98 K1500 Thermostat

[Missouri Mule K30]

What is a good temp for L31R crate engine, egr delete, minor port work on intake, and Hookers.
Empty cats, duals out back or under bed, no tail pipes? My "friend" has a very heavy foot. 160?

 

[magimerlin]

Unless programmed otherwise.. the computer will not go into closed loop with that temp... the OEM 195 temp will be perfectly fine.

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[big_mike]

I got a superstat 195 off Summit cheap for my build.

 

[df2x4]

Like others have said, unless the PCM is tuned for a different temp, stick to the OEM ACDelco 195 degree. I've asked my tuner (Black Bear Performance) and my mechanic this same question and they both told me the same thing. Justin at Black Bear told me that these Vortec engines really like the 195 degree stats and there's no gain from running anything cooler.

 

[Missouri Mule K30]

Well looks like 195 is the choice with good reason.

I just cannot get past the heat is a good thing.

Thanks

 

[L31MaxExpress]

Closed loop happens around 120-140°F with factory tuning. Cold startup fuel enrichment is done by 140°F as well. These cast iron head engines like to run cool. I have run a 170°F thermostat for years even with the stock tuning. My coolant temp stays around 176-178°F. Once the PCM sees coolant temps over 180°F it starts pulling large amounts of timing. Anybody that says these engines run best at 195°F and beyond does not have the slightest clue! Justin and I have had massive open disagreements on this topic for years. He has not once provided any data to support his claims. On the otherhand there is not an OBD2 vehicle that I have reduced the operating temperature of that did not perform better at the truck. That includes aluminum head and aluminum block engines.

Also the Marine L31 runs a 140°F thermostat, FWIW. Probably to help control detonation in the constant high load, high rpm abuse it fights.

The attached image is the temperature my Express van runs year round and has not been a problem even with the factory tuning.

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[L31MaxExpress]

Well looks like 195 is the choice with good reason.

I just cannot get past the heat is a good thing.

Thanks

There is power and performance to be gained running cooler than 195°F as well as more resistance to detonation in hot weather.

One specific test when I had my 2006 Hemi Ram. I took a 170°F thermostat and a drain pan to the track with me. I made 4 passes at the track. I let the engine cool down a bit, drained some coolant and replaced the 205°F factory thermostat with a 170°F thermostat. In 4 back to back passes my ET reduced nearly 2/10ths of a second and I gained nearly 1.5 mph in 1/8th mile.

 

[L31MaxExpress]

I will also add further proof. With the factory settings from the 2002 L31 van 0411 tune you will be in closed loop very quickly even on a 30°F cold start. Long term fuel trim learn enables at 140°F but it is in closed loop long before that using short term fuel trims. CEL was on for a bad knock sensor at the time one of the few times I have even seen that light over the last 12 years.

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[big_mike]

I'll call BS on that L31, a fool is born everyday but I'm not one. You will not pick up no damn 2/10 at the track from a damn thermo swap. That's not reality. I have spent too many years around race cars to buy that ****. Now I would buy you got better traction and better 60ft to change the numbers that much but nothing cooling related.

And I know for a fact the LS motors thrive at a little warmer temp too, plenty of experience there as well.

Now if your talking a full race application at the track things change a little, especially if hot lapping. But then your dealing with a entire new set of cooling issues to contend with over a street driven daily driver.

 

[L31MaxExpress]

I'll call BS on that L31, a fool is born everyday but I'm not one. You will not pick up no damn 2/10 at the track from a damn thermo swap. That's not reality. I have spent too many years around race cars to buy that ****. Now I would buy you got better traction and better 60ft to change the numbers that much but nothing cooling related.


And I know for a fact the LS motors thrive at a little warmer temp too, plenty of experience there as well.

Now if your talking a full race application at the track things change a little, especially if hot lapping. But then your dealing with a entire new set of cooling issues to contend with over a street driven daily driver.

Its all based on what is in the PCM programming. Almost every engine I have ever messed with pulls timing when coolant and intake air temps are elevated. When you drop the coolant temp the air entering the engine also cools down which is practically free HP. Finally running cooler also helps keep the clutch fan from engaging. The clutch fan can have a huge effect on ETs as well even if it is not fully engaged. The cooler the engine runs the more it free wheels.

I am not sure what you mean by cooling issues on a daily driver. If the cooling system is functioning correctly, you change the thermostat, it opens sooner and the engine runs cooler, period.

In 90°F weather and that Ram with the factory cooling system it was very much a reality. All runs were dead hook back then in that truck. 5,500 lb truck with stock 3.55 rear gear, stock torque converter and P305/50R20s assured that. I wemt from a 9.8 to a 9.6 in the 1/8th and my 60` was even slightly better from the increased torque and throttle response of the PCM running more timing advance.

The LS engines also run a little better cooler than OEM temps as well. My buddies cammed 6.0L just made 345 RWHP through a 4L80E in 2nd gear with an unlocked 2,800 stall converter.