Include

[Hoss350]

[ QUOTE ]
The supercharger robs power from the crankshaft to generate the boost thus decreasing fuel efficiency. Why take power from the crank that can go to the flywheel when you can just use free energy in the exhaust?

The supercharger's boost also does not change based on load, only with engine RPM.

[/ QUOTE ]
Period. [img]/ubbthreads/images/graemlins/biggrin.gif[/img] Well said.

The big one that is one here is that again, the supercharger boost does not change based on load, only on engine RPM, so that really sucks for diesel engines that redline at 1800 RPM. With a turbo, you could feasibly be making maximum boost at any RPM you want (depending on setup, turbo map, etc). This means that you don't need to be at redline to get maximum boost from the charger.

Also, IN GENERAL (this isn't absolute, so no one needs to get on here and prove me wrong with one exceptional example) the supercharger makes power at the expense of efficiency. Typically, you can see loads from a super heading towards 25% of NA engine rating. There is a net gain of horsepower, but at a loss of total efficiency.

A turbo, on the other hand, generally creates a net GAIN in efficiency, because the only load it places on the engine is an amount of exhaust backpressure, which is generally in the 2 to 8 percent total NA rating range.

So, in an industry where one half of one mile per gallon can mean millions on the bottom line of a big enough company, power with efficinecy dominates the day.