Quote:
Originally Posted by Setanta
hopefully you're driving one quicker than me...
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Quote:
Originally Posted by Setanta
hopefully you're driving one quicker than me...
Oooh.. interesting and entertaining discussion. I was bouncing between buying a Sportivo and Accord Euro, so I did quite a read up and research on the different variable valve systems. Here's my take. Flame me if you wish. :)
First off, there is no point in comparing K20's, B18's and 2ZZ's against each other to DETERMINE whether (i-)VTEC or VVTL-i is better. Because the engines are in different state of tunes. The B18C in the ITR has lightened and matched conrods, lightned and molybdenum-coated pistons, oval springs, lightened valves and crankshaft, optimised intake system and much more, all done by hand at the factory. Obviously it is well tuned, makes more power and will let the engine rev much quicker (i.e. faster response) and this is not necessarily reflected in the peak power which are the only figures that have been quoted.
Toyota's 2ZZ-GE doesn't have any lightened components, just a balanced crankshaft and the MMC liner. It is a mass production engine. And in it are very aggressive cams and the VVTL-i system to compensate for drivablility at low revs.
If you put the B18C and 2ZZ-GE in the same body/chassis, it is obvious that the B18C will be faster to accelerate because of the higher torque below the VTEC point courtesy of the lightened components.
It is not the peak power that shows you how fast your car is (unless you stay at that particular RPM all the time. CVT anyone?) but the total area under the power curve of the dyno chart. The larger the area, the faster your car will be at a given point.
Traditionally, if you put in aggressive cams, your drivability is shot to pieces because the car won't move at low rpms. So imagine 4000rpm take offs from a traffic light or when turning at a stop sign. Not a pretty sound at stand still and bad on your fuel consumption. VTEC, i-VTEC (DOHC VTEC style) and VVTL-i systems that give you variable cam profiles lets you put in aggressive cams and yet have a 2nd set of cams for low end drivability. Look at your (i-)VTEC and VVTL-i as a way to regain drivability and not to make extra power. It is this misconception that cause many people to think VTEC/VVTL-i means extra sound.
No point arguing which variable valve system is better. Because you can say now that VVTL-i gives you more power for such a small capacity! Just swap the VTEC camshafts for ones with more aggressive cam profiles (so many brands offer this in Japan) and suddenly, your Honda engine is making a humongous difference in power at the VTEC zone. But was this increase in power provided by VTEC/VVTL-i? Or was it the cams that provided the power?
In the end, VTEC, i-VTEC and VVTL-i is just a means to putting in multiple cam profiles so that you can have both power and drivability. Like the saying, you can have your cake and eat it. (i-)VTEC/VVTL-i is NOT the cake. It is the ABILITY to let you have the cake and eat it.
just my $2.02
Aaron
Thats pretty much what your whole post said. Good explanation for a noob, but doesn't really compare VVTL-i and VTEC/i-VTEC.Quote:
Originally Posted by aaronng
-Win
Thanks, Win. I still find it pointless to compare VVTL-i and (i-)VTEC. Because you can't compare it based on the power it makes like what everyone has been doing. All you can compare is the reliability, the time it takes for it to switch cams and the smoothness when it switches. Power is not produced by the VVTL-i/(i-)VTEC systems, it is produced by the aggressive cams and altered air/fuel ratio by the ECU.Quote:
Originally Posted by wynode
Based on this, in my opinion, i-VTEC should be the most refined of the three.
Aaron
Yes they both do the same thing.............what the topic title is asking is 'which one does it better' "Better" being the hard word to decipher.
what is continous variable valve timiing if u dont mind me asking? how many cam lobs can there be? Serious dont know whats goin on here- not trying to be sarcastic....
And jsut a matter of stopping argument sake...
What do u mean by vtec? twin 16v? or single stick.
We're referring to DOHC VTEC (twin 16v?)
Might have to check out howstuff works if you're not sure about what variable valve timing is :)
so SOHC VTEC is basically same as VVTI and DOHC VTEC is same as VVTL-I
Not really.
There is no 'equivalent' as such.
SOHC VTEC provides no variable valve timing but provides variable intake valve lift
VVT-i provides variable valve timing, but no variable valve lift.
The missus drives a 2001 ZR celica with vvt-i and I ust admit it goes pretty hard....not as hard as my lude, but still, you have to give it credit :)
The thing just screams when it hits high rpm...but the speed doesnt match the sound imo....but yer....im biased :D
6 speed gearboxes are nice tho.
most modern fuel injected cars vary the timing regardless of the vvt / vtec or likes... even old fuel injected xf fords varied the timing...
vvt / vtec is an extra system which will increase the duration of the intake, exhaust cams, or both.. etc... this can be done by turning the cam - ie nissan engines or having another set of lobes on the cam as per vtec on hondas