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In theory, any increase in peak torque is a concern. But here in real life, we are seeing that the autoboxen are not having problems, with or without mods. Many do avoid the higher levels of possible boost or ECU staging.
You can always set a MBC to less that the max possible boost. In most cases you would have to do that anyways to avoid fuel cuts due to pressure overshoots inherent in the action of all/any ball-spring MBCs. That can be overcome very very well, simply and inexpensively, with a MBC+A. The +A is with an anticipator circuit that is a specific type of air pressure regulator that is designed for regulation of low pressures. Search for MBC+A here and on the performance BB for more background if interested. The MBC+A allows for higher boost that is solid, weather-temperature stable. The boost comes on faster and the overall engine is more responsive. The application is easy and reversable. No factory hoses are cut.
If you are in KC, I can assist in installs if desired. Another option is a SMBC that will make the turbo more responsive, but, when properly adjusted, will not increase peak torque. Easy to install and inexpensive.
When you install a MBC, SMBC, MBC+A, the turbocharger will spool up at its own pace and will not be held back (masked) by controller induced boost lag. In this situation, the turbocharger's sensitivity to intake and exhaust restrictions will not be masked. The system then responds very well to improvements such as air box duct mod, K&N filter, turbo discharge silencer removal (if fitted), TBTC mod!!, exhaust system, Viggen IC.
When you install a MBC+A, the complete setup includes pressurizing its MBC from the TB, aka 'a TB (pressure) tap'. The anticipator makes this arrangement idea, which is otherwise not obtainable with a basic MBC install, as that would applify the shortcomings inherent to ball-spring MBCs. Which begs the question of other types of MBC. The answer is that there is nothing else that works better, balls-spring types are what one needs to use. The +A simply provides perfect boost.
The turbos will spool up very fast and abruptly with these setups. This is a result of typical OEM turbo setups where the turbo is basically undersized to get boost at lower RPMs. The turbo is fundamentally undersized. So it wants to spool up fast. But the OEM boost control makes the boost 'linear'. Turbos are non-linear in nature. While this is different, most really like the change and quickly adapt with different throttle technique. Even in snow and ice there is no problem at all working the throttle as required by the situation.
posted by 68.93.19...
, Sun, 11 Jul 2004 20:52:37
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