Message

). When I initially installed = the new Setrab oil cooler (behind the radiator), the oil temps never got = above 180F, even in a climb to 10000 ft. The water temps were being = controlled by the thermostat, so they were 180 as well. Since then, = I've tried to even up the water and oil temps, by blocking off part = (half) of the radiator, and removing the thermostat. The goal was to = figure out how large the Rev 2 radiator needs to be. The initial = indication is that this may have caused my oil temps to be high. Water = is up to maybe 160F max, so there still seems to be too much radiator, = but oil will top 220F if allowed. =20 What has just occurred to me, is that by blocking off part of the = radiator, and raising the water temp, I'm probably increasing the air = temp that the oil cooler sees behind the radiator. Has anyone measured = the air temp behind the radiator when the water temp is around 160 or = 180? I'm curious just how hot this is. =20 Bottom line is that I'm thinking I may have to put the oil cooler in = front of the radiator, and leave the radiator oversized enough to = compensate for the hot air from the oil cooler. FWIW- if you've got = the space, I highly recommend keeping the oil and water cooler separate, = as most everyone (with sense) knows already :-) Cheers, Rusty (need beer to cool my brain) =20 Rusty, my cooling capacity model indicates that the stock Mazda cooler = does not adequately cool at speeds below approx 120 MPH with high power = setting (like 150-160HP or above) . The model indicates that up to that = point at least, the radiators are carrying the extra load of the oil = cooler or at least trying. Since the oil specific heat is only about = 1/2 that of water, it requires approx twice the flow rate (based on that = difference along) of coolant to bring the same amount of heat to the = cooler. Then if the airflow through the oil cooler is impeded in any = way (or you are pumping hot air into it) the situation becomes worst. I know its just a simple model, but it seems to jive with my = experience with coolant and oil temps. =20 You may not get this message for days as for some reason none of the 7 = messages I posted yesterday or today have gotten through to the list. I = must have pissed Marv off over something {:>) Or else been filling up = too much of his disk space. Ed Anderson ------=_NextPart_000_001E_01C39756.CA698340 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message

----- Original Message = -----

From:=20 Russell=20 Duffy
To: Rotary motors in = aircraft

Sent: Monday, October 20, 2003 = 9:51=20 PM

Subject: [FlyRotary] temps = behind=20 radiator?

Greetings,

In trying to = make sense=20 of my latest cooling problems, I've thought of yet another variable = (just what=20 I need <g>). When I initially installed the new Setrab oil = cooler=20 (behind the radiator), the oil temps never got above 180F, even in a = climb to=20 10000 ft. The water temps were being controlled by the = thermostat, so=20 they were 180 as well. Since then, I've tried to even up the = water and=20 oil temps, by blocking off part (half) of the radiator, and removing = the=20 thermostat.  The goal was to figure out how large the Rev 2 = radiator=20 needs to be. The initial indication is that this may have caused = my oil=20 temps to be high. Water is up to maybe 160F max, = so there=20 still seems to be too much radiator, but oil will top 220F if=20 allowed.

What has just = occurred to=20 me, is that by blocking off part of the radiator, and raising the = water=20 temp, I'm probably increasing the air temp that the oil cooler = sees=20 behind the radiator.  Has anyone measured the air temp = behind=20 the radiator when the water temp is around 160 or 180? I'm = curious just=20 how hot this is.

Bottom line = is that I'm=20 thinking I may have to put the oil cooler in front of the = radiator,=20 and leave the radiator oversized enough to compensate for the hot air = from the=20 oil cooler.   FWIW- if you've got the space, I highly = recommend=20 keeping the oil and water cooler separate, as most everyone (with = sense)=20 knows already :-)

Cheers,

Rusty (need = beer to cool=20 my brain)

Rusty, my cooling=20 capacity model indicates that the stock Mazda cooler does not = adequately cool=20 at speeds below approx 120 MPH with high power setting (like 150-160HP = or=20 above) . The model indicates that up to that point at least, the = radiators are carrying the extra load of the oil cooler or at least=20 trying. Since the oil specific heat is only about 1/2 that of = water, it=20 requires approx twice the flow rate (based on that difference along) = of=20 coolant to bring the same amount of heat to the cooler.   = Then if=20 the airflow through the oil cooler is impeded in any way (or you are = pumping=20 hot air into it) the situation becomes worst.

I = know its just a=20 simple model, but it seems to jive with my experience with = coolant and=20 oil temps.

You = may not get=20 this message for days as for some reason none of the 7 messages I = posted=20 yesterday or today have gotten through to the list. I must have = pissed=20 Marv off over something {:>) Or else been filling up too much = of his=20 disk space.

Ed=20 Anderson

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