VansAirForceForums  
Home > VansAirForceForums

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

- Today's Posts | Insert Pics

  #1  
Old 08-19-2019, 02:34 PM
bjdecker's Avatar
bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 71
Default The mystery of #4...

Greetings,

I have a bit of a mystery and would like to appeal to the brain-trust for assistance.

The configuration: RV-7, Lycoming YIO-360-A1B6, Hartzell F7497 CS Prop, Dual Lightspeed Plasma III - timed to 20°, Denso IK27 plugs, Avstar AVX-5VA1 fuel injection servo, Standard pistons (8.7:1 CR), Custom Plenum, SW 8406R oil cooler mounted on firewall fed by 3" SCEET duct from above #4 cylinder, Temperature risers are installed in front of #1 and #2 cylinders - #1 is 1/4" lower than "stock", #2 is 3/4" lower than "stock", #2 cylinder is the hottest - followed by #3, #1 and ultimately #4.

The symptom: during climb out, and in all subsequent phases of operation at or above 80 Kias, the #4 cylinder will run ~30° colder than the other 3 cylinders (#4 max is 336°F, others max ~365°F).

Additional data: all 4 cylinders "peak" within .1GPH (e.g. 9.3GPH at 6500msl), and all EGTs are within 75°F of each other for all phases of flight. Probes have been swapped, tested, and appear correct.

My objective is to get #4 up to the same temps as the rest. Any ideas would be greatly appreciated.

B
__________________
Quae nocent, saepe docent...
Reply With Quote
  #2  
Old 08-19-2019, 04:24 PM
JohnInReno's Avatar
JohnInReno JohnInReno is offline
 
Join Date: Jun 2005
Location: Prescott Valley/Chandler AZ
Posts: 334
Default Check this

http://www.vansairforce.com/communit...ghlight=baffle
__________________
John Morgensen
RV-9A N946PM 600+ hours since 2013
Nevada/Arizona
Reply With Quote
  #3  
Old 08-19-2019, 05:43 PM
bjdecker's Avatar
bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 71
Default Check this -- not that...

Quote:
Originally Posted by JohnInReno View Post
Hey John -- thanks for the reply; unfortunately - nothing in the attached thread was applicable; K-type probes and K-type configs, #2 and #3 gaps are ok, problem is with #4 getting too cold, not the others running too hot...

I wonder if the temp riser in front of #1 is too high and there is a cross-flow behavior that's pushing more air to #4 as a result? #1 sits in front of #2 laterally, and #1 catches the air spilling off the trailing edge of the prop moving DOWN -vs- #2 which catches the air spilling off the trailing edge of the prop moving UP...

B
__________________
Quae nocent, saepe docent...
Reply With Quote
  #4  
Old 08-19-2019, 07:48 PM
RV8Squaz's Avatar
RV8Squaz RV8Squaz is offline
 
Join Date: Feb 2006
Location: Senoia, Georgia
Posts: 703
Default

Quote:
Originally Posted by bjdecker View Post
Greetings,

I have a bit of a mystery and would like to appeal to the brain-trust for assistance.

The configuration: RV-7, Lycoming YIO-360-A1B6, Hartzell F7497 CS Prop, Dual Lightspeed Plasma III - timed to 20°, Denso IK27 plugs, Avstar AVX-5VA1 fuel injection servo, Standard pistons (8.7:1 CR), Custom Plenum, SW 8406R oil cooler mounted on firewall fed by 3" SCEET duct from above #4 cylinder, Temperature risers are installed in front of #1 and #2 cylinders - #1 is 1/4" lower than "stock", #2 is 3/4" lower than "stock", #2 cylinder is the hottest - followed by #3, #1 and ultimately #4.

The symptom: during climb out, and in all subsequent phases of operation at or above 80 Kias, the #4 cylinder will run ~30° colder than the other 3 cylinders (#4 max is 336°F, others max ~365°F).

Additional data: all 4 cylinders "peak" within .1GPH (e.g. 9.3GPH at 6500msl), and all EGTs are within 75°F of each other for all phases of flight. Probes have been swapped, tested, and appear correct.

My objective is to get #4 up to the same temps as the rest. Any ideas would be greatly appreciated.

B

Sounds like you have the same numbers I’ve had on my IO-360A1A powered RV-8 for the last 12 years and 1700 hours. Those numbers are identical to my friends’ RV-8’s with the same engine. Many years ago, I trimmed the dam in front of #2 with no appreciable change. That cylinder just runs cooler than the rest. Think of the cooler temp on #4 as a bonus and enjoy.
__________________
Jerry Esquenazi
RV-8 N84JE
Reply With Quote
  #5  
Old 08-19-2019, 08:33 PM
sjhurlbut sjhurlbut is offline
 
Join Date: Jan 2005
Posts: 643
Default UP?

Bring CHT up? Why? Temps are looking good. Think of CHT and cylinder peak pressure instead. You never want to increase it.
__________________
"Aerodynamics is for people who can't build engines"
Enzo Ferrari

Steve H
Cold Lake, Alberta
RV7A #70015 - C-FZQX - built - sold
RV7A #71629 - C-FSIS - built - sold across Atlantic
RV7 #70215 - C-GOJU - flying - sold
RV7 #70703 - C-GMIY - flying - sold
RV6 #60119 - C-FHBZ - built - Airventure 2016 Bronze Lindy - sold
RV10 #41779 - built emp - sold
RV8 #82842 - C-FSBG - Fastback with big hp IO-360-A1B6 10:1 - built - flying
Reply With Quote
  #6  
Old 08-20-2019, 07:30 AM
Snowflake's Avatar
Snowflake Snowflake is offline
 
Join Date: Oct 2009
Location: Victoria, BC, Canada
Posts: 3,461
Default

I agree with Steve. Try to bring the other three cylinders *down*, not #4 up.
__________________
Rob Prior
1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
Reply With Quote
  #7  
Old 08-20-2019, 01:38 PM
scsmith scsmith is offline
 
Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,144
Default

Quote:
Originally Posted by RV8Squaz View Post
Sounds like you have the same numbers I’ve had on my IO-360A1A powered RV-8 for the last 12 years and 1700 hours. Those numbers are identical to my friends’ RV-8’s with the same engine. Many years ago, I trimmed the dam in front of #2 with no appreciable change. That cylinder just runs cooler than the rest. Think of the cooler temp on #4 as a bonus and enjoy.
Me too. #4 runs coolest by 30F. For me, it is more like 265F when the others are in the 290--300 range.
__________________
Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet"
Hobbs 580
also LS-6-15/18 sailplane
VAF donation Jan 2019
Reply With Quote
  #8  
Old 08-20-2019, 03:39 PM
bjdecker's Avatar
bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 71
Default

Quote:
Originally Posted by scsmith View Post
Me too. #4 runs coolest by 30F. For me, it is more like 265F when the others are in the 290--300 range.
Thanks for the data Steve(s), Rob, Jerry. I was beginning to wonder if it was something that I had done.

I guess I'll just enjoy the temps
__________________
Quae nocent, saepe docent...

Last edited by bjdecker : 08-20-2019 at 03:41 PM. Reason: Updates to attribution.
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 06:30 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.