Power Flow performance testing

[aaronk25]

It's all of 5kts. But the higher the altitude (m.p.) the less speed return. Actually somewhere around 14k D.A. It actually returns the same speed as pre-install and at 17k it's a few knots slower. Maybe you can explain that?

The largest returns are at 4K and exponential higher at lower altitude. It's laying down right around 167-168kts at 3.5-4K and I couldn't break 160-161kts pre-install.

At higher M.P. This really shines. I'm not sure why they advertise it as "optimized at higher altitudes" as I think that's kind of misleading. It really gives it some lungs down low and yep I was guessing 30hp.

[ArtVandelay]

5 knots?  That's like 30-40 HP. I can see near that on a C model with the exhaust they got but not a J. I can't see it's very much better and certainly not 5 knots worth....

I think it's more like 13hp.

[rbridges]

how does one determine the compatibility between all the STCs ?

power flow and new cowling ?

power flow and MT or Hartzell prop ?

just wondering since I recall seeing someone here having to resell a component because of STC compatibility (I cannot recall if it was a prop or a power flow) 

My plane has a 201 cowling, and the previous owner said it took some adjustments to get the powerflo exhaust installed.  I think he actually flew the plane to them.

[jetdriven]

I flew with a gentleman who had the trifecta, a LoPresti cowling, Powerflo exhaust, AND an HID landing light. It wouldnt all fit. He got a field approval for a PAR36 HID landing light. It was just small enough.

[Bennett]

[Bennett]

I flew with a gentleman who had the trifecta, a LoPresti cowling, Powerflo exhaust, AND an HID landing light. It wouldnt all fit. He lgot a field approval for a PAR36 HID landing light. It was just small enough.

I have all three: LoPrest cowl, PowerFlow exhaust, and the HID landing light:

[carusoam]

That Lopresti guy was good!

The match between the spinner and cowl is nicer than current M20Rs...

Best regards,

-a-

 

[bradp]

Bennett the first generation is the only one that fits with your Lopresti cowl, correct? What are the differences in the two generations ?

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[Bob - S50]

Bennett the first generation is the only one that fits with your Lopresti cowl, correct? What are the differences in the two generations ?

 

 

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I think the question most inquiring minds want to know is what kind of speeds/power settings/fuel flow are you getting with all those mods?

[Bennett]

As I understand it, LoPresi initially sold two HID landing lights, and the one they fitted to their cowl for Mooneys was the less powerful version. I fly with it on most of the time as its MTBF is supposed to be something like 2000 hours, and I want to be seen. It makes for a good landing light, but in all candor I had a better setup in my K model (261 conversion). I had the dual nose bowl lights of the 252 cowl, and I had dual landing lights added to each wing. These were the old Quartz lights, and drew a lot of amps, but they sure lit up the runway when landing, and there was little question about being seen at night on approach.

I now have added LED wingtip "recognition" lights, which through a panel switch change from alternating to "on" and act as supplemental landing lights. These LEDs are extremely bright

[mooniac15u]

 

I now have added LED wingtip "recognition" lights, which through a panel switch change from alternating to "on" and act as supplemental landing lights. These LEDs are extremely bright

 

What brand of LEDs did you use for your wing tips?  I'm interested in switching to LEDs but I haven't seen an STC for the J.

[Bennett]

What brand of LEDs did you use for your wing tips?  I'm interested in switching to LEDs but I haven't seen an STC for the J.

These were done under a one time field approval.

The are some LED strobe and navigational lights with STCs for Js, for example Whellen (spelling) has several models, but I don't know of any STCs for the type of "recognition" lights I used. They were sold as Landing lights for LSAs and Experimentals, but through switches they can be blinked, or alternated, or turned on as landing lights.

[pfactor]

Ok, I did the "before" tests. My plane is in the shop for its annual and getting the Power Flow exhaust installed. Here's the results from my before-installation performance tests.

10/24/2015 - 12:30 PDT / 1930Z - KRHV
Aircraft 1977 Mooney M20J before installing PowerFlow exhaust
Winds calm. Temp 27C.
Field elevation: 135 ft. Density altitude: 1,600 ft.

Actual weight: 2520 lbs. (max gross 2740 lbs.)
Adjust V speeds for weight: V' = V * SQRT(2520 / 2740)
Adjusted Vx: 62 kts
Adjusted Vy: 84 kts.

Short-field takeoff:
POH chart: 993 ft. ground roll; 1537 ft. over 50 ft. obstacle
Actual: 1100 ft. ground roll; 1500 ft over 50 ft obstacle

I measured the actual performance by using a video camera under the wing and looking at when the wheels actually left the ground. Here's the video of the short-field takeoff. Cloud Ahoy says the takeoff distance was 1483 ft. I was pretty happy to get the POH performance . 

Climb performance:
I climbed until I couldn't keep a consistent 200 fpm climb, which was around 14,500 ft indicated altitude (16,000 density altitude). See the before-climb-chart.PNG attached.

Cruise performance:
I measured cruise performance at 14,500 ft, then I tried to replicate the PowerFlow Mooney M20J tests at 2500 & 2700 RPM at 11,500 ft, 7,500 ft and 2,500 ft. I couldn't quite get to 2700 RPM so I used 2600 RPM instead.

I got pretty close to the POH performance (within 5%) at all altitudes.

I've attached charts showing the actual speed & fuel flow compared to the POH values both as knots/gph and as a % difference from the POH.

When I get the plane back, I'll repeat these tests with the PowerFlow installed. The weather conditions will be different, but hopefully comparing against the POH values will allow for a fair comparison.

Phil
 

[carusoam]

Phil,

Its official.  You ARE Mooniacal!

1) complete set of 'before' data.

2) data collected using an app, not just looking out the window.  What GPS device did you use with CloudAhoy?

3) detailed video of the whole event. Inside and out.

4) Are you an engineer, mechanic or just a Mooniacal pilot? 

Best regards,

-a-

[pfactor]

18 minutes ago, carusoam said:

Phil,

Its official.  You ARE Mooniacal!

1) complete set of 'before' data.

2) data collected using an app, not just looking out the window.  What GPS device did you use with CloudAhoy?

3) detailed video of the whole event. Inside and out.

4) Are you an engineer, mechanic or just a Mooniacal pilot? 

Best regards,

-a-

Thanks!

I used the GPS data from my Garmin 796 to upload to CloudAhoy. I'm an engineer and a Mooniacal pilot

Phil

[garytex]

I'm waiting for your results with bated breath :-)

[Guitarmaster]

On October 20, 2015 at 4:36:43 PM, PTK said:

 

How do you define "real hot rod?" What's the delta compared to without these mods?

 

I saw a triple-turbo Durarmax Diesel Mustang run inside of 8 seconds.  Does that qualify?  :)

[Piloto]

A dominant factor on TAS and climb rate performance is aircraft weight and density altitude. You can easily see 5 kts and 300fpm difference from full fuel to 1/4 tank. And from 90F to 40F ground temp. When comparing make sure weight and DA are the same for both tests.

José

[aaronk25]

I'll bet you notice a few things that power flow doesn't tell you.

1. Higher RPMs yield much larger gains in TAS where lower rpm such as 2300rpm show almost zero net gain.

2. The most speed gains will be at lower altitudes 4-8, using 2600-2700rpm.

3. The mixture setting that yields the best BSFC or the most power for the least amount of fuel will not be 25LOP it will be 5lop to Peak (stoichiometric).

4. Mpg won't improve more than 5% but you will have the option of going faster, on more fuel if you desire.

5. Chts will be 20-30f lower do to the vaccum created in the exhaust system which extracts more hot exhaust out of the cylinder.

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[pfactor]

I got my plane back from annual with the PowerFlow installed, and I'm happy with the results. I repeated the performance tests that I did before installation (see my first post in this thread).

Obviously the weather was quite different this past weekend than it was a few weeks ago when I did the before tests. I've tried to equalize that by comparing the actual performance against the POH performance charts. With book performance as the benchmark, the closest I can get to a fair comparison is to see how the actual performance compared to the book.

 

For the time-to-climb performance, I'm comparing the time to the same density altitude which should be equivalent. The aircraft weight was identical for both the before and after flights.

 

After PowerFlow installation test flight

11/14/15 - 16:50 PST / 2350Z - KRHV

Aircraft 1977 Mooney M20J

Winds 290@11. Temp 16C.

Field elevation: 135 ft. Density altitude: 450 ft.

 

Actual weight: 2520 lbs. (max gross 2740 lbs.)

Adjust V speeds for weight: V' = V * SQRT(2520 / 2740)

Adjusted Vx: 62 kts

Adjusted Vy: 84 kts

 

Short-field takeoff:

POH chart: 803 ft. ground roll; 1387 ft. over 50 ft. obstacle

Actual: 880 ft. ground roll; 1384 ft over 50 ft obstacle

 

I measured the ground roll using video, and the altitude over a 50ft obstacle using CloudAhoy (and the video looks like that value is about right too).

 

I got right at book values for the short-field takeoff, which is also what I had before the PowerFlow was installed. I have a video of the takeoff, which is only from the under-wing camera. The in-cockpit camera didn't record properly.

 

Climb performance

The two immediate improvements I saw were in climb performance and cooler CHTs. I was able to climb to 17,000 ft indicated (density altitude 18,240 ft.).  See the chart for the Stock vs. PowerFlow climb performance.

 

Right around 9,000 ft density altitude, the PowerFlow climb was slightly better and kept going long. With the stock exhaust, the plane was pretty much done climbing by 16,000' density altitude. With PowerFlow, I was able to climb to 18,240' density altitude (I stopped at 17,000' indicated, and probably could have climbed a bit more but didn't want to bother with an IFR clearance). I've also attached the stock & powerflow climb charts too.

 

CHTs

The CHTs were dramatically cooler in the climb and cruise. See the CHT chart. During the climb, I try to keep the highest EGT around 1200F (about what I get when full-rich on a sea-level takeoff), and keep the CHTs below 380F. Normally when doing a cruise climb, I can keep the CHTs down by doing a cruise climb with the cowl flaps trailing open. During these tests, I was climbing at Vy until there was no climb left.

 

During the Vy climb test with the stock exhaust, I had to keep a close eye on the CHTs even with the cowl flaps full open. I had to richen a bit more a few times in the climb to keep the CHTs under 380. With the PowerFlow exhaust, CHTs were much easier to manage.

In cruise, the max and average CHTs were way lower with PowerFlow than the stock exhaust.

 

Cruise performance

I replicated the PowerFlow Mooney M20J tests at 2500 & 2600 RPM at 11,500 ft, 7,500 ft and 2,500 ft. I couldn't quite get to 2700 RPM so I used 2600 RPM instead. I saw very small increases in true airspeed (1-4 knots) compared to the stock exhaust using the POH as a benchmark. Here's a chart comparing the stock & PowerFlow performance vs. the POH values for the conditions.

 

Small differences from the "before" tests originally posted.

When I originally posted my "before" data showing my airplane's performance vs. the POH values, I made some minor errors in doing the interpolation. I've corrected those now and have included updated charts in this post. Finally, I didn't do a cruise performance test at 14,500 during the after test (I did one at 17,000 instead). After getting back home, I realized the cruise performance charts top out at 14,000 so I don't have POH values to compare against for 17,000. I removed the 14,500 cruise performance values from the "before" chart to make it easier to see the difference with the "after" chart.

 

I have also attached the before & after cruise performance charts to this post. You'll notice that the fuel flow was much higher during the PowerFlow test at 2,500 ft. That's because I didn't want to run so close to peak EGT at that high of a power setting (I should have done the same on the before test).

Weight penalty
For the record, the PowerFlow exhaust weighs 5 lbs. more than the stock exhaust that was removed (20 lbs vs. 15 lbs.). Not a big deal for me, but I wanted to mention this.

Overall conclusions
I'm happy with my purchase, and I'd make the same decision again if I needed to. The better climb performance and cooler CHTs are worth it. I saw slightly better cruise speeds, but I wouldn't call this a speed mod.

Powerflow claims the following for a Mooney 200 HP

• 5 -7 knots faster cruise speeds
• 10% – 15% increase in rate of climb
• 0.5 – 1.5 gph reduction in fuel burn at equivalent airspeed
• Improved Take-Off Performance (100’ – 300’ reduction in ground roll)
• Increase in Service Ceiling of 2,000’ – 5,000’
• Cooler CHT’s

I did not see 5-7 knots faster cruise on my test flight. I spent about 5 minutes at each altitude for the cruise tests. Maybe if I gave it more time, I'd see bigger gains. I'll pay attention to this on future flights. I can probably do some more comparisons against previous flights where I've got true airspeed data available.

The climb performance was better. Because the temperatures and density altitudes were different on the two flights, it's hard to do a real apples-to-apples comparison, but I'd say a claim of 10%-15% increase in climb rate is reasonable.

I didn't measure the "reduction in fuel burn at equivalent airspeed" this time. I may test that later.

For takeoff performance, I did not see a 100'-300' reduction in ground roll.

I did see an increase of at least 2,000' of service ceiling, and most definitely saw cooler CHTs.

Phil

[carusoam]

That is a great collection of data!

Thanks for sharing.

Best regards,

-a-

[Shadrach]

Thanks for taking all of the time and effort to put this together!  I see that you calculated and adjusted Vx and Vy by weight, did you adjust your speed in the climb as altitude increased?

[Raptor05121]

I'd love for OP to have a go with a C's before and after as well.

[garytex]

Thanks for your effort

Gary

[pfactor]

17 hours ago, Shadrach said:

Thanks for taking all of the time and effort to put this together!  I see that you calculated and adjusted Vx and Vy by weight, did you adjust your speed in the climb as altitude increased?

Yeah, I did. The POH says that Vy at 10,000' is 82 kts, and adjusting for weight that's 79 kts. I started out climbing at 84 kts (sea level Vy adjusted for weight), and tried to spread the 5 knot IAS reduction over the climb to 10k. Above 10k, I pretty much kept the same trim setting and went with it. Sometimes I'd try giving a bit more up elevator or up trim, but that didn't seem to help much.

Phil