VTEC - Revision history

85.107.139.37: /* i-VTEC */

2009-09-11T21:13:26Z

i-VTEC

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	i-VTEC (intelligent-VTEC [http://www.acura.com/index.aspx?initPath=TSX_Learn_FeaturesOptions_Performance_Engine_iVTEC]) introduced continuously variable camshaft phasing on the intake cam of DOHC VTEC engines. The technology first appeared on Honda's K-series four cylinder engine family in 2001 (2002 in the U.S.). Valve lift and duration are still limited to distinct low- and high-RPM profiles, but the intake camshaft is now capable of advancing between 25 and 50 degrees (depending upon engine configuration) during operation. Phase changes are implemented by a computer controlled, oil driven adjustable cam gear. Phasing is determined by a combination of engine load and rpm, ranging from fully retarded at idle to maximum advance at full throttle and low rpm. The effect is further optimization of torque output, especially at low and midrange RPM.		i-VTEC (intelligent-VTEC [http://www.acura.com/index.aspx?initPath=TSX_Learn_FeaturesOptions_Performance_Engine_iVTEC]) introduced continuously variable camshaft phasing on the intake cam of DOHC VTEC engines. The technology first appeared on Honda's K-series four cylinder engine family in 2001 (2002 in the U.S.). Valve lift and duration are still limited to distinct low- and high-RPM profiles, but the intake camshaft is now capable of advancing between 25 and 50 degrees (depending upon engine configuration) during operation. Phase changes are implemented by a computer controlled, oil driven adjustable cam gear. Phasing is determined by a combination of engine load and rpm, ranging from fully retarded at idle to maximum advance at full throttle and low rpm. The effect is further optimization of torque output, especially at low and midrange RPM.

	For the K-Series motors there are two different types of i-VTEC systems implemented. The first is for the performance motors like in the RSX Type S or the TSX and the other is for economy motors found in the CR-V or Accord. The performance i-VTEC system is basically the same as the DOHC VTEC system of the B16A's, both intake and exhaust have 3 cam lobes per cylinder. However the valvetrain has the added benefit of roller rockers and continuously variable intake cam timing. The economy i-VTEC is more like the SOHC VTEC-E in that the intake cam has only two lobes, one very small and one larger, as well as no VTEC on the exhaust cam. The two types of motor are easily distiguishable by the factory rated power output: the performance motors make around 200 hp or ~~more in stock form and the economy motors do not make much more than 160 hp from the factory.~~		For the K-Series motors there are two different types of i-VTEC systems implemented. The first is for the performance motors like in the RSX Type S or the TSX and the other is for economy motors found in the CR-V or Accord. The performance i-VTEC system is basically the same as the DOHC VTEC system of the B16A's, both intake and exhaust have 3 cam lobes per cylinder. However the valvetrain has the added benefit of roller rockers and continuously variable intake cam timing. The economy i-VTEC is more like the SOHC VTEC-E in that the intake cam has only two lobes, one very small and one larger, as well as no VTEC on the exhaust cam. The two types of motor are easily distiguishable by the factory rated power output: the performance motors make around 200 hp or activated, one of the two intake valves in each cylinder closes well after the piston has started moving upwards in the compression stroke. That way, a part of the mixture that has entered the combustion chamber is forced out again, into the intake manifold. That way, the engine "emulates" a lower displacement than its actual one (its operation is also similar to an Atkinson cycle engine, with uneven compression and combustion strokes), which reduces fuel consumption and increases its efficiency. During the operation with the "economy cams", the (by-wire) throttle butterfly is kept fully open, in order to reduce pumping losses. According to Honda, this measure alone can reduce pumping losses by 16%. In higher rpms and under heavier loads, the engine switches back into its "normal cams", and it operates like a regular 4 stroke Otto cycle engine. This implementation of i-VTEC was initially introduced in the [[Honda R engine\|R18A1]] engine found under the bonnet of the 8th generation Civic, with a displacement of 1,8lt and an output of 140Ps. Recently, another variant was released, the 2-litre [[Honda R engine\|R20A2]] with an output of 150Ps, which powers the EUDM version of the all-new CRV

	In 2004, Honda introduced an i-VTEC V6 (an update of the venerable J-series), but in this case, i-VTEC had nothing to do with cam phasing. Instead, i-VTEC referred to Honda's cylinder deactivation technology which closes the valves on one bank of (3) cylinders during light load and low speed (below 80 mph) operation. The technology was originally introduced to the US on the Honda Odyssey Mini Van, and can now be found on the Honda Accord Hybrid and the 2006 Honda Pilot.

	An additional version of i-VTEC was introduced on the 2006 Honda Civic's R-series four cylinder SOHC engines. This implementation uses the so-called "economy cams" on one of the two intake valves of each cylinder. The "economy cams" are designed to delay the closure of the intake valve they act upon, and are activated at low rpms and under light loads. When the "economy cams" are activated, one of the two intake valves in each cylinder closes well after the piston has started moving upwards in the compression stroke. That way, a part of the mixture that has entered the combustion chamber is forced out again, into the intake manifold. That way, the engine "emulates" a lower displacement than its actual one (its operation is also similar to an Atkinson cycle engine, with uneven compression and combustion strokes), which reduces fuel consumption and increases its efficiency. During the operation with the "economy cams", the (by-wire) throttle butterfly is kept fully open, in order to reduce pumping losses. According to Honda, this measure alone can reduce pumping losses by 16%. In higher rpms and under heavier loads, the engine switches back into its "normal cams", and it operates like a regular 4 stroke Otto cycle engine. This implementation of i-VTEC was initially introduced in the [[Honda R engine\|R18A1]] engine found under the bonnet of the 8th generation Civic, with a displacement of 1,8lt and an output of 140Ps. Recently, another variant was released, the 2-litre [[Honda R engine\|R20A2]] with an output of 150Ps, which powers the EUDM version of the all-new CRV

	With the continued introduction of vastly different i-VTEC systems, one may assume that the term is now a catch-all for creative valve control technologies from Honda.'''		With the continued introduction of vastly different i-VTEC systems, one may assume that the term is now a catch-all for creative valve control technologies from Honda.'''

Red marquis: /* External links */

2008-10-29T11:13:06Z

External links

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	[[Category:Valve timing tradenames]]		[[Category:Valve timing tradenames]]
	[[Category:Honda]]		[[Category:Honda]]
	[[Category:~~Engines~~]]		[[Category:Engine technology]]

Red marquis at 07:27, 4 September 2007

2007-09-04T07:27:22Z

← Older revision		Revision as of 07:27, 4 September 2007
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	[[Image:Honda VTEC Engine.jpg\|thumb\|400px]]		[[Image:Honda VTEC Engine.jpg\|thumb\|400px]]
	'''VTEC''' is an acronym for '''Variable Valve Timing and lift Electronic Control'''. VTEC is a valve train system developed by [[Honda]] to improve the volumetric efficiency of a 4-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]] and so on). It was invented by Honda R&D engineer Ikuo Kajitani[http://asia.vtec.net/hardcore/VTEC/index.html]. It can be said that VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC.~~<ref>~~http://world.honda.com/motorcycle-technology/vtec/p3.~~html</ref>~~		'''VTEC''' is an acronym for '''Variable Valve Timing and lift Electronic Control'''. VTEC is a valve train system developed by [[Honda]] to improve the volumetric efficiency of a 4-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]] and so on). It was invented by Honda R&D engineer Ikuo Kajitani[http://asia.vtec.net/hardcore/VTEC/index.html]. It can be said that VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC. [http://world.honda.com/motorcycle-technology/vtec/p3.htm]

	==Introduction to VTEC==		==Introduction to VTEC==

Red marquis: /* DOHC VTEC-DI */

2007-09-04T07:20:06Z

DOHC VTEC-DI

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	==DOHC VTEC-DI==		==DOHC VTEC-DI==

	Honda also had a demonstration engine back in end 1999 where a 1.4 liter DOHC Honda engine was equipped with a VTEC-DI system. This was Honda’s first demonstration of direct injection to the public. The engine was installed in a Honda Logo (the predecessor to the Honda Fit/Jazz) and made power and torque outputs of 107 hp at 6200 rpm and 133 Nm at 5000 rpm. ~~<ref>Honda's I-VTEC I Engine: Direct Injection~~ [http://paultan.org/archives/2007/04/18/hondas-i-vtec-i-engine-direct-injection/]~~, Retrieved April 21, 2007</ref>~~		Honda also had a demonstration engine back in end 1999 where a 1.4 liter DOHC Honda engine was equipped with a VTEC-DI system. This was Honda’s first demonstration of direct injection to the public. The engine was installed in a Honda Logo (the predecessor to the Honda Fit/Jazz) and made power and torque outputs of 107 hp at 6200 rpm and 133 Nm at 5000 rpm.[http://paultan.org/archives/2007/04/18/hondas-i-vtec-i-engine-direct-injection/]

	==3-Stage VTEC==		==3-Stage VTEC==

Red marquis: /* i-VTEC I */

2007-09-04T07:19:27Z

i-VTEC I

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	Honda’s i-VTEC I Engine is a variant of the K-series DOHC engine family featuring gasoline direct injection. It made it’s debut in the previous generation 2004 Honda Stream 7-seater MPV in Japan, but the current Stream does not use this engine anymore, instead using a 2.0 liter version of the R-series i-VTEC SOHC engine.		Honda’s i-VTEC I Engine is a variant of the K-series DOHC engine family featuring gasoline direct injection. It made it’s debut in the previous generation 2004 Honda Stream 7-seater MPV in Japan, but the current Stream does not use this engine anymore, instead using a 2.0 liter version of the R-series i-VTEC SOHC engine.

	The engine featured the ability to use ultra-lean air-fuel mixtures of about 65:1, much leaner compared to the the usual direct injection engine 40:1 ratio, and of course so much more leaner than the stoichiometric air-fuel mixture of 14.7:1 - this saves fuel. Fuel consumption dropped to 15km per liter. Power ratings remain the same at about 155 horsepower~~. <ref>Honda's I-VTEC I Engine: Direct Injection~~ [http://paultan.org/archives/2007/04/18/hondas-i-vtec-i-engine-direct-injection/]~~, Retrieved April 21, 2007</ref>~~		The engine featured the ability to use ultra-lean air-fuel mixtures of about 65:1, much leaner compared to the the usual direct injection engine 40:1 ratio, and of course so much more leaner than the stoichiometric air-fuel mixture of 14.7:1 - this saves fuel. Fuel consumption dropped to 15km per liter. Power ratings remain the same at about 155 horsepower[http://paultan.org/archives/2007/04/18/hondas-i-vtec-i-engine-direct-injection/].

	==Advanced VTEC==		==Advanced VTEC==

Red marquis at 07:16, 4 September 2007

2007-09-04T07:16:38Z

← Older revision		Revision as of 07:16, 4 September 2007
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	[[Image:Honda VTEC Engine.jpg\|thumb\|400px]]		[[Image:Honda VTEC Engine.jpg\|thumb\|400px]]
	'''VTEC''' is an acronym for '''Variable Valve Timing and lift Electronic Control'''. VTEC is a valve train system developed by [[Honda]] to improve the volumetric efficiency of a 4-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]] and so on). It was invented by Honda R&D engineer Ikuo Kajitani~~.<ref>The Father of VTEC~~ [http://asia.vtec.net/hardcore/VTEC/index.html]~~, Retrieved March 10, 2007</ref>~~ It can be said that VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC.<ref>http://world.honda.com/motorcycle-technology/vtec/p3.html</ref>		'''VTEC''' is an acronym for '''Variable Valve Timing and lift Electronic Control'''. VTEC is a valve train system developed by [[Honda]] to improve the volumetric efficiency of a 4-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]] and so on). It was invented by Honda R&D engineer Ikuo Kajitani[http://asia.vtec.net/hardcore/VTEC/index.html]. It can be said that VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC.<ref>http://world.honda.com/motorcycle-technology/vtec/p3.html</ref>

	==Introduction to VTEC==		==Introduction to VTEC==

68.51.84.194: /* VTEC in motorcycles */

2007-09-03T20:33:29Z

VTEC in motorcycles

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	==VTEC in motorcycles==		==VTEC in motorcycles==

	Apart from the Japanese market-only Honda CBR400F Super Four HYPER VTEC~~<ref>http://world.honda.com/motorcycle-technology/vtec/p3.html</ref~~>, introduced in 1983, the first worldwide implementation of VTEC technology in a motorcycle occurred with the introduction of Honda's VFR800 sportbike in 2002. Similar to the SOHC VTEC-E style, one intake valve remains closed until a threshold of 7000 rpm is reached, then the second valve is opened by an oil-pressure actuated pin. The dwell of the valves remains unchanged, as in the automobile VTEC-E, and little extra power is produced but with a smoothing-out of the torque curve. Critics maintain that VTEC adds little to the VFR experience while increasing the engine's complexity. Drivability is a concern for some who are wary of the fact that the VTEC may activate in the middle of an aggressive corner, potentially upsetting the stability and throttle response of the bike.		Apart from the Japanese market-only Honda CBR400F Super Four HYPER VTEC>, introduced in 1983, the first worldwide implementation of VTEC technology in a motorcycle occurred with the introduction of Honda's VFR800 sportbike in 2002. Similar to the SOHC VTEC-E style, one intake valve remains closed until a threshold of 7000 rpm is reached, then the second valve is opened by an oil-pressure actuated pin. The dwell of the valves remains unchanged, as in the automobile VTEC-E, and little extra power is produced but with a smoothing-out of the torque curve. Critics maintain that VTEC adds little to the VFR experience while increasing the engine's complexity. Drivability is a concern for some who are wary of the fact that the VTEC may activate in the middle of an aggressive corner, potentially upsetting the stability and throttle response of the bike.

	== References ==		== References ==

Red marquis at 07:42, 11 August 2007

2007-08-11T07:42:09Z

← Older revision		Revision as of 07:42, 11 August 2007
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	[[Image:~~K20 head~~.jpg\|thumb\|400px]]		[[Image:Honda VTEC Engine.jpg\|thumb\|400px]]
	'''VTEC''' is an acronym for '''Variable Valve Timing and lift Electronic Control'''. VTEC is a valve train system developed by [[Honda]] to improve the volumetric efficiency of a 4-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]] and so on). It was invented by Honda R&D engineer Ikuo Kajitani.<ref>The Father of VTEC [http://asia.vtec.net/hardcore/VTEC/index.html], Retrieved March 10, 2007</ref> It can be said that VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC.<ref>http://world.honda.com/motorcycle-technology/vtec/p3.html</ref>		'''VTEC''' is an acronym for '''Variable Valve Timing and lift Electronic Control'''. VTEC is a valve train system developed by [[Honda]] to improve the volumetric efficiency of a 4-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]] and so on). It was invented by Honda R&D engineer Ikuo Kajitani.<ref>The Father of VTEC [http://asia.vtec.net/hardcore/VTEC/index.html], Retrieved March 10, 2007</ref> It can be said that VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC.<ref>http://world.honda.com/motorcycle-technology/vtec/p3.html</ref>

Red marquis at 07:41, 11 August 2007

2007-08-11T07:41:33Z

← Older revision		Revision as of 07:41, 11 August 2007
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			[[Image:K20 head.jpg\|thumb\|400px]]
	'''VTEC''' is an acronym for '''Variable Valve Timing and lift Electronic Control'''. VTEC is a valve train system developed by [[Honda]] to improve the volumetric efficiency of a 4-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]] and so on). It was invented by Honda R&D engineer Ikuo Kajitani.<ref>The Father of VTEC [http://asia.vtec.net/hardcore/VTEC/index.html], Retrieved March 10, 2007</ref> It can be said that VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC.<ref>http://world.honda.com/motorcycle-technology/vtec/p3.html</ref>		'''VTEC''' is an acronym for '''Variable Valve Timing and lift Electronic Control'''. VTEC is a valve train system developed by [[Honda]] to improve the volumetric efficiency of a 4-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]] and so on). It was invented by Honda R&D engineer Ikuo Kajitani.<ref>The Father of VTEC [http://asia.vtec.net/hardcore/VTEC/index.html], Retrieved March 10, 2007</ref> It can be said that VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC.<ref>http://world.honda.com/motorcycle-technology/vtec/p3.html</ref>

Red marquis: /* Introduction to VTEC */

2007-08-11T07:41:10Z

Introduction to VTEC

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	==Introduction to VTEC==		==Introduction to VTEC==
	~~[[Image:K20 head.jpg\|thumb\|right\|The [[i-VTEC]] system found in the [[Honda]] [[Honda K engine\|K20Z3]].]]~~
	In the regular [[four-stroke cycle\|four-stroke]] automobile engine, the intake and exhaust [[valve]]s are actuated by lobes on a [[camshaft]]. The shape of the lobes determines the timing, lift and duration of each valve. ''[[Valve timing\|Timing]]'' refers to an angle measurement of when a valve is opened or closed with respect to the piston position (TDC or BDC). ''[[Valve lift\|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.		In the regular [[four-stroke cycle\|four-stroke]] automobile engine, the intake and exhaust [[valve]]s are actuated by lobes on a [[camshaft]]. The shape of the lobes determines the timing, lift and duration of each valve. ''[[Valve timing\|Timing]]'' refers to an angle measurement of when a valve is opened or closed with respect to the piston position (TDC or BDC). ''[[Valve lift\|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.

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	The opposite approach to variable timing is to produce a camshaft which is better suited to high RPM operation. This approach means that the vehicle will run very poorly at low RPM (where most automobiles spend much of their time) and much better at high RPM. VTEC is the result of an effort to marry high RPM performance with low RPM stability.		The opposite approach to variable timing is to produce a camshaft which is better suited to high RPM operation. This approach means that the vehicle will run very poorly at low RPM (where most automobiles spend much of their time) and much better at high RPM. VTEC is the result of an effort to marry high RPM performance with low RPM stability.

	Additionally, [[Japan]] has a tax on [[engine displacement]], requiring Japanese auto manufacturers to make higher-performing engines with lower displacement. In cars such as the [[Toyota Supra]] and [[Nissan 300ZX]], this was accomplished with a [[turbocharger]]. In the case of the Mazda [[RX-7]] (turbo) and [[RX-8]], a [[Wankel engine\|rotary engine]] was used. VTEC serves as yet another method to derive very high specific output from lower displacement motors.		Additionally, Japan has a tax on [[engine displacement]], requiring Japanese auto manufacturers to make higher-performing engines with lower displacement. In cars such as the [[Toyota Supra]] and [[Nissan 300ZX]], this was accomplished with a [[turbocharger]]. In the case of the Mazda [[RX-7]] (turbo) and [[Mazda RX-8\|RX-8]], a [[Wankel engine\|rotary engine]] was used. VTEC serves as yet another method to derive very high specific output from lower displacement motors.

	==DOHC VTEC==		==DOHC VTEC==