I have
also experimented with a few different stall converters. I finally settled on a 2500RPM
stall instead of the factory 2200RPM. I tried a 2900RPM converter, but pointing at 45
degrees for 50 metres down the road after taking off at the lights was a little
impractical! It also robbed me of some top end grunt and highway economy...having so much
slip in the stall. The new stall is tame enough to give good top end grunt and fuel
economy yet spools up just before the tubo hits full boost allowing great take off's at
the lights.
A few
tips for VL turbo owners, to squeeze that extra bit out of their turbo (without replacing
it) are:
(1)
Where the turbo dump pipe connects to the exhaust flange there is a 2mm lip on the inside
of the dump pipe. Machining this out cost me nothing but a few hours time yet gave me 10HP
at the tyres and a noticeable drop in both exhaust and engine coolant temperature.
(2)
Connecting a straight through 3 inch muffler and removing the resonator gives a good power
increase. Fitting a straight through 3 inch resonator after the muffler creates so much
turbulance (& therefore back-pressure) in the exhaust that the power drop is almost
unbelievable (close to 20HP on my car!)
(3) On
modified EFI (chipped) cars only: When increasing boost pressure by bleeding boost before
the wastegate actuator (most common method on the VL), plumb the bleed side back into the
turbo plumbing AFTER the airflow meter. This ensures that every bit of boost generated is
ingested by the engine.
(4)On
non-modified EFI systems (not chipped): Use larger diameter bleed hoses for incresing
boost....waste more air. Whilst this sounds foolish, actually it has a beneficial effect.
Venting more air to atmosphere actually fools the computer into creating a richer fuel
mixture, thereby reducing engine pinging caused by lean-out.
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