of averaging 35mpg on his Type IV engine recently...
I hadn't heard this, and it seems really unlikely to me. Here we have
a really
similar engine, but with larger displacement, larger swept diameter in
the same
number of piston rings (I don't know about the stroke.) The larger
displacement
should give you greater pumping losses, and the larger rings would
give you
larger friction losses there (unless the bore is smaller...) so I just
don't
see how you can make this statement unless you're also doing something
else
which you could do to the type 3 engine, too, and get even better
mileage.
Comments from those of you who already have type 4 engines?