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Joined: Aug 2001
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Originally posted by liquidX:
Originally posted by DemonSVT:
For every 10 degrees cooler the engine runs it requires 1 less octane point. (I.E. more boost, timing, etc per octane from pump gas)
You wonder why I could run my race program until the mean heat of summer...  Well besides good tuning 
Even now I switch to it if I'm driving at night.
What difference is that on a stock or mail order chip car. Not much if any.
For ref
Stock t-stat starts to open at 190-192.
Stock fans are 216/224. 
BTW, Tom, thanks for the corrective and informational post. Who needs a car forum when they have friends like you?
Okay so let me get this straight. Right now my SCT tune and program has my main cooling fan coming on at 200F, and shutting off at 180F. I will need a 180F thermostat in order for the dF to be compliant both from the fan and the thermostat in synchro correct? Stock is 192/195 at Autozone, and the Mustang one I have in the box here is 160f, but they also provide a 180f one as well. 3 Choices, and I need to pick one by Friday. Thanks guys...
XL
Not exactly.
Stock runs like 225 turn on and 210 turn off or something like that. The ultimate temp you can go without coolant boilover is determined by the cap. THe higher it can get the better it sheds heat but the more pressure....yada yada.
You already have it then go ahead and run it. It isn't going to change much unless you are in a cool climate already.
Having the fans come on at 200F is no big deal either other than you don't use the cooling system to its max potential due to the whole heat transfer thing. I would use a 220-200 range myself.
Again, the t-stat will be the minimum operating temperature for your engine. The engine will run warmer most of the time except cold start and highway cruise with cool ambient temps.
This is the only reason I give credence to what Demon was just saying. It may allow him a little more timing under certain conditions but only when the engine temp is lower than 180 and that doesn't happen too often. For the most part I think it is a placebo and that it was more likely his combustion chamber prep and his tuning that allowed the better timing numbers.
So if I didn't already say it, you will be fine with the setup you are going to except in the afore mentioned initial startup, cold start/cold temp emissions and with the lower fan turn on temp and the slightly slower rate of cooling associated with it.
Just remember that your cooling fans will be running all the time now except in very cool weather and you may end up having to replace them due to the reduced longevity.
Don't you ever wonder why they put higher pressure radiator systems in cars? THey have been raising the pressure on radiator systems consistenly for almost 100 years as engines advanced. THey are now up to 20lbs pressure wheras 30 years ago they ran 6-10lbs.
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
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Tom is correct. In the winter, when I rarely drive my car, it does run cooler, and also on the e-way, but in traffic it is NO different
2000 SVT Turbo 295hp/269ftlb@12psi
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Knuckles rebuilt w/new bearings $55
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Well, stock thermo's are 225/220, but the Advanced Auto Parts replacement is 195/192. I guess the 20 degree difference would help a little since down here we just don't get a breakaway from heat & humidity levels during the summer. The thermo is still in the box unused so it's far from unreturnable. I just think I am going to go back to my more efficient 210/200 cooling fan operating temp (you're right, the thing never turns off) from the first SCT tune, and get the 192/195 AAP replacement thermostat, that way reducing operating temperatures while still retaining most of the cooling system's efficiency.
Very informative posts guys, it's a pleasure to receive advice from 3 of the biggest masterminds of this forum: Stazi, Greg, and Tom. Many thanks guys, this thread is definitely going down in the search books to help many a CEGer to come.
XL
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If you want to improve cooling, get yourself a bottle of Water Wetter from Autozone and add that to the coolant - yes it does work.
2000 SVT Turbo 295hp/269ftlb@12psi
#1 for Bendix Brakes Kits!
Knuckles rebuilt w/new bearings $55
AUSSIE ENDLINKS $70
Gutted pre-cats $80/set
A lack of planning on your part does not constitute an emergency on mine!
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My cars been running Water Weter for several years and I just flushed my coolant and added it in with the new once again. You can tell it works, my car runs at ALL times in the "N" area of the guage. It has never budged in these last many years, no matter how many traffic jam crawls or highway cruises, or city driving with A/C on I do. Take that thermo back, keep the stock one til it dies, and add some Redline Water Weter (~$5.50).
If you haven't flushed the coolant.. get it done NOW because that Miami heat will play a toll on your cooling system. (I beleive you said you DID have it done). You will basically want to remove the amount of coolant you add in with the water wetter (not much, maybe 2 ounces) so that you keep the dilusion that redline suggests.
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Not trying to start a flame war here but you are only partially correct in your statement. True Q = kA (Ti-To) which describes the conductivity of the radiator. However the heat removed from the system through the coolant is Q = k * mass flow rate of coolant * temp. change of coolant (Q = km(Ti-To)
The t-stat reduces the mass flow of coolant which increases the temp of the system (the energy into the system remains unchanged; therefore if the mass flow rate decreases the temp differential must increase); this is what keeps the temp up when little heat is added to the system. If you remove the t-stat and compare coolant temps (same ambient conditions, some vehicle speed) of the same vehicle running w/o a t-stat will give you lower temps. The heat into the system is unchanged (comparing with and w/o a t-stat) yet the temps are different. It is just a balancing act between the difference in coolant mass flow rates and the coolant temperature.
Example - While on the highway with my 165F t-stat my coolant temp runs at 165F. The power required to move the car at highway speed (65 MPH) is fairly small (I'm guessing maybe 20-30 Hp). With the t-stat removed I run about 150F on a summer day. However in an application where much higher Hp is used (i.e. more heat into the system), such as on track, my coolant temperature is much greater than 165F (near 200F).
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Kinda curios as to why the rate of coolant cooling is even considered. The thermostat will cycle just as the fans do, and will keep the temps regulated to an overall lower temp. The amount of heat transfered has little to nothing to do with it the way I see things. The overall idea is to control the level of heat in the motor. So long as the rate of heat transfer from the coolant/radiator to the air, is HIGHER than the rate of transfer from the motor to the coolant, then the coolant temps will drop with a new thermostat. In any decently designed cooling setup, the radiator will be able to dump more heat than the motor can produce (assuming XXXcfm airflow). In traffic, I can see the temps being regulated by the fans, as that is the airflow regulator. On the highway, or about anywhere constant over 35mph or so, the thermostat will be the controlling factor.
So the way I see things, to get the best use of the thermostat you need to alter the fan settings as well. However assuming some movement, I can't possibly see how the 160 is in any way a waste.
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Quote:
So the way I see things, to get the best use of the thermostat you need to alter the fan settings as well. However assuming some movement, I can't possibly see how the 160 is in any way a waste.
I agree 100%
Quote:
So long as the rate of heat transfer from the coolant/radiator to the air, is HIGHER than the rate of transfer from the motor to the coolant, then the coolant temps will drop with a new thermostat.
True indeed
Quote:
Kinda curios as to why the rate of coolant cooling is even considered. The thermostat will cycle just as the fans do, and will keep the temps regulated to an overall lower temp. The amount of heat transfered has little to nothing to do with it the way I see things. The overall idea is to control the level of heat in the motor.
Here is where you err, Grasshopper. The heat into the system is everything. The t-stat does not cycle as you think. Once it is full open it has no effect on cooling (other than it is a flow restriction). Its function is to limit the minimum coolant temp, not the max. Once you are past full open (assuming you are applying high Hp) now you are at the mercy of the efficiency of the radiator, ambient air temp, vehicle speed, and mass flow rate of the coolant (or engine speed). When you are not adding much heat to the engine (such as highway driving) then your coolant temp will run at the t-stat setting (assuming a clean radiator). Remember Qin = km(Ti-To). (Ti-To) is basically fixed by the t-stat temp and ambient air temp. The only way to vary the heat is to alter the mass flow rate of the coolant (remember heat is a function of the fluid, mass of the fluid, and temperature). Once Qin is greater than that which the radiator can exchange (the equilibrium temp between the t-stat, radiator, and heat in) the temp. will begin to rise assuming constant coolant and air mass flow rates and ambient air temp.
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Originally posted by liquidX:
Well, stock thermo's are 225/220, but the Advanced Auto Parts replacement is 195/192.
Tom meant the stock fans.
Also they come on at 216/224 like I stated in my post.
The stock t-stat starts to open at 190-192.
A 180 t-stat start to open around 180-184.
A 160 starts to open around 160-163.
A t-stat only controls the minimum temperature when that temperature can be sustained by ambient temperature and the efficiency of the engine's cooling system. (coolant mix, radiator, fans, w/p)
In my setup I run 70% water / 30% Zerex OAT with water wetter, fans on at 186/196, SVT radiator, revised w/p, and 160 t-stat. Normal operating temp is 175-185.
It's rare the primary fan kicks on unless I am in bumper to bumper traffic in hot weather.
2000 SVT #674
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Wish I could get mine to run that cool all the time. Track day - 210F easy.
'98 SVT Red/midnight blue - a few mods
E0 wheels for sale - PM me
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