"mm" wrote in message
...
OT An interest in hemi engines stirred me, and I found this site

http://auto.howstuffworks.com/hemi1.htm

which gave as the advantage of the hemi that 2 valves could be placed
opposite each other, instead of next to each other, and thus could be
made bigger, for more power.

I had assumed that the advantage was with fewer corners, etc. in the
combustion chamber, there was less chance of power-losing knocking.

OTOH, now it occurs to me that if the combustion chamber is domed, it
might be bigger than one with a flat top, leading to a lower
compression ratio and less power.

So why are hemi engines powerful?

The hemi design was great in it's time pre-OHC. Other designs are as good or
even better. What makes them so popular to day is their reputation and
advertising hype. The pentroof allows four valves per cylinder. That have
been many other types of head designs that just never had the advertising
catch that the hemi achieved.