VVT-i VS. VTEC ?...

VTEC is a cam changing form of variable valve timing and lift. VTEC stands for Variable valve Timing and lift Electronic Control. VTEC is an on/off switch type of control. There is a preset RPM at which the cam switch occurs. Basically, one cam is mild, the other is wild. Keep the engine spinning above the RPM switchover point and you will always be running on the wild cam. Below the switchover point you will be on the mild cam. The cams vary the lift and valve timing overlap of the intake and exhaust valves.

Toyota's VVT-i stands for Variable Valve Timing with intelligence. VVT-i is NOT the same as VVTL-i. VVT-i is a form of cam phasing variable valve timing. VVT-i does not control the lift of the valves, it only controls the timing. The intelligence part of VVT-i indicates that it is continuously variable, and takes into account not only engine speed, but acceleration, going uphill/downhill, etc. VVT-i is always at work, unlike VTEC, which has one set point at which it engages.

VVTL-i is Toyota's system of Variable Valve Timing and Lift with intelligence. The VVT portion of VVTL-i is the same as VVT-i but incorporates variable valve lift like VTEC. The lift portion is also an on/off switch like VTEC. The continuously variable timing of VVTL-i allows it to be more flexible at lower RPMs than VTEC. At high RPMs the variable lift allows VVTL-i to achieve a big power boost. The only Toyota to employ this system so far in the United States is the 2000+ Toyota Celica GT-S.

The Type R engine should be superior to the Celica engine. The Type R is a special model and is not a mass produced engine. The Celica GT-S engine is a mass produced engine that gets no special treatment. The Type R is a very focused car, not like the GT-S, which is targeting a broader market.

Another good point that was brought up is that VTEC allows better performance throughout the RPM range compared to non variable systems. It allows a smooth idle and tame performance and allows wild performance over the crossover point. But compared to continuously variable systems it lacks flexiblity.

(Edited massed produced to mass produced...jeez I think I need some sleep )

[This message has been edited by HIBBoyScott (edited November 10, 2000).]

Originally posted by mrclam:
and the celica's system sucks because you have to shift at redline in every gear to keep the system engaged.

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Clam, you shouldn't say the Celica's system sucks because you have to shift at redline to stay on the big cam, which isn't possible unless you shift above redline. Remember that gearing has a lot to do with it. For whatever reason Toyota has chosen to make the gears seemingly too tall, maybe for better magazine 0-60 times, EPA mileage estimates, whatever. The Celica's power curve may also be solvable through the ECU. There is a huge power surge at the crossover, and the engine may be able to make power even if the crossover was lower. There is at least one VVTL-i controller in the works. Too bad TRD isn't allowed to sell chips to the public as they have access to all the necessary stuff to do so. TRD can screw with the ECU all they want, but only for race purposes. Toyota will not allow TRD to sell it to the general public.

Currently, I think that VTEC is utilized on both the intake and exhaust valves and VVTL-i is utilized on only the intake valves. VVT-i is used on both intake and exhaust on the 4 cylinder Altezza where it develops 210 horsepower from 2.0L. Perhaps Toyota has a surprise in store in the future. Could VVTL-i on both intake and exhaust boost performance significantly? Maybe this is laying in wait for VTEC-i, which Honda has to answer VVTL-i with. Who knows?

[ July 18, 2001: Message edited by: HIBBoyScott ]

Originally posted by AntiCt:
Actually, the "L" portion also works on the exhaust cams, and of course, there is no cam-phasing deal on those cams. The intake cams are continuous phasing, with switchable lift and duration.

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Oh jeez, I am contradicting myself...I think I've had to many of these VVTL-i/VVT-i/VTEC posts. Here is a post I made a long time ago in another thread:
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This is how I understand this...VVTL-i is not used on any model of Toyota/Lexus in the US except for the Celica GT-S. VVTL-i controls both valve timing and lift. The variable lift portion is on/off, just like VTEC. The VVT-i portion, which is used on most current Toyota/Lexus models, is just variable valve timing, but is continuously variable, not just on/off at one RPM. BMW's Double Vanos is only variable valve timing, not lift, but is employed on both intake and exhaust. VVT-i is used on the intake only, except in the Altezza (JDM) where it is called BEAMS Double VVT-i (BEAMS = Breakthrough Engine Advanced Management System, or something along those lines). Altezza (forum member) told me that Dual VVT-i is the same thing as VVTL-i, but I respectfully disagree. The Toyota Japan website says the Celica has VVTL-i and the Altezza has Dual VVT-i, so I don't think it is the same thing. Anyway, using Dual VVT-i, the JDM Altezza achieves 210 HP (manual) and 200 HP (auto) from a 2.0L engine. The US Celica gets 180 HP from 1.8L, and the JDM Celica gets 190 HP (I think). Of course there are other variables to the power output like exhaust piping, etc. Apparently both Dual VVT-i and VVTL-i are capable of producing 100+ HP per liter, so I don't know why one or the other is used. Both are employed on the intake and exhaust, but it might have to do with the power distribution. The Celica has a huge power surge when it hits the x-over, below that point not much goes on. Since the Altezza with Dual VVT-i is JDM I haven't read to much about it's power distribution, but I think the DUAL VVT-i has a slight edge on torque.
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Okay so I was once right and am now wrong and upon reviewing myself I am right again...

Originally posted by TEG:
You guys are getting so good at dealing with these questions. Now all I have to do is sit back and enjoy...

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Yeah you lazy bastard...

Originally posted by ckolsen:
When Toyota sells an engine that makes 240 hp out of 2.0L, then I'll agree. How about 260 hp out of that CL 3.0L V6? When I test drove the Celica GT-S, the sound coming out of that engine at 7500 rpm made me cringe - that motor didn't sound happy - nothing like the sweet sounds from a VTEC motor at 8000 rpm.

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Your argument about engine sound holds no water. The old school big V8s sound better than the engines today...that doesn't mean they were better, does it? Even the current big engines in domestics sound better than the imports. I still don't want a domestic though.

Originally posted by Juggaknot:
I've got a question.
Let me start off by saying, I'm not a car genius or physics major or blah blah.
You guys say "VVT-i is a hell of a lot more advanced than VTEC"
ok... so...

Nissan Maxima
3.0L V6 engine produces 222hp

Lexus IS300
3.0L I6 VVT-i engine produces 215hp

alrighty.... where are the performance gains that the VVT-i made for that 3.0L I6 engine? i mean.. unless the Maxima _does_ have a VVT-i-like mechanism, I really don't see how this VVT-i is supposed to help. If you are going to tell me it's because the IS300 is an I6, then please tell me why the IS300 with an I6 WITH VVT-i would produce less power than a V6 WITHOUT VVT-i or the like.
Well, maybe that's not a good comparison because the Maxima is made by Nissan and the IS300 is made by Toyota... so... would that give me the reason to say Toyota sucks at making engines? maybe, but only because u guys say VTEC sucks.
Well lets do another comparison.

Acura Integra Type-R
1.8L I4 DOHC VTEC produces 195hp

Acura Integra GS-R
1.8L I4 DOHC VTEC produces 170hp

Acura Integra LS/GS
1.8L I4 DOHC produces 140hp

Civic Si
1.6L I4 DOHC VTEC produces 160hp

Civic EX (under 2001)
1.6L I4 SOHC VTEC produces 125hp

Toyota Celica GT-S
1.8L I4 DOHC VVTL-i produces 180hp

Toyota Celica GT
1.8L I4 DOHC VVT-i produces 140hp

So............. Where is the logic in saying that VVT-i is better than VTEC? Do u guys mean VVTL-i is better than VTEC? or do u guys mean that VVT-i is better than SOHC VTEC engines? What do u guys mean? please explain it to me

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I think you have to remember that exhasut and intake all come into play when rating the output of an engine. The same engine that is used in the IS3 is also used in the 4th gen NA Supra where it is rated at 225 HP. In the GS300 the same engine is rated at 220 HP. Also, you don't know how close to the edge of performance Toyota tuned the engine. The Supra Turbo engine is most definitely detuned...the engine is capable of putting out about 460 HP with basic mods. Note that I am not saying that Honda or Nissan is tuning their engines closer to the edge of reliablilty and longevity...I really don't know. The reason that the technology of VVTL-i is seen as superior to VTEC is that VVTL-i is a combination of VVT-i technology with a variable lift component. VVT-i is continuously variable and VTEC is not. Peak values alone also do not tell the whole story. As discussed in other threads, it is the curve and the area under it that matters. Clint gave a very good analogy for HP and torque. "Let's equate it to a simple example. Torque is like the length of your running stride. It tells you nothing about how fast you can run. HP tells you how many feet you can run per second, which is just a function of stride length (torque) and strides per second (rpm)."

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By making this post I am not claiming to be an expert of any sort on the topic and should not be taken as such. It's just my opinion and worth what you paid for it.

Originally posted by West:
Wow, you guy seem to really know what you're talking about it... I really learned a lot. Seems that everybody brings a new angle which makes the whole issue more clear.

I have a few questions for you though:

So this variable valve timing gizmo varies when and how far the valves open, right?
But why do you need to do that? Why not just take the most "hot" (I think that's the term) cam profile and put it on the engine??
Do you loose low end torque?? Why?

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The valve timing has to do with controlling when the valves open and close, which controls how much overlap there is when the intake and exhaust valves are open or closed. In all things there is compromise. You cant just stick the big cam on the engine and expect it to operate the engine at peak efficiency throughout the rpm range. For more top end power a cam that gives long duration and lots of lift. However this cam is only going to be good for racing, not street use. Racing cams have a rough idle and the low rpm conditions cause "eight stroking" where the engine is firing every four revolutions instead of every two. It causes the rough idle and makes lots of hydrocarbon pollution. I think everyone wishes it was as easy as slapping the big cam on the car and making the most power.