powerflow exhaust needs repair. who can do it?

[Super Dave]

The laws of physics simply will not allow you to decrease hp and increase airspeed.

When rop it is airflow that determines hp. Study the hp curve. What do you see? Do you still think you're seeing increased speed at peak egt?!

The only thing a tuned exhaust does is increase airflow somewhat. Air flow is a function of rpm and mp, i.e. Rop.

Does a tuned exhaust make more sense on my high revving bike? You bet! On my Mooney? No!

Who am I to wake you from your dreams! Physics will however, set you free!

Just like eating the third slice of pizza... I know I'll probably regret this, but I just can't help myself, so here goes.

Increasing airflow will result in a higher fuel flow at peak EGT or any given degree LOP. So yes, a tuned exhaust will increase HP and TAS even at peak or LOP.

[aaronk25]

Ok I got him now.....post P.F. the cowl flap linkages can be adjusted FULLY CLOSED, instead of having to leave them 3/8" open, so there is aerodynamic gains as well.

2. No where in the operating instructions does the P.F. require to be operated at WOT, so power can be reduced, to save fuel, but either way CHTs are 30f less so the P.F.is also a cooling mod too.

[Andy95W]

Gettin' out the popcorn...

[helitim]

My Powerflow experience was on a previously owned 172 with an 0-320 D2G 160 hp RAM conversion. In order to try and justify my purchase, I spent quite a bit of time and effort testing the aircraft before and after the conversion. Starting at a home field elevation of 1130' I performed a time to climb to 9500' doing my best to control the airspeed the exact same on all tests. I completed the time to climb on runway heading then landed and repeated it off the runway 180 degrees the opposite direction to try and compensate for winds aloft. That afternoon we installed the PF system and I repeated the same flight tests the next morning with temperature and winds aloft almost exactly the same as the initial flights. End results were what I expected to see. Increased climb rate of 130' fpm. The aircraft did not have a CHT or EGT gauge so, I was unable to monitor for those parameters. The oil temp settled in about one needle width lower on the open faced gauge so I know the engine was in fact running a little bit cooler. How much, I don't know. Prior to this test, I had been flying at 2400 rpm in cruise with a fixed pitch prop and burned 9.3 gph over an average of almost 200 hours. After the PF, the fuel burn dropped to 8.8 gph. At the same setting. Best I could tell, it gained between 2-3 kts in cruise. The older airspeed indicators make it a bit more difficult to quantify that number but, I do believe it increased a small amount. The most important number of all for me at the time was take-off roll. I was operating off a 2000' grass strip. The PF decreased my take-off distance almost exactly 150'. That may not sound like much but when you are coming off grass and are heavy loaded, that extra confidence was absolutely worth the cost of the system in my opinion.

You guys can argue the square root of this or that, or whatever you want. The fact is, the system works well in a Cessna 172. If and when I need a system for the Mooney, I would not hesitate to order another one.

Tim