Timmerman "Shrapnnel-Knobben" mod et. al.

Swann, Benjamin R. (BSWANN) BSWANN at arinc.com
Tue Oct 17 17:04:57 EDT 2000

Chris Shepley asked:
Thanks for the information...  Do you know where I can get specifics on some
of the DIY mods?

Todd Phenneger enquired:
Can you send me the specs for this resistor mod.  I want to put
a mac-11 in there in place of the mac-07 and would like to do
this to it.

Peter McConnel also wonders: which mod is this??

I'll outline some of this here and address in more detail including
pictures, on my web site: 

when I get some time(hah!).

To get the boost, a variable pressure regulator is installed in place of the
frequency valve.  The regulator set the output pressure proportional to the
input pressure.  The output goes to the wastgate pressure control fitting(in
place of the frequency valve control).  The result is you can set the
wastegate to stay clamped.  The mod was originally devised by Paul
Timmerman.  I don't know if he still sells the kit.  I think an adjustable
pressure regulator can be obtained from places like a welding shop - anyone
know where to get these? 

To keep the fuel pump cutout from kicking in, you need to modify the ECU,
either by chip, or some less elegant way, eg. the resistor mod.  A 475 ohm
resistor is placed between pins 1 and 10 on the ECU pressure transducer,
which fakes the ECU into getting the value for a lower pressure.  this 1)
make the fuel pump shutoff at a much higher point, somewhere around 2.7 Bar,
and will advance timeing across the board.  I have modified mine so I can
set the value a bit higher as the timing with 475 ohm tends to be a little
to much advance, especially on a hot day under load.  A fixed value closer
to 600 ohm may be a better bet.

A stiffer wastgate spring can be used instead or in conjunction with the
pressure regulator to get the boost higher.  There are many combinations and
variations being used.

Oh, before you do any of this, strap your intercooler, as you will blow the
end caps off if you don't.

That's it in short for now as I'm cutting into my work time.  Again when I
have time I can show some diagrams/pictures of the mod(s) on my web site,
perhaps I can take some pictures this eve. and upload them tommorow, but
only if my baby daughter is being cooperative.

In retrospect, I will add, that getting a proper chip to modify the ECU is
probably a more sane approach to modifying the ECU, although it costs much

I hope this helps.


Ben Swann
''87 5KCSTQW - Timmerman "Shrapnnel-Knobben" mod + variable(470ohm+)
resistor, onboard diagnostics switch, 1.6 Bar Spring(soon to be 2 Bar
spring, double cross strapped intercooler - all DIY mods.

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