RS2 turbocharger

[Dave Eaton]

what the rs2 turbo torque graph says (if you believe them) is that the rs2
turbo is providing useful *boost* over 2200 (boost threshold), - at this
point it is supposed to be providing the same boost as the k24.

what driving it tells you is there is no "kick" until after 3,000 rpms
(lag).  as i have stated, i'd assume that a lot of this is simply spool-up
time, or that the graph is "wrong" or at the least measured differently.
the stopwatch and my butt, concur.

i absolutely agree that the rs2 is made for spirited driving.  that is why
one is in my garage, and has been for 6 years.  just don't try and compare
it to a k24 at low engine speeds, because it doesn't come close.

dave
'95 rs2
'90 ur-q

-----Original Message-----
Date: Wed, 12 Jun 2002 09:03:39 -0700
Subject: Re:  RS2 turbocharger
From: "Jonas K." <jkarlsso at metabolex.com>
To: Quattro list <quattro at audifans.com>

On 6/11/02 6:30 PM, "David Eaton <deaton at tranzrail.co.nz> wrote:

> the rs2 turbo is only providing better acceleration to the avant
> when operating over 3,000 rpms.  a close look at the numbers (particularly
> the 50-70 vs the 60-80) also indicates the steep ramp-up in the rs2 turbo
> performance.  this again is what your butt tells you when you are driving
> the car.  it is the classic definition of "turbo lag".

Wrong. This is the definition of "boost threshold".

Boost threshold (BT) - (n) that point in the RPM range above which a
turbocharger will make boost. Below this point there is no useful boost.

Turbo Lag - (n) the time it takes for the turbo to generate boost following
full throttle application, measured above the BT.

> once again, these are cars with the same flywheels (that nasty old dual
> mass flywheel) & transmissions, and very similar weight.  i don't see how
you
> can come to any other conclusion other than that the k24 turbo is
responsible
> for the much better performance of the s2 at low engine speeds, over the
> rs2.  which was my 1 and only original point.

True. The K24 is a "smaller" turbo than the RS2. Predictably they have a
different BT. Of course the k24 will perform better while it has reached
it's BT but the RS2 has yet to reach it's BT.

Dave, the numbers you posted are excellent. It has convinced me that the RS2
really is the better turbo. 3000 rpm to me (and I'd say any spirited driver)
is barely above idle. What your numbers show me is that the RS2 outperforms
the k24 anytime you're above 3000 rpm. Awesome. The solution is simple to
the daily driver situation. Don't upshift into lower than 3000 RPM. If
you're cruising below 3000 RPM and want to sprint quickly, you'll need to
downshift. None of these are inconveniences to me. They certainly would not
make me pick the k24 as my turbo of choice.