>How does a turbo work then?  I assume that 10 PSI boost means that the
>manifold pressure is 10 PSI greater than the atmosphere pressure.  So
>wouldn't that mean that you are still making less power at altitude than at
>sea level?  Perhaps I am totally wrong here - heck this is why I am asking
>the question! :-)

I have vague memories of how they work in aircraft . . .

IIRC, turbocharged aircraft engines maintain sea level power output
until you reach the engine's "critical altitude" above which the power
output starts to drop.

I'd guess that the turbo waste gate is set to deliver more boost with
increaseing altitude until till either some internal limit is reached
or until there just isn't enough air to cram in any more.

I do know that some old aircraft (DC-4s?) had a gearshift on the
supercharger (engine driven blower) that enabled the pilots to select
more boost at higher altitude.

Doug
--
Douglas L. Urner <dlu@canishe.com>  Port Orchard, WA   +1 360 769 5565