VTEC vs VANOS

[hyptnochicken]

My son has a Honda with a VTEC engine, you notice and can feel it when the variable timing kicks in. I have a ZHP and it moves when I punch it but no kick. Is VANOS more subtle? Are you supposed to feel the timing change?

[Tangent]

VTEC switches from one cam profile to another at a specific rpm.
VANOS continuously varies cam timing based on engine load, throttle position, rpm, and several other factors through an infinite range, not just from position 1 to position 2. You don't feel VANOS because it's not as crude of a system. Newer VTEC systems are supposed to be better than the old on/off system like your son's car has I think.

[Ianbiz]

If you do a second gear pull without flooring it to redline, you can almost feel it.

[SuckaGDog]

I was about to ask the same question yesterday! My friend has a 08 Honda Civic Si and i love it when the vtech kicks in at 6,000 rpms you can definitely hear it. It sounds amazing paired with his intake. But here's the info i got from another forum.





"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."

Catch the discussion here http://www.dtmpower.net/forum/genera...hat-vanos.html

Vanos further explained here http://www.usautoparts.net/bmw/technology/vanos.htm

[Mstearnsy]

Vanos works across the whole rev range, not just mid RPMs. VTEC was incredible technology once upon a time, but so was a typewriter. Both are antiques now!

[Blanco]

VANOS would be more comparable to i-VTEC found in '01+ Civics/Integras (and whatever years Honda switched out the rest of their VTEC engines for i-VTEC). The i-VTEC found on '01-'05 Civic Si's is pretty comparable to an E36 in that only the intake cam position is changed. The JDM equivilent has it on both cams, like dual-VANOS.

[S15NOB]

how do you know if your car is the VANOS system, if it is double or single..? and how would you know if it breaks down, since you can barely feel the power?

[Mstearnsy]

- Your car has Dual Vanos
- Your car would run like ass and have lots of warning lights if it broke down.
- The point of our system is so that it's a linear, torquey powerband, not an on-off switch like VTEC. You only "feel" the power of VTEC because for the first 6000 RPM there's NO power.

[S15NOB]

Originally Posted by Mstearnsy

- Your car has Dual Vanos
- Your car would run like ass and have lots of warning lights if it broke down.
- The point of our system is so that it's a linear, torquey powerband, not an on-off switch like VTEC. You only "feel" the power of VTEC because for the first 6000 RPM there's NO power.

oh thank youuuu, i learn something new today! =]

[Blanco]

Originally Posted by S15NOB

how do you know if your car is the VANOS system, if it is double or single..? and how would you know if it breaks down, since you can barely feel the power?

http://en.wikipedia.org/wiki/VANOS

I don't know about E46s, but with an E36 the horrid rattling from the VANOS unit is usually a dead give away. You barely feel it because you've never not felt it. Disconnected, you'd notice the difference the first time you went through the rev range.

Originally Posted by Mstearnsy

- Your car has Dual Vanos
- Your car would run like ass and have lots of warning lights if it broke down.
- The point of our system is so that it's a linear, torquey powerband, not an on-off switch like VTEC. You only "feel" the power of VTEC because for the first 6000 RPM there's NO power.

VTEC crossover is actually around 4500rpm for all but the extremely high-strung Type R B18C and B16B. That isn't helped any by the 4.75 final drive.

The point of VTEC in street cars (it was originally racing tech) is to provide the best of both worlds. You essentially get a daily driver cam lobe for putzing around town with good fuel economy and idle quality. Then when you hit the crossover point you get passing/fun power. If you used just the VTEC lobes you'd get a slight lope at idle and if you used just the non-VTEC lobes you'd have a DX instead of an EX/Si, SiR, or Type R.

[99AMGJ]

Im not trying to be funny or anything but i honestly feel a boost in power in the 5-7k(chipped) rpm band. on my car its almost like vtec feeling but not as hard of a kick in, i dont know if thats normal or what

[nathancarter]

The VANOS unit should last the life of the engine, but the seals on the VANOS pistons are known to fail, which allows oil pressure to slip past the seals, which means the pistons don't move correctly, which means the camshafts are not adjusted properly. There is a replacement seals kit available from Beisan Systems (google it or forum search). IMO, it's a must-do repair, definitely good for some torque improvement when shifting. For the price, it's probably the best power "mod" that you can do.

Here are some fun VANOS diagrams:

[EURO M3 CSL]

hm intresting. how would you know when the seals need to be replaced? i just changed my valve cover gasket and overlooked this process.

[nathancarter]

Originally Posted by EURO M3 CSL

hm intresting. how would you know when the seals need to be replaced? i just changed my valve cover gasket and overlooked this process.

Check the Introduction, Symptoms, and Diagnosis sections here:
http://www.beisansystems.com/procedu..._procedure.htm

Depends on who you ask. Some say that the rubber (Buna) O-rings are completely plasticized within about 10k miles of new. If you have an M52tu motor (323/328), you may notice poor idle when cold, that goes away when it's warmed up. Otherwise, you might not notice any symptoms, because either the symptoms came on gradually, or they've always been there since you got the car.

[toocool4657]

in my opinion, you can sort of feel a difference but not much

when your at WOT you seem to have more aggressive power between the 4-6k range

and i can tell a difference in my exhaust tone, but i am unsure is that has anything to do with my vanos system

[calypso325i]

i used to be able to hear and feel the difference between 5-7000 rpm on my old 325i single vanos e36.

[southpaw]

My Vanos kicks in 24/7.

[weenstan]

Can't really feel it.

[w3God]

here this is what you are looking for

http://videos.streetfire.net/video/N...e-of_40076.htm

[boardspinna]

Originally Posted by weenstan

Can't really feel it.

thats what she said....ZING!!!