I think your missing the fact of turbo lag.
On top end you would probably gain about 4" of pitch (600 rpms or so).
On the hole shot that would kill you since you don't have the power at 600
to 1000 rpms to turn that big a prop.
Now, a torque shift would work but the power on top end would tear the
gears/springs out of it. Plus it is not the most efficient for top end
which is what your looking for.

Racers use them but they are not looking at hole shot but rather sustained
high end speed.

--
Tony
My boats and autos - http://t.thomas.home.mchsi.com



"Hemicuda" wrote in message
om...
Has anyone tried turbocharging a 5.0 L or 5.7 L Merc engine in this
group? I know that it used to be done back in the 70's but I can't
find any info about any current set-ups. From what I can find it
seems like it might be advantageous by allowing you to run a better
pitch prop for higher top end speed and reduced RPMs for cruising
which seem like it would be good for efficiency and engine life. I
don't think it would drop your low end that much because the
compression on stock marine engines is close to 9:1 and you can
probably run 10PSI of boost on 8.5:1 engines. Any thoughts or
comments? I am more familiar with turbo applications on cars so I
might be missing something. Thanks for the help!