LudwigB

Does anyone know besides Nissan and BMW, who else is using this technology?

Automobile magazine has criticized BMW engines for not being reliable in their long term test cars. In fact, everyone of their long term test cars from BMW all have engines issues.

Is this a mature engine technology?

whassupG

There are only variants of this technology per se. There is Honda's i-VTEC, Porsche Variocam Plus, Toyota's VVTL-i, Mitsubishi MIVEC etc... All of them don't have continuous variable control over valve lift, some types are better than others, so that means they don't have absolute control of value activites unlike VVEL and Valvetronic.

I think only BMW and Nissan are the only manufacturers using this technology for consumer vehicles. Actually BMW's valvetronic includes variable timing on exhuast camshafts also but VVEL does not.

nghiars

iTrader: (1)

honda started it all and now everyone is developing their own(or buying like how ford bought the vtec design from honda... honda sold it after they developed i-vtec and for calls it ztec..iirc) it all comes down to valve timing

whassupG

If they added direct injection to this technology, that would be a world first.

2prestige

it wasnt honda that started Variable valve timing, (or VVT), it was actually Fiat that patented this tecnology in the late 1960s or early 1970s. Then, different manufacturers tweaked the technology. What Honda did introduce was the ability for an engine to use two different cam profiles (called VTEC).

zmoothg

Thank you. I was waiting for someone to get it right.

Jeff92se

iTrader: (10)

I contend that Nissan was using their own varible lift cam tech in Japan before Honda brought it here.

G35Frank

^that is correct. Nissan was using this technology before Honda. Honda jut made it famous by introducing it in the NSX.

verbal assassin

actually, honda was the first to add "lift" to the variable valve timing.. not only did it improve performance, but was good on gas and a reliable hi-reving engine.

unlike our current G35 engine. Infiniti was late on this technology.

from Wiki...

VTEC is an acronym for Variable valve Timing and Electronic lift Control. VTEC is a valve train system developed by Honda to improve the volumetric efficiency of an 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 (VVTL-i from Toyota, VarioCam Plus from Porsche, VVL from Nissan and so on). It was invented by Honda R&D engineer Ikuo Kajitani.[1]

ElixXxeR

That description is accurate but incomplete. Changing of the cam profiles, more specifically, is dictated by oil pressue levels in the V-TEC system, not simply "electronically."

Ahujadaddy

The Toyota Corolla XRS has valve lift too! lol.... VVTL-i Variable Valve Timing with Lift Intelligence
Hondas hit VTEC, Corollas hit LIFT, G37 hits VALVE EVENT and LIFT, lol

derek

Finally a winner. Honda with the NSX was the first manufacturer to introduce both variable valve timing and variable lift technology, in a production vehicle.

DB

KPierson

iTrader: (2)

It acomplishes this task by firing electronic solenoids that control the oil pressure. So, technically its an electronically controlled hydrolic system. The important part, though, is the electronics. By making it electronic the computer can factor in several different factors, such as RPM, speed, load, coolant temp, oil pressure, etc. to make the system effective and safe.

Jeff92se

iTrader: (10)

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 September 1975, General Motors patented 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 to use a variable valve timing system in production cars (US Patent 4,231,330). The 1980 Alfa Romeo Spider 2.0 L had a mechanical VVT system in Spica fuel injected cars sold in the USA. Later this was also used in the 1983 Alfetta 2.0 Quadrifoglio Oro models as well as other cars.

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 (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 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 is a high lift, long duration profile and comes into operation at high engine speeds to provide an 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 powered by the C30A 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 1991, Clemson University researchers patented the Clemson Camshaft which was designed to provide continuously variable valve timing independently for both the intake and exhaust valves on a single camshaft assembly. This ability makes it suitable for both pushrod and overhead cam engine applications.[1]

In 1992 BMW introduced the VANOS system. Like the Nissan NVCS system it could provide timing variation for the intake cam in steps (or phases), the VANOS system differed in that it could provide one additional step for a total of three. Then in 1998 the Double Vanos system was introduced which significantly enhances emission management, increases output and torque, and offers better idling quality and fuel economy. Double Vanos was the first system which could provide electronically controlled, continuous timing variation for both the intake and exhaust valves. In 2001 BMW introduced the Valvetronic system. The Valvetronic system is unique in that it can continuously vary intake valve lift, in addition to timing for both the intake and exhaust valves. The precise control the system has over the intake valves allows for the intake charge to be controlled entirely by the intake valves, eliminating the need for a throttle valve and greatly reducing pumping loss. The reduction of pumping loss accounts for a 10% increase in power output and fuel economy.

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.

In 2005 General Motors offered the first Variable Valve timing system for I-head V6 engines, LZE and LZ4.

In 2007 DaimlerChrysler became the first manufacturer to produce a cam-in-block engine with independent control of exhaust cam timing relative to the intake. The 2008 Dodge Viper uses Mechadyne's concentric camshaft assembly to help boost power output to 600 Bhp.

hai109

iTrader: (1)

Thanks Jeff for the history...If Fiat was the first to patent it...Does the rest pay royalties to the company? It's pretty much the same concept but different design right?