LS3 Thermostat Degree Question
Thread Starter
Racer
Joined: Mar 2015
Posts: 292
Likes: 53
From: Wesley Chapel North Carolina
LS3 Thermostat Degree Question
I'm building a 69 Coupe restomod with LS3 engine and was wondering what degree temperature thermostat I should run. I would like to run a 160 or 180 degree thermostat. Is there any issues with computer by running these cooler thermostats than factory? Please advise and thanks in advance for input to my question!
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
If you are using the computer, I think you will have to install a 195*F stat. The computer won't go into closed-loop mode until a required temperature is reached.
If you have some concerns about operating temps for the engine, just use full synthetic oil. It is much more tolerant of engine heat; and the engine itself couldn't care less that it is 15*F warmer.
If you have some concerns about operating temps for the engine, just use full synthetic oil. It is much more tolerant of engine heat; and the engine itself couldn't care less that it is 15*F warmer.
Burning Brakes
Joined: Apr 2008
Posts: 825
Likes: 40
From: Glasgow, Scotland
If you are using the computer, I think you will have to install a 195*F stat. The computer won't go into closed-loop mode until a required temperature is reached.
If you have some concerns about operating temps for the engine, just use full synthetic oil. It is much more tolerant of engine heat; and the engine itself couldn't care less that it is 15*F warmer.
If you have some concerns about operating temps for the engine, just use full synthetic oil. It is much more tolerant of engine heat; and the engine itself couldn't care less that it is 15*F warmer.
Melting Slicks
Joined: Sep 2010
Posts: 3,315
Likes: 697
I typically run a 180 degree thermostat in my LS swaps. Tons of debate over on LS1 Tech forums. ECM runs the fan. On at 205 and off at 195 degrees. The exception is my Jeep Wrangler LS1 swap. I use it to plow snow in the winter. To get a little more heat in the cab I run a 197 degree thermostat. I'd have to check with my tuner but I think the ECM can be modified to go into closed loop at different temps.
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
I would put a 180* thermostat in it.
Any GM EFI from the 90's up that I have looked at went into closed loop WELL before 160*F. All the cold start fuel enrichment stuff is long done by that temperature. This is NOT a problem with the GM systems like it's so often made out to be. A 160* thermostat will not make a GM engine run rich and in open loop.
Any GM EFI from the 90's up that I have looked at went into closed loop WELL before 160*F. All the cold start fuel enrichment stuff is long done by that temperature. This is NOT a problem with the GM systems like it's so often made out to be. A 160* thermostat will not make a GM engine run rich and in open loop.
Burning Brakes
Joined: Apr 2008
Posts: 825
Likes: 40
From: Glasgow, Scotland
Iam using a 180 degree with no issues, but iam running different ecu
Last edited by corvettedave383; Oct 29, 2018 at 02:31 PM.
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Instructor
Joined: Mar 2011
Posts: 165
Likes: 31
From: space coast florida
I personally wouldn't use that low of a thermostat, and without some tuning software like HPTuners, would stick with what the OEM used. I put a 5.3 in my boat, (with closed loop cooling) and after it was all said and done with mapping fuel tables, wide band O2, spark, etc. etc. would have been better off just keeping the factory settings and adjusting fuel enrichment to start at 50% throttle. While I'm not an expert in the algorithms on the newer chevy engine management systems, engine temp has to play a big part in it and without full knowledge of what that is prefer to stick with what the stock settings were. Modified engines are a different story.
If there's a cooling issue, it's best to solve it from a system point of view vice trying to manage it with a thermostat. I swapped a V8 into a Vega 40 years ago and cooling was an issue. Never ran quite right, and it dawned on me several years later that the top of the radiator was below the thermostat housing (with no expansion tank), and that was probably the source of my cooling problem, as it was never full and "burped".
If there's a cooling issue, it's best to solve it from a system point of view vice trying to manage it with a thermostat. I swapped a V8 into a Vega 40 years ago and cooling was an issue. Never ran quite right, and it dawned on me several years later that the top of the radiator was below the thermostat housing (with no expansion tank), and that was probably the source of my cooling problem, as it was never full and "burped".
Melting Slicks
Joined: Sep 2010
Posts: 3,315
Likes: 697
Nice thing about the newer LS motors the thermostat is kind of like old small blocks not part of the thermostat housing like the earlier LS1's so they are much cheaper. So changing to different temps is cheap. The LS1 thermostats are $50 each.
