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M20C with Power Flo & LOP


DJE22

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I’ve never seen or read what the actual horsepower gain results from adding Power Flo exhaust.

1) any specifics from users 

2) my aircraft has higher fuel consumption than most C’s (from what I am reading) but I am typically flying 75% settings....and seeing higher TAS numbers

3) (not necessarily related) Your thoughts about LOP operation in carbureted engine 

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Welcome aboard, DJE...

1) The power flow website has some good info from actual Mooney owners.

2) Realistically The PF design is good, or better than the 60s exhaust design. But not spectacular...

3) lots of cost to get the smallish gains...

4) @Hank has written a bunch regarding LOP in his M20C.  Guidance about getting as close as possible with the tools that you have... including carb heat, the secondary fuel nozzle, and turbulent flow in the carb...

5) Are you familiar with the second fuel nozzle and how to close it down?

How long have you owned your M20C?

The search function can help you find all of this.

Best regards,

-a-

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8 hours ago, DJE22 said:

I’ve never seen or read what the actual horsepower gain results from adding Power Flo exhaust.

1) any specifics from users 

2) my aircraft has higher fuel consumption than most C’s (from what I am reading) but I am typically flying 75% settings....and seeing higher TAS numbers

3) (not necessarily related) Your thoughts about LOP operation in carbureted engine 

  1. @jasona900 is a good resource on the PowerFlow. Search his posts and you'll find a lot of good detail.
  2. Why 75% settings? Or maybe what are you running at 75%? I'm pretty sure everyone around here runs their N/A engines at WOT all the time.
  3. @Hank is your resource here. But basically, it might or might not work, some of the time. But it's certainly worth trying... and if you don't succeed... try, try, again. I used to get my M20C to run LOP about 50% of the time. But when it did, the range was unbelievable. 140 knots/hr on 6.5 gph!
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welcome DJE,

What altitude are you flying at?

I usually run my C rich of peak due to the difficulty of getting an even fuel distribution from the carb. I have found that I can go LOP if i'm above 7.5K running almost WOT. what I mean by this is I go WOT then start to pull the throttle back just a bit of the stop. if you have a FF gauge you will see a slight drop in FF as you do this, the total I pull back is probably less then a 16th of an inch. it takes the throttle of the stop and induces a minor change in the airflow that seems to improve the fuel disbursement with out reducing power. as gsxrpilot said it is a hit and miss thing with carbed engines. 

Honestly what I have found for the most consistency and efficiency, I go back to the old fashioned way to lean. I lean the engine until it starts to run rough, then give the knob three turns rich. my FF is consistently around 9 gph or lower when flying at 7.5k and above approx 65% power.

Brian     

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Thanks all. Getting to know my C... have lots of time in an F (years ago) but even then we did not run engine LOP.  More recent time in a sweet RV4 with IO320 and much of my flying was LOP but it was simpler with injected engine.

@Hank, thanks for the detail. I was told (presumably by administrator) that you had written on this topic.

so far my flights have all been $100 hamburger type...within an hour +\- of my base but the plan includes some regular trips to ATL and South Georgia (from Wi)

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Though it has been claimed, I have as yet to see convincing evidence that any carb'd Mooney can run smoothly LOP on more than one or two cylinders at a time.  And when leaning that far, the lousy cooling on the Cs often becomes limiting in cruise before roughness does.  

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  • 1 year later...

Welcome DJE, I sent you a message that hopefully helps, but the majority of what I stated have been covered in this thread by others.  As far as fuel consumption goes, I tend to run a bit on the richer side.  I have always flown this way, due to the fact the the overhaul will be on my dime.  I recently flew from KSQL to KSBP.  Nice tail wind on the way down and of course had to pay for it on my return flight.  Total tach time was 3 hours, and fuel burn was 23.9 gallons = 7.97gph.  This seems to be very typical for my plane.

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1 hour ago, 1967 427 said:

...  I ten to run a bit on the richer side.  I have always flown this way, due to the fact the the overhaul will be on my dime...

Very interesting...

That's one of the reasons I run LOP:D

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On 12/11/2018 at 7:07 AM, DJE22 said:

1) any specifics from users 

2) my aircraft has higher fuel consumption than most C’s (from what I am reading) but I am typically flying 75% settings....and seeing higher TAS numbers

You have a PowerFlow installed? Then this would make sense.

I have one and love it, here's why:

Salzburg%20March%202015%20017.JPG

That is a stock 1965 C model, no aerodynamic improvements but it has the PF exhaust since before I own it.

Fuel flow there was about 9 gph, that is running it flat out.

Normally, if you set your power per POH you can do one of several things:

- Set up for the fuel flow in POH and note TAS. It will be slightly higher than the corresponding FF

- Set up for TAS as per POH and note MP and FF you need to achieve it. Usually you will need about 1 inch MP less to achieve the same TAS at FF corresponding to TAS.

As a sideline, I've had my C model fly at FL170 with OAT 0°C, which means ISA plus 20°C. that is a DA of 22000 ft. I don't think a regular C can do that.

 

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  • 3 weeks later...

Well I got my Powerflow exhaust installed on my C.  No verdict yet on performance gains, but it is a tad louder.  I wonder if that fat thing sticking out into the wind might negate any improvement over my removed aging Knisley exhaust, which had a much lower profile tailpipe.  Regardless, I’m as proud as a teenager who just spent his allowance putting a fart can on his old Honda Civic :P

 

Picture1.jpg

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