Re: A4 30v performance - what to expect?

[ScharfR@aol.com]

In a message dated 96-11-12 12:40:17 EST, reinerf@microsoft.com (Reiner Fink)
writes:

< Is there any reason to think the added hp (from 174 to 196?) will help
< the low-end performance significantly?
 
<< Not really. From my understanding, the extra valves really help at
    _higher_ rmp, where the engine can really benefit from the extra valves
    by being able to cycle air through and exhaust out more quickly. I'm not
    saying there wont be any low end improvement, just that the high end is
    what really benefits as you add more valves. Also, 192 was what I recall
    being the hp quote for the 30-valve 2.8L engine. >>

Not sure I agree.  In fact, I'm sure I don't agree.

On Audi's 5-valve, the center of the three intake valves opens slightly
earlier than the other two.  This is supposed to add to the swirl/tumble of
incoming air and to aid in low rpm torque.  The five-valve V6 (at lease as
used in the European A8) also has variable camshaft control, in addition to
the variable intake path geometry common to the 2-valve 2.8L V6.  The results
in every European test I've seen indicates much better performance over the
full range than the 2-valve engine.

The 5-valve engine may not be a paragon of low-rpm grunt, but it was designed
to deliver at the bottom as well as at the top.  A look at the numbers
indicates that there is a higher overall torque peak, slightly higher up the
range.
  - the 2-valve 2.8L V6 produces 184 lbs. ft. of
    torque (250 nM) @ 3,000 rpm
  - the 5-valve 2.8L V6 produced 206 lbs. ft. of
    torque (280 nM) @ 3,200 rpm
I don't have the two torque curves handy, but "eyeballing" the curve on the
5-valve shows that it achieves 177 lbs. ft at 2,000 rpm and peaks at 206 lbs.
ft at 3,200 rpm.  Compare this to the absolute peak of 184 lbs. ft. at 3,000
rpm on the 2-valve and it seems not unreasonable to expect that the 5-valve
will deliver stronger response throughout the range, including the bottom
end.  I suspect that it is the combination of variable intake path geometry,
variable intake valve phase and 5-valves that makes this possible.

As to horsepower, the current 2.8L produces 172 SAE hp (174 DIN) at 5,500
rpm.  The 5-valve version makes 193 DIN hp at 6,000 rpm.

Acceleration times for otherwise similar cars, using the two V6s engines as
the variable, show 0-100 km improvement for the 5-valve engine, plus a higher
top speed and better fuel economy.  All data based on European comparisons.

Finally, to the extent that road test impressions are valid, the German
magazines ("Auto Zeitung", "Auto Bild", and "auto, motor und sport") have all
remarked on the excellent low-rpm power of the 5-valve engine.  This is
especially relevant with respect to comparisons to the 2.8L BMW and
Mercedes-Benz engines - both of which are nearly identical in their peak hp
and torque values, although they both achieve peak torque much higher up the
range.