What is Vtec?
10-12-2006, 04:58 PM
#16
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Originally Posted by voltar
Oh yes quite a few V8s have VVT. GM has had VVT for a while in NorthStars 4.6s, the GenIV small blocks, even the Toyota Tundra has VVT...
And before people get overexcited remember that Honda didn't invent the concept.
And before people get overexcited remember that Honda didn't invent the concept.
VTEC (standing for Variable valve Timing and lift Electronic Control) is a system developed by Honda to improve the combustion efficiency of its internal combustion engines throughout the RPM range. This was the first system of its kind and eventually led to different types of variable valve timing and lift control systems that were later designed by other manufacturers (VVTL-i from Toyota, VarioCam Plus from Porsche, and so on). It was invented by Honda's chief engine designer Kenichi Nagahiro.
10-12-2006, 05:08 PM
#17
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Ok the basic concept of VTEC is VALVE TIMING, a concept put into mass production before Honda by Alfa Romeo and Nissan. Theres a difference between taking an existing idea imporving, refining it and adding to it, then inventing it.
Sorry you are wrong
Sorry you are wrong
10-13-2006, 12:53 AM
#18
variable valve timing is popular throughout many manufactures both domestic and imports, but may just have different names or variations (vtec,ztec,vvt,ivtec,vtti,vanos,vvl),. It has been around for quite some time now and honda had not been the first.
JUST TO BE CLEAR I FOUND THIS BIT OF INFORMATION
Fiat was the first auto manufacturer to patent a functional variable valve timing system which included variable lift. Developed by Giovanni Torazza in the late 1960s, the system used hydraulic pressure to vary the fulcrum of the cam followers (US Patent 3,641,988). The hydraulic pressure changed according to engine speed and intake pressure. The typical opening variation was 37%.
In the mid 1970s General Motors had worked to develop a system intended to vary valve lift. GM was interested in throttling the intake valves in order to reduce emissions. This was done by minimizing the amount of lift at low load to keep the intake velocity higher, thereby atomizing the intake charge. GM encountered problems running at very low lift, and abandoned the project.
Alfa Romeo was the first manufacturer who used variable valve timing system in production cars (US Patent 4,231,330). Model year 1980 Alfa Romeo Spider 2.0 L had VVT in Spica fuel injected cars in USA. Later this was used also 1983 Alfetta 2.0 Quadrifoglio Oro models and other cars as well.
In 1986 Nissan developed their own form of VVT with the VG30DE{TT) engine for their Mid-4 Concept. Nissan chose to focus their NVCS(Or Nissan Valve-Timing Control System) mainly at low and medium speed torque production because the vast majority of the time, engine RPMs will not be at extremely high speeds. The NVCS system can produce both a smooth idle, and high amounts of low and medium speed torque. Although it can help a little at the top-end also, the main focus of the system is low and medium range torque production. The VG30DE engine was first used in the 300ZX (Z31) 300ZR model in 1987, this was the first production car to use electronically controlled VVT technology.
The next big step was taken in 1989 by Honda with the VTEC system. Honda had started production of a system that gives an engine the ability to operate on two completely different cam profiles, eliminating a major compromise in engine design. One profile designed to operate the valves at low engine speeds provides good road manners, low fuel consumption and low emissions output. The second profile is comparable to the profile of a race cam and comes into operation at high engine speeds to provide a large increase in power output. The VTEC system was also further developed to provide other functions in engines designed primarily for low fuel consumption. The first VTEC engine Honda produced was the B16A which was installed in the Integra/CRX/Civic Hatchback available in Japan and Europe. In 1991 the Acura/Honda NSX became the first VTEC equipped vehicle available in the US. VTEC can be considered the first "cam switching" system and is also one of only a few currently in production.
In another development in 1991, Clemson University researchers had developed and patented the Clemson Camshaft which improved fuel economy. [1] The Clemson Camshaft system provided a continuously variable system. One cam shaft rotates inside the other creating infinitely more settings. Similarly, General Motors, the maker of Cadillac employed an advanced technology to develop a continuously variable system for the Cadillac Northstar System, VVT (Variable Valve Timing). The NorthStar VVT provides continuously variable system throughout the RPM range. The overhead cam (OHC) Cadillac NorthStar, already a fuel efficient V-8 engine, became even more efficient with VVT. GM engines use the double overhead cam varying both intake and exhaust for better performance. In 2005, General Motors offered the first Variable Valve timing system for overhead valve V6 engines, LZE and LZ4.
In 1992, BMW introduced VANOS, their version of a variable valve timing system, on the BMW M50 engine used in the 3 Series. VANOS significantly enhances emission management, increases output and torque, and offers better idling quality and fuel economy. The latest version of VANOS is double-VANOS, used in the new M3. Double-VANOS adds an adjustment of the intake and exhaust camshafts.
Ford became the first manufacturer to use variable valve timing in a pickup-truck, with the top-selling Ford F-series in the 2004 model year. The engine used was the 5.4L 3-valve Triton.
JUST TO BE CLEAR I FOUND THIS BIT OF INFORMATION
Fiat was the first auto manufacturer to patent a functional variable valve timing system which included variable lift. Developed by Giovanni Torazza in the late 1960s, the system used hydraulic pressure to vary the fulcrum of the cam followers (US Patent 3,641,988). The hydraulic pressure changed according to engine speed and intake pressure. The typical opening variation was 37%.
In the mid 1970s General Motors had worked to develop a system intended to vary valve lift. GM was interested in throttling the intake valves in order to reduce emissions. This was done by minimizing the amount of lift at low load to keep the intake velocity higher, thereby atomizing the intake charge. GM encountered problems running at very low lift, and abandoned the project.
Alfa Romeo was the first manufacturer who used variable valve timing system in production cars (US Patent 4,231,330). Model year 1980 Alfa Romeo Spider 2.0 L had VVT in Spica fuel injected cars in USA. Later this was used also 1983 Alfetta 2.0 Quadrifoglio Oro models and other cars as well.
In 1986 Nissan developed their own form of VVT with the VG30DE{TT) engine for their Mid-4 Concept. Nissan chose to focus their NVCS(Or Nissan Valve-Timing Control System) mainly at low and medium speed torque production because the vast majority of the time, engine RPMs will not be at extremely high speeds. The NVCS system can produce both a smooth idle, and high amounts of low and medium speed torque. Although it can help a little at the top-end also, the main focus of the system is low and medium range torque production. The VG30DE engine was first used in the 300ZX (Z31) 300ZR model in 1987, this was the first production car to use electronically controlled VVT technology.
The next big step was taken in 1989 by Honda with the VTEC system. Honda had started production of a system that gives an engine the ability to operate on two completely different cam profiles, eliminating a major compromise in engine design. One profile designed to operate the valves at low engine speeds provides good road manners, low fuel consumption and low emissions output. The second profile is comparable to the profile of a race cam and comes into operation at high engine speeds to provide a large increase in power output. The VTEC system was also further developed to provide other functions in engines designed primarily for low fuel consumption. The first VTEC engine Honda produced was the B16A which was installed in the Integra/CRX/Civic Hatchback available in Japan and Europe. In 1991 the Acura/Honda NSX became the first VTEC equipped vehicle available in the US. VTEC can be considered the first "cam switching" system and is also one of only a few currently in production.
In another development in 1991, Clemson University researchers had developed and patented the Clemson Camshaft which improved fuel economy. [1] The Clemson Camshaft system provided a continuously variable system. One cam shaft rotates inside the other creating infinitely more settings. Similarly, General Motors, the maker of Cadillac employed an advanced technology to develop a continuously variable system for the Cadillac Northstar System, VVT (Variable Valve Timing). The NorthStar VVT provides continuously variable system throughout the RPM range. The overhead cam (OHC) Cadillac NorthStar, already a fuel efficient V-8 engine, became even more efficient with VVT. GM engines use the double overhead cam varying both intake and exhaust for better performance. In 2005, General Motors offered the first Variable Valve timing system for overhead valve V6 engines, LZE and LZ4.
In 1992, BMW introduced VANOS, their version of a variable valve timing system, on the BMW M50 engine used in the 3 Series. VANOS significantly enhances emission management, increases output and torque, and offers better idling quality and fuel economy. The latest version of VANOS is double-VANOS, used in the new M3. Double-VANOS adds an adjustment of the intake and exhaust camshafts.
Ford became the first manufacturer to use variable valve timing in a pickup-truck, with the top-selling Ford F-series in the 2004 model year. The engine used was the 5.4L 3-valve Triton.
Last edited by crazyae; 10-13-2006 at 01:00 AM. Reason: Automerged Doublepost
11-27-2006, 10:06 AM
#21
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Originally Posted by voltar
Oh yes quite a few V8s have VVT. GM has had VVT for a while in NorthStars 4.6s, the GenIV small blocks, even the Toyota Tundra has VVT...
And before people get overexcited remember that Honda didn't invent the concept.
And before people get overexcited remember that Honda didn't invent the concept.
11-27-2006, 08:56 PM
#23
well ofcourse honda invented vtec! Variable valve timing is an invetion all on its own and each manufacturer took the idea and made into there own variation.
ei. honda = vtec, system that gives an engine the ability to operate on two completely different cam profiles
Bmw = Vanos operates on the intake camshaft in accordance with engine speed and accelerator pedal position. At the lower end of the engine-speed scale, the intake valves are opened later, which improves idling quality and smoothness. At moderate engine speeds, the intake valves open much earlier, which boosts torque and permits exhaust gas re-circulation inside the combustion chambers, reducing fuel consumption and exhaust emissions. Finally, at high engine speeds, intake valve opening is once again delayed, so that full power can be developed.
ei. honda = vtec, system that gives an engine the ability to operate on two completely different cam profiles
Bmw = Vanos operates on the intake camshaft in accordance with engine speed and accelerator pedal position. At the lower end of the engine-speed scale, the intake valves are opened later, which improves idling quality and smoothness. At moderate engine speeds, the intake valves open much earlier, which boosts torque and permits exhaust gas re-circulation inside the combustion chambers, reducing fuel consumption and exhaust emissions. Finally, at high engine speeds, intake valve opening is once again delayed, so that full power can be developed.
11-28-2006, 08:14 AM
#24
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vtec is like turbo lag without the boost, kinda like waiting for bad sex. 
JK it's already explained here. A conservative cam profile is used until the engine is really spinning is a safe way to get max power from a small engine. The bigger overlap in valves when vtec engauges isn't what a boosted car likes but neither are high compression pistons and the Civic community seems to have overcome these obsticles over the years with their popularity.
The best innovation I have seen in a while is the variable flow turbo that Honda built for the turbo Acura suv, imo that's a capital idea!
JK it's already explained here. A conservative cam profile is used until the engine is really spinning is a safe way to get max power from a small engine. The bigger overlap in valves when vtec engauges isn't what a boosted car likes but neither are high compression pistons and the Civic community seems to have overcome these obsticles over the years with their popularity.
The best innovation I have seen in a while is the variable flow turbo that Honda built for the turbo Acura suv, imo that's a capital idea!
11-28-2006, 08:39 PM
#26
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does the vtec controller control just the movement of the cam or does it shoot in some more air/fuel??? i had an SI in for an e-test and the parameters seems like it was running to lean, and i dont think the vtech was working as i warmed up the vehicle before the test.... any input would be great
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