Stray vacuum line

Nick turborotary at
Sat May 21 13:18:51 EDT 2005

Does anyone have a compressor map for the k24 turbo? I'm wondering how
close it actually comes to overspinning the turbo, since I'd like to
replace the WGFV solenoid with a manual boost controller. I know I'd
lose some safeguards the ecu has, but I just can't quite stomach $800
for a chip (you can buy a standalone ecu for that much...). The only
problems I see running into is if theres an overboost limit on the
ecu, or if the fuel and timing maps on the ecu arent corrected after
1.8bar.  Hopefully someone on the list knows the answer to the first,
and I can check the second myself with a wideband 02 gauge.

On 5/21/05, alan cordeiro <alancordeiro at> wrote:
> The wastegate spring provides just enough force to keep the wastegate
> from popping open to 1.4 bar.  If the ECU does not "intervene",
> this is where your boost will end.
> If the ECU perceives the requirement for more boost, it turns on
> the WGFV solenoid, which begins to bleed of some of the excess
> pressure below the wastegate diaphragm, decreasing the upwards force
> on the wastegate (i.e. raising the allowable boost).
> (Note, older designs used to ADD manifold pressure at the top)
> If you look at the boost vs rpm curve, the ECU starts
> trimming down the boost after 4000 rpm to keep the
> turbine from spinning past its maximum allowable rpm
> ( is this 150,000 or 200,000 rpm?) and self-destructing.
> Alan
> ----- Original Message -----
> From: "Michael Sylvester" <msylvester at>
> To: <turborotary at>
> Cc: <200q20v at>
> Sent: Friday, May 20, 2005 10:10 PM
> Subject: Stray vacuum line
> The spring alone will allow only 1.4bar.
> To get greater than 1.4bar the ECU needs to pulse the WGFV.
> If the spring were set to allow 1.8 bar of boost, you would certainly
> destroy the engine in short order.
> Mike Sylvester
> --------------------
> Thanks for the response, the end of the hose is cracked, so it makes
> sense that the heat caused it to deteriorate and fall off the bypass
> valve.Though, if the wastegate frequency valve is bypassed, shouldn't
> the wastegate only open when the boost equals whatever the internal
> spring is set to (which I assume is 1.8 bar?)
> _______________________________________________
> 200q20v mailing list

More information about the 200q20v mailing list