VVT-i VS. VTEC ?...
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i heard toyota's variable valve timing electronic uplift is alot better then honda's..
Info on V6 & I6:
http://www.howstuffworks.com/question366.htm
Info on VVT-i and VVTL-i
http://www.newcelica.org/other/faq/vvtl-i/vvtl-i.htm
Vtec:
http://www.honda2001.com/models/accord_sedan/engineering.html?show=vtec
http://www.acura-tl.com/ubb/Forum11/HTML/000229.html
http://www.acura.com/model_cl/cl_perf2.asp
http://www.acura.com/engineering/eng_engines.asp
Engines info including VTEC and VVTL-i
http://www.fortunecity.com/silverstone/lancia/58/technical_school/tech_index.htm
[This message has been edited by Chiphead (edited November 10, 2000).]
http://www.howstuffworks.com/question366.htm
Info on VVT-i and VVTL-i
http://www.newcelica.org/other/faq/vvtl-i/vvtl-i.htm
Vtec:
http://www.honda2001.com/models/accord_sedan/engineering.html?show=vtec
http://www.acura-tl.com/ubb/Forum11/HTML/000229.html
http://www.acura.com/model_cl/cl_perf2.asp
http://www.acura.com/engineering/eng_engines.asp
Engines info including VTEC and VVTL-i
http://www.fortunecity.com/silverstone/lancia/58/technical_school/tech_index.htm
[This message has been edited by Chiphead (edited November 10, 2000).]
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http://www.edmunds.com/edweb/editorial/innovations/valve.html
"Honda was the first to offer what it called VTEC in its Acura-badged performance models like the Integra GS-R and NSX (it has since worked its way into the Prelude and even the lowly Civic). VTEC stands for Variable Valve Timing and Lift Electronic Control. It basically uses two sets of camshaft profiles-one for low and mid-range rpm and one for high rpm operation. An electronic switch shifts between the two profiles at a specific rpm to increase peak horsepower and improve torque. As a VTEC driver, you can both hear and feel the change when the VTEC "kicks in" at higher rpm levels to improve performance. While this system does not offer continuously variable valve timing, it can make the most of high rpm operation while still providing solid driveability at lower rpm levels. Honda is already working on a three-step VTEC system that will further improve performance and efficiency across the engine rpm range.
Toyota saw the success Honda was having with VTEC (from both a functional and marketing standpoint) but decided to go a different route. Instead of the on/off system that VTEC employs, Toyota decided it wanted a continuously variable system that would maximize valve timing throughout the rpm range. Dubbed VVTi for Variable Valve Timing with intelligence (Is this a dig at Honda, suggesting their system isn't intelligent?), Toyota uses a hydraulic rather than mechanical system to alter the intake cam's phasing. The main difference from VTEC is that VVTi maintains the same cam profile and alters only when the valves open and close in relation to engine speed. Also, this system works only on the intake valve while VTEC has two settings for the intake and the exhaust valves, which makes for a more dramatic gain in peak power than VVTi can claim."
basically Toyota's VVTI (not VVTL-I as stated earlier, my bad) is better than Honda's Vtec because you don't have to wait for it to kick in (as in the case of the Vtec)...but install a Vtec controller and thats another story.
[This message has been edited by DonCorleone (edited November 10, 2000).]
"Honda was the first to offer what it called VTEC in its Acura-badged performance models like the Integra GS-R and NSX (it has since worked its way into the Prelude and even the lowly Civic). VTEC stands for Variable Valve Timing and Lift Electronic Control. It basically uses two sets of camshaft profiles-one for low and mid-range rpm and one for high rpm operation. An electronic switch shifts between the two profiles at a specific rpm to increase peak horsepower and improve torque. As a VTEC driver, you can both hear and feel the change when the VTEC "kicks in" at higher rpm levels to improve performance. While this system does not offer continuously variable valve timing, it can make the most of high rpm operation while still providing solid driveability at lower rpm levels. Honda is already working on a three-step VTEC system that will further improve performance and efficiency across the engine rpm range.
Toyota saw the success Honda was having with VTEC (from both a functional and marketing standpoint) but decided to go a different route. Instead of the on/off system that VTEC employs, Toyota decided it wanted a continuously variable system that would maximize valve timing throughout the rpm range. Dubbed VVTi for Variable Valve Timing with intelligence (Is this a dig at Honda, suggesting their system isn't intelligent?), Toyota uses a hydraulic rather than mechanical system to alter the intake cam's phasing. The main difference from VTEC is that VVTi maintains the same cam profile and alters only when the valves open and close in relation to engine speed. Also, this system works only on the intake valve while VTEC has two settings for the intake and the exhaust valves, which makes for a more dramatic gain in peak power than VVTi can claim."
basically Toyota's VVTI (not VVTL-I as stated earlier, my bad) is better than Honda's Vtec because you don't have to wait for it to kick in (as in the case of the Vtec)...but install a Vtec controller and thats another story.
[This message has been edited by DonCorleone (edited November 10, 2000).]
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6,151 Posts
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.
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.
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i stand corrected.
i knew i missed something, i was trying to recall what i had read back when i was shopping cars and the GT-S was one of em... thanks for correctin me brah, good watchin out.
i knew i missed something, i was trying to recall what i had read back when i was shopping cars and the GT-S was one of em... thanks for correctin me brah, good watchin out.
People always miss the point about VTEC, you're not only gaining when it's on-cam above 5000 rpm (or whatever), you also gain at low rpms because you're running a different timing than you'd be forced to run without VTEC. So it improves power(torque) at all rpms, not just high. Honda has been at this game longer, and has its Formula 1 manufacturer's championships to back up it's pedigree. The engine in the Integra Type R is a superior engine to the Celica GTS, I doubt anyone would argue otherwise. It's more powerful, better sounding, and smoother at high rpms.
mrclam, I hope you're talking from personal experience -- not bashig 'cause it's what you think it is..
As an owner of such a system, it's highly rewarding to see the tach sweep from 6000 to 8200 fuel cutoff before shifting. It's a rush -- S2000 owners would have an even tremendous rush -- almost like a turbo boost.
And even S2K owners would have to shift at redline too. And I tell ya, I creamed my pants driving this (S2K) perfect machinery for the first time. The Celica, while not too close, substituted rather nicely.
When I first got my IS, I had to consciously tell myself to shift (when in M mode) or otherwise I'd shift at 5500+ which is my normal shift point in the GTS. Now that I drive more of my IS, I have to (semi) consciously tell myself NOT to short shift the GTS...
[This message has been edited by AntiCt (edited November 10, 2000).]
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damn, again i have been slapped in the face, ouch, i must have gotten ahold of some bad info then, i remember reading vvti was better than vtec in three different magazines and a few webpages, guess some journalists dont know what they're talking bout....sorry for the misinformation, apparently what i've read and learned were not from a dependable sources as i had thought...like learning algebra from the janitor or believing election results from MSNBC or bobby bouchet listenin to his mamma or trollin lessons from grishuila
wiht a honda if you don't go all the way to redline it is possible to stay in the next gear with VTEC engaged, such is not possible with the celica, you MUST shift at the highest possible rpms to insure engagement in the next gear. i've driven both cars and know this from personal experience.
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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
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[This message has been edited by HIBBoyScott (edited November 10, 2000).]
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).]
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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 ]
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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.
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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...
The differences between VVTL and dual VVT are that:
1. VVTL is cam phasing only on intake cams
2. VVTL also has cam switch on both intake and exhaust.
3. Dual VVT is cam phasing on both cams
4. Dual VVT doesn't use switchable cams
The Celica uses a system that uses engine oil pressure to drive both VVT and the "L" portion (driven seaprately). I believe the Altezza uses a set of helical gears driven from the ECU and oil pressure to phase the cams - similar to IS, GS, and LS.
1. VVTL is cam phasing only on intake cams
2. VVTL also has cam switch on both intake and exhaust.
3. Dual VVT is cam phasing on both cams
4. Dual VVT doesn't use switchable cams
The Celica uses a system that uses engine oil pressure to drive both VVT and the "L" portion (driven seaprately). I believe the Altezza uses a set of helical gears driven from the ECU and oil pressure to phase the cams - similar to IS, GS, and LS.
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