Largest car maker
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its more of the shape....a more oval cam gives more duration wheras a pointier cam gives more lift....Originally posted by alleggerita:You should be the one Reading more?
How much the valve lifts is dependent on the lobes on the camshaft. -
Hmmm.... if its only 1 cam profile.. then why they call it 'VARIABLE VALVE TIMING"??? just a question...
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Originally posted by alleggerita:
DOHC also 2 camshaft, you should say it is the selection of lobe on the camshaft.
You should be the one Reading more?
How much the valve lifts is dependent on the lobes on the camshaft.
your post is misleading. -
Actually i'm not quite into toyota engine coz they really sux.... except 2JZ-GTE with VVTi... coz lately i mod 1 piece of tht baby... the power really impressed me... alot...lol...
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the 'all leg girly' mislead you.Originally posted by jinxmy:Hmmm.... if its only 1 cam profile.. then why they call it 'VARIABLE VALVE TIMING"??? just a question...
actually is it call 'infinite profile' cos the valve timing can advance between +- 10-15 degree.
1 camshaft not = to 1 profile -
it means that the timing which the valves open or close can be altered....NOT DURATION in which the vales open/close....thats 2 different things...Originally posted by jinxmy:Hmmm.... if its only 1 cam profile.. then why they call it 'VARIABLE VALVE TIMING"??? just a question... -
yes it is...go read up before blowing yr trumpet here....unless yrs is a VTEC cam...then it only has ONE profile...cam like i said before..VVT-I is cam phasing which alters the timing in which the valves open/close like for eg. 12deg Before TDC the inlet valves will open but not altering how long the valves STAY open...thats duration....get these facts right...and theres no such thing as an infinite profile...if thats the case the cam will just be an eccentric cam and the valves will always stay open...Originally posted by mh2:the 'all leg girly' mislead you.
actually is it call 'infinite profile' cos the valve timing can advance between +- 10-15 degree.
1 camshaft not = to 1 profile
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wth are u talking abt....Originally posted by mh2:DOHC also 2 camshaft, you should say it is the selection of lobe on the camshaft.
your post is misleading.
DOHC is 2 camshaft... not ALSO....
and he did say is the selection of lobes ah...
eh pls fcuk off... dun come here and irk pple with ur ignorance can?? cb... -
thankew..Originally posted by AE86tofu:yes it is...go read up before blowing yr trumpet here....unless yrs is a VTEC cam...then it only has ONE profile...cam like i said before..VVT-I is cam phasing which alters the timing in which the valves open/close like for eg. 12deg Before TDC the inlet valves will open but not altering how long the valves STAY open...thats duration....get these facts right...and theres no such thing as an infinite profile...if thats the case the cam will just be an eccentric cam and the valves will always stay open... 
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VVT-i, or Variable Valve Timing with intelligence, is an automobile variable valve timing technology developed by Toyota, similar to the i-VTEC technology by Honda. The Toyota VVT-i system replaces the Toyota VVT offered starting in 1991 on the 4A-GE 20-Valve engine. The VVT system is a 2-stage hydraulically controlled cam phasing system.
VVT-i, introduced in 1996, varies the timing of the intake valves by adjusting the relationship between the camshaft drive (belt, scissor-gear or chain) and intake camshaft. Engine oil pressure is applied to an actuator to adjust the camshaft position. In 1998, "Dual" VVT-i (adjusts both intake and exhaust camshafts) was first introduced in the RS200 Altezza's 3S-GE engine. Dual VVT-i is also found in Toyota's new generation V6 engine, the 3.5L 2GR-FE V6. This engine can be found in the Avalon, RAV4, and Camry in the US, the Aurion in Australia, and various models in Japan, including the Estima. Dual VVT-i is also used in the Toyota Corola (1,6 dual VVT-i 124bhp). Other Dual VVT-i engines include the upcoming 1.8L 2ZR-FE I4, which will see implementation in Toyota's next generation of compact vehicles. By adjusting the valve timing, engine start and stop occur virtually unnoticeable at minimum compression, and fast heating of the catalytic converter to its light-off temperature is possible, thereby reducing HC emissions considerably. -
In 1998, Toyota started offering a new technology, VVTL-i, which can alter valve lift (and duration) as well as valve timing. In the case of the 16 valve 2ZZ-GE, the engine has 2 camshafts, one operating intake valves and one operating exhaust valves. Each camshaft has two lobes per cylinder, one low rpm lobe and one high rpm, high lift, long duration lobe. Each cylinder has two intake valves and two exhaust valves. Each set of two valves are controlled by one rocker arm, which is operated by the camshaft. Each rocker arm has a slipper follower mounted to the rocker arm with a spring, allowing the slipper follower to move up and down with the high lobe with out affecting the rocker arm. When the engine is operating below 6000 rpm, the low lobe is operating the rocker arm and thus the valves. When the engine is operating above 6000 rpm, the ECU activates an oil pressure switch which pushes a sliding pin under the slipper follower on each rocker arm. This in effect, switches to the high lobe causing high lift and longer duration.
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MIVEC (Mitsubishi Innovative Valve timing Electronic Control system)is the brand name of a variable valve timing engine technology developed by Mitsubishi Motors. MIVEC, as with other similar systems, varies the timing, lift and duration[2] of the valves by using two different camshaft profiles. At low speeds, a mild (low-lift) cam lobe provides stable idle, lower emissions and increased torque at lower speeds, while above a fixed engine speed a second set of cam lobes are activated, providing higher lift and duration; therefore a greater quantity of air into the combustion chamber which increases the power and torque output over a broad engine speed range.
From 4B1 engine family onward, MIVEC has fully evolved into a continuous variable valve timing system (dual VVT on intake and exhaust valves). [3] MIVEC incorporated in 3B2, 3A9 and 4A9 engine family continuously varies only the intake valves. Many older implementations only vary the valve timing (the amount of time per engine revolution that the intake port is open) and not the lift.
MIVEC was first introduced in 1992 in their 4G92 powerplant, a 1,597 cc naturally aspirated DOHC 16 valve straight-4.[4] At the time, the first generation of the system was named Mitsubishi Innovative Valve timing and lift Electronic Control.[5] The first cars to use this were the Mitsubishi Mirage hatchback and the Mitsubishi Lancer sedan. While the conventional 4G92 engine provided 145 PS at 7000 rpm,[6] the MIVEC-equipped engine could achieve 175 PS at 7500 rpm.[7] Similar improvements were seen when the technology was applied to the 1994 Mitsubishi FTO, whose top-spec GPX variant had a 6A12 1997 cc DOHC 24 valve V6 with peak power of 200 PS at 7500 rpm.[8] The GR model, whose otherwise identical powerplant was not MIVEC-equipped, produced 170 PS at 7000 rpm by comparison.[9]
Although initially designed to enhance performance, the system has subsequently been developed to improve economy and emissions, and has been introduced across Mitsubishi's range of vehicles, from the i kei car to the high-performance Lancer Evolution sedan. -
VTEC (Variable Valve Timing and Lift Electronic Control) is a valvetrain system developed by Honda to improve the volumetric efficiency of a four-stroke internal combustion engine. This system uses two camshaft profiles and electronically selects between the profiles. This was the first system of its kind. Different types of variable valve timing and lift control systems have also been produced by other manufacturers (MIVEC from Mitsubishi, VVTL-i from Toyota, VarioCam Plus from Porsche, VVL from Nissan, etc).
In the regular four-stroke automobile engine, the intake and exhaust valves are actuated by lobes on a camshaft. The shape of the lobes determines the timing, lift and duration of each valve. Timing refers to an angle measurement of when a valve is opened or closed with respect to the piston position (TDC or BDC). Lift refers to how much the valve is opened. Duration refers to how long the valve is kept open. Due to the behavior of the working fluid (air and fuel mixture) before and after combustion, which have physical limitations on their flow, as well as their interaction with the ignition spark, the optimal valve timing, lift and duration settings under low RPM engine operations are very different from those under high RPM. Optimal low RPM valve timing, lift and duration settings would result in insufficient filling of the cylinder with fuel and air at high RPM, thus greatly limiting engine power output. Conversely, optimal high RPM valve timing, lift and duration settings would result in very rough low RPM operation and difficult idling. The ideal engine would have fully variable valve timing, lift and duration, in which the valves would always open at exactly the right point, lift high enough and stay open just the right amount of time for the engine speed in use. -
Now that i truely understand that VVTi dun have 2 cam profile... my bad my bad...
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so u see? that proves it...I dont need to say anymore about valve timing and valve duration....
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Wow..now then I saw this post..How fcuking retarded can you get to start calling people names?Originally posted by mh2:the 'all leg girly' mislead you.
actually is it call 'infinite profile' cos the valve timing can advance between +- 10-15 degree.
1 camshaft not = to 1 profile
And my nick is pronounced as aller-gir-rita, not your whatever "all leg girly"..
If you know you are wrong, admit it and just say "sorry, my bad" or something along that line and NOT to resort to such childish methods..
New account, yet same old ways.. -
Originally posted by AE86tofu:
u mear concentric ar?
if thats the case the cam will just be an eccentric cam and the valves will always stay open... -
Originally posted by n0x:
Double overhead camshaft obviously is 2.
wth are u talking abt....
DOHC is 2 camshaft... not ALSO....
and he did say is the selection of lobes ah...
eh pls fcuk off... dun come here and irk pple with ur ignorance can?? cb...
Double = 2
get it? -
o yes ,Originally posted by alleggerita:Wow..now then I saw this post..How fcuking retarded can you get to start calling people names?
And my nick is pronounced as aller-gir-rita, not your whatever "all leg girly"..
If you know you are wrong, admit it and just say "sorry, my bad" or something along that line and NOT to resort to such childish methods..
New account, yet same old ways..
my mistake!
it should be "all leg girly la" -
I think India will overtake China as the world factory. At least, it will cut China's dominance by a sizable chunk.Originally posted by Mitsubishi hater:Will Toyota be the known world largest car maker in 2007?
It bet it will by 92%.
Any car maker can match their 'valvematic' technology?
Hardly i think. Pls enlighten any1.
Nano is good example. They can if they wanna. -
Really, how farking retarded can you get? You wanna come back as mh3 is it?Originally posted by mh2:u mear concentric ar?
Eccentric means unable to predict..it will do whatever it likes..so AE86tofu is right to use "eccentric".. -
Another post to show that you are so FARKING RETARDED and ready to get banned again..Originally posted by mh2:o yes ,
my mistake!
it should be "all leg girly la" -
hey hey,
Nissan car population in sg drop to 3rd spot le.
Toyota ranking is unbeatable...in 1st spot for so many year. -
why are u fcuking repeating what i said...Originally posted by mh2:Double overhead camshaft obviously is 2.
Double = 2
get it?
yah is obviously 2...
but in ur previous post u mentioned the word ALSO...
so the statement means that there are other acronymns of 2 camshafts...
getit??? ur english sucks...