Power Flow and New Engine

[MyNameIsNobody]

I have no standing here...as I don't have a PFE, BUT I do know how to read and the reason to pay thousands of dollars for something is to actually have that something DO something.  I have read actual articles that stated: "The powerflow exhaust has significant performance benefits in big block engines.  In a four-banger, Not so much".  Now subjectively there are those that think it "looks cool" and sounds better than stock.  If you have a lot of money to burn on subjective stuff.  Go for it.

My interpretation of the thread title was asking for opinions.  There is mine on PFE.  It is likely worth less than or equal to what you "paid for it".

[MyNameIsNobody]

19 minutes ago, aaronk25 said:

So you wanna go to kLNR for breakfast tomorrow is that what your saying?


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Chasing pheasants.  Likely just exercise for me and my young pointer...but you never know.  Thanks for the invite.

[Bob_Belville]

On 11/26/2016 at 9:52 PM, MyNameIsNobody said:

Chill Honeybunny...Chill.  I wasn't wondering at all.  I was questioning...

Bob- to quote you "It might provide better performance".  Thus my reply...

Chilax...Like anybody needs to justify anything to me ever...

I have no before and after data, I have no double blind studies. I bought the PFS with AOG. My "might" statement should indicate I "know" something I can't "prove".

I do know and can show that my tired 51 year old M20E can do close to 160 kts in real world cruise conditions. 

[aaronk25]

The more I think and analyze the PF I think the 2500rpm cruise speed is within a knot of the factory exhaust.

Here is where the difference is:

1. At 2700rpm at all configurations. At 2900lbs the plane climbs out at 700fpm at 1,300 with DA at 2,500. The roll is shorter so is the time to transition to climb.

The 2700rpm cruise is improved by 5kts ish. I have no idea why PF says it's optimized at 2550rpm unless they were flying it on a 20btdc timed engine where the slightly less rotating speed brought the peak pressure more in line. I'm at 25btdc so that may be the difference.

The biggest benefits i like is climb ability when heavy in high DA and reduction of chts at all configurations by as much as 30f. This will make the cylinders last longer. The system make a vacuum behind the cylinder about to fire so it sucks more of the hot spent gasses out of the cylinder compared to the stock muffler which requires more effort of the piston to push out the gasses. Either way getting more hot out is good as there is less residual heat to raise the chts and more room for cooler (more 02) denser air for the next Ignition event creating more power.

The only reason I put it on is my muffler was getting thin in areas and could have been rebuilt but I got thinking about the headers and other things that may need attention down the road so with a complete overhaul cost of around $2,500 or $4,000 ish for the PF I decided what the hell lets do it. Not sure it makes financial sense but it added a edge to the engine. Not a mind blowing amount of power but the gains per Kts or benefit are about the same as other aviation upgrades.......expensive as hell.


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[Bob_Belville]

4 minutes ago, aaronk25 said:

The more I think and analyze the PF I think the 2500rpm cruise speed is within a knot of the factory exhaust.

Here is where the difference is:

1. At 2700rpm at all configurations. At 2900lbs the plane climbs out at 700fpm at 1,300 with DA at 2,500. The roll is shorter so is the time to transition to climb.

The 2700rpm cruise is improved by 5kts ish. I have no idea why PF says it's optimized at 2550rpm unless they were flying it on a 20btdc timed engine where the slightly less rotating speed brought the peak pressure more in line. I'm at 25btdc so that may be the difference.

The biggest benefits i like is climb ability when heavy in high DA and reduction of chts at all configurations by as much as 30f. This will make the cylinders last longer. The system make a vacuum behind the cylinder about to fire so it sucks more of the hot spent gasses out of the cylinder compared to the stock muffler which requires more effort of the piston to push out the gasses. Either way getting more hot out is good as there is less residual heat to raise the chts and more room for cooler (more 02) denser air for the next Ignition event creating more power.

The only reason I put it on is my muffler was getting thin in areas and could have been rebuilt but I got thinking about the headers and other things that may need attention down the road so with a complete overhaul cost of around $2,500 or $4,000 ish for the PF I decided what the hell lets do it. Not sure it makes financial sense but it added a edge to the engine. Not a mind blowing amount of power but the gains per Kts or benefit are about the same as other aviation upgrades.......expensive as hell.


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Very interesting. My Scimitar prop seems to like 2550 so that's where I normally cruise unless I'm going for max range to avoid a fuel stop. I have never cruised at 2700 though I usually climb at full RPM of slightly less. I'll have to check it out to see if temps stay acceptable at the higher power setting. (I am 25 BTDC as well.)

 

[Bennett]

I too use 2550 RPM with the Top Prop (2 blades) and the PFE. 2700 sounds high for cruise, but I will try it on my next flight (actually 2690 as my JPI. 830 RPM display goes red at 2700).

I believe that LASAR did a same day before and after test of the PFE. I'll ask them for a copy and see if they will allow the results to be disseminated.


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[aaronk25]

Jetdriven and I have the same round tip 2 blade prop and he has wrote several times how the prop is oddly more efficient at higher Rpms. We know the engine is more efficient (bsfc) at lower rpms (full throttle) but running efficiency gains at lower rpms are offset by reduce prop efficiency. It sounds like that top prop is a nice piece of equipment.

I only run 2700rpm cruise at 9k and above to stay in the 75% range.


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[Bob_Belville]

14 minutes ago, aaronk25 said:

I only run 2700rpm cruise at 9k and above to stay in the 75% range.


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With RAM air and PFS I have to get pretty high to not be over 65% which is where I generally run unless I want to blow it out to take a pic of KTAS on the Aspen.

RAM air in an old E is worth about 1.1" MAP. Below 8000 I seldom use it, even @ 2550 RPM. 

[carusoam]

TopProp also likes 2550 rpm for the 310hp, three blade cruise speed...

Best regards,

-a-

[MyNameIsNobody]

11 hours ago, Bob_Belville said:

I have no before and after data, I have no double blind studies. I bought the PFS with AOG. My "might" statement should indicate I "know" something I can't "prove".

I do know and can show that my tired 51 year old M20E can do close to 160 kts in real world cruise conditions. 

 

Good for you Bob.  Glad I could get another "real world" view of your panel.  I guess I will just open my ram air and get the same speed increase of the PFE for free.