IW STi Forum banner

21 - 30 of 30 Posts

·
Premium Member
Joined
·
5,332 Posts
deleted when I realized it was "old"
 

·
Registered
Joined
·
725 Posts
I have the subaru block heater which is 450 watts i believe. After having it plugged in for 4 hours the entire motor and the oil pan are warm to the touch. Plus since we have the oil cooler in our cars it acts as an oil warmer when the coolent is already warm.
Old thread, but I want to ask because I've just moved and now have a very short commute in a decently cold NE Ohio. How does the OEM "block" heater warm up the oil when the car is off? My understanding is it's just a heater plug in the bottom of the radiator. Is it that effective that all of the coolant inside the radiator and the upper hose into the block gets warm?
 

·
Registered
Joined
·
1,751 Posts
Old thread, but I want to ask because I've just moved and now have a very short commute in a decently cold NE Ohio. How does the OEM "block" heater warm up the oil when the car is off? My understanding is it's just a heater plug in the bottom of the radiator. Is it that effective that all of the coolant inside the radiator and the upper hose into the block gets warm?
It's not a plug in the radiator, it's in the block near where the header mates up. However, you are correct that it's still in the coolant passages, not the oil. Convection does allow a lot of the coolant to be warmed, but no, I wouldn't say all of it does.

At any rate, it warms the coolant which eventually warms the block which eventually somewhat warms the oil. It still takes some time idling or driving before oil temps come up.

If you want the oil warmed up your best bet is the oil pan heaters. You can get magnetic ones or you can basically JB weld / epoxy / whatever one on there. That seems to be what people do in the truly bone-chilling areas where a standard block heater is not adequate. As a side note, if it's that cold for you I'd definitely have a battery tender and battery blanket just to help the battery not struggle so much.
 

·
Premium Member
Joined
·
5,332 Posts
The ENTIRE engine, and our pan, is aluminum (transfers heat faster than any metal)
Ouch Chris. I'll let you straighten this out . . .


so where you place the heat source is not all that relevant. Once it reaches thermal equilibrium, the difference becomes how much current you're putting into
In the block sure, but the op was asking about heating the pan and its oil. So, how much heat transfer will you get on the pan edge and convection compared heating the block and anti-convection. Seem the block will store more energy.

I have concerns about a cold oil entering a warm engine. They may be completely unfounded but I worry that the cold oil entering the block cools it and forms a local pressure restriction. Then as the oil travels it heat and thins and has low pressure. This condition would be short lived, but it is what I worry about in winter mornings and why I don't get on it for a few miles.
 

·
Registered
Joined
·
5,433 Posts
In the block sure, but the op was asking about heating the pan and its oil. So, how much heat transfer will you get on the pan edge and convection compared heating the block and anti-convection. Seem the block will store more energy.
Keep in mind I'm speaking in generalizations here as no one here has the same conditions. If you're going to bring thermal mass into the equation, how long are they (the heaters(s)) plugged in for? larger thermal masses will take longer to thermally stabilize.

I have concerns about a cold oil entering a warm engine. They may be completely unfounded but I worry that the cold oil entering the block cools it and forms a local pressure restriction. Then as the oil travel it heat and has low pressure. This condition would be short lived, but it is what I worry about in winter morning and why I don't get on it for a few miles.

At startup, you shouldn't worry. In cold climates all kinds of things are doing to heat engines and/or specific areas of the engine without any negative effects. When using a heater, you're generally talking about maximum 100°f delta, which isn't enough to amount to anything concerning. If we were talking about a +200°f delta then it would be something you'd want to consider.


FWIW, if you really want block/oil heating, we have made a couple with this drain block. It add a 1" NPT ports that allows the use of a big-rig oil heater. They were for cars in extremely cold temperatures. Think -60°f. One was in Alaska and another on the Hudson Bay in Canada. I don't recall the temps they maintained, but the customers did tell us they worked well (which is unusual, because you typically only hear back when things don't work :p).


 

·
Premium Member
Joined
·
809 Posts
I did this, and no, I don't need it in California. From just some general observations, it's about 2x as powerful as it needs to be. Could be too much, unless you were in Alaska/Canada. 70F rise in oil temps in 30 minutes.

 

·
Registered
Joined
·
1,751 Posts
I did this, and no, I don't need it in California. From just some general observations, it's about 2x as powerful as it needs to be. Could be too much, unless you were in Alaska/Canada. 70F rise in oil temps in 30 minutes.

Nice. That could be good if a timer wasn't a great option for some reason. Perhaps someone living in an apt close enough to the car that an extension cord is feasible but it's not reasonable to keep the car plugged in overnight etc.

I guess you could technically rig up a thermostat situation. I did this with a baby livestock heat mat in a dog house to keep my pup from freezing or frying, the trick thing would be figuring out how to have the temp probe be easily removable or disconnected. That and getting something that can detect the surface temp vs do you rig up a fluid temp sensor somehow. Likely not worth the effort. Could probably just go next size down :lol:
 
21 - 30 of 30 Posts
Top