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To Powerflow or not to Powerflow - That is the question


Bart Chilcott

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Just now, madjano said:

Can't say enough good things about AWI. On time, as quoted, and fit perfectly. The welding really is art. Not knocking Bob or PF, I just don't like the looks of the tail pipe. Not so bad on Mooney's but I think they look ridiculous on 172s. Guess I'm in the CB club.

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Well, if looks are what polishes your plow... but it is my understanding that the C172 performance benefits tremendously from the PFS.

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Well, if looks are what polishes your plow... but it is my understanding that the C172 performance benefits tremendously from the PFS.


It's a vintage Mooney, looks are a big part of the equation for me. And a polished bird will pick up a knot for free.

My point to the OP is there are some good weld shops out there with a fairly quick turnaround if not in stock. I think PF had one on the shelf if I wanted it in a couple days, it's all about choices.

I'm sure Dmax has his opinion too.

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Based on this thread, the current offering of the Powerflow exhaust for M20C at 0.7 amu discount is tempting. My exhaust is old as heck. And it would be great if my #2 could run cooler - hadn't realized this was a potential benefit - everything else has failed and I can't make the doghouse any tighter. But alas my aged exhaust seems just fine, and so I may be too much a cb. And there is that maintenance induced failure thing. 

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The history of Mooney exhausts includes two different designs internally.

It may be helpful to know which one you have.... 

The newer one was better for heat transfer?

The change was mid 60s?

My 65C had some internal parts become loose. It's exhaust tubes had an orange peal effect.  Nothing resembling the smooth tubes that they started out as.... the tail pipe was eroded and the seam needed to be welded.  It all got paper thin over the years...

As far as lowering back pressure goes...Its use is good to improve hp. But, it takes out the residence time the exhaust has in the muffler.  Less time = less heat transfer.  To put the heat transfer back, additional surface area may be used.

The PFe got a few decades to improve over the original design.  I bet they did a good job. But, I would ask a few questions to feel better about my decision before pulling the buy trigger....

Sorry to bring up more questions than answers.  Hopefully this gives you some things to look for...

Best regards,

-a-

Edited by carusoam
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The history of Mooney exhausts includes two different designs internally.
It may be helpful to know which one you have.... 
The newer one was better for heat transfer?
The change was mid 60s?
My 65C had some internal parts become loose. It's exhaust tubes had an orange peal effect.  Nothing resembling the smooth tubes that they started out as.... the tail pipe was eroded and the seam needed to be welded.  It all got paper thin over the years...
As far as lowering back pressure goes...Its use is good to improve hp. But, it takes out the residence time the exhaust has in the muffler.  Less time = less heat transfer.  To put the heat transfer back, additional surface area may be used.
The PFe got a few decades to improve over the original design.  I bet they did a good job. But, I would ask a few questions to feel better about my decision before pulling the buy trigger....
Sorry to bring up more questions than answers.  Hopefully this gives you some things to look for...
Best regards,
-a-


Is this an upgrade we can install to help the back pressure as well???:)
78e3256c5349c805fa0aa6b07c573fee.jpg



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If that is a set of valves, one intake and one exhaust...

1) Intake: That may be the backfire promoter valve?

2) Exhaust: That may be the power reducing flame thrower valve?

This is my attempt of using some limited knowledge and combining it with some limited sense of humor.

it would probably take a really good muffler to restore engine power to an engine outfitted with those valves.  :)

Where did they come from?

Best regards,

-a-

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  • 1 year later...
On 4/10/2017 at 8:17 PM, Bob_Belville said:

I've had PFS on my M20E for 5 years. 

  1. I do not understand the noisy complaint, mine has the extended tailpipe and I don't think it is louder than conventional but I do have a real David Clark headset.
  2. I do the slip joint lube at annual, it takes no longer than what ought to be done on a conventional muffler. 

Today I returned from PDK to MRN at 9000' pulling 22.1" MAP. 70% HP. I would credit PFS and Mooney Power Boost which added 1.2" MAP when I pulled it out. 

What is this Mooney power boost that you speak of, how much power does it add, and how much is it!?

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37 minutes ago, Supercop0184 said:

What is this Mooney power boost that you speak of, how much power does it add, and how much is it!?

The ram air bypass of the air filter was standard equipment on Es, Fs, and early Js. I'm pretty sure it was never available for carbuetored Cs.

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On 4/11/2017 at 9:00 PM, Bob_Belville said:

Well, if looks are what polishes your plow... but it is my understanding that the C172 performance benefits tremendously from the PFS.

In the late 90s early 2000s I used to rent various aircraft from Phoenix Aviation (Middle River Aviation) at Martin State north of Baltimore. They had all manner of fixed gear singles on the rental line.  There was an O320 powered 172 with one of the earliest PFS exhausts.  The Exhaust really woke that airplane up compared to the other Lyc powered 172s. Shorter TO roll and significant climb improvement (~200fpm).  Despite being ugly (original 1970s green and orange trim), it was often the first scheduled because of how it performed.

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35 minutes ago, Shadrach said:

In the late 90s early 2000s I used to rent various aircraft from Phoenix Aviation (Middle River Aviation) at Martin State north of Baltimore. They had all manner of fixed gear singles on the rental line.  There was an O320 powered 172 with one of the earliest PFS exhausts.  The Exhaust really woke that airplane up compared to the other Lyc powered 172s. Shorter TO roll and significant climb improvement (~200fpm).  Despite being ugly (original 1970s green and orange trim), it was often the first scheduled because of how it performed.

That matches the testimony I hear from Lynn (@AGL Aviation re C172s here. And he says the PFS lasts 2000 hours in a flight school environment - 3 or 4 times that of stock mufflers. 

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On 4/10/2017 at 6:55 PM, Whiskey Charlie said:

D Max has informed me that my stock exhaust on my 65 M20E has passed away.  In considering a replacement or repair, I've looked into a complete rebuild ($1800.00) or a Powerflow system ($4,000.00).  I've been told by my shop that he has have removed as many of the Powerflow systems as he has installed (excessive noise seems to be a major complaint)  I've read about the advantages of the Powerflow but I'd also like to hear from anyone who has had theirs removed and gone back to stock and why.  I figure if the shops are removing 50% of the sysytems, someone will surely be able to chime in.  Thanks in advance for your input!

Powerflow says a stock exhaust leaves behind about 20% of spent gases while their exhaust allows almost 95% intake of pure fuel air. Difference being about 15%.

So they are being removed because a 15% difference at best does not warrant a 222% in cost over stock.

Edited by m20kmooney
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9 minutes ago, m20kmooney said:

Powerflow says a stock exhaust leaves behind about 20% of spent gases while their exhaust allows almost 95% intake of pure fuel air. Difference being about 15%.

So a 15% difference at best does not warrant a 222% over stock cost increase! This is why they are being removed.

You make no sense what so ever. This argument is an argument against purchasing the PF system. It's not like you get your money back if you remove it. So no one would remove a working system just because the improvement was small compared to the cost. The cost is spent at that point.

Try again.

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1 hour ago, gsxrpilot said:

You make no sense what so ever. This argument is an argument against purchasing the PF system. It's not like you get your money back if you remove it. So no one would remove a working system just because the improvement was small compared to the cost. The cost is spent at that point.

Try again.

Agree that the argument makes no sense.. I don't fully follow the math either.  But I think the point being made is how well the PFS scavenges the spent exhaust gases when compared to the stock exhaust. 

One note though.. if you don't like it, you can return it 60 days after the first flight (http://www.powerflowsystems.com/warranty.php)  You would be out the labor and shipping of course.  

I was not a fan of the different tone the engine produced.  The sound was a bit more raspy, and a slightly higher pitch compared to the stock exhaust on the C I owned.  But I quickly got use to it, and really enjoyed 15-20 degrees cooler CHTs and the extra power during climb.  Didn't have the plane long enough to really get some good fuel flow numbers...but you're only going to save fuel if you fly slower... which I did not.

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On 11/14/2018 at 12:35 PM, gsxrpilot said:

You make no sense what so ever. This argument is an argument against purchasing the PF system. It's not like you get your money back if you remove it. So no one would remove a working system just because the improvement was small compared to the cost. The cost is spent at that point.

Try again.

Actually you do get your money back if removed and returned during the trial period (30 days?)....

Edited by Shadrach
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1 hour ago, Shadrach said:

Actually you do get your money back if removed and returned during the trial period (30 days?)....

That's true and it's actually 60 days. But that's not the situation that was referred to here. 

If PF was taking back 50% of the systems they sold and giving refunds, they'd have been out of business by now.

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On 11/14/2018 at 1:53 PM, jasona900 said:

Agree that the argument makes no sense.. I don't fully follow the math either.  But I think the point being made is how well the PFS scavenges the spent exhaust gases when compared to the stock exhaust. 

One note though.. if you don't like it, you can return it 60 days after the first flight (http://www.powerflowsystems.com/warranty.php)  You would be out the labor and shipping of course.  

I was not a fan of the different tone the engine produced.  The sound was a bit more raspy, and a slightly higher pitch compared to the stock exhaust on the C I owned.  But I quickly got use to it, and really enjoyed 15-20 degrees cooler CHTs and the extra power during climb.  Didn't have the plane long enough to really get some good fuel flow numbers...but you're only going to save fuel if you fly slower... which I did not.

Which concepts of arithmetic give you the most trouble? Multiplication and percentages? The point is how poorly the PFS scavenges the spent exhaust gases when compared to stock in view of its cost.

 

Edited by m20kmooney
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17 minutes ago, m20kmooney said:

Which concepts of arithmetic give you the most trouble? Multiplication and percentages? The point is how poorly the PFS scavenges the spent exhaust gases when compared to stock in view of its cost.

They are effectively out of business. They are grossly overpriced because they don’t exactly fly off the shelf.

Complete lie. They've been around since 1977 and doing well. I've never owned a Mooney for which the Powerflow was available, but if I did I would seriously consider their system. 

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7 hours ago, gsxrpilot said:

That's true and it's actually 60 days. But that's not the situation that was referred to here. 

If PF was taking back 50% of the systems they sold and giving refunds, they'd have been out of business by now.

I'm not sure of that. Do you have some insight into their business model?  My math tells me that if the sell more than one per business day (>260 units a year) they likely have the margins to handle a high return rate (maybe not 50%) as long as the returned units can be sold as new (which I bet they can with minimal cleaning and reconditioning).  If they could not be resold as new, Powerflow would likely offer "demo" exhausts at a slight discount, which I don't think they do. 

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1 hour ago, m20kmooney said:

Which concepts of arithmetic give you the most trouble? Multiplication and percentages? The point is how poorly the PFS scavenges the spent exhaust gases when compared to stock in view of its cost.

 

Well, I was never really good at calculus, but I don't think that is what you are referring to.  

Your comment about the value of an exhaust costing 222% more than the stock is subjective.  If that is not worth it to you, then don't buy it.  However, there are several other (documented) improvements that in my opinion, justify the extra cost.  

I'd be curious to see what statistics you have to support your comment that implies they are being removed in mass numbers.  Having spoken to their general manager at Sun N Fun, they do get one returned every now and then, but it seems overall, they have a fleet of happy customers flying with a PFS.

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