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08-31-2019, 01:08 PM
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Join Date: May 2016
Location: Granbury TX
Posts: 36
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CHT Overheating issue
We installed the Dynon HDX in our RV7A over 2 years ago. We also redid all of the engine baffling. The CHT on #4 always ran hot on takeoff. We replaced a number of components and traced it to a wire. The probe itself was ok.
Now, on take off 2,3 and 4 all show hot at 410 to 425 on #4.
Any thoughts?
It was suggested I install cowling Louvers to provide more air flow.
The carburetor was overhauled last year and I installed a new fuel pump. It came out of annual this past spring.
Thanks.......
Steven
Superior 0-360 with fix pitch
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08-31-2019, 01:35 PM
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Join Date: Jan 2017
Location: Phoenix, AZ
Posts: 198
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CHT
I just went through it myself. I can share what my issues were.
History: O320 and installed a Dynon system. New probes, wires. Conditioned in May 19. No issues found.
Issue: High CHT (405-425)
Solution:
1) Timed both mags. They were advanced a few degrees. Ok, maybe a lot of degrees. Lol. It was a certified new engine w 250 TTSN.
2) Dynamically balanced the prop. It was .034”. It’s now .006”
The timing dropped my CHT so much that I can now climb at Max gross at 1,900 ft/min through 5,000. Then 1,200 ft/min through 9,500 and stay below 400. Cruise is now 360s.
And my fuel flow went from 7.5 to 6.7 gph at 65% / 142kt.
Not sure if it helps, but if you haven’t checked timing in the last 50 hours, I’d start there. Good luck with your search.
__________________
Cheers, Josh
NXXLJ RV6 IO360 200HP - Purch Pending
N67LJ RV9-A - SOLD
N83LJ Sonex - SOLD
rvpilotlife.wordpress.com
'20 supported!
Last edited by jjbardell : 08-31-2019 at 01:37 PM.
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08-31-2019, 02:26 PM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Check your magneto timing.
If you have P-mags, PM me your number and I'll walk you through it.
If you have even a small leak in your baffles, it can make a surprisingly large difference in CHT's.
Louvers are a last ditch effort and should be avoided.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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08-31-2019, 07:25 PM
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Join Date: Jan 2017
Location: Phoenix, AZ
Posts: 198
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CHT
I forgot a third change that helped a lot
3) Cut the bottom cowl back at a 45 degree
__________________
Cheers, Josh
NXXLJ RV6 IO360 200HP - Purch Pending
N67LJ RV9-A - SOLD
N83LJ Sonex - SOLD
rvpilotlife.wordpress.com
'20 supported!
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09-01-2019, 06:39 AM
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Join Date: Jul 2017
Posts: 344
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Quote:
Originally Posted by jjbardell
I forgot a third change that helped a lot
3) Cut the bottom cowl back at a 45 degree
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Can you post a pic of the cut you made? I have a 9 and yesterday in cruise 1:44 flight my #4 was at 411. Reduced power from 70% to 64% and #4 CHT only dropped to 401. Burning 9 gph at 6000?, OAT 70 degrees.
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09-01-2019, 07:37 AM
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Join Date: Jun 2005
Location: Cedar Park, TX
Posts: 3,156
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Quote:
Originally Posted by ALagonia
Can you post a pic of the cut you made? I have a 9 and yesterday in cruise 1:44 flight my #4 was at 411. Reduced power from 70% to 64% and #4 CHT only dropped to 401. Burning 9 gph at 6000?, OAT 70 degrees.
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There is something else going on there. More mass flow isn't what you're looking for here.
__________________
Scott Card
CQ Headset by Card Machine Works
CMW E-Lift
RV-9A N4822C flying 2200+hrs. / Cedar Park, TX
RV8 Building - fuselage / showplanes canopy (Done!)
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09-01-2019, 07:50 AM
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Join Date: Jul 2017
Posts: 344
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Quote:
Originally Posted by scard
There is something else going on there. More mass flow isn't what you're looking for here.
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What are your thoughts? Please share
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09-01-2019, 08:11 AM
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Join Date: Jan 2007
Location: Bay Village, OH
Posts: 886
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Other temps and info required
What are your other CHTs, oil temp, are you running
rich, at or lean of peak, carb or injection, what injection, ignition? Engine model? Thx.
__________________
Rick
RV-9A N183RC/90432: tip-up, O320H2, Ellison, Dynon D180, CPi2, Sen GA, at KLPR
RV-8 83718, wing kit, tanks done, with a four year plus plan - on hold due to home move
2011-2020 VAF contributor
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09-01-2019, 09:00 AM
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Join Date: Jul 2017
Posts: 344
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Quote:
Originally Posted by rjcthree
What are your other CHTs, oil temp, are you running
rich, at or lean of peak, carb or injection, what injection, ignition? Engine model? Thx.
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I wrote them all down but left my pad in the airplane but other CHT?s were well below 400 rich of peak, carbureted and all EGT?s were below 1400. O-360 Barrett engine with less than 200 hours since new.
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09-01-2019, 09:00 AM
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Join Date: Jul 2017
Posts: 344
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Quote:
Originally Posted by rjcthree
What are your other CHTs, oil temp, are you running
rich, at or lean of peak, carb or injection, what injection, ignition? Engine model? Thx.
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Not electronic ignition. Straight mags
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