Exhaust decisions / PowerFlow debate

[AlexLev]

Thought I'd open a can of worms...

AWI-AMI currently has my stack and instead of the $700 I thought it would cost, they said some of the risers have pitting so they are now quoting

Option 1: $1446 for the muffler + risers overhaul.

Option 2: The other option is to get a system from Knisley for $2300. 3 week turn around time. Comes with a new tailpipe too.

Option 3: Third option is a PowerFlow for $4600 (potential 400 rebate after SunNFun).

With a G model, a PowerFlow is tempting -- could be a way to get better performance on the 180hp engine. I currently true 136-138KTS at altitude, and can get 142-144KTS at 3500ft running at 24sq. Having an extra 4 knots would be useful and the extra climb performance could be helpful, especially with a trip out west planned in a few months. However, not sure if PowerFlow would cause more cabin noise, more wear on airframe...and the extra maintenance every annual sort of sucks too. Plus the price is about 3X what an exhaust overhaul would cost me, so I am not sure it makes financial sense either.

What would you choose? As exciting as a PF would be, I am leaning toward sticking with the AWI-AMI overhaul mainly due to $$$, but thought I'd see what people's thoughts were.

Edited April 3, 2019 by AlexLev

[Hank]

I was in your spot three or four years ago, muffler with a huge hole but risers were good. I have a new muffler and tail pipe, and it's not Power Flow.

Good luck with yours! If you convert, please post numbers so that the rest of us can have actual data instead of only their marketing information.

[ArtVandelay]

5 years ago I went with Option 1. I don’t like how the PF exhaust sticks out.

It’s so bad the cowl flaps can’t completely close:

 

Tom

 

[Prior owner]

I wish there was some real, independent data for this product, in addition to the manufacturer’s claims... 

[Culver LFA]

Power flow test results on a J

 

[Nokomis449]

I was in a similar boat with my G a few years ago.  Needed an exhaust NOW; no time to send out for a rebuild/OH.  No one in the U.S. had an overhauled on the shelf, but Knisley had their version in stock and ready to ship.  Install was easy/straight forward.  New tail pipe is longer than stock, similar in looks to the Powerflow, but the G cowl flaps are fixed and there's no interference.  I don't have before/after numbers, but I swear it's 4-5 knots faster.  I questioned Knisley about the extra performance, and all they'd say is that it wasn't certified with performance claims, so they can't comment on it.  Per the 3-way GPS speed test at 6,000, 7,000, and 8,000 ft I true out at 143 knots at cruise settings, which is not too shabby for "The slowest Mooney model".  You might ask them if they can help you make a decision by lowering their price; seems mine was $1,700-$1,800 a few years ago.  I liked the fact that theirs was a totally new exhaust replacement from risers to tailpipe; no worries about repairing/replacing something today and something else tomorrow.  (*Exception: you'll re-use your existing heater shroud.)

Another advantage to the Knisley over stock is that the stock muffler is "ribbed" like a soup can, with the heater shroud resting against the ribs.  Inspection requires the heater shroud to be removed to inspect the muffler.  The Knisley uses short standoffs welded in rows to hold off the heater shroud.  Simply loosening the shroud and running a cheap borescope camera up and down the rows allows you to inspect/video the entire muffler without removing the shroud.

Good luck with whatever you decide.

[Yetti]

A&P Mooney owner put a powerflow on his E model.   Took it off and sold it since it did not increase anything.    I would think on the carburated models there would be some improvement.

[Culver LFA]

33 minutes ago, Yetti said:

A&P Mooney owner put a powerflow on his E model.   Took it off and sold it since it did not increase anything.    I would think on the carburated models there would be some improvement.

I wonder why he would sell it rather than return it, did he buy low and sell high to make a quick buck?

"If within 60 days from the date of the first flight after installation the customer is dissatisfied for any reason, they can return the system to Power Flow Systems and they will be entitled to a full refund of the purchase price of the system (exclusive of shipping charges and labor) once the system has been received ..."

[Bob_Belville]

I am puzzled about the tail pipe issue. The PFS on my '66E has a decent rake... I have had to replace rubber hangers a couple of times and would suggest that at least with the E there is no problem using the hangers and the swivel fitting to swing the tailpipe backward. 

[Culver LFA]

@Bob_Belville  I believe his PFS is a GEN 1 version and yours is Gen 2?

[Bob_Belville]

13 minutes ago, Culver LFA said:

@Bob_Belville  I believe his PFS is a GEN 1 version and yours is Gen 2?

I think you're right, the J had to get the Gen 1, probably because of the cowl flap differences. I don't know if that's still the case. Lee Fox has a J with a Lopresti cowl and PFS custom fitted a Gen 2 to work with that cowl.

[Yetti]

49 minutes ago, Culver LFA said:

I wonder why he would sell it rather than return it, did he buy low and sell high to make a quick buck?

"If within 60 days from the date of the first flight after installation the customer is dissatisfied for any reason, they can return the system to Power Flow Systems and they will be entitled to a full refund of the purchase price of the system (exclusive of shipping charges and labor) once the system has been received ..."

Maybe ebay does not have the same policy.....

[cctsurf]

I appreciate my powerflow.  I'm not going to make performance claims, but I believe them to be true, I have used tuned exhausts on snowmobiles and for other motor sports, they do make power.  I also note that my installation is not nearly as ugly and out in the wind as the one pictured  above.  I will also mention a couple of negatives to the powerflow:  1. The scat tubing will have to be re-routed (and lengthened) for the install.  2. There really isn't a muffler on the powerflow.  Yes, there is a glasspack, but it really doesn't do much for sound reduction.

[KSMooniac]

I've read a lot of positive 172 owner PIREPs for their PF installation on the older carb'd models re: performance boost. I've read very few for fuel injected Mooneys... If I had a C or G I'd be very tempted, or at least more than I am as a J owner.

Sent from my LG-US996 using Tapatalk

[takair]

9 hours ago, AlexLev said:

Thought I'd open a can of worms...

AWI-AMI currently has my stack and instead of the $700 I thought it would cost, they said some of the risers have pitting so they are now quoting

Option 1: $1446 for the muffler + risers overhaul.

Option 2: The other option is to get a system from Knisley for $2300. 3 week turn around time. Comes with a new tailpipe too.

Option 3: Third option is a PowerFlow for $4600 (potential 400 rebate after SunNFun).

With a G model, a PowerFlow is tempting -- could be a way to get better performance on the 180hp engine. I currently true 136-138KTS at altitude, and can get 142-144KTS at 3500ft running at 24sq. Having an extra 4 knots would be useful and the extra climb performance could be helpful, especially with a trip out west planned in a few months. However, not sure if PowerFlow would cause more cabin noise, more wear on airframe...and the extra maintenance every annual sort of sucks too. Plus the price is about 3X what an overhaul would cost me, so I am not sure it makes financial sense either.

What would you choose? As exciting as a PF would be, I am leaning toward sticking with the AWI-AMI overhaul mainly due to $$$, but thought I'd see what people's thoughts were.

Recently did option 1. It is essentially all new.  Started off like you, just a muffler, but then all but one riser and tailpipe.  They bead blast them when they inspect them, so they get thinner.  In fairness, if the muffler is shot, the risers are in an even hotter region with more erosion. I’m satisfied with it so far and the price was better than the rest.  My old favorite was Dawley, but their prices went up and lead time went way up.

[AlexLev]

7 hours ago, Nokomis449 said:

I was in a similar boat with my G a few years ago.  Needed an exhaust NOW; no time to send out for a rebuild/OH.  No one in the U.S. had an overhauled on the shelf, but Knisley had their version in stock and ready to ship.  Install was easy/straight forward.  New tail pipe is longer than stock, similar in looks to the Powerflow, but the G cowl flaps are fixed and there's no interference.  I don't have before/after numbers, but I swear it's 4-5 knots faster.  I questioned Knisley about the extra performance, and all they'd say is that it wasn't certified with performance claims, so they can't comment on it.  Per the 3-way GPS speed test at 6,000, 7,000, and 8,000 ft I true out at 143 knots at cruise settings, which is not too shabby for "The slowest Mooney model".  You might ask them if they can help you make a decision by lowering their price; seems mine was $1,700-$1,800 a few years ago.  I liked the fact that theirs was a totally new exhaust replacement from risers to tailpipe; no worries about repairing/replacing something today and something else tomorrow.  (*Exception: you'll re-use your existing heater shroud.)

Another advantage to the Knisley over stock is that the stock muffler is "ribbed" like a soup can, with the heater shroud resting against the ribs.  Inspection requires the heater shroud to be removed to inspect the muffler.  The Knisley uses short standoffs welded in rows to hold off the heater shroud.  Simply loosening the shroud and running a cheap borescope camera up and down the rows allows you to inspect/video the entire muffler without removing the shroud.

Good luck with whatever you decide.

Aw, shoot. Wish I didn't read that, ha.

I ended up going with option 1 simply because they AWI already did the work on my muffler and I'd feel like a bit of a dick if I told them to kick it now, that and Knisley had a 3 week development lead time for the unit, whereas AWI was already practically done with mine. 

Thanks for all the feedback.

[bonal]

34 minutes ago, AlexLev said:

Aw, shoot. Wish I didn't read that, ha.

I ended up going with option 1 simply because they AWI already did the work on my muffler and I'd feel like a bit of a dick if I told them to kick it now, that and Knisley had a 3 week development lead time for the unit, whereas AWI was already practically done with mine. 

Thanks for all the feedback.

Respect 

[tangogawd]

Did mine last winter. option 1. AWI did an amazing job. The "repair" is new stuff. I really don't buy into PF, not for what they cost. I know plenty of owners in other makes switched back to more stock style exhausts. and, at least my E, removal of the shroud was easy, much faster than using a bore scope. and much more thorough inspection. 

[Nokomis449]

14 hours ago, tangogawd said:

Did mine last winter. option 1. AWI did an amazing job. The "repair" is new stuff. I really don't buy into PF, not for what they cost. I know plenty of owners in other makes switched back to more stock style exhausts. and, at least my E, removal of the shroud was easy, much faster than using a bore scope. and much more thorough inspection. 

While techniques and opinions will vary, I'm concerned about the statement "...much more thorough inspection".  Attached are screengrabs of last year's 8 minute video inspection.  In what way(s) is this method inferior to yours, so I can inform the IA?

 

 

[Guest]

I think that unless you have a borescope with tens of thousands of dollars a visual inspection of the muffler is best accomplished with the cowls off and the muffler shroud removed.

Clarence

[Raptor05121]

On 3/25/2019 at 1:15 PM, ArtVandelay said:

5 years ago I went with Option 1. I don’t like how the PF exhaust sticks out.

It’s so bad the cowl flaps can’t completely close:

Tom

 

 

Tom, per the maintenance manual, the cowl flaps are not supposed to completely close. There's supposed to be a 1-2" gap (depending on model) when in the full-close position

[tangogawd]

I don't want to discredit a fellow IA. They may be very skilled with a scope.

For me its hard to see around each stud, and every bit of weld around the edges where the caps are welded to the core. There are a lot of places where a small leak can go missed. 

I will admit that my memory is that of a gold fish..... I don't recall off the top of my head if mooney has an AD on the exhaust, but many planes do, such as pipers and champs. And it specifies to remove that shroud for inspection. If you think the Mooney is hard.... try inspecting a piper pacer every 50 hrs!

A scope is an amazing tool, I personally have invested well over $2000 in them over the years. They are a great tool for inspecting things that would otherwise never be seen... Spars, cylinders, cams, turbine blades...... but they don't see everything, and I don't believe an exhaust shroud is all that difficult to remove...... besides, most shrouds have half the hardware missing or loose by the time it gets to me.

[ArtVandelay]

Tom, per the maintenance manual, the cowl flaps are not supposed to completely close. There's supposed to be a 1-2" gap (depending on model) when in the full-close position

Not for the J:

“Adjust both the left and right cowl flaps so that in

the closed position the outboard trailing edges are flush with the lower engine cowling”

 71-11-02

 

Tom

 

[Oldguy]

1 hour ago, Raptor05121 said:

Tom, per the maintenance manual, the cowl flaps are not supposed to completely close. There's supposed to be a 1-2" gap (depending on model) when in the full-close position

5 minutes ago, ArtVandelay said:

Not for the J:

“Adjust both the left and right cowl flaps so that in

the closed position the outboard trailing edges are flush with the lower engine cowling”

Tom

While that is what is in the service manual (71-13-01), discussions at the Mooney Summit with Bob Kromer brought out the fact there is a reverse flow from the cowl openings when the cowl flaps are adjusted per the manual. Test flights found with a cowl flap opening between 0.5" - 1.0" when the cowl flaps are closed, the J model has lower CHTs and picks up a knot or two in speed. I believe Alex is referring to Bob's recommendation.

 

 

[ArtVandelay]

While that is what is in the service manual (71-13-01), discussions at the Mooney Summit with Bob Kromer brought out the fact there is a reverse flow from the cowl openings when the cowl flaps are adjusted per the manual. Test flights found with a cowl flap opening between 0.5" - 1.0" when the cowl flaps are closed, the J model has lower CHTs and picks up a knot or two in speed. I believe Alex is referring to Bob's recommendation.
 
 

This is were my J is different I think:
Both cowl flaps are the type with contouring for the muffler, I obviously only have the muffler on the right side, so even with cowl flaps fully close, there is opening for airflow.

Anyone with a J have this?


Tom