Laminova oil cooler for Rotrex ? Nah...
I have been trying to figure out where to put my conventional 10x30x5 cm Setrab oil-cooler for the Rotrex unit and avoid having to stack 3 coolers (oil, IC, coolant) in the grille opening.
Both my fog-light openings in my bumper are already occupied for the engine oil-cooler and CAI.
I have heard of water to air intercoolers but did not know there were water to oil coolers available for automotive use before reading about laminova coolers from www.laminova.se :
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This looked like a major win: No airflow needed, the amount of oil from rotrex will not tax water cooling much, clean install etc.
After ditching AC I have enough space ato add a ~ 20 cm long C43 Laminova unit in the hose going from rad to engine block. Problem solved ?
Not.
The Rotrex inlet oil temperature should be max 80 C which is quite cold when dealing with petrol engines where optimal coolant/oil temp are around 90-100 C. My oil and coolant temps can reach as high as 120/105 C on track days.
According to testing done by Flyin Miata the temperature drop for a radiator in a Miata is only around 5 C when inlet coolant temp is 105 C –> http://www.flyinmiata.com/tech/rads.php
<table border="1" cellpadding="2" style="background-color: white; font-family: Verdana, Arial, Helvetica, sans-serif;"><tbody><tr><td style="font-size: smaller;">radiator</td><td style="font-size: smaller;">Ambient temp</td><td style="font-size: smaller;">Rad inlet</td><td style="font-size: smaller;">Rad outlet</td><td style="font-size: smaller;">Improvement over stock</td><td style="font-size: smaller;">Temperature drop</td><td style="font-size: smaller;">Time to temp</td><td style="font-size: smaller;">Outlet temp compared to ambient</td></tr><tr><td style="font-size: smaller;">stock 1990-97</td><td style="font-size: smaller;">35º</td><td style="font-size: smaller;">105º</td><td style="font-size: smaller;">100º</td><td style="font-size: smaller;"> </td><td style="font-size: smaller;">5º</td><td style="font-size: smaller;">-</td><td style="font-size: smaller;">+65º</td></tr><tr><td style="font-size: smaller;">Brand X aluminum race radiator</td><td style="font-size: smaller;">38º</td><td style="font-size: smaller;">105º</td><td style="font-size: smaller;">101º</td><td style="font-size: smaller;">+1º</td><td style="font-size: smaller;">4º</td><td style="font-size: smaller;">15:44</td><td style="font-size: smaller;">+63º</td></tr><tr><td style="font-size: smaller;">FM crossflow</td><td style="font-size: smaller;">43º</td><td style="font-size: smaller;">102º</td><td style="font-size: smaller;">98º</td><td style="font-size: smaller;">-2º</td><td style="font-size: smaller;">4º</td><td style="font-size: smaller;">17:09</td><td style="font-size: smaller;">+55º</td></tr><tr><td style="font-size: smaller;">dual pass</td><td style="font-size: smaller;">44º</td><td style="font-size: smaller;">102º</td><td style="font-size: smaller;">97º</td><td style="font-size: smaller;">-3º</td><td style="font-size: smaller;">5º</td><td style="font-size: smaller;">11:55</td><td style="font-size: smaller;">+53º</td></tr></tbody></table>
That means a laminova cooler would act as a heater instead of cooler if used with the Rotrex.
But what about using it as regular oil-cooler for the engine and use my current engine cooler for the Rotrex ?
Here are some graphs from laminova.se for the C43 with 120 c oil inlet temp and 85 c coolant temp:
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</div> I have not found any coolant or oil flow numbers for the Miata but this site says an oil pump typically delivers between 8-12 gpm or 30-40 litres/min
As for coolant flow I don’t have a clue. I found an example here where a 20 gpm water pump actually delivers 0 gpm at 6psi pressure drop. Lets just say the miata pump can deliver 160 litres/min to make it near optimal for a laminova cooler with a bypass.
A C43-182 would then cool my 120c oil down to 116 given my coolant inlet temp was 85C.
However my coolant temps are most likely 100+ C which I’m afraid would make this cooler useless as anything other than an oil heater.
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