427 4th gen running warm
Thread Starter
Joined: Mar 2011
Posts: 3,699
Likes: 168
From: Wilmington, DE
427 4th gen running warm finally got my 2000 4th gen with an N/A 427 in it back and moving around. The tuner didnt like my temps running at 198-200 while cruising, despite outside temp being very high 60s to low 70s. Im running a stock pump with a larger aluminum radiator, unsure of brand. i believe it had a 186 thermostat in it on the previous 427, and that too ran at 198-200. He replaced the thermostat with another 186, and again, it still running at the 198-200. i have a plx coolant temp gauge that reads off of the obd2 port so it reads whatever the ecu sees off the stock sensors. He is now thinking that my big SSRA is blocking too much of the radiator. I will most likely remove it completely to test for a nice gentle cruise around to see what it does, but he wants to see it lower than 200. if this does turn out to be the issue, i assume my only option would be if i didnt want to look into other radiator options is to maybe trim 5 inches or so off the bottom of the SSRA? i assume drilling holes in the SSRA would be a bad idea since that defeats the "ram airness" of the intake? if i remember correctly the intake is basically sitting flat against the radiator since both the intake and radiator are thicker, so there is little to no airflow between the intake and radiator
Last edited by Floorman279; Oct 15, 2023 at 04:50 PM. Reason: ...........
Thread Starter
Joined: Mar 2011
Posts: 3,699
Likes: 168
From: Wilmington, DE
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
I know they do, the truck thermostat is in the 190s stock. He swapped thermostat just to make sure the older one wasnt having issues. It's his preference to run high 180s low 190s if possible. I'm at 12 to 1 on pump 93 so I think he wants a buffer for when it's hot out and 200 is too close to the temp that he has set for the ecu to pull timing out. No reason that an aluminum radiator my size shouldn't allow us to run cooler than what it is
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
A 186°F T-stat (I actually think they are an 86°C unit, which is closer to 187°F) won't even be fully open by the upper 180s. If that's the running temps your tuner wants to see, especially in hot weather, you're going to need a lower temp t-stat regardless of your cooling system capacity. If the lower temp t-stat can't keep you in the desired range, only then would I consider making any further changes to the cooling system or airflow path.
Thread Starter
Joined: Mar 2011
Posts: 3,699
Likes: 168
From: Wilmington, DE
i actually misspoke, it does have a 180 degree thermostat in it now. I remember the conversation i had with him about it now.....i was confident it had a 186 thermostat in it (i never tested it to verify the actual opening temp), so we decided to try the 180 and see what is happening. It is trunning the same temps as the 186-187 thermostat, which is what leads him to think an airflow to the radiator is an issue.
i drove it today, was 50 degrees, today it ran 193-195 with the 180 thermostat compared to 196-198 with the 180 thermostat. on a 65 degree day.....Im not sure if that helps.
Im not trying to be an ***, i just like to know as much about how my setup runs/should run etc which is why im coming here.
i understand coolant temps are one of those things many tuners/modders etc will have various opinions on, heck think of all those 160 t stats sold back in 2005-2010 when cam swaps were the big thing on an ls1 and all the sales guys were saying run it as cool as possible to make more power lol. My guy just doesnt like it running that high and has full confidence in my cooling system, but would like to see it 10 degrees cooler consistently or so, especially becuase if its 200ish on a 60 degree day, how will it be on a 95 degree day?
i drove it today, was 50 degrees, today it ran 193-195 with the 180 thermostat compared to 196-198 with the 180 thermostat. on a 65 degree day.....Im not sure if that helps.
Im not trying to be an ***, i just like to know as much about how my setup runs/should run etc which is why im coming here.
i understand coolant temps are one of those things many tuners/modders etc will have various opinions on, heck think of all those 160 t stats sold back in 2005-2010 when cam swaps were the big thing on an ls1 and all the sales guys were saying run it as cool as possible to make more power lol. My guy just doesnt like it running that high and has full confidence in my cooling system, but would like to see it 10 degrees cooler consistently or so, especially becuase if its 200ish on a 60 degree day, how will it be on a 95 degree day?
Last edited by Floorman279; Oct 16, 2023 at 08:02 PM. Reason: .....
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Verdad Gallardo Thread Starter
Joined: Mar 2011
Posts: 3,699
Likes: 168
From: Wilmington, DE
i dont. no gauge for that whatsoever. stock gen 3 sensors, stock gen 3 ecu, only thing extra is the multigauge plugged into the obd2. i am running 10w 30 driven oil and with the ported mamo ported 10296, my hot idle psi is right about 42, crusing 2200 rpm is 51-52......doubt that tells u much