Aftermarket thermostats

[Evil Rocky]

I have the Full blown and Full blown radiator and Spal fans. I only got it for extra security with opening up sooner.

[Compelica]

Another update - did another test on a long highway uphill recently.

Ambient temperatures were at 36C, with gears intentionally held lower to get more heat into the coolant, and the temps stayed lowest at 86C throughout the entire run. Oil temps were averaging 109C, with a Forester water to oil exchanger.

With the new thermostat opening at 82C I could manage only 86C - this indicates that the stock radiator does have additional cooling capacity, but not much left given in a tropical setting.

Regarding oil temperatures I am seeing a slightly more substantial drop, about 5C peak to peak. As the coolant further cools, more heat from the engine oil gets transferred to the coolant due to the larger temperature difference which then brings back up the coolant temps.

With owners in Japan reportedly are running at around 84-85C with the same setup - this is as far I can probably get with the stock radiator.

[dynarun55]

Originally Posted by Compelica

Another update - did another test on a long highway uphill recently.

Ambient temperatures were at 36C, with gears intentionally held lower to get more heat into the coolant, and the temps stayed lowest at 86C throughout the entire run. Oil temps were averaging 109C, with a Forester water to oil exchanger.

With the new thermostat opening at 82C I could manage only 86C - this indicates that the stock radiator does have additional cooling capacity, but not much left given in a tropical setting.

Regarding oil temperatures I am seeing a slightly more substantial drop, about 5C peak to peak. As the coolant further cools, more heat from the engine oil gets transferred to the coolant due to the larger temperature difference which then brings back up the coolant temps.

With owners in Japan reportedly are running at around 84-85C with the same setup - this is as far I can probably get with the stock radiator.

Hey I'm not sure where you are located but I am located in Austin, TX. My commute also consists of long uphill highways and ambient temps last summer were 43 C on a few days with 10000% humidity (what it feels like) !!!! I drive a built FA20 with a JRSC!! So I had to upgrade from stock rad to CSF rad. I stuck to the stock thermostat though as advised by many on this thread. My temps topped around 97-98 C at the peak of the summer!!! But this example of yours has convinced me to get a lower stat. Thank you!! Hopefully it gives me more headroom.

Sent from my Pixel 6 Pro using Tapatalk

[Compelica]

Originally Posted by dynarun55

Hey I'm not sure where you are located but I am located in Austin, TX. My commute also consists of long uphill highways and ambient temps last summer were 43 C on a few days with 10000% humidity (what it feels like) !!!! I drive a built FA20 with a JRSC!! So I had to upgrade from stock rad to CSF rad. I stuck to the stock thermostat though as advised by many on this thread. My temps topped around 97-98 C at the peak of the summer!!! But this example of yours has convinced me to get a lower stat. Thank you!! Hopefully it gives me more headroom.

Sent from my Pixel 6 Pro using Tapatalk

Personally I think it may not make any difference, given that the stock thermostat is fully open at 95C - which basically means your thermostat is already fully opened to the radiator at the temps you mentioned. You may gain some additional time till it tops off at 97-98C however.

Alternatively you can gain some further headroom by venting the hood or the undertray (which I've done the latter and posted some findings here).