VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #21  
Old 08-02-2012, 07:05 PM
David-aviator David-aviator is offline
 
Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,489
Default

Quote:
Originally Posted by RV10inOz View Post
Folks, the info I have provided already is proven good data.

As some have shown, the IO390x is about 20GPH, funny enough for 200HP engines at 2700 RPM full rich at ISA, thats HP/10

On the rich side of peak EGT the HP is determined by MAss Air Flow, so in rough terms if you have a fixed pitch prop and get 2200 RPM on a ISA day (15deg C and 1013/29.92) you should see 146 HP and a fuel flow around 14-14.5GPH.
And in "rough terms" 13.5 gph is in the ball park.
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2018 This place is worth it!
Reply With Quote
  #22  
Old 08-03-2012, 12:16 AM
rvsxer rvsxer is offline
 
Join Date: May 2007
Location: Inver Grove Hgts, MN
Posts: 286
Default

I'm sitting here looking at my G3X data log for the last flight and the fuel flows talked about on this thread seem right on the money for my setup, O-360/FP/Carb/Mags. When my RPM's are down around 2250 or so I see about 13.5-13.8 GPH and as I flattened the climb a little the RPM's went up to 2450 or so and the fuel flow went up to 15.5, so the RPM/Rated Power vs. Fuel flow argument holds. The OAT was 77F and the hottest CHT peaked at 399.

By the way, be careful reducing power during initial climb with a carbed engine. At WOT the mixture is a lot richer than just below WOT. If you pull the throttle back just a little you will do more harm than good.
__________________
Mike Hilger
RV-6 N207AM w/G3X, 1,500 hours +
South St. Paul, MN (KSGS)
Manager - Panel Design, SteinAir, Inc.
A&P, EAA Tech Counselor

We're all here because we're not all there...
Reply With Quote
  #23  
Old 08-03-2012, 01:49 AM
RV10inOz's Avatar
RV10inOz RV10inOz is offline
 
Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,122
Default

Quote:
Quote:
Originally Posted by RV10inOz
Folks, the info I have provided already is proven good data.

As some have shown, the IO390x is about 20GPH, funny enough for 200HP engines at 2700 RPM full rich at ISA, thats HP/10

On the rich side of peak EGT the HP is determined by MAss Air Flow, so in rough terms if you have a fixed pitch prop and get 2200 RPM on a ISA day (15deg C and 1013/29.92) you should see 146 HP and a fuel flow around 14-14.5GPH.
And in "rough terms" 13.5 gph is in the ball park.
David, seek further advice if you wish, but I would say that 93% of optimum is not in MY ball park.

YMMV

rvsxer

Your data quoted is incomplete to all parameters, however I am confident that your flow is not in the desired range. I fly Jamie Lee's RV7A with a O-360 FP from time to time and his RPM is 2250 static and fuel flow is more like 15GPH. So should yours. At 2450 RPM you would expect closer to 16 - 16.3 GPH

Cheers

DB
__________________
______________________________

David Brown


The two best investments you can make, by any financial test, an EMS and APS!
Reply With Quote
  #24  
Old 08-03-2012, 06:02 AM
hevansrv7a's Avatar
hevansrv7a hevansrv7a is offline
 
Join Date: Jul 2005
Location: Detroit, MI
Posts: 1,549
Default It should be a little higher than this

Quote:
Originally Posted by N743RV View Post
Lars,

I agree with you. I think the your value of 0.5 lb/hp-hr is just about right for my IO 360 with the Hartzel blended airfoil prop and Lasar ignition.
Bob Cowan


Best power would be around .48 to .50 but we normally take off full rich so it will be well above .55 pounds per HP per hour.


And since I have a FP prop I agree that you can't compare it to a CS prop on takeoff or climb because if it is pitched for proper cruise it can't reach more than about 2200 rpm, roughly speaking.
__________________
H. Evan's RV-7A N17HH 215 hours
"
We can lift ourselves out of ignorance, we can find ourselves as creatures of excellence and intelligence and skill. We can be free! We can learn to fly!" -J.L. Seagull
my website
Paid $25.00 "dues" net of PayPal cost for 2015 and 2016 and 2017.

Reply With Quote
  #25  
Old 08-03-2012, 09:28 AM
rvsxer rvsxer is offline
 
Join Date: May 2007
Location: Inver Grove Hgts, MN
Posts: 286
Default

Quote:
Originally Posted by RV10inOz View Post

rvsxer

Your data quoted is incomplete to all parameters, however I am confident that your flow is not in the desired range. I fly Jamie Lee's RV7A with a O-360 FP from time to time and his RPM is 2250 static and fuel flow is more like 15GPH. So should yours. At 2450 RPM you would expect closer to 16 - 16.3 GPH

Cheers

DB
I would agree except for the following: My CHT's are well within my comfort range, even in the steeper, 2250 RPM climb. Any additional fuel will only cool the CHT's further, which is a waste. Futhermore, this engine has 1000 hours SMOH and wear is going to erode power output a bit. This will lower the "hp" value in your equation so my figures look even closer to your "norm".

You've been asked several times for data to back up your thinking and I realize it's pretty involved. However, the guys I listen to closest are not the "data" guys. They are the people who've seen thousands of engines come through their shop and the conditions in which they operated and the shape the core is in at overhaul. We have a flying club here on our airport (KSGS) that has about 30,000 hours on Piper aircraft. Their engines always go to TBO and beyond and look great when torn down. They don't have any of the EM systems we take for granted and they are flown by hundreds of pilots. Sometimes I wonder what we're all fussing about. I am seeing recommendations on these threads but I have yet to see a reply to the affect of "I agree, I had a cylinder that ran XXX degrees CHT and it failed". That's another guy whose input I'll take into account.
__________________
Mike Hilger
RV-6 N207AM w/G3X, 1,500 hours +
South St. Paul, MN (KSGS)
Manager - Panel Design, SteinAir, Inc.
A&P, EAA Tech Counselor

We're all here because we're not all there...
Reply With Quote
  #26  
Old 08-03-2012, 04:41 PM
RV10inOz's Avatar
RV10inOz RV10inOz is offline
 
Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,122
Default

Mike, the data is around, it started back with the Spirit of Saint Lois, the Doolittle raiders, NACA tests, Wright, Pratt & Whitney, TCM and Lycoming even have it. In most recent times the only continued work in this field has been done by GAMI in Ada OK, and they have proven the old stuff and further more have refined the knowledge on a lot of what was once believed because they have the only engine test stand in the world like it. Nobody else has bothered.

Your CHT's may be fine, thats great, but if your position is taken on that, it is like saying well I have never worn a seat belt and I am still alive. But you have not had a big accident so thats why you are alive, despite the fact that if you do the seat belt might just matter.

Please yourself. But some other data point which is not public is the results at APS classes from the mechanics, those who are not pilots either and have no experince playing with an EMS in flight to see what happens. Initially they score the lowest by far in the initial mini quiz. By the end of the weekend they are often all over it.

I have said before, be wary of advice, go get educated yourself. Then when you have a really good understanding, you will know how to interpret the engine guy, the hangar buddy or even some nut case from Australia on an internet form!

If you were to take your fuel flow advice from someone who can stand the test of scruitiny call up John-Paul or Tim at GAMI on Monday and ask them. I think you should not be wasting their valuable work time and you could search this elsewhere yourself, but you could. Call Bill Cunningham at Powermasters, or Don at Airflow....

Or just believe me I am not here trying to sell you fuel.

By the way fuel does not cool.....another OWT. And no I am not going to try to explain this in detail here, DR will run out of bandwidth and the site will be lost forever or something worse

hevansrv7a
indeed! you are correct. My typical full rich sea level ISA day rate is 0.593 to 0.597 lbs/hr And that is exactly as Mr Lycoming and Mr Precission Airmotive set it up to be. Recently serviced by the best engine shop in Oz at Riverina Airmotive.

I would believe they have it pretty much under control.

You can lead a horse to water, you can't make it enjoy the view!
__________________
______________________________

David Brown


The two best investments you can make, by any financial test, an EMS and APS!
Reply With Quote
  #27  
Old 09-11-2018, 06:52 AM
tgmillso tgmillso is offline
 
Join Date: Nov 2012
Location: Launceston, Tasmania, Australia
Posts: 618
Default How rich is rich enough

Hi All,
If you look in the Lycoming IO-360M1A 180hp 8.5:1CR manual (pg20), it says that at full throttle and 2700rpm at sea level, you should expect an 87lb/hr fuel flow, or 14gph. My density altitude is a little higher than sea level (800ft) and I am seeing 176hp on takeoff according to their performance charts, and if leaned to best power I should be seeing 13.9gph. With a full rich mixture, 28.4" MP and 2700rpm, I am observing 15.1gph via my FT-60 (mounted between the fuel servo and fuel spider) and I guess my question is, how rich is rich enough to provide adequate detonation margin? If 14gph for a Lycoming IO-360 at 100% power wasn't safe, why would Lycoming publish this in a chart? I see people talking up to 18gph on takeoff for an IO-360, but this seems like you would be squirting fuel out the back end.
The reason I am asking this is because I am seeing CHT up to 440degF just after takeoff, although a closer look at my baffle rub points on the cowl today indicate that this may be part of the problem, and not so much my low fuel flows compared to others.
Tom.

Reply With Quote
  #28  
Old 09-11-2018, 08:02 AM
airguy's Avatar
airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 4,258
Default

I run about 17 gph on takeoff with the same engine, at 2700' field altitude, and you're right, it's slobbering rich but it runs cool. At about 500' off the ground I pull the RPM back to 2500, leave the throttle all in, and start leaning it for the climb. I keep it just rich enough to hold CHT's at 400 or less and life is good, that's about 14.5 gph or so initially and dropping as I go up of course, and I go LOP once I level from the climb. I think if you run another 1-1.5 gph on takeoff you'll see your CHT be much lower.
__________________
Greg Niehues - VAF 2018 dues paid
Garden City, TX
N16GN flying! http://websites.expercraft.com/airguy/
Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.

Last edited by airguy : 09-11-2018 at 08:04 AM.
Reply With Quote
  #29  
Old 09-11-2018, 09:04 AM
Canadian_JOY Canadian_JOY is offline
 
Join Date: Aug 2007
Location: Ontario, Canada
Posts: 1,732
Default

New O-360A1F6, Hartzell C/S prop with the old F7666 blades. Field elevation of 387'. Depending on OAT I see flows from 16.5 to nearly 18GPH on takeoff with the prop spinning up to 2690RPM. CHT's seem happily below 400F on a reasonably aggressive climb-out. Push the nose down for another 10kts of airspeed and I can see 10F drop in CHT.

Per the Lycoming power chart, these fuel flows are pretty much spot-on, or at least as close as one is likely to get when reading that squinty chart!
Reply With Quote
  #30  
Old 09-11-2018, 04:22 PM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 7,800
Default

Listening to folks insist on fat mixtures for cooling may be Earth's closest equivalent to Vogon poetry.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 05:42 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.