Porsche Variocam Plus Valve Timing. Get the book here: https://www.createspace.com/4321251 Get the DVD-Video here: https://www.createspace.com/374294 VarioCa…
Porsche Variocam Plus Valve Timing. Get the book here: https://www.createspace.com/4321251 Get the DVD-Video here: https://www.createspace.com/374294 VarioCa…
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Porsche is a two-syllable word. It’s Por-sche, not Porsche.
No, no, no… If you persist on hearing what we’re saying and not listening
you’ll never learn anything. This is not a difference of opinion. We do
this for a living. Honda also has variable valve timing, not called VTec.
VTec is valve lift only and can be combined is it often is with valve
timing. We have a whole series on valve timing here, as well as books and
DVD-Videos. We try to explain the different technologies separately, to
avoid confusion. Thanks for posting.
If VTEC has variable valve lift, obviously the cam profile has changed has
it not? Therefore altering the timing of valves closing and opening.The
centre cam profile on the vtec cams is not the same as the outer two lobes
under normal low speed operation. That to me works on a similar principle
to Variocam but uses a different mechanical approach to get similar
results. Honda uses many versions of this system to improve the efficiency
of their engines.
VTEC HAS NOTHING TO DO WITH VALVE TIMING… I don’t know how many times I
see this on comments. VTEC is variable valve lift as opposed to Var. CAM
Timing, which is changing the opening and closing of the valves. Variocam
is no longer in use, but wasn’t a troubled system, so it was designed for
that at a time when Var. Valve Timing was reserved for few cars on
Formula-1 circuit. VTEC is not Var. Valve Timing.
I think the vtec system is better……I see that when Porsche uses a
solenoid to put pressure on the chain ramps to change cam positon, it
accelerates wear on them, as with vtec system it just uses a solenoid
plunger with a pin to lock the rockers. No stress on chains or chain ramps.
The engines on the 996-997 cars can be troublesome.
P.Carrera 4s C2
Take a stethoscope and listen for the sound. It’ll be revealed right away
if it’s the tappets. I tend to think it’s something else, unless you have
lots of miles on the odometer. Thanks for sharing.
In my 911 (996) I can hear a hydraulic tappet noise coming from the right
hand cylinder bank when the idle speed changes a minute or two after
starting up, the noise increases as the revolution go up.
Thank you, this is part of an entire SERIES devoted to Electronic Variable
Valve Timing. Look for the playlist and it’s all FREE for all. A companion
DVD and BOOK will also be available soon. Thank you.
Well, not exactly… It’s impossible to get the level of power 545 HP for
the 911 Turbo and 348 HP for the 911 regular, and on top of it have perfect
idle. These cars are bullets, but well behaved on daily city driving. All
this technology came from the Formula-1 circuit, not out of the whims of
any manufacturer. It’s a tried and tested technology. Thanks for posting.
sick
Well, once you get that the tappets are the keypoint, the actuation is
simple. It’s done by a PWM controlled solenoid, meaning hydraulically.
Makes sense?
Hi there, thanks for the reply. I don’t know how the exhaust noise should
sound like but this is the actual noise, to me it sounds like some tappets
have collapsed but I might be worng! I posted a videoresponse, thanks
Ok, I also own a 911 (996). Are you sure it’s the tappets or is it an
exhaust noise that often sound like tappets. If you need to replace the
tappet, you’d have to lower and remove the engine. Don’t work on it with
the engine on. The job is not difficult but a bit lengthy. thanks for
posting.
I saw your video response and yes it does sound like valve tap. Verify the
side of the noise. Also, while you’re at it if you’re doing the job have
the IM or intermediate bearing replaced as well. Maybe a Pelican ceramic is
a good fit for you. I still can’t believe it’s the tappets. There must be
lots of wear for any tappet to start making noise.
Criminy. I’m beginning to think that the complexity lies not in the systems
themselves, but in all of the 900 names every company uses to describe
them. That, and something about messing with the chain tension does not sit
well with me. Good explanations though. Thank you as always! 🙂
the secret is at the tappets, electro-hydraulically operated switchable
tappets, I still scratching my head how it is actuated…..
Fascinating! Keep up the great educational videos!
And pretty fast too…