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  #1  
Old 08-31-2019, 02:08 PM
727TT 727TT is offline
 
Join Date: May 2016
Location: Granbury TX
Posts: 36
Default 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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  #2  
Old 08-31-2019, 02:35 PM
jjbardell jjbardell is online now
 
Join Date: Jan 2017
Location: Phoenix, AZ
Posts: 227
Default 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.
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Building - Zenith 750 [11323] CruzerDuty27.5
N67LJ RV9-A [90504] - SOLD
N83LJ Sonex [0864] - SOLD

https://rvpilotlife.wordpress.com/blog/home/

Last edited by jjbardell : 08-31-2019 at 02:37 PM.
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  #3  
Old 08-31-2019, 03:26 PM
N941WR's Avatar
N941WR N941WR is offline
 
Join Date: Jan 2005
Location: SC
Posts: 12,887
Default

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.
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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
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  #4  
Old 08-31-2019, 08:25 PM
jjbardell jjbardell is online now
 
Join Date: Jan 2017
Location: Phoenix, AZ
Posts: 227
Default CHT

I forgot a third change that helped a lot

3) Cut the bottom cowl back at a 45 degree
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Cheers, Josh

Building - Zenith 750 [11323] CruzerDuty27.5
N67LJ RV9-A [90504] - SOLD
N83LJ Sonex [0864] - SOLD

https://rvpilotlife.wordpress.com/blog/home/
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  #5  
Old 09-01-2019, 07:39 AM
ALagonia ALagonia is offline
 
Join Date: Jul 2017
Posts: 365
Default

Quote:
Originally Posted by jjbardell View Post
I forgot a third change that helped a lot

3) Cut the bottom cowl back at a 45 degree
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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  #6  
Old 09-01-2019, 08:37 AM
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scard scard is offline
 
Join Date: Jun 2005
Location: Cedar Park, TX
Posts: 3,197
Default

Quote:
Originally Posted by ALagonia View Post
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.
There is something else going on there. More mass flow isn't what you're looking for here.
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RV-9A N4822C flying 2200+hrs. / Cedar Park, TX
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  #7  
Old 09-01-2019, 08:50 AM
ALagonia ALagonia is offline
 
Join Date: Jul 2017
Posts: 365
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Quote:
Originally Posted by scard View Post
There is something else going on there. More mass flow isn't what you're looking for here.
What are your thoughts? Please share
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  #8  
Old 09-01-2019, 09:11 AM
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rjcthree rjcthree is offline
 
Join Date: Jan 2007
Location: Bay Village, OH
Posts: 931
Default 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.
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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
2011-2021 VAF contributor
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  #9  
Old 09-01-2019, 10:00 AM
ALagonia ALagonia is offline
 
Join Date: Jul 2017
Posts: 365
Default

Quote:
Originally Posted by rjcthree View Post
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.
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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  #10  
Old 09-01-2019, 10:00 AM
ALagonia ALagonia is offline
 
Join Date: Jul 2017
Posts: 365
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Quote:
Originally Posted by rjcthree View Post
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.
Not electronic ignition. Straight mags
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