Vortec Thermostat Experiment

[L31MaxExpress]

I recently made a discovery when it comes to thermostats for a Vortec. I had been running a 180F thermostat, that had been keeping my 383 at 185F going down the road. At idle with the AC on it would creep up to 215F. Electric fan, mechanical fan, mechanical with an electric booster fan, it did not matter. I found a 195F high flow thermostat. I put both the old 180F parts house thermostat as well as the new 195F high flow in a pan on the stove and started heating them. Both started opening about where they were rated as they should. That is where the difference showed up. As the temperature of the pan continued to increase toward boiling the highflow 195F thermostat opened much wider than the previous 180F.

I put the 195F unit in the 383 in the van. It now runs consistently 199-203F. It was only 85F today here, but in the same weather I had watched the old 180F heat soak to 215F. After driving it for 30 miles, I let it sit and idle for 20 minutes with the ac cranked up. The highest I saw it climb was 205F. At 11:1 static compression and 9-9.5:1 dynamic compression these aluminum heads still run 32 degrees total timing at WOT and as much as 42 degrees at cruising speeds without detonation on 91 octane. Going down the road the IATs dropped down to ~90F. My long term fuel trims dropped a small amount running the engine hotter. My idle oil pressure dropped 5 psi, but it still carries 30 psi at 725 rpm at hot idle. At hot idle my IAC counts dropped about 5 counts and the engine is pulling about 2 kpa more vacuum. Will be interesting to find out if my next longer road trip breaks 20 mpg.

 

[Supercharged111]

What's the difference in appearance of the 2 stats? And speaking of mpg, I tagged you in my 1500 thread regarding the same thing.

 

[yevgenievich]

I switched to a high flow 185 from a normal 195. Staying below 205 now, but the 20 degree swing shows the fuel trims do change decent amount from 180 to 200. Might try 195 high flow. I was hitting 215 with a normal tstat

 

[L31MaxExpress]

What's the difference in appearance of the 2 stats? And speaking of mpg, I tagged you in my 1500 thread regarding the same thing.

The high flow a slightly larger hole in the center and thicker coils on the spring. When it is hot, the valve portion opens noticeably further than the standard stat. Otherwise, they look pretty much the same to the casual eye. Both have jiggle valves to bleed the air.

 

[L31MaxExpress]

I switched to a high flow 185 from a normal 195. Staying below 205 now, but the 20 degree swing shows the fuel trims do change decent amount from 180 to 200. Might try 195 high flow. I was hitting 215 with a normal tstat

I am really surprised that it is running cooler with a hotter thermostat opening temperature. That being said my coolant temps previously had a 30*F swing. I am not a huge fan of letting the temperature yoyo like that because of thermal cycling. What I like about it now is that it heats up to 198ish and pretty much just sits there between 198 and 203*F. With the ac blasting and the engine idling for a while it slowly climbed to where HP Tuners scanner was flashing 205-207-205-207 and never would fully settle in on 207F. I will call that 205*F as the maximum temperature reached. I captured this screenshot from data I recorded while messing with some of the tuning this afternoon. I shut the engine off HOT, re-flashed the PCM, then connected the scanner back up before starting the engine. When I first re-fired the hot engine; it had heat soaked to 212*F. Once the engine fired and the water pump and clutch fan started spinning, it dropped from 212*F to 199*F in ~30 seconds. While I was purging the cooling system of air, I checked the heater output; it might as well be a blast furnace.

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[spf1268]

What's the brand and part number of your 195F high flow thermostat? Thanks

 

[L31MaxExpress]

What's the brand and part number of your 195F high flow thermostat? Thanks

Motorad 2065195.

 

[Orpedcrow]

Thanks for sharing your finds from this experiment, I’ve wanted to test stats for better fuel economy. Higher temp more complete burn? that same thought process brought about the idea of an electric water pump hooked to a turbo timer (or at least an auxiliary water pump so your main source of cooling isn’t an electronic component) to reduce or prevent heat soak.

 

[L31MaxExpress]

Thanks for sharing your finds from this experiment, I’ve wanted to test stats for better fuel economy. Higher temp more complete burn? that same thought process brought about the idea of an electric water pump hooked to a turbo timer (or at least an auxiliary water pump so your main source of cooling isn’t an electronic component) to reduce or prevent heat soak.

I have several Bosch electric pumps off the 2005-2012 Pathfinders and 2004-2010ish Quest mini vans. The plastic coolant pipes had a habit of breaking and Nissan supplied the assemblies with a new pump. I fit one to my Hemi powered Ram when I raced it. I added a switch under the dash to run the pump and the hvac blower on low speed through the blower resistor for quicker cool downs.

 

[Orpedcrow]

I have several Bosch electric pumps off the 2005-2012 Pathfinders and 2004-2010ish Quest mini vans. The plastic coolant pipes had a habit of breaking and Nissan supplied the assemblies with a new pump. I fit one to my Hemi powered Ram when I raced it. I added a switch under the dash to run the pump and the hvac blower on low speed through the blower resistor for quicker cool downs.

That’s what I was thinking. Something on the heater circuit just to circulate, the blower motor is a good idea, my thought was the auxiliary “condenser fan” that’s optional on our trucks if you were running a mechanical rad fan. The turbo timer could be implemented easily on a daily driver too…