Bill Zaleski wrote:

On Sun, 13 Aug 2006 14:19:17 -0700, Jack Allison
wrote:

Bill Zaleski wrote:

I have had the Air Plains O-360 conversion in my 172N for 16 years
(3500 hours now). I am an A&P and IA. The Air Plains documentation
is much better, the installation is easier, and the product support is
great. It makes a poor man's 182 out of a 172, No complaints. Penn
Yan is right in my back yard, but I don't regret getting my STC from
the Kansas facility.

A '65 C172 that I used to rent had their Air Plains conversion combined
with a Powerflow exhaust. Overall performance seemed comparable to a
new 172SP. Given my experience, if I was facing engine
rebuild/replacement on a similar C172, I'd consider the superhawk
conversion.

I had the Powerflow exhaust on my 0-360. There was absolutely no
measurable increase in power. This measurement was carefully done
using temperature and density altitude corrections. No static
increase in RPM, hence no increase in power. No increase in airspeed
or climb performance. I had over 3500 hours of experience in that 172
prior to the exhaust install. I sent it back and got a refund. At
least I didn't pay an A&P about $700 to put it on, then take it off
again. It MAY give a performance increase on some engines, but not on
my O-360.

If this is true then that's certainly disappointing. Though it
actually transpires the powerflow is cheaper than a new Cessna exhaust
so we are going with the Powerflow anyway.