What is VANOS?

[ken06]

Is VANOS like Honda's VTC (not VTEC!), and what is Double VANOS?

[Zor]

okay there was a whole thead on this subject that I fully explaned how both work. VANOS is nothing like Honda's VTEC and its VTEC not VTC, what VANOS does different from VTEC is that VANOS moves the cams, where as VTEC uses an extra cam lube to increase valve lift time, valve lift time = the time the valve is off the seat. Double VANOS moves both intake and exhaust valves

[ken06]

Thanks

[Zor]

np

[ithrowcraze]

germanys vtec

[MRoadster1382]

Germany's VTEC that's 100 years ahead of the others

[BayBimmerM3]

its been answered already in the thread guys. just another time to do a first

[Zor]

Originally posted by MRoadster1382
Germany's VTEC that's 100 years ahead of the others

no its not, it takes more power to move the whole cam shaft which VANOS does than to move a small piston to lock three valve rockers together so think before you post

[PrinceE30]

VTEC came out before most other variable cam systems (in the late 80s I believe). Started in F1, worked it's way into the Civic (efficiency applications) and NSXs (performance applications)...

VANOS and VTEC are both good with neither being "better" than the other. Just different.

-Prince

[Zor]

VTEC was never in F1 it started with NSX JGGT and Prince your right you can't compair VTEC and VANOS because they do different things

[PrinceE30]

Originally posted by Zor
VTEC was never in F1 it started with NSX JGGT and Prince your right you can't compair VTEC and VANOS because they do different things

I was under the impression that Honda had TRIED to develop the VTEC technology for F1 but it never made it and was thus relegated to street cars and touring cars...

-Prince

[E36DJ]

Um, one is continuously variable.. how can you say neither is better?

I guess you can spare more power to move the valves when the engine give enough in the first place..

[Zor]

VANOS doesn't continuously vary anything it just moves the cam shaft from 3500 rpm to 5000 rpms where as VTEC locks the valve rockers are 5500+ rpms

I'm ripping myself off again with an explantion of VTEC and VANOS again so here we go:

VANOS is a combined hydraulic and mechanical camshaft control device managed by the car's DME engine management system.

The VANOS system is based on an adjustment mechanism that can modify the position of the intake camshaft versus the crankshaft. Double-VANOS adds an adjustment of the intake and outlet camshafts.

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.

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.

VANOS was first introduced in 1992 on the BMW M50 engine used in the 5 Series.



Here's how it works:

In overhead cam engines, the cams are connected to the crankshaft by either a belt or chain and gears. In BMW VANOS motors there is a chain and some sprockets.

The crankshaft drives a sprocket on the exhaust cam, and the exhaust cam sprocket is bolted to the exhaust cam. A second set of teeth moves a second chain that goes across to the intake cam. The big sprocket on the intake cam is not bolted to the cam, for it has a big hole in the middle. Inside the hole is a helical set of teeth. On the end of the cam is a gear that is also helical on the outside, but it's too small to connect to the teeth on the inside of the big sprocket. There is a little cup of metal with helical teeth to match the cam on the inside and to match the sprocket on the outside. The V (Variable) in VANOS is due to the helical nature of the teeth. The cup gear is moved by a hydraulic mechanism that works on oil pressure controlled by the DME.



At idle, the cam timing is retarded. Just off idle, the DME energizes a solenoid which allows oil pressure to move that cup gear to advance the cam 12.5 degrees at midrange, and then at about 5000 rpm, it allows it to come back to the original position. The greater advance causes better cylinder fill at mid rpms for better torque. The noise some people hear is the result of tolerances that make the sprocket wiggle a bit as the cup gear is moved in or out.

Double VANOS


--------------------------------------------------------------------------------

Double-VANOS (double-variable camshaft control) significantly improves torque since valve timing on both the intake and outlet camshafts are adjusted to the power required from the engine as a function of gas pedal position and engine speed.



On most BMW engines that use a single VANOS, the timing of the intake cam is only changed at two distinct rpm points, while on the double-VANOS system, the timing of the intake and exhaust cams are continuously variable throughout the majority of the rpm range.

With double-VANOS, the opening period of the intake valves are extended by 12 degrees with an increase in valve lift by 0.9 mm.

Double-VANOS requires very high oil pressure in order to adjust the camshafts very quickly and accurately, ensuring better torque at low engine speeds and better power at high speeds. With the amount of un-burnt residual gases being reduced, engine idle is improved. Special engine management control maps for the warm-up phase help the catalytic converter reach operating temperature sooner.

Double-VANOS improves low rpm power, flattens the torque curve, and widens the powerband for a given set of camshafts. The double-VANOS engine has a 450 rpm lower torque peak and a 200 rpm higher horsepower peak than single-VANOS, and the torque curve is improved between 1500 - 3800 rpm. At the same time, the torque does not fall off as fast past the horsepower peak.

The advantage of double-VANOS is that the system controls the flow of hot exhaust gases into the intake manifold individually for all operating conditions. This is referred to as "internal" exhaust gas re-circulation, allowing very fine dosage of the amount of exhaust gas recycled.

While the engine is warming up, VANOS improves the fuel/air mixture and helps to quickly warm up the catalytic converter to its normal operating temperature. When the engine is idling, the system keeps idle speeds smooth and consistent thanks to the reduction of exhaust gas re-circulation to a minimum. Under part load, exhaust gas re-circulation is increased to a much higher level, allowing the engine to run on a wider opening angle of the throttle butterfly in the interest of greater fuel economy. Under full load, the system switches back to a low re-circulation volume providing the cylinders with as much oxygen as possible.


This is how VTEC works.

For each pair of valves, there are three cam lobes. The two on the outside are low RPM lobes and the one in the middle is the high RPM lobe. The two low RPM lobes actuate the two valve rockers, which in turn pushes the valves open. The high RPM lobe actuates a follower, which is shaped like a valve rocker, but doesn't actuate any valves.The circular section of the cam lobes touching the valve rockers, and the eliptical section pointing away. Thus the valves are closed in this stage.

During low RPM operations, the two outer cam lobes directly actuates the two valve rockers. These low PRM lobes are optimized for smooth operation and low fuel consumption. The high RPM lobe actuates the follower. But since the follower isn't connected to anything, it doesn't cause anything to happen.

At high RPMs, oil pressure pushes a metal pin through the valve rockers and the follower, effectively binding the three pieces into one. And since the high RPM lobe pushes out further than the low RPM lobes, the two valve rockers now follow the the profile of the high RPM lobe. The high RPM lobe's profile is designed to open the valves open wider, and for a longer duration of time, thus allowing more fuel/air mixture to enter the cylinder. The improved breathing allows the engine to sustain its torque output as RPM rises, thus resulting in higher power output

I hope that clears everything up, oh and Honda introduced the DOHC VTEC mechanism in 1989 on the JDM market and the in 1990 to the USDM market in the NSX. yes they made the DOHC VTEC system before the SOHC.

you really can't compare VANOS to VTEC because they do two different things even tho they're the same type of system. VANOS is used in mid rpm range to provide better torque and hp , where as VTEC works at a high RPM range to produce more power.

THERE NOW READ AND STFU

[PrinceE30]

Originally posted by E36DJ
Um, one is continuously variable.. how can you say neither is better?

I guess you can spare more power to move the valves when the engine give enough in the first place..

You know nothing about the given subject and show it in your first statement and even less in the second. VANOS and VTEC have nothing to do with engine power. They are meant to keep ample amounts of torque at varying RPMs to give either good accelleration or good fuel economy.

HP is just a relative measurement of TQ at various RPMs.

-Prince

[MorningCruiser]

Originally posted by PrinceE30
HP is just a relative measurement of TQ at various RPMs.

-Prince

So very close, it's actually a byproduct of displacement, torque and engine speed. If anyone here begs to differ, read any number of engine design magazines.

I still don't understand how drag motors have 3500+ft-lbs of torque but only like 1200-3000hp. Could be that they're beasty FI, but that's a whole other can of worms.

Either way, Thanks for the huge explaination on VANOS.

Maybe this thread could be STICKIED!