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Michael Price

Michael Price
26 seconds ago (edited)

I went through some 107 deg weather while driving around 80 mph in my 2021 Outback XT. Seems the intercooler would be worthless in cases like this. Does this mean my engine produces less hp? Is my turbo insanely hot? Does my car pull timing? I use 87 octane gas. It did seem like I had to put my foot further down on the gas going up hills.

Thanks for any comments.
 

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Depends on what the temp of the post turbo air charge is. Your radiator still works and the intercooler is no different. The greater the temp difference the more efficient.
Anyone know what the air charge temp is? A lot of variables there, I know.
Bottom line, no, the intercooler isn't worthless, just maybe not quite as affective.
 

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Yes, I do not know the temp of the output of the turbo, but the intake air is 107 deg. My guess is HP could be down even if the intercooler drops the air back down to a number closer to ambient, the hp may be down. Not sure any engine likes to suck in 107 deg air, pressurized or not.
 

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Yes, I do not know the temp of the output of the turbo, but the intake air is 107 deg. My guess is HP could be down even if the intercooler drops the air back down to a number closer to ambient, the hp may be down. Not sure any engine likes to suck in 107 deg air, pressurized or not.
That's a fact. Hot air is less dense than cool air so both NA and FI engines make less power in the heat.
 

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For sure hot intake charge air is going to contribute to some heat soak.
Not for the faint of heart, but I’ve known a lot of ppl (not in the outback crowd however) to mix in 10-15% of their fill up with E85 to raise octane and burn a bit cooler. With todays computerized ecu’s they have the threshold to make the corrections. And it saves a few $ too. I’m not recommending run out and do this, but google and do a little reading.
 

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Not sure any engine likes to suck in 107 deg air, pressurized or not.
Come on, engines have been 'sucking in' 107 degree air, and hotter air, since the internal combustion engine was invented.

Do you honestly think Subaru engineers, or any vehicle manufacturer engineers, did not take into account where and how their engines would be used?

Also, the Subaru Owner's Manual lists the maximum ethanol content at E10 (2.5) and E15 (2.4). If you want to raise the octane, use premium.

Yes, depending on how much fuel is in the tank, and its ethanol content, adding E85 won't result in a tank full of E85. There are plenty of charts available on the Internet which provide estimated octane and ethanol content for various mixtures.
 

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We pulled our new Casita 2,800lb camper from Dallas two weeks ago and saw minimal if and driving feeling at 102 F ( seat of the But Dyno ) Even at 75 MPH it preformed well but we did step to 91 octane as mentioned in the Manual when towing. The scan gage reported IA2 at 112-118 deg at cruising speed It is supposed to be Air charge temp but I doubt it to be true 12 LB+ of boost should be much hotter than 118 even after the intercooler. with short bursts on the Gas peddle. Fortunately we still got15.5 mpg and better mileage at 65 MPH with the trailer and all our gear likely a bit over 3,000 lb
 

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I doubt the turbo is even engaged at 80 mph on the highway in the flats. At 107F, the air isn't all that dense so it's not overcoming the wind resistance you'd encounter in subzero. The car is tuned for fuel economy. You'd have to hook into the ODB II port with an instrument to look at turbo boost but I'd be surprised if there's any boost at all. Maybe fully loaded and with a roof box where you'd get lousy fuel economy.
 

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You can remove your throttle body coolant hoses which heat up the throttle body to match the coolant temperature, which is typically around 200F. If your throttle body were above coolant temperature it would cool it down, but from what I have seen, the output of a turbocharger before the intercooler is about 200+F and after the intercooler it's closer to 100-120F. In high ambient temperatures it might be higher but it shouldn't approach 200F.

The two lines at the top are pre-intercooler and the two at the bottom are post-intercooler. Here Grimmspeed is trying to sell their aftermarket intercooler for a WRX, so this does not apply directly to our Outback XT with its intercooler.



Here I posted that I removed mine:
 
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Guess which make and model of car set a new FIA World Land Endurance Record in the Arizona desert in 1989 when it was introduced to America?
While true, that is misleading. It was far from 100° F when that happened:

Weather in January - Stanfield, AZ
January, the same as December, is another comfortable winter month in Stanfield, Arizona, with average temperature fluctuating between 63.9°F (17.7°C) and 46.4°F (8°C). In Stanfield, the average high-temperature in January is essentially the same as in December - a still comfortable 63.9°F (17.7°C).
 

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I made seats for those cars back in 1989. Never knew there was such a record or that Subaru broke and owned it. Do they still own it?
That old record, while admirable, means zero to today's cars which have nothing but name and a few materials in common. I'd like to see such an endurance attempt made again with today's Subarus. First thing they'd have to modify is the nanny governor because such speeds are no longer possible with the current programming.
 

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To bring the thread back to its original question about the effectiveness of an intercooler - yes it's still effective to the degree that the pre-intercooler temperature is higher than the post-intercooler temperature. It's not a magic box - it's an air-to-air heat exchanger. You can add a distilled water sprayer to make it even more effective.

Car Vehicle Automotive lighting Hood Vehicle registration plate



To get a more accurate calculation you can do a deep dive into turbo efficiency compressor maps and intercooler efficiency. The 75% efficiency is typical and not representative of our particular turbos and intercoolers.
 
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