VansAirForceForums  
Home > VansAirForceForums

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

- Today's Posts | Insert Pics

  #1  
Old 04-11-2018, 01:47 PM
WingnutWick's Avatar
WingnutWick WingnutWick is offline
 
Join Date: Jun 2013
Location: Lemoore
Posts: 94
Default RV-8 O-360 Temps and Fuel Flow issues

Hello all,

Just wanted to push out to all of you to see what you guys think about some of the engine issues I have. O-360, fixed pitch, dual P-Mags, Dynon D10 EMS. CYL #3 runs VERY hot even on cold days, even in cruise with CYL 2, 4 not too far behind. CYL 1 runs much cooler than the others. You can see some temps I see on climb and cruise taken on a winter day at altitude. Anything slower than a 100 KT climb will have my #3 CHT shoot to above 430 rapidly.

Also on climb out and WOT I will see my fuel pressure typically drop quickly from a nominal 3-4 PSI to .5 and 0 PSI which sets off the alarm. I've noticed this is often accompanied by an increase in fuel flow. Turning on the electric pump will push these up to 4. Securing the electric pump, the PSI will gradually decrease again to .5-0. Once throttling back to cruise settings the fuel pressure will climb back to nominal.

I am wondering if any of you have any ideas on the fuel flow and the over heating. What's a good way to check the baffles? Are there any good plenums out there for my configuration that has shown good success in cooling so I can do away with worrying about baffles? Searching through the threads it seems adding a washer helps with cooling but I'm not quite sure where that washer is being added....any photos to show this?

Otherwise the motor runs nicely and no noticeable performance issues associated with the drop in fuel PSI.

Any input is greatly appreciated!


__________________
-Wingnut
Rhino driver by trade
RV-8 O-360

Last edited by WingnutWick : 04-11-2018 at 04:10 PM.
Reply With Quote
  #2  
Old 04-11-2018, 03:12 PM
drill_and_buck's Avatar
drill_and_buck drill_and_buck is offline
 
Join Date: Feb 2005
Location: Bridgewater, MA - KPYM
Posts: 419
Default

Charles,
I have a similar setup with the exception of the prop (Hartzell). Here are my observations.

On a cold day, if I climb with a high angle of attack, my fuel pressure (not fuel flow) will occasionally drop to zero. My fuel flow remains healthy and all other engine parameters are in the green. Turning on the electric boost pumps remediates this. I think the problem may be with the sensor or could be air in the line.

I tend to climb out at 120kts. Anything slower and CHTs will rapidly rise. Due the angle of your climb you have a significant reduction in airflow over the cylinders. High power + reduced flow = high chts.

Your CHT spreads indicate that you most likely have some improvements to make in the baffling. There are plenty of suggestions in the forums on checking your baffles. Here is an example: http://www.vansairforce.com/communit...d.php?t=113134 Look for others. There is no one magic bullet. Collectively they can significantly reduce CHTs. You should do whatever it takes to keep your CHTs below 400.

After you have implemented all the baffle fixes you can always add a cowl flap on the bottom of the cowl. This will allow you climb at a higher angle of attack or join the 90 Kt conga line to KOSH without overheating.
__________________
Mike Draper
RV-8 N468RV
First Flight 11/13/2011
TMX0360, Pmags, CS
Bridgewater, MA
KPYM
Reply With Quote
  #3  
Old 04-11-2018, 03:42 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 4,236
Default

Two suggestions (if not done already & assuming you have checked for mixture issues)

1. Progressively block the front of #1 to warm it up and deflect air back to #3.

2. Open up the back side of #3 where the fins are too shallow. Search for the "washer trick" but better to make a proper chute for it. Many example here. Email me if you want a template for the chute, and a picture of the install. (also here on VAF)
__________________
Bill

RV-7
Op Lims in hand 12-7-17
1st Flight 1-27-18
2017 Dues Paid
Reply With Quote
  #4  
Old 04-11-2018, 04:18 PM
WingnutWick's Avatar
WingnutWick WingnutWick is offline
 
Join Date: Jun 2013
Location: Lemoore
Posts: 94
Default

Mike and Bill,

Thanks for the info and suggestions. Bill, you mention mixture issues: what do you mean in particular? Running it too lean? Even at full mixture it'll drop the CHT's a little but not by much. I would love a template for the chute if you don't mind sending it my way! charleswickware@gmail.com

Cheers!

Wingnut
__________________
-Wingnut
Rhino driver by trade
RV-8 O-360
Reply With Quote
  #5  
Old 04-11-2018, 07:30 PM
Dreamin9 Dreamin9 is offline
 
Join Date: Aug 2016
Location: Near Buffalo, NY
Posts: 44
Default Full Power FF

If the problem still persists after messing with baffle seals and other airflow solutions, check your FF at full power.
It seems some RV engine installs run lean. My O-320 160 was showing 11.8 gph at 98% power. The Lycoming manual says it should be about 13.9. Some say FF should be .9gph for each 10 hp at full power.
I recently had my carb jet reamed going from 42 to 40 and FF went to about 12.8. Further testing is needed to look for CHT improvements.

Good luck with the hunt.
Reply With Quote
  #6  
Old 04-11-2018, 08:54 PM
Dbro172's Avatar
Dbro172 Dbro172 is offline
 
Join Date: Apr 2012
Location: West Fargo, ND
Posts: 1,006
Default

Can you post some pictures of your baffles and cowl inlets? I chased this with every suggestion and when i finally switched to McFarlane cowl saver baffle seals and made sure that they were fully tucked behind the sides of the inlets I saw a drastic improvement in temps, like 30-50 degrees. Now my #3 actually runs coolest, even without the washer...
__________________
Derek Hoeschen
EAA Tech Counselor
RV-9A #92103 - N803DK
G3X, Superior XO-320, Dual Pmags, Catto 3B
www.mykitlog.com/dbro172/

RV-8 #83565 - N184DK - building
1968 Mooney M20C - Sold
1956 C-182 - Sold
Reply With Quote
  #7  
Old 04-12-2018, 04:55 AM
humptybump's Avatar
humptybump humptybump is offline
 
Join Date: Feb 2011
Location: Eastern Shore of Virginia
Posts: 3,020
Default Fuel pressure drop with fuel flow rise

I've seen my fuel pressure drop and fuel flow climb (signifantly). I see this when I'm running a tank to empty. In my airplane it indicates I'm getting air in my fuel.
__________________
- Glen, ESVA
RV-8 FP IFR | Track my RV-8 | 53VG
Reply With Quote
  #8  
Old 04-12-2018, 06:44 AM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
Posts: 3,910
Default

The zero fin depth issue on #3/5 and #2 is a well understood cause of most of these temp issues. The bypass duct solution is a proven fix for the deficient baffle design.

As often as this question comes up, perhaps its time to collect the various "bypass duct" threads and make a sticky? If Vans is not going to fix their baffles, at least this site can provide an easy resource for builders/operators to do so on their own.
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI instalation in work
RV-8 - Flying
1940 Taylorcraft BL-65 -flying
Reply With Quote
  #9  
Old 04-12-2018, 08:35 AM
Raymo's Avatar
Raymo Raymo is offline
 
Join Date: Nov 2014
Location: Richmond Hill, GA (KLHW)
Posts: 1,614
Default

You mentioned dual P-Mags. Make sure you have the jumper installed between 2 and 3 on the connector or, better yet, connect your computer and drop the Adv Shift to 0 or -1.4 and your Max Adv to 36.x.

If set via computer, you don't need the jumper installed.
__________________
Ray
RV-7A - Slider - N495KL - First flt 27 Jan 17
O-360-A4M w/ Catto 3 blade NLE, AFP FM-150 FI, 1 PMag, Vetterman Trombone Exh, SkyTech starter,
PlanePower Alt, FlightLines Interior, James cowl & plenum
All lines by TSFlightLines
NSDQ

"The object of the game, gentlemen, is not to cheat death: the object is not to let him play."
Patrick Poteen, Sgt. U.S. Army
Reply With Quote
  #10  
Old 04-12-2018, 10:20 AM
Red Rooster Red Rooster is offline
 
Join Date: Feb 2017
Location: savannah
Posts: 6
Default

I have the same issues w/ CHT & FF, but.........

One P-mag on a 0-230-D2B w/ Vetterman exhaust RV6 TD. Installed a JPI EDM 830 w/ FF and P-mag at the same time with the jumper . Tons of power, and high CHTs. #3 would reach 425 in climb and full power cruse no matter the altitude. Powering back to 2200 RPM reduced CHT temps.

But.... was able to have low CHTs, after building the harness for the Eicad and setting -1.4 for the shift and 36.4 for the max.Though it feels like some power was lost.

My FF is also low, 11.6 on take off and 12. 8 on climb out. Cruse is high 11's.
Not sure whats up with this. The FF gauge that the JPI replaced was showing 13 something on climb out. The carb was sent to the manufacture 4 years ago for a overhaul. They said the carb was bench flowed at 14 gph.

Both gauges are pretty accurate with fuel used / fuel remaining in reference to how much fuel I put in when at the pump.

I would think more fuel would equal for power / heat?

Any insight is welcomed
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 12:56 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.