ECT Temps

Daily driven Subaru EJ207 engine with a few mods (headers , up pipe , TD05-20g , cai ,parallel fuel system) running on a Link G4+ Xtreme . Drives fine all seems good . On a specific hill climb 11km's distance starting at approx. sea level (app altitude states 35) and reaches peak at 690 . Half way under any condition (whether spirited drive or normal or even as low as slow cruise 2000/2500rpm) when the ac is on at approx. 350altidute water temp will start increasing . Once A/c is off temps will stay normal at 95deg with no issues . Multiple test have been performed on various other mountain passes in the area with similar altidute diferences although the distance might vary with minimum difference in kms being rough 5kms more than the one mentioned . Others are more .

Runining a mishimoto dual row radiator with Spal funs (operating only on high speed when engaged) no shroud (which I believe should solve the issue) and with an aeroflow overflow tank (according to aeroflow it has 50% capacity , I didn't measure to confirm but will) .

Has anyone come across something similar ?

P.S I saw a small rise in temp when stuck in traffic for awhile when the weather was extremely hot like 40deg but generally in traffic it has been steady with and without a/c .

That situation sounds a little unusual, however it's normal that having the AC running is going to put more heat stress into the cooling system. Often a factory temp gauge sits in the middle of its range from maybe 60 deg c through to 110 C and only above that range it will swing to the 'hot' marker so you don't tend to notice smaller fluctuations that are naturally occurring. You haven't mentioned how hot it is getting but this may all just be normal. Improving the cooling system would be the logicval solution if you want to retain the AC.

As Andre said, these increases are normal as,

a/ with the A/C on it's increasing the air temperature them passing through the radiator

b/ the heat being passed into the cooling system is approximately proportional to the work the engine is doing, and climbing hills, etc, will make the engine work harder.

- the question is how far are the coolant temperatures rising? It's acceptable to be a fair bit above the "normal" position, and modern engines are designed to run "hot" for mileage and emissions purposes.

Thank you for the replies . Sorry I forgot to mention that the highest temp I saw was 110 C and I am using an Ecumasters ADU 5 . I understand that the ac will put more heat stress on the engine . The weird part is it only did this on this specific hill climb . Any other hill climbs the temps were if not lower than usual (89-90deg) they will be normal operating temps 95 . Now I was planning on improving the ducting and adding shrouds and maybe increase 1 fan to a more cfm . Upside is I have a year to prepare for this , downside is I will be testing this in a year .

Dimitrios,

That radiator doesn't work as well as stock and their caps are also problematic (bypassing at relatively low pressure), plus if you're running a smaller than stock overflow you'll more likely get air in the system which can cause that sort of behavior.

I'd start by reinstalling the stock overflow, re-installing OEM caps, re-bleeding the system and see if that works well enough. If not, ducting and a better radiator would be suggested next steps. CSF and Koyo both have relatively inexpensive radiators that work better than Mishimoto and stock, or PWR and some others have more costly and higher performing options.