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03-17-2015, 08:03 PM
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Join Date: Jan 2005
Location: Sedona Arizona
Posts: 349
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25 hrs and still running hot.
My IO-375 runs hot in OATs below 60F. This is on my RV7A with new engine from Aerosport with 25 hrs on it and the rings seem to be seated as oil consumption is hardly noticeable.
If this keeps up I am going to have trouble this summer. I have gone over my baffling again and again sealing up any places where air might escape before doing it's engine cooling duty. (Washer behind #3 rear baffle etc.) I verified correct routing of the oil cooler hoses so air should not be trapped in the oil cooler. Running 8432R oil cooler on modified RV10 firewall mount, feeding it with 4" scat off the rear baffle and have 4" butterfly valve to control the air flow, it is working properly. I even made special baffle wraps to fit the tapered cylinder fins on the ECI tapered cylinders, they wrap nicely against the cyl. fins forcing the air between the fins. Differential pressure from top of engine to behind the baffles is always above 10" WC, up to 14" WC at speed with EZ Cool flaps open. Air cannot escape through the upper cowl inlet ramps, they are sealed.
I had anticipated that I would need to partially close the oil air door except in the hot temps of summer, not so. It looks like I will need to keep my EZ Cool cowl flaps open whenever I run at full power, ( I think they are especially helpful on A models as the gear tubes block the normal air exit). Even with them open, at best power mixture setting, it will heat up above my limits.
I can easily control the temps by running way rich of peak, or lean of peak, but if I run at best power, even up above 8000', oil T will head up above 200F, and CHTs will climb above 400F. Both of those are temp limits I would like to keep in place. I know some people feel OK with higher temps than that, I do not, especially with OATs as low as they have been.
I am still running mineral oil for break in, maybe I will see improvement when I change that out?
Could I still be experiencing an extra warm engine due to break in after running it hard for the first 20 hrs? I hear that the Nickle Carbide cylinders generally break in pretty fast.
Possibly related, I am running dual PMags. I set them up for max advance of 26 degrees during the first 20 hrs. Now running A curve and this change did not appear to affect the engine temperatures. During those first 20 hrs I always had more than 24" MAP, and way ROP, trying to make sure I got a good break in.
I am looking for some feedback from others with similar engine configuration that might shed light on this business. Maybe it will get better after some more hours on it??
OK same subject but different: While inspecting for problems and thinking about the heat I look at the cabin heat valve, and see that when closed, it dumps that heat right into the back side of the engine area. The heater seems to work real good in the cabin so I am thinking I don't really need to be dumping that heat near the fuel pump and PMags. So I have this idea of ducting the hot air down closer to the cowl exit. Anybody tried that?
Maybe there is enough air flow back there to get that hot air out before it contributes to heating up items on the accessory case, but who knows?
Randall in Sedona
Maybe I should just keep flying it and try to be patient...
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03-17-2015, 11:03 PM
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Join Date: Aug 2007
Location: northern Cal
Posts: 111
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cabin heat
I thought of the cabin heat also and installed a engine soft plug in the tube to stop the air flow and it didn't make any difference. I will install a ez cool. There is just not enough outlet for it to escape. My 2 cents worth.
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03-18-2015, 12:45 AM
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Join Date: Sep 2013
Location: Olds, AB
Posts: 83
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Hi Randy. I have an Aerosport IO-375 with Catto cruise prop, single electroair plus one mag, and full EMS on my 7A and also battled high CHT's at first. I learned to manage my temperature and can now get the most out of the engine and plane. I find climbing to the mid teens to cross the Rocks the most challenging scenario, not hot summer days.
I think temp is an issue because RV's have little excess cooling capacity/drag, the 375 stroker creates more power/heat than a 360, and because the nose gear fittings create exit interference for cooling air. I learned to manage CHT by:
-Detailing the baffle seals as outlined in previous posts. This did not help much since my seals were not bad to begin with.
-Blocking some of my oil cooler to bring oil temps up to 180-200. This helped bring down CHT a bit.
-Adjusting my flying to meet my engines needs. Once clearing 500 AGL, I cruise climb at 110 knots, make a small reduction to throttle setting, (it gets more even temps with the throttle backed off 1/4 inch) then make an initial leaning adjustment to 200 degrees rich of peak which increases power and smoothness. I then lean slowly during the climb, targeting CHT at 350-360
-I transition to LOP about 7000 with almost full throttle, or lower for local flights with retarded throttle. (My home field is 3360, so I don't often fly below 5000) Running LOP at 50-65% power dramatically reduces CHT. I could lean more, but like to keep CHT between 300 and 330 for cruise
-I added fixed louvers but keep them closed with duct tape most of the time. I open them up whenever I pack oxygen for long trips, and find they really help cooling up high. I like your cowl flaps better.
-the EMS has shown me how amazingly sensitive the engine is to mixture, power, and airspeed, I don't think I could own another plane without one. I set it warn me if I exceed 380 CHT, and use 400 as my personal redline. I only broke 400 once when I had to take off with best power from hot, high, un-mown strip with super cub style obstacles at the far threshold
PS. I love my IO-375. It continued to run smoother and cooler until after I hit 100 hours and now burns about 1 quart every 20 hours with 230 hours
Jay
__________________
RV7-A
C-FXPT
IO-375, Catto, Electroair, Skyview
400 hours
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03-18-2015, 06:44 AM
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Join Date: Feb 2006
Location: Anywhere, USA
Posts: 1,132
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What exhaust system are you using.
If you open the exit it will be a drastic change.
Search on this sight for high oil temps.
Boomer
__________________
Bruce (BOOMER) Pauley
Kathy (KAT) Pauley
RV 7A--"MISS MARIE"--- N177WD (SOLD FLYING)72742
VAF #582-----------------EAA LIFETIME MEMBER
EX -KC-135A -------------BOOM OPERATOR #3633
VAN'S FLIGHT------------#6930
See you in OSHKOSH
http://www.mykitlog.com/users/index....ley&project=84
=VAF= 2006-2020 DUES PAID
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03-18-2015, 06:53 AM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Randy,
Perhaps opening the exit by cutting forward 2 or 3 inches at bottom of cowl would help.
(The idea of opening the exit to facilitate moving more air is not without controversy due to increased drag, but it has always improved cooling for me which has to be accomplished to provide for reasonable normal ops. Nothing is free in this business)
The pipes and gear leg do block a part of the standard exit, opening the cowl forward does increase the exit area and air flow and improves cooling.
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
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03-23-2015, 03:05 PM
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Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 2,791
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check your timing
advanced timing will cause high CHT and low EGT
__________________
Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 800+ for all
Simplicity is the art in design.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com
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03-23-2015, 04:25 PM
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Join Date: Feb 2010
Location: Gardnerville Nv.
Posts: 2,828
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__________________
7A Slider, EFII Angle 360, CS, SJ.
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03-23-2015, 04:53 PM
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Join Date: Jan 2005
Location: Sedona Arizona
Posts: 349
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I ran the first 25 hrs or so with max timing advance at 26 degrees. When I changed over to the A curve with 35 degrees max advance at lower MAP, I saw no difference in the temps.
I do have two of the EZ Cool cowl flaps and I am sure glad to have them. However, if I move mixture to best power, with the EZ Cool flaps open, I can still watch the temps creep up to my limits of 400F CHTs and 200F oil T. Even up above 8000' this will happen.
I think those are reasonable limits, yes no?
Today I changed out the mineral oil for some Phillips XC 20-50 with a little Cam Guard thrown in. Maybe that will help a little. I have adopted the attitude regarding my operating temps that they are completely controllable via the mixture. I don't mind operating this way for awhile and maybe this engine just needs some more time. (It will get hot here in AZ pretty soon...)
Thread drift side note: My air speed was reading nearly 7Kts slow. I have flush mount static ports. Not wanting to dive in and drill out rivets etc. I have glued one half of a washer in front of each static port. I used the thicker washers, figuring if they make too big of a correction I may be able to put a tooth pick in the ports to protect them, and carefully grind down the thickness for adjustment.
So now I have two good reasons for a dawn patrol flight in the morning!
Randall
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03-24-2015, 09:56 AM
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Join Date: Feb 2010
Location: Gardnerville Nv.
Posts: 2,828
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As Steve mentioned above, may want to try retarding the timing a little?
__________________
7A Slider, EFII Angle 360, CS, SJ.
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03-24-2015, 10:38 AM
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Join Date: Jan 2005
Location: Victoria, Canada
Posts: 2,251
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What is the CR of your engine?
I have an AeroSport Io-540 with 9.1 pistons, single Electroair and mag. It was spec'd as 20 degree timing.
I had a few issues with setting the Electronic ignition static timing. It was off by just 2 or 3 degrees (22 to 23 Btdc) as measured with the advance switch off. This had a substantial effect on CHT. Once adjusted to 20 BTDC as measured by the voltage output, I dropped temps by about 20F with or without the automatic advance switched in.
My conclusion is that with electronic ignitions, these engines are very sensitive to timing setup. Try dialing back your pmags to 20 BTDC and test fly again.
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V e r n. ====
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RV-9A complete
Harmon Rocket complete
S-21 wings complete
Victoria, BC (Summer)
Chandler, Az (Winter)
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