The "correct" lower temp thermostat ?

Dinosgt

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Folks:

I recently installed a Lund tune which kicks the High speed fan on at 189 degrees. Currently the stock T-stat is in the car (192 deg), so I am looking for a replacement so the fan doesn't run continually. (a notable side effect, the constant running of the fan and intercooler pump seems to keep the IAT2 values pretty low @ <115-120 degrees).

I have read a dozen threads on this, and the general consensus is to use either the Reische 170 deg T-stat, or go with the 180 deg Napa THM-190, Murray 4138 or Motorad 354-180. Those that went with the latter, claim no issues in real world experience.

I prefer the slightly higher temps, since it gets cold down here in Texas (but I don't drive it under about 50 degrees, as the Cup 2s dont like the cold). BUT - One thing that recently caught my attention was some comments from Reische as follows:

"One thing you can say about the GT500 cooling system is that it works very well. It can still dissipate a great deal of heat even if you run a thermostat that doesn't close the bypass. In order to do this you have to run the fan for longer periods of time to cool the rad output more so when it mixes back in with the bypass you'll get a lower ECT. Many GT500 owners ran improper SOHC and 4.6 DOHC thermostats for years with no problems, however the benefits of running a proper t-stat are more stabilized lower temps and increased electrical efficiency while also increasing the life of the cooling fan. Of course the overall efficiency of the cooling system is improved so under severe conditions it will be able to dissipate more heat but the majority of owners will never take the cooling system to it's limits.

Many people thought the NAPA 180* (which is a 4.6 DOHC t-stat) was the correct thermostat because the diaphragm size and the overall height were the same or very similar. However the bypass on that thermostat functions in a totally different way making it incompatible with the 5.4 DOHC's hot-side setup. As far as I know my unit is the only low temp thermostat made specifically for these cars. "

Anybody have experience switching between the 170 Reische and "correct" 180 stats? (According to Reische, the 170 stat will run hiflow to radiator around mid-180s or so.)

Also - the main gripe about the 180 t-stats is that they are Hot-side vs Cold-side bypass. I dont quite understand the difference nor why its important for proper function.

Thanks much
 

me32

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Why not just have him adjust the fan setting? I dont really see the need to put a lower tstat in the gt500. Unless your road racing.
 

RedVenom48

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It makes a difference in the summer, and if youre trying to hot lap on a road course or at the strip. In conjunction with a dual fan triple pass heat exchanger, it reduces the chance of heatsoak in the car.

Ive been very happy with the performance of my Reische.
 

Dinosgt

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It makes a difference in the summer, and if youre trying to hot lap on a road course or at the strip. In conjunction with a dual fan triple pass heat exchanger, it reduces the chance of heatsoak in the car.

Ive been very happy with the performance of my Reische.

Thanks sir - what are your typical running temps with the 170? My car sits right on 192 right where the stocker opens. Reische alluded to a mid-180 number - but I don’t understand how that relates to the opening temp.


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Catmonkey

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I recently installed a Lund tune which kicks the High speed fan on at 189 degrees. Currently the stock T-stat is in the car (192 deg), so I am looking for a replacement so the fan doesn't run continually. (a notable side effect, the constant running of the fan and intercooler pump seems to keep the IAT2 values pretty low @ <115-120 degrees).
I see your location is TX. If you're running air conditioning, your fans are going to come on and stay on, but they won't necessarily be on full tilt. Your intercooler fans have nothing to do with the thermostat and are controlled by IAT2 temps and are a changeable parameter. I've played around with the on and off temps and they're going to pretty much run all the time. Setting them higher may just delay when they turn on by a minute or two depending on ambient temps. The fans are trigger by the intercooler pump. If the intercooler pump isn't running, it doesn't take long for IAT2 to get to 100*. I wouldn't want to set it lower than that.

I am running the Reische and my logs show operating temps in the low 180* range. The fan controls in the 2011+ are a bit more complicated than a low speed and a high speed setting. Ideally, if you want to drive your car in the winter, put the OEM thermostat back in and switch it when the weather warms up, especially if your car is a daily driver.

But I'm with you. If there was a correct thermostat rated at 180*, I'd be running it.
 

GT Premi

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... Ideally, if you want to drive your car in the winter, put the OEM thermostat back in and switch it when the weather warms up, especially if your car is a daily driver.

...

Sound advice. I have the Reische 170* t-stat. In the winter, the heat isn't as effective at the temperature I like to keep it set to; 71*, or 72*, if it's really cold out.
 

merkyworks

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Live in Houston and daily drive mine all year. Have triple pass HE W/ fans and a 170* Reische.
Summer time it's 95-105*F+ and I can sit in stop and go traffic with AC on and my temps are 185-190*F for radiator and 115-120*F for HE. The HE fans will be running all the time and the radiator fans will as well but I think on low speed.
Winter time has been interesting this year but on days when its been low 30*F my temps are 165-185*F for radiator and 75-105*F for HE. I pulled the fuse for the HE fans so they didn't come on and radiator fans came on maybe but I'm not sure.
 

Dinosgt

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Thanks for all the replies folks. Appreciate it.

Catmonkey - I don’t have HE fans - still running the stock HE. But what I noticed was with the stock fan running on high, which seems to be commanded in the tune at 189, it actually does a decent job keeping the IAT2 down. I know it’s not a great amount of airflow, but it’s enough when ambient is 65 ish to keep me below 110-115 even when sitting at long lights and slow traffic.

Prior to the tune, the fan wouldn’t kick on until 207 and the IAT2s would sour at idle, even with engine temps under 200.

I know the intercooler is commanded to basically always run - and I’m ok with that.

Frankly I like the fan running, but I read in several threads that some folks have toasted the relays or the junction at the fuse box after a tune because it runs so much - something I want to avoid. This is one reason I’m thinking of running a colder thermostat, ie to give the fan a break (once cruising etc).

My fear was that 170 is too cold. But it seems that folks are seeing mid 180s which I am ok with. Reische actually goes as far as recommending a thinner oil - but I’m not feeling that at all...




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Catmonkey

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I gotcha. I was confused by your comment. You'd have to see the fan parameters on a the 11+. With the factory stat, I'd probably leave the higher fan speed to something north of 192*, because I don't think you really need higher speeds until you're above the point that the thermostat is open. There is also a parameter for a/c. I lowered these because the fans on the HE are more than enough to blow air through the condenser. That's the whole reason the fans will run all the time with the compressor on.

While operating temps are important, I like to focus on the cylinder head temps. That's where the combustion process is taking place. When my ECTs are in the mid 180s, the cylinder head temps are in the mid 190s. I have not logged cylinder head temps with the stock thermostat.
 

Dinosgt

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I gotcha. I was confused by your comment. You'd have to see the fan parameters on a the 11+. With the factory stat, I'd probably leave the higher fan speed to something north of 192*, because I don't think you really need higher speeds until you're above the point that the thermostat is open. There is also a parameter for a/c. I lowered these because the fans on the HE are more than enough to blow air through the condenser. That's the whole reason the fans will run all the time with the compressor on.

While operating temps are important, I like to focus on the cylinder head temps. That's where the combustion process is taking place. When my ECTs are in the mid 180s, the cylinder head temps are in the mid 190s. I have not logged cylinder head temps with the stock thermostat.

Thx Catmonkey.

BTW How are you logging cylinder head temp? It’s not a choice on the Lund N gauge. Is it a generic Ford PID?
 

Catmonkey

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I use Live Link with my X4. I don't think it's a PID. I can't seem to find that configuration file either.
 

SCGallo2

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This 180* thermostat works great, no part number on it though:

https://www.svtperformance.com/forums/threads/180-degree-thermostat-option.1061516/

I've been running it for a couple of years with no negative side effects. I experimented with Amsoil SS 10W-30 with this t-stat and felt that the oil was too thin for my operating conditions, so I now use Amsoil SS 0W-40.

I also use LiveLink with my SCT X4 to datalog CHT, and it is a PID for my 2008. I would look into changing your cooling fan trigger temps in your tune first... Lund left those adjustments open for me to set with my X4 as desired when I was using his tune.
 

Dinosgt

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I use Live Link with my X4. I don't think it's a PID. I can't seem to find that configuration file either.

Thanks again Catmonkey

Go with a Reische from Lethal and dont look back

I am almost there - What are your "normal" operating temps? Idle vs freeway?

This 180* thermostat works great, no part number on it though:

https://www.svtperformance.com/forums/threads/180-degree-thermostat-option.1061516/

I've been running it for a couple of years with no negative side effects. I experimented with Amsoil SS 10W-30 with this t-stat and felt that the oil was too thin for my operating conditions, so I now use Amsoil SS 0W-40.

I also use LiveLink with my SCT X4 to datalog CHT, and it is a PID for my 2008. I would look into changing your cooling fan trigger temps in your tune first... Lund left those adjustments open for me to set with my X4 as desired when I was using his tune.

THX - I appreciate the link - I actually have read your thread prior - honestly the reason I havent gone this route is the reports that the 180 stat isn't the "correct" functioning design, even if one uses the "correct" bypass design. I am still trying to figure out why that's the case. Your data seems to suggest it works just fine...
 

jrgoffin

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The MotoRad 354-180 is the same as the Murray 4138 (their part in the Murray box). They are dimensionally identical to the OE replacement thermostat and will function perfectly.

Never got in to that model, but list it as an option on this page of my own site:

http://www.termi-stat.com/gt500.htm
 

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