Power Flow Tuned Exhaust System

[Second Air Force]

Has anyone on WIX had any experience with the Power Flow tuned exhaust system? With the ever increasing cost of avgas I am trying to decide if an upgrade to our old M20E (200 h.p. Lycoming) would be worthwhile. I have searched the web and found both good and so-so comments. If anyone here has any real-world experience with this system (from both maintenance and flight ops viewpoints) I would appreciate feedback.

Thanks in advance,
Scott

[bdk]

No direct info, but just some accounting things to consider:

Do they have believable test data to prove a change to the BSFC, or are they just making an unsubstantiated claim (snake oil)?

If you can't recover the cost in a couple of years, I'm not sure I would spend any money on it. You would be replacing your existing exhaust which likely has life remaining (I'm guessing). If your exhaust was shot and the cost was the same or only slightly higher it might make more sense (assuming there was a documented benefit).

You can also get improved economy through other methods such as fixing any rigging problems (flaps and control surfaces), fixing leaky door seals (including the baggage compartment door), a top overhaul, injector matching, flowing the cylinders, fixing engine baffling, repainting, etc.

Of course for free, you can remove excess weight (extra bottles of oil) and don't top off for short flights.

[bdk]

Rats! The dreaded double post...

Last edited by bdk on Mon Apr 21, 2008 11:43 pm, edited 1 time in total.

[Second Air Force]

Brandon,

Thanks for the input. To answer some of your thoughts, we are already pretty efficient as-is (150/155 kts at 10/10.5gph). Our airplane has gap seals, cowl closure, and is rigged about as close to perfect as I can get it. About the only airframe mod we probably should have done was the 201 windshield, but I didn't want to change the appearance of the airplane from stock any more than necessary, and avionics access is terrible with the sloped windshield.

I have wondered about the "snake oil" aspect of the performance improvements, and that is why I started this thread. Our stock exhaust is only a couple of years since overhaul, so no action is needed, but I value the opinion of the WIX community and thought I'd see if anyone was overjoyed with this mod. Thanks for your two-cents worth!

Scott

[retroaviation]

Scott, a friend of mine took his Piper Arrow to a "well known" facility for speed mods a while back and had grandious dreams of making his once sluggish Arrow into a high speed, low drag, fuel savin' machine. He got cowlings, wheel well gap seals, the works.

The result? 4 knots

The cost? Well, in his disappointed words, "A knot per thousand dollars."

Don't believe everything you hear/read about these mods unless there is absolute proof of it and it's bang for the buck.

Just my $.02 worth.
Gary

[A36pilot]

I have heard great things about this system but have yet to fly behind one. I knew a guy who had one on his cherokee 140 and he had nothign but good things to say about. also, speaking to a few owners at Sun n' Fun this year also echoed his comments. In addition they have a 60 day test program where if you don't like it you can return it for a fulll refund.

In my experience I just found out one of my partners just bought one to put on our cherokee. I think the money could be better spent on other things but he wanted it, and hes paying for it, so i am on board (he wanted it really bad). to me you can put a dress on a pig but its still a pig. We should have the system up and running in about a month so i will report back. I would also like to hear from others who have bought this mod.

[Airlift]

My flying club put a power flow system on one of its Cessna 172N's when they first came out. On the original exhaust the engine would only reach 2300 RPM on takeoff, now it has no problem reach 2500 rpm, and the climb rate improved. I don't think anybody said it was going much faster, and I don't think there was much difference in fuel consumption.

At idle on the ground the power flow system sounds much more like a Harley. It sounds more like the O-540 in our C-182RG.

On an aircraft with a constant speed prop your "mileage" or noticeable effects may be different.

[Second Air Force]

Thanks for the information, guys.

I've pretty much decided to stay with the stock exhaust. A fellow M-20E owner installed one, and with the improvements he claims to have made, it would take many years to get a positive return on the investment.

Scott

[bdk]

Sounds like you were smart not to make an impulse buy!

Have you tried sticking a magnet on the fuel line yet? I hear that aligns the electrons in the fuel and reduces fuel consumption because the fuel can flow through the line with less drag.

[Airlift]

If your exhaust system doesn't pass annual inspection and is in need of repairs it's probably better to get the tuned exhausted over the vanilla version.

But, the performance change wasn't motivating enough to upgrade our other C-172N.

[A36pilot]

We finally got out powerflow installed and signed off on our PA-28 last friday. I flew it for the first time over the weekend and was pretty impressed. It was about 95% and 90% humidity The rate of climb was much stronger then before and it seemd to hold the ROC to a much higher altitude. i was surprised that you could actually feel the airplane pulling a little bit more. I only put about 1.2 hours on it but I am excited to do some xc flights to see if the fuel burn is actually lower at the same airspeed.


I am not sure if i would make this mod if I didn't need a new exhaust uinless I had 5k burning a hole in my pocket. So far so good and I am pretty impressed.

I

[Second Air Force]

Good gravy, Brandon! Don't you know to use three wooden clothespins on the fuel line to achieve impressive results and get rid of that pesky hard starting that the injected Lycoming is so famous for?

Seriously, though--I'm one of the cheapest SOBs around, just ask Gary sometime. Our airplane is already pretty efficient and I had the exhaust overhauled not too long ago, so we're going to save the money for the rainy day that is just around the corner. (I work for an airline--for now, anyway ) I'm glad the system seems to be working on your bird A36pilot, and it will be interesting to see some fuel burn figures if you'd care to update us.

Thanks all,
Scott

[A36pilot]

Here are some of the numbers quick and dirty, I will update this after I get some more time on it. Also, my plane has the 160hp ram conversion.

Stock (when new) Modified
Horsepower: 150 183
Top Speed: 123 N/A
Cruise Speed: 117 130ish
Stall Speed (dirty): 48 48


Rate Of Climb: 660 fpm 1000 - 1500fpm
Ceiling: 14300 ft N/A

I did a few takeoffs and I was consistantly getting 1500fpm for the first 500ft then it settled down to 1000fpm up to 4500ft. I was at tabs and the only one on board.

[US185damiani]

The Power flow system works in the same way a set of headers works on an automobile. it frees up the exhaust. The gains in performance come from the elimination of exhaust system back pressure.

For example when a Lycoming IO-360-A3B6D from a Mooney 201 is tested on the test cell at the factory, it runs say to the spec of 200 HP. when it is installed on the airplane, it will have an induced power loss with the restrictive factory exhaust system of as much as 10% sometimes. sometimes even more. A great example is the can of worms exhaust on a Cherokee 140.

Since it is a Given the exhaust system imposes restrictions which will induce a power loss, one way to make up this airframe induced power loss is to add a system such as the Powerflo. kind of like headers on your
Hot Rod.

Thus the change comes from uncorking the exhaust system and allowing the exhaust gasses to flow freely.

[BigGrey]

I flew an older 172 that had the tuned exhaust put on. It did make a difference as noted in climb performance. I have no idea about fuel burn or other actual numbers. That 172 quickly became the most booked older 172 at the flight school.

Les