9 replies to this topic

[luna_s]

While dismantling, i noticed the engine has a watercooled oil cooler, i didn't realise it had one at all, this oil cooler is situated after the thermostat, on the way to the radiator, Im no engineer, but surely picking up heat from the water on the way to the radiator isnt a good idea ?, I thought it was there to cool the oil (not keeping it at water temp) - is this right ? or am i silly ? , so would it be more efficient removing it and fitting a mocal air cooled rad near the intake grills ? Must be some reason why its there, someone cleverererer than me could explain ? I understand it would be more suited to the car being stationary (watercooled one).

[vocky]

the plus side is the oil warms up quicker

[luna_s]

maybe thats what it is, an oil warmer upper

[error]

Motoroil is designed to do its job at about 100°C. So a water/oil heat exchanger will do its job just fine.

[Winstar]

If you look at the cooling system diagram in the parts list the oil cooler is actually on the return leg, down the pass side ( confirmed as it's was the drivers side of my rad that burst). However you could still put i on the rad outlet side as oil system design temp is around 135 deg constant and 150 peak. where as the coolant side is designed to run between thermostat opening, usually 87, and 110 max.

Edited by Winstar, 23 January 2007 - 12:28 PM.

[luna_s]

The watercooled one is just fine for day to day stuff then, must just help to drop a few degrees without cooling the oil too far I can't see any benefits moving to air cooled, unless i was constantly tracking the car Altho an aircooled setup is quite cheap......

[slindborg]

you need to be careful to not cool oil too far.... the water to oil version is fine imho. but id NEVER go air to oil even with an oilistat.

[Arno]

The watercooled one is just fine for day to day stuff then, must just help to drop a few
degrees without cooling the oil too far
I can't see any benefits moving to air cooled, unless i was constantly tracking the car
Altho an aircooled setup is quite cheap......

A water-oil heat exchanger is very efficient. The Setrab unit fitted to the N/A is not very big though, but a bigger MOCAL laminova unit could be fitted without problems.

BTW The OEM take off from the oil filter housing has a thermostat built in because the cooler is on the rad return side.

For an air-oil cooler to work well in a mid-engined setup tou need to fit the cooler under the radiator in the nose of the car and that means running loooooong hoses to the front and back. Lotus do that on the S1 Exiges and now on the 111R and Exige2. Fragile setup though and the pressure drop across the long lines is questionable.

Biggest single advantage of a water/oil exchanger is that it is not dependant on the movement of the car to cool the oil, so it helps a great deal to dissipate heat from the oil on a cooldown lap and while the car is idling a littl while to cool down. (coolant has very big heat capacity and the normal fan to cool it down while standing still or moving slowly)

Bye, Arno.

[luna_s]

thanks arno, I didn't consider moving a cooler to the front for precisely the reason of pressure drop and fragility, And like you said when i saw the oil cooler, i thought it was far too small to actually acheive anything at all, maybe like i said an air cooled radiator with auxilary fans when over a certain temp, (or just leave it alone altogether ;p) are these coolers fitted to other cars with the z22se engine ? I thought there must be some kind of thermostat there, because as i said - whats the point of transferring the heat of the water to the oil!!!! but that explains it well. but it mustve been designed like that for a reason

[Winstar]

I thought there must be some kind of thermostat there, because as i said - whats the point of transferring the heat of the water to the oil!!!! but that explains it well.
but it mustve been designed like that for a reason

There's no stat on the oil side of the system, but due to the location of the oil cooler then the flow won't start going through the oil cooler until the rad circuit opens up at 87 deg c, before this the coolant circulates around the engine circuit only, so by that point the oil temp should be above the temp of the coolant.

Rob

Edited by Winstar, 23 January 2007 - 10:39 PM.