Question for you turbo experts...

Eric_R_Kissell at Eric_R_Kissell at
Mon Feb 11 17:46:11 EST 2002

On 2/11/2002 10:51 AM "Beatty; Robert" <BeattyR at> wrote:

>I'm contimplating switching the turbo in my 86 5ktq to a K24.  IF I do this
>conversion, what is the OPTIMAL boost pressure for that turbo, while keeping
>the rest of the motor stock.  I will be installing a bypass valve as well,
>but no other real modifications at this time.  I already have a QLCC chip
>installed with a 1.8 bar spring.

>I know the K24 spools up faster and the K26 has a higher top end, but
>someone on here did a bit of comparision with a lower amount of boost on a
>K24 and it seemed to pull better.

You may be referring to me when you say "someone on here did a bit of
comparison with a lower amount of boost on a K24 and it seemed to pull
better" but if it is me you are referring that is not quite the experience
I reported.

I recommend 1.8 bar for the K24.

What I decided was that the rate of spool up to 1.8 bar was too fast with
my adjustable wastegate tightened down too far, so I backed off the preload
in my wastegate. With the wastegate tightened down I could feel a strange
lag sensation at lower rpm's even though the boost was already up to 1.8
bar. According to the K24 turbo maps on SJM's site, it appeared that the
K24 was moving into a lower efficiency region at these rpm's. I adjusted my
wastegate to follow what I estimated was the best path for rpm vs. boost
using the K24 maps and it felt better. As I said then, I have no dyno or
acceleration times to compare. I may get around to doing some in a month or
two. YMMV.

Eric R. Kissell
1986 5000cstq, 1.8 bar (SJM), K24, Fuchs
1989 200q Avant, 1.5 bar (QLCC soon), K24, Bilsteins
1987 VW GTI 16V, 1984cc, Bilsteins
Evansville, Indiana, USA

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