reliability of the allroad? or 2.7T

[Chris Newbold]

On 5/2/07, thejimrose <thejimrose at gmail.com> wrote:

> hmm. I recall reading that the early a6 2.7t was the car with more turbo
> related issues [vs s4tt], despite having an airier engine bay. am i
> remembering wrong?

I can't really comment; I didn't pay much attention to the A6s until
we got the allroad several years later.

> also i find it unlikely that, when these cars were new and +$40k[which is
> when these turbo problems came up], there were too many 'spanker kids'
> driving them. more likely yuppies that didn't even know the car was
> turbocharged.

You'd be surprised what mommy and daddy's money will buy. That and a
bunch of yuppies with more money than sense or experience.

> also you can't 'chip the heck' out of the car. you can 'chip it' but there
> aren't levels. all of the chips are available from VERY reputable tuners

Sure there are levels. GIAC, for example, at least used to have three
different levels of performance-- mainly based on how much boost you
thought you could get away with. The more highly-strung variants were
clearly marketed as requiring 100+ octane race fuel.

Different tuners took different approaches to fiddling with the boost
curve: some went for torque low down, others for top-end horsepower.
There's a huge difference in added stress on the turbos between upping
the boost pressure at low RPM vs. upping it at high RPM. Simply put,
the required turbo compressor RPM is a function of both the desired
boost pressure and engine RPM. The turbo will need to spin _much_
faster to deliver 15psi of boost @ 6000 RPM than to deliver the same
pressure @ 3000 RPM. It took the tuners a while to figure out that the
K03s were not capable of delivering full boost pressure @ redline...

> in it. this gets on my nerves.. if 'chipping' [i hate that term, when we
> mean optimising air / fuel mapping] a vehicle really effects reliability,
> then the roadside should be LITTERED with blown up cars [and motorcycles].

It's upping the boost pressure which spins the turbos faster (turbos
too have a "redline" where they will grenade just like the rest of
your motor...) and generates more heat to cook the turbo's bearing
that causes the trouble.

> the 2.7tt turbo issues have been VERY well documented [not "rumored"] as
> being oil line related - return is too small and oil cokes and starves the
> turbo. hence the recalls and  updates around MY 01.5.

My S4, at least, is a counter example. It came from the factory with
the "upgraded" oil plumbing, and yet that didn't seem to help.
Bearings cooked @ 50k miles...

-Chris
2001.5 S4 Avant 6spd
2004 allroad 2.7T