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Old 02-17-2020, 11:43 PM   #1
Scooby Specialist
Member#: 378421
Join Date: Jan 2014
Location: NC
2005 Cobb Stg2+ Wrx
Platinum Silver

Default Na run hotter than turbo?

Hey guys, something thats been buggin me, do the na ej's typically run hotter than the turbo ej's?

I have a 2005 Wrx turbo ej205 and a 2004 Forester Xs na ej251 (i think) and the Forester runs hotter than the Wrx, but doesnt overheat. No leaks that i can find, coolant is never low. No matter how long or hard I drive, my Wrx coolant temp never goes above 204* before dropping back down according to my scangauge, and my Forester coolant temp never goes above 211* according to the same scan gauge.

Is this normal for the na ej to run hotter than the turbo ej? Its always bugged me and almost worries me that my Forester runs hotter than my Wrx.
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Old 02-19-2020, 04:06 PM   #2
Scooby Specialist
Member#: 29292
Join Date: Nov 2002
Chapter/Region: SCIC
Location: Orange County CA
2004 WRX wagon


probably has a hotter thermostat to keep the emmision down
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Old 02-20-2020, 04:29 PM   #3
Scooby Newbie
Member#: 486361
Join Date: May 2018
Location: New Jersey, USA
2017 WRX
Pearl White


It is 7 degrees difference which is around 4% difference which is within the margin that most electronics are built with. While you are using the same tool to test the temperature the gauges are different which could be causing variances as well. Also the radiator size can cause the difference in temperature.

I would not worry about since both vehicles are running within safe operating temperatures.
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Old 02-20-2020, 07:35 PM   #4
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Member#: 338863
Join Date: Nov 2012
Location: Bethlehem,PA
95 Caprice 6spd Track Rat


AND/OR the cooling fans could be programmed to kick on at slightly different temps. Hotter engines run more efficiently and produce less emissions, within reason.

NA motors at normal RPM operating ranges will also likely build coolant temp at a much less rapid pace when compared to a turbo car, especially one that cools the turbo with engine coolant. Basically turbos can build heat much more rapidly and go kaboom in a much shorter time span, whereas you could romp on your Forester for probably twice as long before it increased the coolant temp to the same level as a WRX.

Either way, that's a very negligible difference between two totally different animals, and you're 100% ok.
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Old 02-21-2020, 11:19 PM   #5
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Member#: 48377
Join Date: Nov 2003
Chapter/Region: MWSOC
Location: "They eat fish soaked in lye"
1996 Gutted, built
XP class Impreza L


Not just for Subaru engines, but across the industry- NA engines are typically tuned to run a bit hotter than similar turbo engines. While they can do this to increase efficiency, a turbo engine is more likely to experience damaging knock at the onset of positive boost pressure. To lower the significance of that effect turbo engines are tuned to run just a few degrees cooler.
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