Re: Why does the engine cover say DOHC? (Was Re: DOHC or not?)

["Jose Gomez" <kwerky@email.msn.com>]

Can you say 'marketing ploy'? :-^)


-----Original Message-----
From: Eric Wang <wangstervr6@hotmail.com>
To: jettaglx@igtc.com <jettaglx@igtc.com>
Date: Monday, March 06, 2000 5:27 PM
Subject: Why does the engine cover say DOHC? (Was Re: DOHC or not?)


>Does anyone know the answer to the question in the subject line?
>
>Eric Wang
>1994 black Vento VR6 / aftermarket Trek edition -- Eibach Pro-Kit, Bilstein
>Sport shocks and struts, Remus cat-back exhaust, Autotech Q-Chip, K&N
>drop-in filter, Mintex Redbox pads, BBS RZ-II, 1998 Green Trek 930
>
>
>From: "Christopher Morgan" <cmor@home.com>
>
>Regardless of what some of the engine covers say, the 12v VR6 is really a
>SOHC motor.  The front cam has the intake and exhaust lobes for the front
>cylinders as does the rear cam for the rear cylinders.  In other words, if
>you look at any one cylinder, the intake and exhaust valves for that
>cylinder are actuated by a single cam.
>
>...however...
>
>The 24v motor is DOHC.  It still has only two cams, but the they are
>separate intake and exhaust cams (thus allowing the use of variable valve
>timing).  For any one cylinder, the intake valves are actuated by one cam
>and the exhausts by another.  It's a pretty clever set-up.  Somewhere I saw
>pics of the valvetrain, which showed how each cam uses regular-length valve
>stems for its 'local' valves and extra-long valve stems that reach across
>the head at an angle for the valves in the opposite bank.
>
>The same write-up also mentioned that the other design goal for the 24v
>motor (besides the 30 extra hp) was an increase in fuel efficiency.  Did
>anybody else notice that the 12v VR6 is not a gas mileage champ?  :-)  For
>comparison, the 174 hp GTI/Jetta GLX 5 spds are rated at 20/28, while the
>190 hp Audi A4/Passat V6 5 spds get 20/29.  The 24v VR6 is 204 hp and is
>supposed to get the same, if not better, mileage as the 12v.
>
>FWIW, the number of cams does not necessarily relate to the number of
>valves.  Using BMW motorcycles as an example, the K75/100 (but not
>K1100/1200) motors are 2 valve per cyl DOHC, while the newer R-bike motors
>are single cam 4 valve units.
>
>-Chris
>
>
>From: <VW155mph@aol.com>
> > In a message dated 02/28/2000 4:43:56 PM Eastern Standard Time,
> > sundie@lunaticfringe.org writes:
> >
> > > So my question is this!  Does the VR6 have 2 cams or 4?
> > >
> > >
> > >   Breathlessly awaiting answers....
> > >
> > >
> > >  Sundie...
> > Just 2..
>
>
>
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