Horsepower debate (was DA40NG)

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Tommy
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Re: Horsepower debate (was DA40NG)

Post by Tommy »

I never heard of Rotax Dave. :scream:
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Sandy
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Re: DA40NG

Post by Sandy »

Antoine wrote:Sandy it would have been unfair in this comparison to ignore the 23 extra HP from the powerflow tuned exhaust. They are real although Diamond were too lazy to update the POH so they left it at the "old performance numbers".
Sorry, Antoine, but it doesn't matter which exhaust system you have. The Lycoming IO-360-M1A is rated at 180 Hp, not 200. The Power Flow exhaust system, or any exhaust system, for that matter, is a passive device, whereby it does not create horsepower. In fact, it decreases the available horsepower from the engine, just as any other exhaust system does. What you really mean is that the Power Flow exhaust results in less of a reduction, but it does not increase the engine's horsepower. Note that there are IO-360 engines that generate 200 Hp, but the Lycoming IO-360-M1A is not one of them.

Sandy
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Re: Horsepower debate (was DA40NG)

Post by robert63 »

Tommy wrote:I never heard of Rotax Dave. :scream:
It’s an aircraft engine also built in Austria. Makes me a proud Austrian :)
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H60 pilot
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Re: DA40NG

Post by H60 pilot »

Sandy wrote:What you really mean is that the Power Flow exhaust results in less of a reduction, but it does not increase the engine's horsepower.
This is just semantics isn't it? The end result is the same; more power available to produce thrust.
Do we agree Lycoming is baselining the IO-360-M1A at 180 hp when equipped with the OEM exhaust shipped from the factory?
Sandy wrote:. . . any exhaust system, for that matter, is a passive device, whereby it does not create horsepower. In fact, it decreases the available horsepower from the engine, just as any other exhaust system does.
Power Flow Systems claims greater scavenging at 2,450 rpm thereby increasing the incoming fuel/air charge for combustion. I would argue the IO-360-M1A is closer to a 200 hp engine that only produces 90% of that when choked back by the OEM exhaust and shipped to Diamond.
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Re: Horsepower debate (was DA40NG)

Post by Antoine »

Sandy: the way a tuned exhaust system works is that it uses carefully adjusted (tuned) exhaust pipes that merge at a precise point. This allows the system to have a resonant frequency (much like an organ tube) at which the pressure wave coming out of cylinder A creates a vacuum at the perfect time and location to scavenge gases out of cylinder B. Around RPM point the exhaust will actually increase horsepower (versus stock exhaust) by allowing each cylinder to breathe better than with a conventional exhaust.
Imagine that the cylinder has less burnt gases left over when its inlet valve opens and it wants to inhale a fresh air load. This air will find less resistance and better fill the cylinder.
Now inject proportionally more fuel into this air and you'll produce a more powerful combustion event.
Mick's post above states the correct "frequency" as communicated by PFS: 2450 RPM for the PowerFlow equipped M1A. I think I have almost always set my engine between 2400 and 2500 RPM in cruise because it "felt right" there.

The system comes from race car technology and I can assure you that it does increase horsepower. BTW one can do the same on the induction side.
PowerFlow claim 23 additional HP. In percentage, this is consistent with what is observed on race car engines. Incidentally, fuel flow also increases when the PowerFlow system is installed.
So it's not "free power" but it is definitely extra power.
Look at the POH numbers which are for the regular plane and compare with the 146-150 KTAS my two DA40s did at 9'000 ft and 75% power. Way off the POH charts...
I believe that the only reason why both PFS and Diamond are keeping the power increase quiet is the cost of recertification.
This said, one item I am not certain of is whether the base M1A engine actually outputs 180 HP when installed in the plane and the PowerFlow gets 200.
It may well be that the base engine only outputs 160 HP in the plane and the PowerFlow-equipped one 180.

This would then be true of the Cessna's IO-540 which is rated for 240 HP but would be outputting less once installed in the plane.
My observation was that the Cessna has 40 more HP and yet the DA40 flies circles around it: better climb, better cruise and better fuel economy.

It would not bother me if you would prove that the delta is actually 60 HP, but I believe it is more like 40 and this is embarrassing enough for the Cessna.

PS: I no longer own a DA40...
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Re: DA40NG

Post by krellis »

H60 pilot wrote:
Sandy wrote:What you really mean is that the Power Flow exhaust results in less of a reduction, but it does not increase the engine's horsepower.
This is just semantics isn't it? The end result is the same; more power available to produce thrust.
Do we agree Lycoming is baselining the IO-360-M1A at 180 hp when equipped with the OEM exhaust shipped from the factory?
Sandy wrote:. . . any exhaust system, for that matter, is a passive device, whereby it does not create horsepower. In fact, it decreases the available horsepower from the engine, just as any other exhaust system does.
Power Flow Systems claims greater scavenging at 2,450 rpm thereby increasing the incoming fuel/air charge for combustion. I would argue the IO-360-M1A is closer to a 200 hp engine that only produces 90% of that when choked back by the OEM exhaust and shipped to Diamond.
No, I don't agree. The original factory exhaust was quite restrictive. When we talked with Darren at Power Flow years ago before the PF install on our old DA-40, he said that their exhaust allowed the IO-360-M1A to make rated power - versus the factory exhaust. We gained about 7 knots TAS with a commensurate increase in fuel burn.
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Re: Horsepower debate (was DA40NG)

Post by waynemcc999 »

For the past couple months I've been collecting some performance data, as quantitative and controlled as I can.

Specifics:
[*] 2008 DA40 XLS
[*] Power Flow Exhaust
[*] ElectroAir Ignition (replacing 1 magneto)
[*] Fine-wire plugs
[*] within 100 lbs. of MGTOW
[*] Wide open throttle
[*] 2450 rpm
[*] Nose Wheel at 18 lb. tension

Attached is a snapshot of data collected to date... True Airspeed vs. Density Altitude:
[*] the red line is "TAS Book", from Section 5.3.9 of the AFM. It is not so noted, but I'm guessing this is Best Power (i.e. Rich of Peak).
[*] the blue dots are TAS Actual running Lean of Peak, with the blue line a trend line.
[*] the orange dots are TAS Actual running Rich of Peak, with the orange line a trend line. I rarely run ROP, but intend to collect more data points for general information.

The following link provides a view of the "live" data as I add future data points. There's also a tab for corresponding Fuel Flow for each data entry.
https://docs.google.com/spreadsheets/d/ ... sp=sharing

Conclusions left to the reader.
Best regards,
Wayne
Attachments
N211WP-TAS-thru-14feb2018.png
Last edited by waynemcc999 on Tue Feb 20, 2018 11:14 pm, edited 1 time in total.
Wayne McClelland
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Antoine
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Re: Horsepower debate (was DA40NG)

Post by Antoine »

Wayne very nice work.
One can really only wonder how DAI managed to make the plane so slow during certification flights...

I checked the spreadsheet and have the following comments:

I do not know what the influence of the ElectroAir ignition is so this can be a possible "smoke screen".

This said, did you check your nose wheel? I fear that you may have the 4-5 knot "speed loss mod" whereby the nose wheel is flying corked and the trim tab is bent accordingly.
How to find out?
1. Make a baseline flight
2. Land, remove the nose wheel fairing (a 5 minute job, owner work OK)
3. Takeoff again and observe the change in speed.
You should lose 2-3 knots in cruise and need NO rudder input to fly straight and level.
If you end up GAINING 1 knot and dropping a wing in cruise, needing rudder to fly straight and level, your nose wheel is corked.

As a reference:
My 2008 XLS would do 140 KTAS on 8 GPH at peak EGT, so you should see better economy LOP.
And it really did 150 KTAS on 10.x GPH (can't remember exact FF value).
The 2007 XL was about 4 knots slower and it lost another 4-5 when the nose wheel started going out of control... Strangely, this issue almost never happened with the 2008 XLS.
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waynemcc999
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Re: Horsepower debate (was DA40NG)

Post by waynemcc999 »

Antoine,

Nose Wheel at 18 lb. tension. I started setting this (and checking it every oil service) a few months before the data collection began, and it made a noticeable difference ~5 KTAS.

My LOP measurements are -15 to -40 degF Lean of Peak EGT. This normally gives me CHTs 330 to 350 degF.
My ROP measurements are to keep CHTs <370 degF.
Last edited by waynemcc999 on Wed Feb 21, 2018 1:09 am, edited 1 time in total.
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Re: Horsepower debate (was DA40NG)

Post by Antoine »

OK great, so your plane is aerodynamically fine. Did you do a before/after test when the ElectroAir was installed?
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