Cylinder Head Temp question.

[mustang1]

GT350 limits RPM until CHT exceed 190F.

Aside from that, with a quick google, we find these :

https://www.cars.com/articles/should-i-worry-about-how-hot-my-engine-is-running-1420680334271/
Should I Worry About How Hot My Engine Is Running?
"The normal operating temperature for most engines is in a range of 195 to 220 degrees Fahrenheit, though most dashboard temperature gauges don't show an exact temperature.


http://www.hotrod.com/articles/engine-oil-temperature/
What Is The Optimum Engine Oil Temperature?
Written by Marlan Davis on August 29, 2013

"For a dual-purpose car, engine oil needs to be at least 220 degrees F to burn off all the deposits and accumulated water vapor. For every pound of fuel burned in an engine, the combustion process also generates a pound of water! If engine sump temperatures rarely exceed 212 degrees (water’s boiling point), the water will mix with sulfur (another combustion by-product) and create acids that can eventually damage bearings

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[Eritas]

Being in S Florida I changed mine to the 170* stat... Head temps went down like 20* which is what I wanted them to, though some say its not needed I feel its a plus.

Computer controlled cars usually will retard timing as temps increase, S Florida is ALWAYS Hot so any little bit of cooling help is welcomed and thus will keep power where it should be. Ford builds their cars to satisfy ALL environments and the perfect balance for them maybe 190* as it helps them achieve the emissions standard they have to meet, doesn't mean that is what is best for performance.

I'm NO engineer but I believe in keeping things simple and being a bit proactive.

L8R

I'm in S. Florida too. Ford Tests in FL, TX, Death Valley, in weather wind tunnels and weather chambers for their calibrations to handle all sorts of weather conditions.

If you have an overheating issue due to ambient conditions or heavy load from track use, the lower thermostat will do NOTHING to improve the cooling ABILITY of your car beyond what the factory dimensions of the radiator and cooling system are.

Lower thermostats won't do crap other than make the average temperature lower when not driving the car hard.

 

[BmacIL]

I'm in S. Florida too. Ford Tests in FL, TX, Death Valley, in weather wind tunnels and weather chambers for their calibrations to handle all sorts of weather conditions.

If you have an overheating issue due to ambient conditions or heavy load from track use, the lower thermostat will do NOTHING to improve the cooling ABILITY of your car beyond what the factory dimensions of the radiator and cooling system are.

Lower thermostats won't do crap other than make the average temperature lower when not driving the car hard.

You're assuming that the stock thermostat is fully open when it hits operating temp. The only reason the lower temp t-stats lower CHTs is because they flow more into the radiator than the stock one does for the same conditions. You're correct that this does not affect max cooling ability of the system under say, road course track use, where coolant temps easily exceed 220 F. A lower temp t-stat will provide some advantage for drag or autocross where you do not have continuous high load, but rather brief spurts of it. It'll also give those who like to do street pulls a little more power (due to the timing advance possible from lower CHTs). If you're overheating, it's not the t-stat, we definitely agree there.

Lower temp t-stats aren't great for daily driven cars in the winter, nor for warm-up emissions (notice I didn't say cold start, where the t-stat is closed), which are the main drivers behind the best compromise that Ford chose.

 

[Dr. Norts]

Ok your right, the stock thermostat is the best and engine temperatures to satisfy emissions are definitely also the best for performance.

/Sarcasm

 

[BmacIL]

Ok your right, the stock thermostat is the best and engine temperatures to satisfy emissions are definitely also the best for performance.

Nope but way to go there with that one...:kickrock:

Producing a saleable car requires compromise. I am not disagreeing that there's a performance benefit to be had...read my whole post next time.

 

[Dr. Norts]

Nope but way to go there with that one...:kickrock:

Producing a saleable car requires compromise. I am not disagreeing that there's a performance benefit to be had...read my whole post next time.

I wasn't replying to what you said.

 

[Eritas]

You're assuming that the stock thermostat is fully open when it hits operating temp. The only reason the lower temp t-stats lower CHTs is because they flow more into the radiator than the stock one does for the same conditions. You're correct that this does not affect max cooling ability of the system under say, road course track use, where coolant temps easily exceed 220 F. A lower temp t-stat will provide some advantage for drag or autocross where you do not have continuous high load, but rather brief spurts of it. It'll also give those who like to do street pulls a little more power (due to the timing advance possible from lower CHTs). If you're overheating, it's not the t-stat, we definitely agree there.

Lower temp t-stats aren't great for daily driven cars in the winter, nor for warm-up emissions (notice I didn't say cold start, where the t-stat is closed), which are the main drivers behind the best compromise that Ford chose.

I never assumed that. But on that note, what is "operating temp"?

What temp is too cold and hurts performance, what temp can you add more timing and get a little more power out of, and what temp starts pulling power?

At best, the lower stat gives you a short period of time before you get to the stock temp -and are no longer at said "advantage". Since there is very little airflow at autoX speeds, I see how a lower stat and cranking the fans on full blast can help keep the car cooler for a run when there not enough air flow for the radiator to work properly when being heavily loaded for the 30-90 sec runs.

 

[BmacIL]

I never assumed that. But on that note, what is "operating temp"?

What temp is too cold and hurts performance, what temp can you add more timing and get a little more power out of, and what temp starts pulling power?

At best, the lower stat gives you a short period of time before you get to the stock temp -and are no longer at said "advantage". Since there is very little airflow at autoX speeds, I see how a lower stat and cranking the fans on full blast can help keep the car cooler for a run when there not enough air flow for the radiator to work properly when being heavily loaded for the 30-90 sec runs.

The point where it's stable (+/- a couple degrees over a time period of say, a minute) for a given set of inputs/torque demand. That can be different depending on a whole variety of things (ambient temp, load demand, airflow, etc) but will generally be in the 190-200 range. Obviously, the only time that kind of thing happens is sustained cruise.

I don't actually know the exact values where the performance is improved or reduced, but it's real. The tune should be adaptive though. The best power is going to come right at the threshold of knock, as higher combustion temps will produce more cylinder pressure (thus, torque), but also produce a lot more NOx emissions from the dissociation reactions at the very hot center of the combustion. This is the reason EGR works to reduce emissions, FYI.

 

[Eritas]

Of course, that's why fir track cars, dump the EGR and use a catch can for PCV & valve covers. Get that oil and exhaust crap out of the intake.

Maybe up north you see 190*CHTs but down in FL I rarely see below 200*F.

What temp do the fans come on? Iirc, it's quite a bit higher than 200* and thus in stop and go traffic, CHTs increase until the fans kick on and bring the temps back down until the fans shut off. And this cycle repeats itself, so there will rarely be a "point where it's stable (+/- a couple degrees over a time period of say, a minute)"

 

[lwnslw]

I'm in S. Florida too. Ford Tests in FL, TX, Death Valley, in weather wind tunnels and weather chambers for their calibrations to handle all sorts of weather conditions.

If you have an overheating issue due to ambient conditions or heavy load from track use, the lower thermostat will do NOTHING to improve the cooling ABILITY of your car beyond what the factory dimensions of the radiator and cooling system are.

Lower thermostats won't do crap other than make the average temperature lower when not driving the car hard.

NO overheating issues....Daily drive her in stop and go traffic all day.
Its a practice I have been doing for years, installing lower temp stats. Operating temps are operating temps, lower stats just open at an earlier temp to get water flowing sooner. I have never had an ill effect from running lower temp stats.

I know everyone has there opinion and I for one enjoy learning from others experiences BUT in the end its all personal preference. The only statement I don't agree with is that "Ford" designed it that way so its best..... These cars benefit from MODS... whether suspension, intake, exhaust, entertainment, seating..etc...etc...

 

[mustang1]

You're assuming that the stock thermostat is fully open when it hits operating temp. The only reason the lower temp t-stats lower CHTs is because they flow more into the radiator than the stock one does for the same conditions.

Is there technical specs that show the flow rate?

And at what point does the stock thermostat fully open? If CHT shows 195F, is the stock thermostat still partially closed ?

 

[Dr. Norts]

Of course, that's why fir track cars, dump the EGR and use a catch can for PCV & valve covers. Get that oil and exhaust crap out of the intake.

Maybe up north you see 190*CHTs but down in FL I rarely see below 200*F.

What temp do the fans come on? Iirc, it's quite a bit higher than 200* and thus in stop and go traffic, CHTs increase until the fans kick on and bring the temps back down until the fans shut off. And this cycle repeats itself, so there will rarely be a "point where it's stable (+/- a couple degrees over a time period of say, a minute)"

My fans come on full at 196 CHT (186 ECT). I'm tuned with a 170 stat so stock or tuned + different stat will be different.

Fans are generally set to come on 15-16 degrees above the rated temperature of your tstat since that's when it's open fully and flowing @ maximum.

 

[BmacIL]

Of course, that's why fir track cars, dump the EGR and use a catch can for PCV & valve covers. Get that oil and exhaust crap out of the intake.

Maybe up north you see 190*CHTs but down in FL I rarely see below 200*F.

What temp do the fans come on? Iirc, it's quite a bit higher than 200* and thus in stop and go traffic, CHTs increase until the fans kick on and bring the temps back down until the fans shut off. And this cycle repeats itself, so there will rarely be a "point where it's stable (+/- a couple degrees over a time period of say, a minute)"

Well I'd argue that you're at the stable point if you've gone into the cyclic on-off of the fans. My example was applicable mainly to highway, as it's keeping variables constant or of very minimal change (let's assume constant speed and relatively flat ground...load will be constant, as will airflow, so heat rejection to the coolant will stabilize). The fan won't be on then either.

 

[BmacIL]

Is there technical specs that show the flow rate?

And at what point does the stock thermostat fully open? If CHT shows 195F, is the stock thermostat still partially closed ?

I'll try and find that, and yes.

 

[mustang1]

I don't think it will be easy to get rid of excess heat with just a 170 t-stat. That probably requires an open grille. And possible a hood mod as well. But daily drivers with an open grille will take a lot longer to get to full operating temps, particularly in winter. So then the car will need active grille shutters. Block until the car is 195F, and then wide open.

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