STS Turbo System on 4.4L

[HPIA4v2]

From my limited experience, I wouldn't buy turbo kit w/o S/W nor peripherals, way too much headaches unless you really like tweaking it all the time.

I upgraded my Audi KO3 to KO4 and needs different MAF, several S/W update from GIAC and fuel regulator, not to mention cooler spark-plugs etc to remedy surging issue. This is on a car that already turbo (KO3 is smaller than KO4 turbo wise), cant' imagine doing an NA engine to turbo.

BTW, GIAC is a pro company doing many developments on Audi/VW/BMW and it still not plug and play

Then stress on xfer-case/trans cause you may launch the car from stop more often, cause it's fun.

I wonder if it's better/cheaper in long run to go with CPO X6 and get GIAC S/W to get 500HP out of it (no changes in H/W or plumbing)

[JCL]

Originally Posted by jgood

Has it been proven that these transmissions are failing due to load/power? I see a lot of supercharged 4.4's that don't seem to have many issues. A turbo would be no different, other then more torque at a lower RPM with more abrupt spooling (still not harsh though, it's not going to "shock" the drivetrain).

No, with one exception, it seems to be the opposite. Transmissions have failed for a lot of reasons on the 3.0 and 4.4 models, but those failures are just as often as not related to sensors and electrical issues. More power is going to put more heat into them, raising the duty cycle, same as towing a large load. Posters who have towed 8000+ lbs have shown that the transmissions can handle a lot without giving problems.

The exception, IMO, is the early 3.0 diesel model. They failed transmissions regularly, due to their torque. Later models got the ZF which can handle more torque than the smaller GM model.

Transfer case chains may be another issue.