wrote in message
ps.com...

I presume there are no (bicycle or) other pumps that are both
affordable and that could do a decent job (aid efficiency a lot more
than they reduce it).

There are lots of pumps that can pressurize the intake on an engine, they
are generally large and take a lot of power to operate which is what you
would expect when you consider the amount of air being compressed. A small
pump (like a turbo) will have to operate very rapidly (~100,000rpm) and
won't be cheap while a large pump will not have to operate very fast but
will be heavy.

it seems odd for our engines to remain
essentially oxygen starved, or to have a turbo which costs $20k and
seems to cause all sorts of reliability problems on top of it.

All engines can be considered to be "oxygen starved" since an engine
operating on pure O2 will produce about twice the power of one operating on
air. The turbosupercharger is an efficient (over 70%) pump that uses energy
that is normally wasted to operate. The turbo is very reliable, most the
problems attributed to turbos are more a function of trying to operate the
engine at high altitudes and high power where it is difficult to cool the
cylinders.

Mike
MU-2