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Countering the extreme heat


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Hey guys I would like to start a discussion about how to counter the heat. Yesterday and the day before were probably the hottest days of this year at 117F and 116F respectively. Yesterday when I got home from work here are the temps I was looking at: (This is parked in the shade!)

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During the commute home the AC turned off several times, especially on the freeway at moderate freeway speeds between say 45 and 65 (traffic). That was pretty uncomfortable. So what can be done about this?

I'd like to keep AC on the hottest days, and if I could get some (safe) performance too that would be awesome.

 

Currently I have: TBE, FMIC, Mishimoto Radiator, OEM STI lower temp thermostat, Primitive skidplate with OEM plastic splash guard. I have not plugged the hood scoop, and both fender splash guards are not on the car at the moment. My coolant is steady at the full mark with about 75% water to 25% coolant (I mixed the 50/50 premixed from the dealer with distilled water). On days under 100F, my coolant temp does not exceed 212F which makes me think that my cooling system does not have a problem.

What's next? Intercooler or radiator sprayer? Oil cooler?

 

I did find some WRX/STI threads about this, but they usually recommend wrapping UP, DP, and turbo, and other things that don't really apply to my car.

Edited by Sarang
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^^that would be a good start, I would be concerned the fmic is blocking some of necessary airflow through the condenser and or transferring heat through them as opposed to fresh air...

 

You might try to enlarge the air opening in the front bumper somehow, maybe cut away some of the black plastic pieces. I think anything at the front that could block air might make a bigger difference than almost anything else, except maybe moving the intercooler.

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Thanks, I am very interested in that product! Couldn't hurt, right?

 

I actually had to remove the black plastic and cut away some of the painted bumper cover to fit the FMIC. Here's a couple recent pics: https://imgur.com/AsFgx9p https://imgur.com/nuj9N15

 

The other day in traffic it seemed like my coolant temps were creeping up, like my cooling system was insufficient. I was wondering what can be done to cure that. It seems like the ECU turns off the AC when it's getting close to overheating, so if I can avoid that it would solve the AC issue.

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There is an all aluminum radiator that may help, Mishimoto I think. I can't remember which member has one installed, possibly acumenhokie and I think someone else. That might help some and using an intercooler sprayer may also be of benefit.

 

It would be nice if there were fan upgrades for Subarus, but I have yet to see one recommended over the stock fans.

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There is an all aluminum radiator that may help, Mishimoto I think. I can't remember which member has one installed, possibly acumenhokie and I think someone else. That might help some and using an intercooler sprayer may also be of benefit.

 

It would be nice if there were fan upgrades for Subarus, but I have yet to see one recommended over the stock fans.

Lol I deleted all my responses to this, because I realized Sarang already has the mishi rad on his car

 

Sent from my ONEPLUS A5000 using Tapatalk

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I do have the Mishimoto STI-08 installed.

 

So would the next logical step be an oil cooler?

 

I was also thinking about tee-ing into the washer fluid sprayer line and adding a nozzle to spray the radiator.

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I do have the Mishimoto STI-08 installed.

 

So would the next logical step be an oil cooler?

 

I was also thinking about tee-ing into the washer fluid sprayer line and adding a nozzle to spray the radiator.

There is this that would at least help cool cylinder #4 more https://www.iagperformance.com/GDT-Cylinder-4-Chamber-Cooling-System-WRX-STI-p/gdt-1001.htm

 

Sent from my ONEPLUS A5000 using Tapatalk

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I think I would try removing that lower grille and see if that makes any difference, I don't think an oil cooler is going to really do much for the coolant temps. An intercooler/condenser sprayer would be the next logical step to me in your situation.

 

Just for kicks have you checked the relay for the AC compressor, that could be on its way out and just not holding when it gets too hot. It might be worth swapping it with one in a different spot.

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I was also thinking about tee-ing into the washer fluid sprayer line and adding a nozzle to spray the radiator.

 

Now that's an idea. A solenoid to switch between the windshield leg and the intercooler side controlled by a switch inside, so it operates off of the stalk as usual. If I weren't headed back to cooler ambient temps I would do this just for fun...

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Another thing to try could be the STI coolant thermostat that opens earlier?

 

I forgot to mention in my first post that I do have that. When I installed the radiator I put in the lower temp STI thermostat.

 

I think I'll pursue tee-ing into the washer sprayer line as a proof of concept. If that works, then putting in the additional time and money to put in an Outback tank with dual pumps and wire one up for a system will make sense.

 

Thanks for the input guys. Out of curiosity, when would an oil cooler be the answer?

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How much does your skid plate block off? Your engine bay is a low pressure zone when in motion, as air enters the nose/hood scoop it need a place to exhaust the convection cooling of the radiator, engine, condenser, etc. It has to exit at another low pressure zone, so under the car or out the cowl at the windshield.

 

Are your fans kicking on?

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Fans work. The skid plate and the oem lower splash guard are on, so I think that is working pretty well.

 

The car does great when it's only 100F out. The coolant stays below 212F and the AC is ice cold. My question is really about what I can do for those extreme, ridiculously hot days or situations like the other day.

 

I am thinking that I will make a styrofoam block for the scoop since that'll be very cheap and reasonably easy. Maybe that will help with keeping that area low pressure.

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Well it looks like you have pretty much all the coolant cooling mods you can put.

 

IIRC oil needs to be hot, but not too hot. So it needs to be exceeding a certain temperature consistently for an oil cooler to be recommended, and even then it is highly recommended for it to have a thermostat so it only is cooled when needed.

 

If the oil temps are at or beyond threshold when the AC starts cutting off, then I think an external oil cooler will help.

 

But the only way to tell for sure is to monitor and log oil temps.

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I would agree with the thermostatic switch, and being that our turbo is also using that oil to cool it might not be a bad idea to add a cooler. That would give you something to mount in the airflow of the scoop also.
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More cores can help and hinder by blocking air flow through the fins, typically that's 3 and 4 row stuff.

 

Have you pressure washed (or just washed out) the radiator fins? My friends Dodge 2500 Cummins was overheating and thats what made it go away. Airflow is key. I'd drop the skid plate and see if it allow more flow out the bottom.

Edited by nads
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Sorry guys, I've been busy with work and dealing with a power outage at home.

 

I did receive the sprayer nozzles from Amazon, so one of these days I'll tee into the oem sprayer line and do a proof of concept. I also ordered the condenser cleaner, so I'll be doing that soon too.

 

Another interesting note: I changed my oil this weekend and filled up with 20w50 (replacing the 5w40 that was in there) and my coolant temps have not been higher than 208.4 since. Even today in stop and go traffic at ~108 it was rock solid. I'm not sure if that makes the difference, but I guess I'll switch to 20w50 earlier next year. So I guess this is just a friendly reminder that Subaru does recommend different oil weights for different climates.

 

My Mishimoto radiator is pretty beefy. I had to grind off some of the oem fans supports to fit it, so I don't think trying to put in a bigger one would be worth it. I also happen to work at a mechanical/refrigeration contractor and I'm pretty skeptical of the marginal increase in cooling capability that a slightly larger radiator would add.

 

I think that a thermostatic oil cooler would be the next upgrade if the sprayer mod doesn't seem to do the trick.

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