KKK turbo aspect ratio?

[mlp]

From: "Michael Gough" <mdg3369 at mac.com>
To: <quattro at audifans.com>
Sent: Friday, December 07, 2001 2:31 AM

> Hello list,
> I am considering moving from the KKK turbo to a Garrett. I am
wondering if
> anybody knows the A/R of the exhaust housing on the K26 (MC1) or K24
(MC2,
> 20v) Does anybody have any data on these, or is this some of the
"secret"
> info KKK won't give up? I'll probably go with a T3 Garrett with a
.48 A/R,
> though......
> Thanks
> Mike

Your secret KKK code is (? should be) cast inside the throat of the
hot side "scroll."

Most KKK units (YMMV) that I've seen use a Number 6 scroll.  That's
certainly been the case in the K24/K26 units I've seen on the UrS4/6
cars I know of.  A few cars, such as the hi-po 944 Turbo S 944 (vs.
the regular 944 Turbo) use a Number "8" scroll.  The "regular" 944
Turbo uses a Number 6 K26 hot side scroll.  There may be a couple of
"mystery" AudiSport K26 based units floating about that may use a
different hot side, but my guess would be they are not very common.

In my limited experience (i.e., I needed to find one), Number 8
scrolls are harder to find than Number 6's, at least in North America.
I don't know if the K24 configuration ever came with a #8 scroll, but
if you were willing to swap the center bearing sections my guess would
be that you could mix & match.

As for the relationship between KKK's #6, #8 and Garrett's A/R .48 or
.63 (or as low as .36 & as large as  an .82 A/R in the Garrett
T3/T31/T350 family), I don't know of any definitive answer or source
for information.

A guess bare naked guess on my part would be that the #6 and .48 would
be comparable; likewise the #8 and .63.  A better "rough" guess would
be to get the hot side exhaust bore diameters and compare those to one
another vs. your best guess as to the relative rough diameters of the
housings.

If I recall correctly, a K24's exducer is roughly 46mm/@ 1.8"; and the
RS2's #6 housing is @ 55mm or 2.16"  If you have access to Bell's
"Maximum Boost" take a look at his chart for a very rough
approximation of Exducer Bore vs. sustainable compressor delivery,
figure 3-10.  From my 'eyeball' of the flow rates vs. what Audi
reports the 20valve engines as making, his figure biased towards the
"low" side, but then again it is only a rough approximation, & YM and
manufacture's claims I suppose do vary.

Oh, the K26's have a bigger "r" for the same size A/R in comparing the
K24 family to the K26.


mlp