VansAirForceForums  
Home > VansAirForceForums

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

- Today's Posts | Insert Pics


Go Back   VAF Forums > RV Firewall Forward Section > Traditional Aircraft Engines
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 05-15-2019, 11:59 AM
RV7ForMe RV7ForMe is offline
 
Join Date: Jul 2015
Location: Europe
Posts: 447
Lightbulb IO-360-M1B Fuel Flow question? Need help Please

Hello engine people... I need your help.

So we are getting ready to fly this thing (RV7-A, IO-360-M1B, CS all STOCK from VANS) GARMIN G3X Touch with Red Cube FF and everything else that comes with the Garmin Engine Monitor Kit for the lyc.

We did some engine ground runs and have a few problems that may be related.

So far we did a static run up to 2570 RPM / 23,8 MAP just to see if the governor and all that worked. Engine sounds and runs smooth.
However
CHT were very hot. Spread is very close except for #1 running about 35F hotter)
EGT at about 1400-1440 across all 4.
Fuel flow was at about 11 G/H (indicated). According to the Lyc Manual the engine needs about 14G/H at this RPM

I may need an explanation on how a fuel servo works in the injector engine or where I can read about it.

How can I test the fuel flow and adjust it without running the engine? I do not want to run the engine under these bad cooling conditions for any more time than it needs to. This engine needs to fly!

Adding the boost pump did nothing for the fuel flow.

Also I am not sure if the reading from the Red Cube are accurate (located at the right before the spider on the engine). Since the fuel servo wont let a lot of fuel through without the engine running and sucking air.

Please help us: What is the procedure for setting this up correctly with the Horizontal Induction fuel servo IO360 from VANS? The thing is I do not know if I can trust any of the readings because it is all new.

__________________
VAF dues paid until 10/2019
RV7-A (N137MX Reserved) - Empennage 95% done
RV7-A (N137MX Reserved) - Wings Started...
RV7-A - Rebuild Done.
Cessna Rocket 210HP - Best dang 172 Ever made! (sold)

Last edited by RV7ForMe : 05-15-2019 at 12:27 PM.
Reply With Quote
  #2  
Old 05-15-2019, 12:15 PM
airguy's Avatar
airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 4,560
Default

You would definitely need more fuel than that for full power - but if you were at 2600 rpm with partial throttle that might be about right. How much manifold pressure were you showing at 2600 rpm?

My same engine will show about 16.5 gph at takeoff power (2700 MSL at home) with a constant speed prop.
__________________
Greg Niehues - PPSEL, IFR, Repairman Cert.
Garden City, TX VAF 2019 dues paid
N16GN flying 400 hrs and counting! Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.
Reply With Quote
  #3  
Old 05-15-2019, 12:28 PM
RV7ForMe RV7ForMe is offline
 
Join Date: Jul 2015
Location: Europe
Posts: 447
Default

Quote:
Originally Posted by airguy View Post
How much manifold pressure were you showing at 2600 rpm?
2570 RPM / 23,8 MAP I added it to the above text....
__________________
VAF dues paid until 10/2019
RV7-A (N137MX Reserved) - Empennage 95% done
RV7-A (N137MX Reserved) - Wings Started...
RV7-A - Rebuild Done.
Cessna Rocket 210HP - Best dang 172 Ever made! (sold)
Reply With Quote
  #4  
Old 05-15-2019, 01:56 PM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
Posts: 2,746
Default

Quote:
Originally Posted by RV7ForMe View Post
2570 RPM / 23,8 MAP I added it to the above text....
I think 11G is just about right for 23" of manifold and 2600 RPM for that engine. Your EGT shows that you are a bit on the lean side.

You can always test your fuel flow rate thru your plumbing and pump by disconnecting the fuel line from the servo and run your pump for X number of minutes and see how many gallon you get. A simple calculation will show how many G/H your pump will push fuel and will remove any doubts of inaccuracy of reports by your engine instruments.
__________________
Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
Reply With Quote
  #5  
Old 05-15-2019, 02:21 PM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 8,379
Default

Quote:
Originally Posted by Bavafa View Post
Your EGT shows that you are a bit on the lean side.
Not necessarily. The absolute values alone tell nothing. Full rich EGT value compared to peak EGT value tells the tale.

Quote:
You can always test your fuel flow rate thru your plumbing and pump by disconnecting the fuel line from the servo and run your pump for X number of minutes and see how many gallon you get. A simple calculation will show how many G/H your pump will push fuel and will remove any doubts of inaccuracy of reports by your engine instruments.
Good idea...a check for the accuracy of the red cube.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #6  
Old 05-15-2019, 02:25 PM
RV7ForMe RV7ForMe is offline
 
Join Date: Jul 2015
Location: Europe
Posts: 447
Default Thanks but ?

Quote:
Originally Posted by Bavafa View Post
I think 11G is just about right for 23" of manifold and 2600 RPM for that engine. Your EGT shows that you are a bit on the lean side.

You can always test your fuel flow rate thru your plumbing and pump by disconnecting the fuel line from the servo and run your pump for X number of minutes and see how many gallon you get. A simple calculation will show how many G/H your pump will push fuel and will remove any doubts of inaccuracy of reports by your engine instruments.
Glad you brought this up because it is what is confusing to me in terms of how the fuel servo works.

We did multiple test even in simulated take off attitude during final assembly about a month ago. (BTW we have the AFP pump Vans sells)

1. Test:
"free flow" plumbing disconnected right before the fuel servo:
We actually let the pump empty a full tank and timed it in 2 minutes intervals.
We got an average of 46.5 G/H. No Air found!

2. Test:
plumbing disconnected right before spider (after fuel servo) with engine off obviously.
We got an average of 3.6 G/H

This led me to believe I do not fully understand the works of the fuel servo. I understand it mixes air and fuel. Thus it only takes what it needs. When the engine is off even with the pump trying to pump 46 G/H it only lets 3.6 G/H pass?

Is the ram air pressure needed for the fuel servo to work properly? In other words will it set the fuel flow to right number when on the ground and not flying?

Forgive my ignorance but I have tried to google this and I can't find the answer.
__________________
VAF dues paid until 10/2019
RV7-A (N137MX Reserved) - Empennage 95% done
RV7-A (N137MX Reserved) - Wings Started...
RV7-A - Rebuild Done.
Cessna Rocket 210HP - Best dang 172 Ever made! (sold)
Reply With Quote
  #7  
Old 05-15-2019, 02:30 PM
RV7ForMe RV7ForMe is offline
 
Join Date: Jul 2015
Location: Europe
Posts: 447
Default Good call

Quote:
Originally Posted by DanH View Post
Good idea...a check for the accuracy of the red cube.
OK this test is one I have not done. I could disconnect the line at the spider and let the pump do its job with the red cube still connected. If the G3X matches the 3.x G/H I can measure with a bucket and see if its the same?

Are these red cubes accurate over the entire spread? I want it to be accurate at about 14 gal but I cant test that with the engine off? correct? In other words are we sure if it is accurate between 3-4 G/H it will be at 14-16?
__________________
VAF dues paid until 10/2019
RV7-A (N137MX Reserved) - Empennage 95% done
RV7-A (N137MX Reserved) - Wings Started...
RV7-A - Rebuild Done.
Cessna Rocket 210HP - Best dang 172 Ever made! (sold)
Reply With Quote
  #8  
Old 05-15-2019, 02:32 PM
sglynn's Avatar
sglynn sglynn is offline
 
Join Date: Mar 2008
Location: Anacortes, WA
Posts: 748
Default fuel flow

I have the same engine & prop all from Van's and just started Phase 1. I've got about 10 hours on it. I'm also using Red Cube. Here is what I'm seeing.

1. I did two engine idle tests but didn't allow CHTs to get over 250F per advice from Lycoming. Only full power test was run up before first flight.
2. Did several fuel flow tests by running boost pump. But this doesn't really test the spider or injection nozzles. Did find slight plug in a vent line.
2a. Dedicated first flight to break-in for engine. Cruised around at 24.5x24.5 for about an hour, with some fluctuations. I'm hoping this was at least 75%.
3. I do see 16GPH climbing at 29.6MP and 2710 RPM which is full power climb at 1500 msl and 117kts.
3a. I'm seeing 12 GPH cruising around at 25x25,
3b. I see about 10GPH or less when below 23x23 cruising around.
4. Had one CHT that was hot. Turned out to be #3 and it needed a dent on the forward side of the aft baffle where the fins go flush. 1/8" dent lets some air flow around aft side of cylinder.
5. Had one high EGT turned out to be partial plugged nozzle. Plug was just a small hair, that was barely visible. Quick cleaning fixed it.

I hope that helps. I'm still concerned I'm not getting full rich. And a little concerned about CHTs which do get up to 400. More flying and testing to do.
__________________
Steve Lynn
RV-7A
Flying Phase I
Anacortes, WA
www.mykitlog.com/sglynn
Reply With Quote
  #9  
Old 05-15-2019, 03:39 PM
airguy's Avatar
airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 4,560
Default

Quote:
Originally Posted by RV7ForMe View Post
Glad you brought this up because it is what is confusing to me in terms of how the fuel servo works.

We did multiple test even in simulated take off attitude during final assembly about a month ago. (BTW we have the AFP pump Vans sells)

1. Test:
"free flow" plumbing disconnected right before the fuel servo:
We actually let the pump empty a full tank and timed it in 2 minutes intervals.
We got an average of 46.5 G/H. No Air found!

2. Test:
plumbing disconnected right before spider (after fuel servo) with engine off obviously.
We got an average of 3.6 G/H

This led me to believe I do not fully understand the works of the fuel servo. I understand it mixes air and fuel. Thus it only takes what it needs. When the engine is off even with the pump trying to pump 46 G/H it only lets 3.6 G/H pass?

Is the ram air pressure needed for the fuel servo to work properly? In other words will it set the fuel flow to right number when on the ground and not flying?

Forgive my ignorance but I have tried to google this and I can't find the answer.
The fuel servo does not mix air and fuel - it meters the correct amount of fuel for the amount of air passing through the servo, and sends that metered fuel to the flow divider. The mixture knob can tweak the metered flow rich or lean of the target, and can be used to provide a positive cut-off of fuel to kill the engine. If the mixture is NOT in ICO position, and the engine is stopped (no air flow through the servo) there is a minimum amount of fuel that continues to pass through for priming and start. That amount is usually in the ~3gph range, yes.

In my airplane for instance, to start I have throttle and mixture full in, turn on my fuel pump, wait for 1 second (warm weather) or 2 seconds (cold weather) then pull the throttle closed and hit the starter. That one or two second period allows fuel to trickle through the injectors and prime the engine for start prior to cranking, and allows enough fuel to allow the engine to start and come up to RPM, where the air flow through the servo then becomes the controller to how much fuel is passed.
__________________
Greg Niehues - PPSEL, IFR, Repairman Cert.
Garden City, TX VAF 2019 dues paid
N16GN flying 400 hrs and counting! Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.
Reply With Quote
  #10  
Old 05-15-2019, 03:57 PM
RV7ForMe RV7ForMe is offline
 
Join Date: Jul 2015
Location: Europe
Posts: 447
Default Thanks guys

Quote:
Originally Posted by sglynn View Post
I have the same engine & prop all from Van's and just started Phase 1. I've got about 10 hours on it. I'm also using Red Cube. Here is what I'm seeing.
Thank you for your numbers Steve. How did you adjust and check the engine gets 16G/H at full power before first flight?

Quote:
Originally Posted by airguy View Post
The fuel servo does not mix air and fuel - it meters the correct amount of fuel for the amount of air passing through the servo...
Thanks Greg for explaining that to me.

---

Ok so I will check the red cube as suggested above.

But what is the "proper" process in adjusting and testing the engine gets what it needs before first flight?
__________________
VAF dues paid until 10/2019
RV7-A (N137MX Reserved) - Empennage 95% done
RV7-A (N137MX Reserved) - Wings Started...
RV7-A - Rebuild Done.
Cessna Rocket 210HP - Best dang 172 Ever made! (sold)
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 12:36 PM.


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.