No tune with new Thermostat?

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[Cobra Jet]

That link says nothing about the 170 being detrimental to modern engines. Just shows how it works and tells us how to tune the fans.

Putting in a 170 T stat will not harm your engine, it may not help anything either. On the coyote the number 8 cylinder runs hottest and the temp sensor is next to cylinder number 4. To me it makes sense to run the engine a bit cooler.

YMMV.

EDIT
From looking at tunes the PCM thinks the engine is fully warmed up at 160 degrees.

See this link; my original was bookmarked, grabbed it quick to post, but looking at it now - I posted the wrong link…
https://www.reischeperformance.com/WhyLowTemp.html

Even Reische is stating in that above link:

But typically I don't recommend one if your engine is still running on the stock tuning. Simply because a cooler engine does not necessarily make much more horsepower.

The key point I was trying to get across is on a stock N/A Coyote not used for any track events, with the stock PCM parameters, dropping in a lower rated thermostat will have little impact or benefit. Also to go along with that, as others have stated, yes the PCM needs to be “tuned” in any 1986-current computer controlled vehicle in order TO benefit from such a mod.

Why anyone believes dropping in a 170* stat in a N/A Coyote that is just used a driver would be beneficial is beyond me. If the car sees 75-85% track use or full time track use, sure…

 

[K4fxd]

With a N/A Coyote, you risk the chance of causing more harm than good to the engine if using a 160, 170 or even 180 stat (seriously).

You have a lot of cred on this forum and telling people they will harm their engine is not true. It may not gain anything except peace of mind seeing 190-200 degree CHT's instead of 205-215.

Ford programs the PCM to believe 160 degree coolant temp is fully warmed up. The 170 degree keeps coolant temps right around 180.
Cooler head temps reduce detonation and with the coyote's hot running #8 cylinder can benefit from cooler operating temps.

Telling people it is not necessary is fine, that is your opinion.

Here is the rest of the paragraph you chose not to paste.

FROM THE LINK
"" Sure you may lose a few degrees of incoming air temperature and see some small gains but primarily I like to think of lower coolant temperatures as protection against engine-damaging detonation. Remember the knocking sound you heard when trying to accelerate an overheating vehicle? That is detonation and this can quickly destroy a high horsepower engine being pushed to maximum performance. But aside from possibly saving your engine there are a couple ways that a low temp thermostat can actually help make more power:""

Some of the people who have detonation on the FRPP tunes might benefit from a 170 degree T stat.

 

[Cobra Jet]

You have a lot of cred on this forum and telling people they will harm their engine is not true. It may not gain anything except peace of mind seeing 190-200 degree CHT's instead of 205-215.

Ford programs the PCM to believe 160 degree coolant temp is fully warmed up. The 170 degree keeps coolant temps right around 180.
Cooler head temps reduce detonation and with the coyote's hot running #8 cylinder can benefit from cooler operating temps.

Telling people it is not necessary is fine, that is your opinion.

Here is the rest of the paragraph you chose not to paste.

FROM THE LINK
"" Sure you may lose a few degrees of incoming air temperature and see some small gains but primarily I like to think of lower coolant temperatures as protection against engine-damaging detonation. Remember the knocking sound you heard when trying to accelerate an overheating vehicle? That is detonation and this can quickly destroy a high horsepower engine being pushed to maximum performance. But aside from possibly saving your engine there are a couple ways that a low temp thermostat can actually help make more power:""

Some of the people who have detonation on the FRPP tunes might benefit from a 170 degree T stat.

I put the facts out there and included the link. I purposefully didn’t include the rest of the paragraph from the link, because of the fact that there is no benefit to change out the stock thermostat on a stock vehicle that is driven in a normal manner - and not used on a track AT ALL. That’s why I captured and posted only the first few lines of what is in the link….

Pick apart the post(s) as you wish. I’m not putting out BS, but educating folks that plunking in a lower thermostat isn’t the key to “running cooler”, certainly not in a modern day computer controlled vehicle without changing the as built PCM parameters.

Putting a 170* stat in a vehicle that also sees 4-seasons operation could be bad for when that vehicle is driven during the colder months.

Here, read this older post on SVT Performance, it’s not S550 specific, BUT the tech goes deeper about using colder Tstats.
https://www.svtperformance.com/threads/cooler-thermostats-how-does-it-effect-your-oil.761968/

Anyone can do what they wish, that’s fine - but changing out a Tstat to a “colder” one just because others do it too - isn’t always best advice and doesn’t always apply to every other S550 out there, as much as anyone here wants to believe it - or push it.

The other thing too is people freaking out over seeing any gauge readouts in the dash cluster for XYZ sensors without knowing how Ford Engineers designed, programmed the PCM, used optimum min/max parameters, and tested all engine functions and operations not just for normal driving, but also extreme driving scenarios in many conditions. Why didn’t Ford Engineers use a 170* stat in the Coyote? Does Cyl 8 get hotter than the other cyls? Yes, sure it does - however is it detrimental to a S550 that is driven daily? No - and 90% of the owners who buy a S550 Coyote drive them hard and don’t have any issues at all.

It’s ok to disagree, no harm, no foul.

 

[Cory S]

Why didn’t Ford Engineers use a 170* stat in a Coyote?

IMO, the same exact reason why every other manufacturer has raised operating temperatures by as much as 30°F over the last 15-20 years. Emissions and MPG efficiency. A hotter engine as you know, will allow more efficient combustion, in which lowers emissions and improves fuel economy in general.

It’s common of many ICE’s now to be set/calibrated to operate from 200-220°. However, there is a slight loss of potential WOT power as a caveat.

 

[markmurfie]

A lower temperature thermostat by its self doesn't control the engines temperature. It does set the base temperature of the engine.
With any thermostat that is closed, they should restrict waterflow so that the engine warms up at the exact same rate. Once they start to open, the engine starts to warm up the capacity of the cooling system.
Thermostats have an inital opening temperature and a fully open temperature. You do not want to over work your fans by having them run when the thermostat is not fully open. You can check the actual temperatures for this by using a pot of temperature controlled water and watching the actuation.
Putting in a properly functioning lower temperature thermostat with out a tune, is not going to cause problems, and you might even get a slight benefit from it under certain conditions where cooling isn't fan controlled, but vehicle speed controlled.

The biggest problem with just throwing in an aftermarket thermostat, is you get some brands that do not open half as much as the stock one did. This reduces the over all water flow and thermal efficency of the cooling system and makes the engine run hotter than it should be. There is nothing a tune can do about this, other than something like forcing the engine to run rich, which is not anyones goal. Poorly designed thermostats are why many people on forums push that they are no benefit and could damage your engine. These same people have never put their aftermarket and OEM thermostats in a pot to see how they should adjust their temperatures for proper fan control. Other wise they would have noticed the aftermarket thermostat was not going to do waterflow any favors.

 

[Cory S]

Very happy with my 170° Reische unit. Inferred ECT temps between 179-190°, with Cyl head temps between 189-202°. This is in ambient temps of 55-95°F

Low speed fan is set to come on at 185° cyl head temp. 198° for high speed.

 

[Cobra Jet]

Very happy with my 170° Reische unit. Inferred ECT temps between 179-190°, with Cyl head temps between 189-202°. This is in ambient temps of 55-95°F

Low speed fan is set to come on at 185° cyl head temp. 198° for high speed.

Cory - did you set your fan speeds via Forscan by modifying the As Built or an aftermarket tune has those parameters?

 

[Cory S]

Cory - did you set your tan speeds via Forscan by modifying the As Built or an aftermarket tune has those parameters?

Done in the tuning as requested.

 

[Unas2k5]

I have a Mishimoto 160 and a Lund tune. I bought a new thermostat a Reische 170 I was told would be a good upgrade. Now since I do have a custom tune would I need a new tune for the 170 thermostat? My car is in the 230 + and 250 at idle .

 

[K4fxd]

I have never heard anything but bad results from the 160 Tstat. The reische should lower temps as it supposedly flows the same as the stock Ford unit. I don't think any fan changes will be needed from the 160. No tune revisions are needed except for possible changing the fan settings. I like my fans to kick on about 180-185.

 

[engineermike]

Yep, just fan settings if you want to take full advantage of a tstat.

 

[Unas2k5]

I have never heard anything but bad results from the 160 Tstat. The reische should lower temps as it supposedly flows the same as the stock Ford unit. I don't think any fan changes will be needed from the 160. No tune revisions are needed except for possible changing the fan settings. I like my fans to kick on about 180-185.

Thanks and you’re right about the tune no changes needed because it was already tuned to turn the fans on earlier. Take a look at my new thread. Only one fan is working when I use a scan tool to turn it on the high setting and both fans don’t respond when I turn it onto the low settings. I got some replies about maybe checking relays so that’s where I’m at so basically only one fan was turning on.

 

[Robottrainer]

I have a 170 T stat. My cylinder head temps range from 190 to 205. My ECT's range from 180 to 195. Definitely not too cold.

You can get away without a tune for the fans, but the car will see higher temps in stop and go traffic and stop lights.

I have my fans set to come on 100% at 195.

Just went through this. I had a 170 installed when I bought the car and had the the Roush SC dealer installed. Roush would not change the fan strategy.

What happens is its fine and good while you are moving. it will drop down to 181. without the tune and when stopped idling in the heat it will climb to about 200 at which time the fan will jump to 100% speed.

With the tune the temp will be held to around 190 while idling in the heat, as it will go to 60% at 185 and 100% at 190.

I notice the car is more responsive in the heat. colder engine means a colder intake

 

[Robottrainer]

No shit. You didn’t answer the question. The car comes with a perfectly fine thermostat. Why change it when you already said it will go to 210° at a light.

It wont if you change the fan settings for the cooler T stat. mine hits 190 max. 10 deg is significant.

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