My premise, and you quoted it, is using the same prop before and after. Zenith 601's use fixed pitch props. Now maybe this one is unusual and has an electric controllable prop, but I seriously doubt it. In level flight and at any air density and prop pitch, there is a single curve of prop torque consumed vs rpm, and thus a single curve of hp expressed vs rpm. So, if the owner is turning the same fixed pitch prop at the same rpm and altitudes before and after the engine mods, it is making the same power over the duty cycle as it did before, and will have the same heat rejection.Can you please elaborate on this statement? There are many things to do to an engine to increase efficiency/torque output at the same RPM. Throw a big turbo on an O-200 and it will make several hundred percent more power at the previous data plate redline RPM - for a minute or two.
Porting, induction, exhaust, big compression, EI, camshaft profile - all contribute to the BMEP of any Otto cycle engine.
A friend has a bit of a puzzler. He has a Zenith 601 with a Continental O-200. He bought the airplane in coastal Alabama. He winters there. He few it there and oil temperatures were good. He left Alabama in the spring to fly the airplane to western Colorado. He didn't make it far. One of the rocker pins came adrift and wore itself through the valve cover. Engine didn't like that and he made a forced landing.
He had the engine rebuilt and repaired the airframe damage. The engine rebuilder installed different pistons to make a claimed 118 HP. My friend flew it in the southeast for a while and said oil temps were normal. He started west and started having high oil temperature problems over New Mexico which have continued.
He installed an oil cooler adapter under the oil filter and installed a nine row oil cooler. The oil cooler adapter is on the left side of the engine and he hung the oil cooler on the right side of the engine so there is a good three feet of AN6 hose coming and going. He originally had a 2" scat hose feeding air to the cooler off the baffles on the right side. The oil cooler didn't help at all. He then replaced the oil temp sender. I suggested he run a 3" scat hose instead and he did that. He tested it today and it didn't make any significant difference. Hard to say if it helped because conditions were not the same.
He doesn't have an ideal setup. The scat hose first makes a 30 degree bend downward from the plenum and then makes a 90 degree bend to enter the cooler. He has at least 6' of AN6 hose connecting the cooler to the adapter. Also elbows on the adapter and the cooler. Not an optimum setup. Even so, it seems like the oil cooler should help some.
The oil cooler adapter has a pressure relief spring that bypasses the cooler when oil is cold and oil pressure is high. It sends oil to the cooler when the oil warms and the oil pressure drops. I am suspicious of that unit also but he claims they checked it.
It may be a perfect storm of poor airflow to the cooler because of the bends in the scat hose and to much AN6 oil hose with to many 90 degree elbows. Also the higher density altitudes here. However, I am wondering if there something that could have happened inside the engine to dump more heat into the oil? Incidentally CHT's are fine, somewhere around 300 degrees.
That is not correct. The by-pass valve prevents oil starvation when cold, thick oil is clogging the cooler. It also prevents oil starvation if the cooler becomes clogged with debris/sludge. Dependant on the susceptibility of the cooler to these issues, the latter functions can be vastly more important than a fast warm-up. The by-pass does need to be checked, including for correct orientation. Removal for test purposes is reasonable. However, the first priority in this instance is check and calibration of the instrumentation - replacing the instrument does not in itself assure that the temperature data is correct.Try deleting the by-pass valve - its sole function is to speed engine/oil warm up in cold climates. Its an unnecessary complicating, that may also be defective. I have always found oil coolers to be effective, even with minimal air flow they will do something to cool the oil.
There was a break-in abrasive compound for small 2 stroke model airplane engines many many decades ago called Fox Lustrox. You were supposed to put a tiny coke spoon's worth of this stuff on the edge of the carburetor venturi, and it would slowly siphon off a tiny little bit at a time over a mnute or two, and then "break in" (or hone or polish, whatever) the engine internals.Snort Bon ami scouring powder ? [cuts the glaze]
It takes an hour and 15 minutes to brake in on the schedule - power and rest power and rest monitor oil and CHT it's in the manualThe owner of the airplane and oil cooler made a test of the installation this morning. He had made one change since he flew it last. He shifted the cooler over a bit to give the 3" scat hose feeding the cooler a little straighter path to the cooler. The move also gave the exit air more room to exit.
This morning he blocked off the air to the cooler and flew the plane. OAT was 67F. Density altitude would have been in the 6000' range. The oil temp quickly climbed to 220 degrees so he landed. He then restored the air flow to the cooler, invited me along and we took off again. The oil temp was 185 on takeoff. It went to 207 in the climb and stabilized there. It dropped back to 202 in cruise. So he is satisfied for the time being since the airplane is now useable in cooler temps.
The engine has 65 hours on it since OH. I don't know how long it takes an O-200 to break in?
That is not correct. The by-pass valve prevents oil starvation when cold, thick oil is clogging the cooler. It also prevents oil starvation if the cooler becomes clogged with debris/sludge. Dependant on the susceptibility of the cooler to these issues, the latter functions can be vastly more important than a fast warm-up. The by-pass does need to be checked, including for correct orientation. Removal for test purposes is reasonable. However, the first priority in this instance is check and calibration of the instrumentation - replacing the instrument does not in itself assure that the temperature data is correct.
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