2.7T v 4.2 A6

[Ti Kan]

Matt Evans writes:
> Is there anything especially novel about the B6 S4 engine ?  The D2 A8 4.2
> is spec'd to 300hp, the D2 S8 4.2 is specced at 360.  What makes the B6 S4
> 4.2 a 340hp motor?  How does it differ in tune from the 4.2 engine in the
> other cars ?

The B6 S4's 4.2 is the newer-gen Audi V8 with a timing chain located
at the rear of the engine instead of a timing belt at the front.  In
the case of the B6 S4, it also has a ECU-controlled variable muffler
in the exhaust system.  This same V8 is also used in the latest C6 A6 4.2
and the allroad quattro 4.2, slightly detuned at 300hp.

> On a similar vein, what were the differences between the B5 S4 2.7TT and the
> A6 2.7 turbo motor ?  Were there any differences at all ?  Was the A6 a
> single turbo ?

No appreciable difference, they are all biturbo.  Somewhat different
ECU programming between the B5 S4, A6 2.7T and the allroad 2.7T versions,
that is all.  All rated at 250hp and 258 lb-ft for the US versions.

> It seems like (relatively) lower displacement, forced induction, and
> mechanical AWD are a strong audi heritage, certainly for S cars.  The B6 S4
> only has one of the three.  (And honestly, it makes only 8 more hp than the
> E46 M3 out of one additional liter, and is slower in a straight line with 2x
> the launch traction).

The B6 S4 is heavier than the M3.  The V8 engine only makes slightly
more hp than the M3's I6 but it's not as high-strung.

-Ti
-- 
Ti Kan
http://www.amb.org/ti
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