An We Discuss IO360A1A Fuel Flow?

[MBDiagMan]

The IO360A1A in my ‘67 F went through overhaul last year and it seems like it is showing higher fuel flow numbers than it did before the overhaul.

I have not yet recorded data, but I will begin to do so.  Before the overhaul I saw 9.5 to 10.5 GPH on the JPI much of the time.  I commonly ran at low power settings.  Since the overhaul I have been running 75% or more power as seen on the JPI because of suggested break in procedures.  Climbing out I commonly see 14.5GPH with everything forward.  Once leveled off at 75% power I will lean out some, but still see 11.5.  

Part of what I’m trying to get used to may only be different positioning of the controls.  Unlike before the overhaul, when I lean out to 11.5 or so, the control is so far back it feels like I am going to kill the engine.  Not knowing how things work in the injection system I don’t have any understanding of how a simple cable adjustment might effect it.

I realize that I rambled about this, but I’m hoping some of you especially those who have engine monitors can share some of the fuel flow values that you see under certain conditions.  The engine isn’t broken in yet, and I’m wondering if it is running too rich and slowing down the breakin process.

[PT20J]

First, what does your POH show?

The Lycoming operators manual for your engine shows fuel consumption at 75% should be about 12 gph for best power mixture and 10.5 gph for peak EGT. But that’s in a test cell and the installed numbers may be slightly different due to the induction and exhaust system losses. Your numbers seem pretty reasonable.

Skip

[Ragsf15e]

Do you have an engine monitor and are leaning it to a set ROP or LOP point?  If you’re just leaning to rough and richening slightly, it might be hard to tell.  I’d definitely say 14.5 in a climb is normal if not low (depends on altitude, should be 18ish at SL takeoff).  11.5 in cruise also seems legit at 75% and ROP.  If you set 65% and just LOP (say 10 degrees on the richest), you should see ~9gph.

[Ragsf15e]

Yeah, what Skip said is what I wanted to say.  The numbers seem similar to my F though for climb at target egt and rop cruise.

[Mooney Dog]

22 minutes ago, PT20J said:

First, what does your POH show?

The Lycoming operators manual for your engine shows fuel consumption at 75% should be about 12 gph for best power mixture and 10.5 gph for peak EGT. But that’s in a test cell and the installed numbers may be slightly different due to the induction and exhaust system losses. Your numbers seem pretty reasonable.

Skip

Ive always been curious about some of the model changes from year to year. For example. My 65E says i should be getting around 11.2 gph but the 66poh says 9.9. As far as i know nothing major changed between those two years, why the huge difference? In practice i get 9.4 to 10gph anyways. 

[Ragsf15e]

 

3 minutes ago, Mooney Dog said:

Ive always been curious about some of the model changes from year to year. For example. My 65E says i should be getting around 11.2 gph but the 66poh says 9.9. As far as i know nothing major changed between those two years, why the huge difference? In practice i get 9.4 to 10gph anyways. 

depends on what power setting, rpm, manifold pressure, and choice of mixture setting.  Early pohs have full rich to 75% power, leaning after that.  With engine monitoring many of us fly differently now.  There are still variations by poh but we’ve got to start at the same altitude, mp, rpm and mixture.  Then yes, they should be the same.

[MikeOH]

My 70F is a bit low at 16.5 gph for takeoff.  I run 65% LOP in cruise and see about 9 gph.

[Mooney Dog]

1 hour ago, Ragsf15e said:

 

depends on what power setting, rpm, manifold pressure, and choice of mixture setting.  Early pohs have full rich to 75% power, leaning after that.  With engine monitoring many of us fly differently now.  There are still variations by poh but we’ve got to start at the same altitude, mp, rpm and mixture.  Then yes, they should be the same.

According to the POH, they're not. And thats where my confusion comes from. In reality yeah, 2 planes should be getting both about the same with the same set ups. 

Here's a 65 POH. For me I cruise around 2400rpm and 23mp. This says 11.2gph here.

Here's a 66/67 poh. For the same settings (24/23) it says 9.9gph. 

[A64Pilot]

I believe your way lean at full power depending on field elevation, I see 19 GPH at sea level.

You need to run it rich and high power for break in, Rich for two reasons, first to make high power requires about 150 or so ROP and secondly rich at high power runs cooler and a new motor has a tendency to run warm.

Save the LOP for after break in

Edited May 11, 2022 by A64Pilot

[Ragsf15e]

9 hours ago, Mooney Dog said:

According to the POH, they're not. And thats where my confusion comes from. In reality yeah, 2 planes should be getting both about the same with the same set ups. 

Here's a 65 POH. For me I cruise around 2400rpm and 23mp. This says 11.2gph here.

Here's a 66/67 poh. For the same settings (24/23) it says 9.9gph. 

Are the notes different?  My ‘68 poh says 10.3 for that power/alt, but here’s the notes.  The 50 year old poh is not an exact science… they were kind of a work in progress.

[MBDiagMan]

Wonderful feedback guys!  You’ve given me what I need to start on a more detailed look at this.  Thanks a bunch!

[Mooney Dog]

11 hours ago, Ragsf15e said:

Are the notes different?  My ‘68 poh says 10.3 for that power/alt, but here’s the notes.  The 50 year old poh is not an exact science… they were kind of a work in progress.

This holds true for both POH's

[Ragsf15e]

2 minutes ago, Mooney Dog said:

This holds true for both POH's

Ouch, that one shows 25degrers ROP as an option for best economy.  Generally we wouldn’t use that setting for anything today.  My ‘68 poh doesn’t list that setting at all.  I guess that’s what I’m saying, the POHs weren’t perfect and they kept improving them as they went along.  If you want the best idea for an E, find the most recent E model poh (~1970?) and use that.  For an F, use the ‘75 poh.  

[carusoam]

We have two things that drive the FF number….

1) Engine set-up for the fuel injection system…. Mechanically set up properly by your mechanic….

2) Engine use…. How you use the red knob….

Max FF for the IO360… is often found during the T/O run at or near sea level…. Close to 20gph… (200hp)

Similarly for the IO550…. Close to 30gph (310hp)

 

Max FF is in the POH in the early pages…

If an engine change has occurred using an STC… the STC paperwork will have the updated FF numbers…

Use caution, some might give numbers in LBs/hr…. And need to be converted…. 

Some data are given in ranges… select the high end of the FF range, you can use the red knob to cut back… you won’t be able to get more….

PP thoughts only, not a mechanic…

Best regards,

-a-

[Mooney Dog]

15 minutes ago, Ragsf15e said:

 I guess that’s what I’m saying, the POHs weren’t perfect and they kept improving them as they went along.

Thats what i was original getting at anyways. Real world data says i get 9.6gph in cruise.

[carusoam]

Engine data from the early POHs are generated by the engine manufacturers….

Back in the day….

There were no word processors…

The person putting the table together may not know what they were typing….

The numbers may not make sense as you go down a column or across a row…

 

They never expected you to have a digital fuel flow meter measuring actual FF numbers in your actual plane….   
 

Lots of inconsistencies you can probably circle in a red color….

 

We have come a long way…

Best regards,

-a-

[M20F]

On 5/10/2022 at 8:42 PM, MBDiagMan said:

 Climbing out I commonly see 14.5GPH with everything forward. 

As others have pointed out this is very lean.  I would go back and see whomever installed your engine, your local mechanic, etc. to get that set correctly.  

[PT20J]

44 minutes ago, Ragsf15e said:

Ouch, that one shows 25degrers ROP as an option for best economy.  Generally we wouldn’t use that setting for anything today.  My ‘68 poh doesn’t list that setting at all.  I guess that’s what I’m saying, the POHs weren’t perfect and they kept improving them as they went along.  If you want the best idea for an E, find the most recent E model poh (~1970?) and use that.  For an F, use the ‘75 poh.  

Mooney seemed to like 25F ROP for “best economy” a lot. It’s in my 1978 and 1994 M20J POHs. My guess is that it provided some fuel savings compared to best power, but didn’t slow you down too much. Gas used to be cheaper.

I know it drives the APS folks apoplectic (ICP!, ICP!, Red Box!!, Danger, Will Robinson) but really the pressures are higher at full power and the little Lycoming four bangers are rated to run all day at full power. Lycoming has always permitted leaning to any mixture below 75% power if you keep the CHTs below 400F. I’ve never seen any published data showing that running below 75%, and below 400F CHT at any mixture strength harms an IO-360.

I do believe that Mike Bush has shown by example that running at 65% power and below is beneficial for longevity. The airlines used to cruise the big radials at around 55%.

Skip

 

[Fly Boomer]

15 hours ago, PT20J said:

I’ve never seen any published data showing that running below 75%, and below 400F CHT at any mixture strength harms an IO-360.

I do believe that Mike Bush has shown by example that running at 65% power and below is beneficial for longevity.

And to flesh those numbers out, the 75% and 400dF are probably okay numbers for a Lyc.  Most of Mike's personal experience is with a big-bore Continental (520), and Continentals seem to be more delicate.  Plus, his 310 is turbocharged.

[carusoam]

More delicate engine?

-a-

[Fly Boomer]

3 minutes ago, carusoam said:

More delicate engine?

I haven't bought cylinders yet, but I suspect that the 400dF number will be expensive for (especially) big-bore Continentals.

[carusoam]

Cost per cylinder…. Similar, just two more….

Cylinder quality… Continental has had some crummy valve construction history…

One cylinder isn’t any more delicate than the next…

Temperature sensitivity and why we choose 380°F as a preferred CHT limit…. Is a material limitation…. And owners that like cylinder longevity over TOHs…

All good news… for everyone…

Best regards,

-a-

[A64Pilot]

17 hours ago, Mooney Dog said:

Thats what i was original getting at anyways. Real world data says i get 9.6gph in cruise.

9.6 at what MP/RPM altitude and how far LOP or ROP? For 9.6 to be a valid number you need the rest

[A64Pilot]

17 hours ago, PT20J said:

Mooney seemed to like 25F ROP for “best economy” a lot. It’s in my 1978 and 1994 M20J POHs. My guess is that it provided some fuel savings compared to best power, but didn’t slow you down too much. Gas used to be cheaper.

I know it drives the APS folks apoplectic (ICP!, ICP!, Red Box!!, Danger, Will Robinson) but really the pressures are higher at full power and the little Lycoming four bangers are rated to run all day at full power. Lycoming has always permitted leaning to any mixture below 75% power if you keep the CHTs below 400F. I’ve never seen any published data showing that running below 75%, and below 400F CHT at any mixture strength harms an IO-360.

I do believe that Mike Bush has shown by example that running at 65% power and below is beneficial for longevity. The airlines used to cruise the big radials at around 55%.

Skip

 

You won’t see set numbers that will say that normally because there are no set numbers, the numbers will vary based on other things so there is no set number. There are conditions where you can lean it any way you want well above 75%, and some where 75% is pushing it, so to give a number it has to be conservative.

But then even “hurt” is a variable, you can be sure though that running one hot and hard will definitely shorten its life, that’s why some can easily go well beyond TBO as TBO is a conservative number, sort of a warranty if you will and it’s set usually at max continuous power, which I thought for a Lycoming recommended is 75%? They call it I believe max recommended cruise power, it may be a recommendation and not a limit though. High temp operation damage is cumulative, whether it be a turbo Diesel or a turbine engine so exceeding temp limits unless super high are unlikely to result in immediate failure, but cumulative operation will shorten life and it will eventually fail, which confuses some because they think I’ve been running it like that and nothing happened.

Then it’s Lycoming that recommends for max engine longevity a cruise power of 65% or LESS and they have for a very long time

So in other words the lower power settings that result in lower temps will increase life, so while you can run one hard and most likely make it to TBO, if your wanting to go past, take it easy.

This is meant for the big turbo motors, but as it says it can be used for little motors too, don’t get hung up on numbers, the obvious take away is warm it up slowly, cool it down slowly and don’t run the snot out of it if you want it to last.

https://www.lycoming.com/content/tips-extending-tbo

I do agree with you on the red box thing, it’s also a variable thing, at lower power there are times where 25ROP or peak is a very logical temp, and I agree both Mooney and Lycoming have always been reticent on LOP because of the performance hit and of course complicating things

The more you back off of “best power” of course the more power you lose, hence calling it “best” power.

‘My IO-540W1A5D recommend 50 ROP for cruise and peak for economy, I’m sure for power

 

 

Edited May 12, 2022 by A64Pilot

[Guest]

On 5/10/2022 at 9:42 PM, MBDiagMan said:

The IO360A1A in my ‘67 F went through overhaul last year and it seems like it is showing higher fuel flow numbers than it did before the overhaul.

I have not yet recorded data, but I will begin to do so.  Before the overhaul I saw 9.5 to 10.5 GPH on the JPI much of the time.  I commonly ran at low power settings.  Since the overhaul I have been running 75% or more power as seen on the JPI because of suggested break in procedures.  Climbing out I commonly see 14.5GPH with everything forward.  Once leveled off at 75% power I will lean out some, but still see 11.5.  

Part of what I’m trying to get used to may only be different positioning of the controls.  Unlike before the overhaul, when I lean out to 11.5 or so, the control is so far back it feels like I am going to kill the engine.  Not knowing how things work in the injection system I don’t have any understanding of how a simple cable adjustment might effect it.

I realize that I rambled about this, but I’m hoping some of you especially those who have engine monitors can share some of the fuel flow values that you see under certain conditions.  The engine isn’t broken in yet, and I’m wondering if it is running too rich and slowing down the breakin process.

14.5 GPH is pretty lean for full power, 9% of rated horsepower is a quick and easy number to remember.  Precision fuel injectors are not field adjustable with regards to full power fuel flow, they have to go to a shop with a proper test bench.

Clarence