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  #81  
Old 10-20-2020, 03:53 PM
romaja romaja is offline
 
Join Date: Jan 2016
Location: Portland Oregon Area
Posts: 97
Default

Quote:
Originally Posted by DanH View Post
It would control pressure in the lower cowl. DeltaP (upper vs lower) dictates mass flow for both cylinder fins and oil cooler.
Thanks Dan,

Makes sense.
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Rans S20 Raven Sold Built in 2016
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  #82  
Old 10-21-2020, 07:47 PM
RobB52 RobB52 is offline
 
Join Date: Nov 2013
Location: Shreveport, LA
Posts: 64
Default 5" SCAT Mod

Tom and others,

I thought I found the smoking gun on the high oil temp. I failed to RTV any of the baffles at the base of the cylinders. I spent an hour or so caulking those and then used a light to look for holes. I flew today expecting lower oil temps, BUT NO! OAT was about 10 degrees warmer (62) than previous flight (52) and oil temps were 7 degrees hotter than last flight!! Here are my numbers at 21.5 hours on the engine.

75% Power, MAP 24.2, RPM 2500, Full Rich, 4500'
OIL 217
CHTs 333, 340, 311, 309
EGTs 1215, 1200, 1245, 1235

71% Power, MAP 24, RPM 2400, Full Rich 4500'
OIL 212
CHTs 330, 345, 309,307
EGTs 1215, 1195, 1240, 1230

I have no confidence the 5" SCAT mod I'm going to do this weekend will help.

Van's site says to check the operation of the Venatherm if CHTs are normal (or low) and oil temps are high but they don't tell you how to check it. So, how does one CHECK the Vernatherm?

I'm about ready to order a new temp sensor, Vernatherm and oil cooler and just replace all components.

Also, I bought a bore scope thing to look at the baffles under the cowl and they are all folded the correct direction and making contact with the cowl. No obvious issues with baffle/cowl contact.

Thoughts again?
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RV-14 Flying
EAA Chapter 343 (DTN)
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Last edited by RobB52 : 10-21-2020 at 07:51 PM.
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  #83  
Old 10-21-2020, 11:25 PM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,515
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Bob,
It is a good idea to check both the sensor and Vernatherm but I am not too optimistic to find issues with those.
Both are rather easy to check, I did both of them and they checked out right on the spot. I pulled the temp sensor and put it in the hot liquid while still connected and had a thermometer in the same jar of hot liquid. I also bought another sensor and compared it and both were right on the money.

I pulled the Vernatherm and put it in pot and slowly brought it to boil. You measure the length it increases at different temps. At 212F, it should increase by around .244” and also I made sure that it is seating in place and fully closes the passage when closed. Again, mine was right on the money.

With these engines, I think you will need to aim for incremental improvements rather a big jump. The 5” scat tubing will help but won’t bring it to 180 or 190 if you are expecting that.

If you have not double checked your timing, I would highly suggest to do that. I have PMAG and if I reduce the advance to 4 degree instead of 10 in the air, I see a change in oil temp within just a couple of minutes.
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N825SM RV7A - IO360M1B - SOLD
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Last edited by Bavafa : 10-21-2020 at 11:27 PM.
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  #84  
Old 10-22-2020, 08:42 AM
RobB52 RobB52 is offline
 
Join Date: Nov 2013
Location: Shreveport, LA
Posts: 64
Default Emag Timing

Mehrdad,

Can you expand on your emag timing comment? Does reducing the advance lead to higher temps or lower temps? I am running dual emags, jumper installed, set at TDC (or very close to it). Reading the emag manual, I can set the mags up to 6 degrees after TDC to "reduce the advance further." What would you recommend trying to reduce oil temps?
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  #85  
Old 10-22-2020, 09:28 AM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,515
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Quote:
Originally Posted by RobB52 View Post
Mehrdad,

Can you expand on your emag timing comment? Does reducing the advance lead to higher temps or lower temps? I am running dual emags, jumper installed, set at TDC (or very close to it). Reading the emag manual, I can set the mags up to 6 degrees after TDC to "reduce the advance further." What would you recommend trying to reduce oil temps?
Bob,
If you have set your timing at TDC, that is incorrect and you are advancing about 15 degrees instead of the 10 with the jumper in. This certainly yield a higher oil temp and I believe it may account for your situation.

Please note that PMAG, unless it is reprogrammed, fires at 25BDC by default which is for most 320/360 engines whereas IO390 timing is at 20BDC. So, you will need to either reprogram your PMAG or retard the timing set by around 5-6 degree which is the easiest.

To answer your question, reducing the advance, lowers the oil temp. I have EICommander and can change the timing in the air.

If any further question on this, we can talk for further clarification.
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N825SM RV7A - IO360M1B - SOLD
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  #86  
Old 10-22-2020, 12:11 PM
RobB52 RobB52 is offline
 
Join Date: Nov 2013
Location: Shreveport, LA
Posts: 64
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Mehrdad,

Thanks. I will adjust timing and fly again later today. Fingers crossed.

I will post my results.
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RV-14 Flying
EAA Chapter 343 (DTN)
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  #87  
Old 10-30-2020, 10:35 AM
RobB52 RobB52 is offline
 
Join Date: Nov 2013
Location: Shreveport, LA
Posts: 64
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Mehrdad,

I was finally able to get in the air again. I clocked the emags at 5 degrees after TDC (retarded 5 degrees) as discussed previously. Jumpers in. Unfortunately it had little if any impact on oil temps. Here is my data from todays flight:

Alt 4500'
OAT 55 degrees (8 degrees cooler than last flight)
MAP 24.0
RPM 2400
Mixture Full Rich
OIL TEMP 210 (2 degrees colder than last flight)
CHTs 334, 344, 308, 309
EGTs 1230 1195 1240 1240

Next step is to install the 5" SCAT, but am not getting my hopes up for lower oil temps.

Temp Probe was tested by shooting oil filter with temp gun after landing. Filter showed 196 and oil temp on gauge was 197.

I have not removed vernatherm for testing. Considering new oil cooler also.

I will report back after the 5" SCAT install and test.
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RV-14 Flying
EAA Chapter 343 (DTN)
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  #88  
Old 10-30-2020, 12:29 PM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,515
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Rob,
Thank you for reporting back. The 5 degree retard was certainly needed to set the timing correct for this engine but I was hoping to have a bigger impact on your oil temp, sorry it did not.

Considering your CHTs are also higher from what I would expect them to be and compared to most RV14s , especially for the relatively low OAT, it may also be good to look at your baffling. The 5 scat tubing ought to help but please keep in mind that I will also affect your CHT.

Some other random thoughts that you might want to do,
- Do a compression check to see if there is possibly some excess gas/heat is passing your rings
- Check your oil temp in the sump right after landing and compare to oil temp reported by the sensor
- Double check your baffles
- Do you have your wheel pants/fairing installed, if you are slower than this could affect your temp
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N825SM RV7A - IO360M1B - SOLD
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  #89  
Old 11-02-2020, 12:34 PM
avatty avatty is offline
 
Join Date: Sep 2015
Location: Walnut Creek, CA
Posts: 45
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Probably it would have been considered in developing the -EXP119, but would a larger oil cooler be helpful/practical? Or just expose my ignorance on the subject? Airflow Performance makes 15 and 17 row coolers, in addition to the 2006X. Also, the company's website advises "Go up one size for piston squirters, cold air induction, aerobatic and/or float plane applications."
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1949 Cessna 140A - IRAN'd 2017
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  #90  
Old 11-02-2020, 09:50 PM
Qui Qui is offline
 
Join Date: Aug 2013
Location: Poplar Grove, IL
Posts: 27
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I'm sure this isn't the issue causing the higher oil temps but after reading about higher temps with the wheel fairings off (less airflow) I thought I should mention this just in case. When I thought I had completed the fiberglassing/sanding of the the cowl inlet holes, I stepped back to take a look and to my surprise, the left inlet was much wider than the right. After many hours of re-forming the holes etc, I ended up with 2 even holes but both were, what I considered, much larger than the original. I haven't flown mine yet, so I can't offer a comparison.
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