So I've decided to piece together an oil cooler for my 86 rather than order a kit, this way I can get something closer to exactly what I want (especially in fitment, I'm putting it behind the radiator for better balance, an easier install, and easy drainage when changing oil) while saving some money at the same time. I've already ordered a 30-row core. I could complete this kit with a bit of custom bracketry, a thermostatic sandwich plate, and some lines and fittings...OR I could do something really unusual, a low-pressure oil cooler setup that pulls oil from the pan with an electric pump and then returns it back to the pan. This would seem to have some advantages:
1. No effect on engine oil pressure: A conventional oil cooler system is fed by the engine's high-pressure oil feed and thus causes oil pressure drop.
2. Generally safer: Less pressure on everything in the system, if something springs a leak there's no loss of engine oil pressure and slower loss of oil supply, less worry of contamination. Could even use low-pressure hoses and fittings, but I've already bought an AN10 core...
3. Better temperature control: Who needs a wax plug thermostat that doesn't seem to be available with opening points over 180F when you can switch the pump on and off?
Disadvantages:
1. Possibly less efficient since you're not cooling the oil right before the engine gets it and there could be some circular oil cooling going on within the pan
2. Somewhat heavier due to the pump
Thoughts? Looks like suitable pumps can be had from $80 to Ludicrous Dollars, assuming a diff/trans cooler pump on the lower end of the range can work.
The low pressure part sounds reasonable. But I wouldn't add that complexity just for better temp control. There are oil thermostats hotter than 180* available. And there's also the option of an oil/coolant heat exchanger if you have enough radiator capacity. The heat exchanger lets you keep the oil lines and cooler further away from debris exposure as well.
You can get a power steering cooler for cheap money.
Fit it into the oilpan, and plumb coolant hoses (coolant thru fittings brazed into oilpan, etc)
Grassroots oil/coolant heat exchanger.
Helps get the fluids up to temp quickly & prevents oil from getting too hot.
No oil thermostat needed, no scoops or ducts needed, and no high pressure oil hoses exposed to damage.
They also make the pancake style that fit between oil filter & engine (VW?), but seems to me that
their thermal capacity is low.
I did consider the oil/coolant option before going the oil/air route, the biggest downside of that is massive engine oil pressure drop compared to an oil/air cooler - also you're putting more load on the radiator, which is sufficient in stock form, but may not be if you're throwing more heat at it from the engine oil. The oil/air cooler instead increases heat exchange capacity with another core.
The complexity isn't too bad - it basically just has the pump in place of the sandwich plate (Edit: Or maybe an H-shaped thermostat is a better analogy), with the control circuit as the only additional complexity. Could be as simple as a manual on/off switch I turn on at the track.
That should work but I'm not convinced that the problems you're trying to solve really need solving.
APEowner said:
That should work but I'm not convinced that the problems you're trying to solve really need solving.
Yeah really thinking about it, the main advantage is safety...sounds good on paper, but I've been running a regular oil/air setup on my AE92 for years with no problems. Is safety/reliability not really a problem or do I have survivorship bias?
In reply to GameboyRMH :
I think if you use good parts, monitor the condition of the lines, keep them as short as practical and make sure the cooler isn't mounted in a spot where it's likely to get whacked with debris, it's a pretty small risk.
You're answering a question a no one asked. You are taking something very simple and making it dramatically more complex because.................reasons?
I'm not sure how you're coming up with the massive oil pressure drop statement.
It's expensive, but if I had a daily driver twin right now, this is the route I'd go. I actually had one of these years ago I didn't get a chance to install before I traded the BRZ for the 135i.
https://jacksonracing.com/product/fr-sbrz-dual-radiatoroil-cooler/
I have long thought about running a rotary's oil pressure regulator output external to the pan and through a second oil cooler. Most of the benefit would be to return the oil below the oil level to cut down on aeration.
In a Mazda rotary, ALL oil pump output goes to the oil cooler, then into the engine. The regulator is in the engine and not the pump, so more oil goes through the cooler than the engine, so it is already a pretty good setup for cooling. I just don't like how the regulator dumps its oil out above the oil level. Fill a bucket with a hose above the water then below the water and you'll see what I mean.
In your behind the radiator placement scheme, how does air get to the cooler?
dps214 said:
In your behind the radiator placement scheme, how does air get to the cooler?
It'll be right behind one of the radiator fans, so it will also get cooling when the car's stopped. Tests done by MotoIQ showed that there was very little loss of cooling power from putting an oil cooler behind the radiator.
