here have an 06 2.0L? They added S-VT for 2006, anybody driven with and without and noticed a comparable difference?

[Fuman]

Originally posted by MZ3_GS
Anyways, does anyone here have an 06 2.0L? They added S-VT for 2006, anybody driven with and without and noticed a comparable difference?

its new for 06? never knew that.
I\'ll see if I can get my hands on my friend\'s 05 hatch. I\'ll get back to you on this.
If I don\'t reply within 2-3 days, means my friend is being protective.

[Nolat]

BMW system... please...

Doubble vanos only changes valve timing by 12 degrees. Though on both intake and exhaust. Dual vvti moves much more. Look at the 1grfse! 315hp, 28mpg, Direct injection gas. thats amazing. Not knocking BMW though, they sure can make a straight 6.

If you want the best, look at ferrari. Thier 3d camshafts increase valve lift as the cam slides across the face of the head. Controlled by oil once again. Really makes em sing.

[MZ3_GS]

Originally posted by Fuman



Originally posted by MZ3_GS
Anyways, does anyone here have an 06 2.0L? They added S-VT for 2006, anybody driven with and without and noticed a comparable difference?

its new for 06? never knew that.
I\'ll see if I can get my hands on my friend\'s 05 hatch. I\'ll get back to you on this.
If I don\'t reply within 2-3 days, means my friend is being protective.

The hatch has the 2.3L therefore it has always had it.

I\'m talking about the 2.0L in the Sedan GS or GX trims.

[MZ3_GS]

Originally posted by Nolat


BMW system... please...

Doubble vanos only changes valve timing by 12 degrees. Though on both intake and exhaust. Dual vvti moves much more. Look at the 1grfse! 315hp, 28mpg, Direct injection gas. thats amazing. Not knocking BMW though, they sure can make a straight 6.

If you want the best, look at ferrari. Thier 3d camshafts increase valve lift as the cam slides across the face of the head. Controlled by oil once again. Really makes em sing.

Double Vanos can also control lift. 12 Deg is a lot anyways.

I am not aware of a 1GRFSE, maybe you mean 2GRFSE in the IS350? And yes the Dual VVT-i is impressive as well.

[Nolat]

yeah the 1 was a typeo.

Vanos only changes lift by .9mm, its more of an effect than anything else. It\'s proportional to the movement of the cam. VVTL-i changes lift by 3.95mm. and independantly changes timing 43 degrees.

http://www.bmwworld.com/technology/vanos_cutaway.jpg

Single vanos cutaway example.

[MZ3_GS]

Now I know that Toyotas 43 Deg is in relative to the crank.

Is the 12 Deg in BMWs Crank or Cam?

[Nolat]

Crank. Still allows a good amount of overlap. Thats why they push 100hp/l+. :D