Re: DOHC or not?

["Brandon Wilson" <brandon@eicsoftware.com>]

Can you get the 24v VR6 in the US????


Brandon Wilson

----- Original Message -----
From: Christopher Morgan <cmor@home.com>
To: <jettaglx@igtc.com>
Sent: Sunday, March 05, 2000 7:26 PM
Subject: Re: DOHC or not?


> 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..
>
>