Quote:
Originally Posted by bmwme  How much boost can a stock engine take? |
With a good tune 15-17 psi daily. I dogged the $hit out of a M44 for 76K miles then used that motor as a core. That motor had approximately 180K total miles when I used it as a core. The shop (Metric Mechanic) said that core was in very good condition with miles left on it.
My opinion: Major factors that destroy turbo M4x motors.
1st and the main reason most of these motors "self destruct" is incorrect tuning or a bad tune including injectors that can't flow enough fuel for the additional air being packed into the motor under boost.
2nd is the "Money Shift", stock rotating assemblies on the M4x are ok but don't like the very high RPM that happens during the money shift. Also stock valve springs can "float" during the money shift causing the piston to contact the valve.
That is about all I know about issues and max boost for the stock motor. Maybe some other members can add to the list of issues. I've been lucky and have not had too many issues running high boost.
Best, John S