In Reply to: THIS MAY BE A STUPID QUESTION-SUPERCHRGR & TURBOS? posted by Chad Bleakney on June 30, 2001 at 11:31:06:
The effective boost ceiling for the M62 motor is @ 6-7 psi. without modifications to the motor. (Forged pistons, compression reduction, ignition timing, intercooler, computer controlled variable rate fuel pressure, etc.) To go beyond 6-7 lbs. boost would require an intercooler to cool the air before it enters the motor. This is needed to prevent detonation, which would destroy your pistons in a matter of seconds, in an extreme instance.
To answer your question, there would be little benefit to spending the cash to do both systems, as either system could exceed the motor's capacity for "forced induction". I have been quoted between $30,000.00 to $40,000.00 just for twin turbos alone. A comparable supercharger comes in @ $6,000.00 with you doing the installation to the $14,000.00 Dinan (hopefully someday).
One thing I would recommend is an external oil cooler if you do a forced induction system to try and improve your motor's life.
In any case, the effect of such modifications is loss of warranty if your car is a CPO.
An important issue for any forced air system is the ECU re-mapping. A poor ECU set-up will make the gains from any boost system small. Many may deride me, but I would have a professional do the work, were I paying for all this, as each motor subsystem, depends upon the other subsystems in order to function properly.
Another concern is the transmission. I was quoted $3,500.00 for transmission mods, to ensure the increase in power does not destroy the automatic transmission. The other alternative is to convert to manual transmission which was quoted at $9,200.00 in parts, (excluding a custom drive shaft), and 3 days of labor @ $75.00/per hour.
I plan on a forced induction system at some point in the future. I am waiting to see who can do it right.