Ideal temps and fan setpoints?

[CV355]

We finally got our Mach 1 finished, tuned, and on the road.  We had a 180f thermostat installed and a dual Spal electric fan setup.  Both fans can be controlled independently with outputs from the Holley EFI system, so I currently have the on/off setpoints as: 
Fan 1 On:  185
Fan 1 Off:  180
Fan 2 On:  190
Fan 2 Off:  185

The engine seems "happy" around 185-190.  The hottest it has been is 215f when one of the fan harness connectors came loose, shorted, and blew the fuse.  We drove home 7 miles without a fan, not a single drop in the puke tank.  I made an all new fan harness with dual fuses and 6ga primary feed, so that problem should never happen again.  Even with that, at 215 it was running beautifully, oil pressure strong even at hot idle.

I'm averaging about 8-9mpg so far which seems decent for what it is.  484ci with the Procharger F1D.

What's the consensus on operating temps?  Where do you like to see them, and what would you recommend for fan setpoints?

[jayb]

I had the fan temps on my supercharged FE turn on at 180 and turn off at 170.  I figure the cooler temps help keep the engine out of detonation, and also further away from an overheating situation if something goes wrong, both of which are more of a concern with a blower motor than they would be with a naturally aspirated motor - Jay

[CV355]

I had the fan temps on my supercharged FE turn on at 180 and turn off at 170.  I figure the cooler temps help keep the engine out of detonation, and also further away from an overheating situation if something goes wrong, both of which are more of a concern with a blower motor than they would be with a naturally aspirated motor - Jay

Makes sense to me.  What temp thermostat did you run with those setpoints? 

[cleandan]

The ideal temp range depends on your engines use and projected time between rebuilds.
For the vast majority of street engines, performance or not, a range between 185-210 is a great place to be.

We often get misdirected a tiny bit, concerning engine temps, by what drag racers try to accomplish.
They almost always seem to be running as "cool as possible", often in the 156-160 range.
What we forget is they are working towards consistency for each run, not long term engine operation as the drive across town, or the state.

They stage at 150, and by the time they are done with that run they are in the 190-210 range....where they go back to the pits and wait for the next round.
If they happen to go back to back rounds you will see all sorts of methods used to coll the engine between rounds, so going as far as to have dump valave installed to dump the hot water and install cool water.

This, accidentally, leads to some thinking 160 is a good temp because that guy runs fast and consistent.

There is also a big difference between overheating, running warmer than "normal", and controlling the temps.

When you overheat it means the cooling system was not capable of controlling the heat the engine is producing for the duty cycles being asked of the engine.

When you run warmer than normal, but don't overheat, it usually means you are running in high ambient temp conditions (100*F summer drive), low airflow conditions (stuck in traffic) highly loaded conditions (towing at max capacity or autocrossing) or maybe you just had a brief short stop (getting gas or short shopping stop)
None of these "high" temps really matter as long as they are controlled and the temps either come back down, or stabilize at a slightly higher than normal temp.

When you run too cool your engine does not come to full temp, which causes tolerances to be off, oil to retain moisture, and if the engine is computer monitored it can lead to tune issues because the engine thinks it is still "cold".

185*F is a great T-stat temp to run for most engines, and 195* is a close second depending on climate and use.

Mostly though, build your cooling system so it can control the temp wherever you decide to set the T-stat because temp control is the main concern.

[Cyclone03]

I look at it a bit backward,I want the fan off going down the road. TStat 185,off temp 190 on 195,fan 1. Fan 2 On 200 off 205. Fans run off a trianarry switch with AC on so fans only come on when high side pressure is high.

[CV355]

The ideal temp range depends on your engines use and projected time between rebuilds.
For the vast majority of street engines, performance or not, a range between 185-210 is a great place to be.

We often get misdirected a tiny bit, concerning engine temps, by what drag racers try to accomplish.
They almost always seem to be running as "cool as possible", often in the 156-160 range.
What we forget is they are working towards consistency for each run, not long term engine operation as the drive across town, or the state.

They stage at 150, and by the time they are done with that run they are in the 190-210 range....where they go back to the pits and wait for the next round.
If they happen to go back to back rounds you will see all sorts of methods used to coll the engine between rounds, so going as far as to have dump valave installed to dump the hot water and install cool water.

This, accidentally, leads to some thinking 160 is a good temp because that guy runs fast and consistent.

There is also a big difference between overheating, running warmer than "normal", and controlling the temps.

When you overheat it means the cooling system was not capable of controlling the heat the engine is producing for the duty cycles being asked of the engine.

When you run warmer than normal, but don't overheat, it usually means you are running in high ambient temp conditions (100*F summer drive), low airflow conditions (stuck in traffic) highly loaded conditions (towing at max capacity or autocrossing) or maybe you just had a brief short stop (getting gas or short shopping stop)
None of these "high" temps really matter as long as they are controlled and the temps either come back down, or stabilize at a slightly higher than normal temp.

When you run too cool your engine does not come to full temp, which causes tolerances to be off, oil to retain moisture, and if the engine is computer monitored it can lead to tune issues because the engine thinks it is still "cold".

185*F is a great T-stat temp to run for most engines, and 195* is a close second depending on climate and use.

Mostly though, build your cooling system so it can control the temp wherever you decide to set the T-stat because temp control is the main concern.

Good info, you sort of touched on a point I was going to bring up earlier.  About 20 years ago, I was on a small local Mustang forum and everyone was pushing 160 thermostats except for the one resident engine builder who was laughing at that approach for the exact reasons you listed.  I've always had "180 is fine" in my mind, but I've had some engines that liked to live around 220-230.   

As for my intended use- literally just cruising around town comfortably and reliably.  That's all I intend on using this car for.  I installed an oversized aluminum radiator with a dual Spal fan setup and shroud.  On a full day on the dyno, it never went a degree above 180.  On the street with the fans set up the way they are, it's at 182-185 reliably.  I never saw the 2nd fan kick on until I was stuck in a line of cars at a stop sign, but temps came down quick. 

I live in SC, so it does get hot...  Not AZ or FL hot, but still toasty.

[jayb]

I like to run a 160 degree thermostat.  This puts the engine at 160 on the highway, assuming the radiator is up to the drill.  Around town, it will cycle between 170 and 180 with the electric fans turning on and off.  Cooler water temps mean more power, because the intake charge isn't heated up as much in the intake manifold.  Now, if I was expecting to get 100,000 miles out of my engines, I'd probably run a 195 thermostat.  But even over many years, its unusual to have even 15,000 miles on one of my engines, before I pull it out to rebuild and change a few things.  So the extra longevity from running a higher temp is not something I care about.

[Rory428]

Have to agree with Jay, I run 160 Tstats on my "hot rod" type cars, and older vehicles. I would rather have my engine running 160-175 most of the time, as if I do get stuck in a traffic jam on a hot day, I have to believe having 30-40 degrees of safety margin before boiling over is preferable to only having 10 or 15 degrees of "wiggle room". And drag racers, especially Stock and Super Stock racers run their engines much cooler than CV355 mentioned. Pretty rare to see a Stocker or S/S car staging with over 120 on the temp gauge, in fact, many of the faster guys has "chillers" which pump ice water thru the cooling system in the pits or staging lanes, often stage at 60-80 degrees F, especially if there is a heads up race, or attempting to set a record, or improve on a qualifying position.
Concerning engine wear, in 1990, I did a ball hone quickie rebuild , with new rings on the factory installed standard pistons on my 1975 390 PU engine. Yes, It had a 160 thermostat, and that is where it normally ran, other than in hot (100+) air temps. I drove that truck until I sold it to another racer in 2014, who is still using it to haul his race car. So, if a standard bore 390 from 1975, is still running fine, and uses no oil between changes, after 33 years since the low buck rebuild, and the bores and pistons have been in service for over 45 years, I have to say that if this supposed "premature" engine wear hasn`t happened yet, when should it be a concern?

[CV355]

I like to run a 160 degree thermostat.  This puts the engine at 160 on the highway, assuming the radiator is up to the drill.  Around town, it will cycle between 170 and 180 with the electric fans turning on and off.  Cooler water temps mean more power, because the intake charge isn't heated up as much in the intake manifold.  Now, if I was expecting to get 100,000 miles out of my engines, I'd probably run a 195 thermostat.  But even over many years, its unusual to have even 15,000 miles on one of my engines, before I pull it out to rebuild and change a few things.  So the extra longevity from running a higher temp is not something I care about.

That's why most of the guys were running 160s, but they had quite different builds.  The engine builder was laughing at most of the guys doing it on daily driven stock or mildly modified mod motors.  I think I was running a 180 for a while until we finished the turbo 5.4 build, and then switched to 160 because it was mainly strip oriented.

For my FE build, I'd love to say it'll last 100k miles with the way I drive, but the likelihood of putting even 2000 miles on it in a year is low.  100k would happen long after my life expectancy... 



 

[CV355]

Have to agree with Jay, I run 160 Tstats on my "hot rod" type cars, and older vehicles. I would rather have my engine running 160-175 most of the time, as if I do get stuck in a traffic jam on a hot day, I have to believe having 30-40 degrees of safety margin before boiling over is preferable to only having 10 or 15 degrees of "wiggle room". And drag racers, especially Stock and Super Stock racers run their engines much cooler than CV355 mentioned. Pretty rare to see a Stocker or S/S car staging with over 120 on the temp gauge, in fact, many of the faster guys has "chillers" which pump ice water thru the cooling system in the pits or staging lanes, often stage at 60-80 degrees F, especially if there is a heads up race, or attempting to set a record, or improve on a qualifying position.
Concerning engine wear, in 1990, I did a ball hone quickie rebuild , with new rings on the factory installed standard pistons on my 1975 390 PU engine. Yes, It had a 160 thermostat, and that is where it normally ran, other than in hot (100+) air temps. I drove that truck until I sold it to another racer in 2014, who is still using it to haul his race car. So, if a standard bore 390 from 1975, is still running fine, and uses no oil between changes, after 33 years since the low buck rebuild, and the bores and pistons have been in service for over 45 years, I have to say that if this supposed "premature" engine wear hasn`t happened yet, when should it be a concern?

You guys are slowly convincing me to abandon my old way of thinking...    I may split the difference and run a 170...  But I'll test out a few more rides.  Went for about 15 miles last night and the temps never left 180-185 once it warmed up.

I can guarantee I'll get stuck in traffic around here.  We live in a very rural "Mayberry-like" town surrounded by suburbs and a city 25 miles down the road.  Lots of light gridlock at certain times.  I'd rather be safe than sorry.

[Jb427]

i run a 160 when do you hear of an engine having to be rebuilt because it was running too cool

[CV355]

i run a 160 when do you hear of an engine having to be rebuilt because it was running too cool

I am going on a 60 mile drive tomorrow in 90f weather, so I'll get to see if the 180 holds up.  The radiator and fan combo seems to be fine, and I'll use Jay's setpoints for on/off so the fans are constantly on.

[mbrunson427]

I saw you had a little trouble with your wiring..... I just used one of these MSD solid state relay deals on my Galaxie and it worked out great so I figured I'd share.

holley.com/products/electrical/wiring_and_relays/parts/75643

Being that you have a Sniper, you can wire the fan wires straight to the ground input side of this relay module.

On my galaxie I used this for fuel pump, gauge lighting, and overdrive. Have one spare terminal now I'm thinking about using for an electric fan.

[Phil Brown]

I was always told that the higher temp thermostats and running temps were for emissions reasons and an effort to increase gas mileage. The automakers did start using them it the mid 70's when all of the emissions stuff started getting crazy.
For me, the old stuff gets 160°, newer whatever lets the computer think that it's warmed up

[fryedaddy]

heres a good point for the 160 guys,ethanol fuels boil in the carb at high temps,and we all know what that causes.i could see it boiling through the sight holes on the side of the carb.thats why i keep mine cool,plus it runs better,win win