Well, I appreciate the responses. I am familiar with aircraft engines
a little, and certainly they are regulated much more than a car engine,
and yes they do run hot constantly (although the throttle is backed off
a little once at altitude--at least in a Cessna 340).

Perhaps that is a better analogy. And I thought about that, but I
guess I wasn't putting planes and boats in the same category. Boats
don't have as much of a problem pulling over per se as planes do. But
I suppose getting stranded would be bad, possibly very dangerous at sea
for a variety of reasons. So, that makes sense. I'd like to reiterate
my ignorance about marine engines at this point.

I just noticed someone saying you can't get much more than X amount of
power from a 305, and I'm thinking hey, that's not so. Perhaps the
better statement is that it wouldn't be the best idea to stress the
engine more than that from a money, maintenance and downtime
standpoint. But, I also see some 300-400 hour boats for sale that are
5-10 years old, and I'm thinking hey, how many miles is that at 110
mph? Upwards of 44K. The G35 won't go a couple hundred thousand miles
running that hot, but it might reliably go over 40K miles at 110 mph if
most of that is fairly constant. But I get the point. I wouldn't want
to do that to the engine even if the roads allowed. And perhaps boat
engines are supposed to run much much longer than that without an
overhaul.

And if it does relate to aircraft, a lot money is involved. Of course,
they do have RAM engine upgrade options for prop plane engines. Hey,
go turbine! Well, OK that's not practical either.

I did notice that there is a marine engine built by Suzuki that is 4.0
liters and puts out 300HP. It is built for marine applicaitons,
although I don't know it's reliability. Interesting though.

As far as HP and torque curves are concerned, I don't recall. I could
research it, but nah.