I am running a AeroSport Power 0375 on my EXP Cub and couldn't ask for anything better as far as power and smoothness. The only concerning thing to me is that my CHT's on cylinders 2,3,4 run over 400 degrees unless I keep my MP below 17.0 inches. My baffels were made by Airforms here in Alaska and I have headed every ones advise on sealing them up. I have kept pretty detailed records along he way and really have not noticed my temp change since day one. I just switched to Phillips multigrade oil and still no change. Just courious if others of you running the 0375 are experiencing similiar temps.
0375 cht
- Thread starter willirw
- Start date
cgoldy
Registered User
Moogerah Queensland Australia
I had the same problem with my o-375. (Great engine) Spent hours fixing all the things that were supposed to be the cause. Finally just disconnected the map tube that advances the e-mag and bingo. Temps dropped 30 deg with no noticeable power loss.
Hope it is that simple for you. Will be interesting to see if you have the same problem.
Hope it is that simple for you. Will be interesting to see if you have the same problem.
Tim
FRIEND
Petersburgh, NY
Did you have the jumper on the E-Mag, so it only advances it to 34deg.
i have a Dynon SkyView system to monitor my engine. The hotest oil temp I have seen has been 195 degrees. My cowling was made by SelKirk Aviation from Idaho. I even sent the bottom cowl back to them to add a little cowl flap to the bottom. I still never noticed any temp change. Yesterday cruising at 5500 feet. OAT 57 degrees 2300 rpm and 17.3 inches cylinders 2,3,4, 400 t0 405. That was full rich. If I barely pull the lean mixture the CHT instantly climb. Those are cruise temps. If I climb hard I can reach about 2500 ft and 2,3,4, will be around 430 CHT and climbing. I always chicken out ad pull the power back to let them cool down before trying to climb again. I have 80 hrs on the engine now.
skywagon8a
MEMBER
SE Mass MA6
Willirw,
So you have sealed everything up nicely forcing all the cooling air through the proper places, are you letting all of the hot air out? What is the gap between your side cowls and the side of the firewall? A lot of hot air needs to escape out the sides. The exhaust exit scoop on the bottom cowl will not be enough. If hot can not escape, then cold can not get in thus causing high CHTs. My IO-360 never gets above 380 on a hot day. It is usually a lot less with a ECI UBG-16.
So you have sealed everything up nicely forcing all the cooling air through the proper places, are you letting all of the hot air out? What is the gap between your side cowls and the side of the firewall? A lot of hot air needs to escape out the sides. The exhaust exit scoop on the bottom cowl will not be enough. If hot can not escape, then cold can not get in thus causing high CHTs. My IO-360 never gets above 380 on a hot day. It is usually a lot less with a ECI UBG-16.
skywagon8a
MEMBER
SE Mass MA6
Colin,
Is there any possibility that your timing on the P-mag was in error? It should be done at TDC. It is possible that you set it at the advanced mark on the fly wheel, which is for the magnetos.
cgoldy
Registered User
Moogerah Queensland Australia
Pretty sure I did it to that mark. If I picked the wrong mark it would be timed to advance to 50 deg wouldn't it. Not sure it would run. But that's not to say that the jumper worked. I can't see how you could check that unless you get the software.
i have two pmags in the RV6. I have had a few people who should know, comment on how smooth the motor runs. And really easy to time. Just set to top dead centre and blow down the tube. Not sure why it does not suit the cub installation.
i have two pmags in the RV6. I have had a few people who should know, comment on how smooth the motor runs. And really easy to time. Just set to top dead centre and blow down the tube. Not sure why it does not suit the cub installation.
skywagon8a
MEMBER
SE Mass MA6
The EGTs will vary from plane to plane depending on the type of probe and installation location which has a lot of variables. My numbers will not necessarily relate to yours. EGTs are used to help determine mixture ratios.
sierra bravo
Registered User
You can use your EGT to check the mixture. You should be able to lean about 125* from full rich while in normal cruise. I've been told 100* is the bare minimum. Less than that requires a carb adjustment.
The single most effective thing I did on my old (Scooter's new) -12 to improve CHT was to switch to a Hot Rod muffler. The muffler it replaced was a very nearly new (not sick) Atlee Dodge standard muffler. Your engine has more cubes and pumps more air than most Cub engines. I'd make sure the exhaust system is up to the task.
The single most effective thing I did on my old (Scooter's new) -12 to improve CHT was to switch to a Hot Rod muffler. The muffler it replaced was a very nearly new (not sick) Atlee Dodge standard muffler. Your engine has more cubes and pumps more air than most Cub engines. I'd make sure the exhaust system is up to the task.
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Scooter7779h
PATRON
Anchorage, Alaska
SB - These current hot (for Alaska) temps of in the low 80's I am getting 190F on oil temp, and 360F on CHT. I lean max EGT under 65% power which is where I run it as it is best economy and not much reduction in cruise that 75%. For any climb it is full rich and monitor CHT with airspeed, and/or stair step climbs. I get proactive of doing something better for cooling once CHTs go much past 410. 65% power on a O-320-B2B is 2350 rpm with fixed pitch. At 75% which is 2450 I lean 75* rich of peak EGT, all of what Lycoming calls for in the operator manuals. Have done this for years (like 40) and haven't had any cylinder or other engine problems. 53M is setup right for cooling.
Northern flyer
Registered User
Willirw,
I have an O-375, as well. I run it on my SQ2 and experienced high CHT temps, upwards 430 on cool days. I consulted with Charlie Center and he recommended replacing the baffling with a Scout type baffling where there is more room behind the rear cylinders. I also removed any top baffling and installed rubber strips from the rear engine that extended up to the top cowling. Noticeable drop in all CHT's. #4 hovers around the 385-405 degrees. All others well below 390 at 2300-2400 RPM.
Northern Flyer
I have an O-375, as well. I run it on my SQ2 and experienced high CHT temps, upwards 430 on cool days. I consulted with Charlie Center and he recommended replacing the baffling with a Scout type baffling where there is more room behind the rear cylinders. I also removed any top baffling and installed rubber strips from the rear engine that extended up to the top cowling. Noticeable drop in all CHT's. #4 hovers around the 385-405 degrees. All others well below 390 at 2300-2400 RPM.
Northern Flyer
All thank you for the replies and suggestions. Many I have already tried. I am running with Bendix mags. Lots of space between the rear of the side cowl and boot cowl, four inches. I am running a WhirlWind 200-G ground adjust prop. It is pretty fat at the hub and I can see how it coud block some airflow. I spoke with AeroSport Power and they were very nice and helpful. Suggested and sent info on how do do a diffrential pressure check. I will complete this when I return from work. They also admitted that the 0375 runs hot and on the ones they manufacture now they install nozzles that spary oil on the back of the pistons. My engine was manufactured in 4/11 and does not have the ability without lots of work. I will let everone know how I am progressing. Randy
Northern flyer
Registered User
Willirw,
I had the Whirlwind 200 prop, as well. I changed it to the RV-10 Whirlwind prop, which helped considerably.
skywagon8a
MEMBER
SE Mass MA6
Ok cub12, here are some numbers for you to study. temperature at start OAT 75F,
Full throttle-27.5"map, 2430rpm, 70mph, fuel flow 16.1gph, oil temp 124F #1- egt 1164 cht 301, #2- egt 1220 cht 345, #3- egt 1171 cht 347, #4- egt 1206 cht 352.
Cruise leaned to 50* rich, #1- egt 1374 cht 319, #2- egt 1450 cht 350, #3- egt 1404 cht 369, #4- egt 1458 cht 345.
power 21.5" map @ 2510 rpm, oil 175 F, fuel flow 8.3 gph
The engine is a IO-360-B1D (180 hp) with balanced injectors, dual P-mags, Whirlwind 200G prop set at 15 degrees. on EDO 2000 floats.
burning 100LL and AeroShell 100W oil.
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skywagon8a
MEMBER
SE Mass MA6
I look at this the other way around. I figure that the wide chord blades push more air through the engine thereby giving more cooling. The bigger paddle has more pushing power than a thin one.
skywagon8a
MEMBER
SE Mass MA6
sierra bravo
I caught your message before it was deleted. You are pushing that IO-520 through the air 30 or 40 mph faster which will produce better cooling.
I caught your message before it was deleted. You are pushing that IO-520 through the air 30 or 40 mph faster which will produce better cooling.
jgerard
Registered User
Seattle, WA
I have heard the gasket type CHT probes read 25-50 deg hotter than the bayonet type probes. Are there any other signs of high CHT other than what your gauge is telling you? Is the paint baking off the heads? Is the oil cokeing up inside the valve cover area? What do the spark plugs look like?
Jason
Jason
