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Re: AUDI & Mercedes
>the 20 valve non-turbo 5 is widely acknowledged to be not one of
>audi's better efforts. all the stereotyping of 4 valve heads apply.
>however, look at the same engine with a turbo (and other refinements,
>such as a lighter dual mass flywheel, direct ignition) as deployed on
>the S4 to such devastating effect. peaky? yeah 1950 rpm max torque,
>perfectly flat thru 4700 rpm and a 280 foot pounds 15 second overboost.
>this engine is an engineer's dream.
Keep in mind: although Audi didn't use the 4 valve head until '91 (in the
US) it was available earlier in Europe AND on the VW 1.8 4cyl motor starting
in '87 (Scirocco). In other words, an "early" multi-valve motor. My folks
had an '88 GLI, 1.8L 16v--yes, the stereotypes do apply. Remember that VW
"announced" that motor in '85 or '86 and took awhile to get the "features"
(no torque, among others) out.
>a vtec can rev to the blazes, but with only 110 lbft or so to play
>with, it is largely a curiousity. and thanks once again to a nice
>cosy relationship to the media, this engine can produce acceleration
>numbers not reproducible in real life. not surprising. a VR6
>powered car or an eclipse turbo is much much quicker than a vtec.
>yes, i have driven them all. it's all about torque.
Wait a minute--you're comparing apples and oranges--the VR6 is 2.8L, the
Eclipse a Turbo (2.0L, 210 hp and close to 200 lb-ft!)--btw, which VTEC?
Integra? Prelude? NSX? BUT--you're absolutely right--torque is the name
of the game--as they say, there's no substitute for cubic inches (or cc's).
As for drivability, I was thinking about say, an '87 Celica and even some
mundane Hondas--our '89 Accord, for example. They don't drive like
multi-valve motors, but then they weren't tuned for high peak
power--especially in the case of the Accord. BTW, who remembers the original
Honda CVCC motor? another multi-valve head, different use, different result
>according to performance car, the current 4 valve head found in all
>audis and VWs came from the 306bhp sport quattro. the current gti
>16V, not currently imported has a new head designed with more torque
>in mind. my guess is that the original 4 valve head design used in
>the S1 was optimized for forced induction, which is why the S4 is such
>a killer and the non-turbo versions pretty tame.
Ummm...the sport quattro I saw (Larry Vollum's, Portland, OR) has a very
different head from that in the current VWs and Audis. I believe one cam is
driven by a toothed belt (like ours) but the second cam is gear driven from
the first, instead of a chain. Also, the head has mechanical lifters.
And...the original VW/Audi 4 valve street motor was not force-fed--just a
bit small and it revved high (7200 redline in the Jetta). Though I never
drove one, I understand the 2.0L 16v ('91 VW GTI/GLI) motor was much improved
in these respects. Just imagine if Audi had taken the 2.0L 16v I4 motor and
made it into a turbo 2.5L 20v I5--I can see 250hp as the starting point, and
by the time Ned finished with it...oh never mind.