The Big Fat Track Car Cooling Thread

[TX-2019-Black_GT]

It has to be. By the time coolant gets to 245*, something has already destroyed itself.

I'm not sure that's right. Most cars used to have 12 to maybe 16 psi radiator caps, and the boiling point of pure water is about 250F at 15 psig. With antifreeze, it's higher. These Mustangs have a 21 psig max pressure, which brings plain water BP up to 275F. As long as the coolant is not boiling, it remains effective. I don't think they would use such a high pressure relief if operating at those temps was a problem.

Keeping the oil below 280F is important, and power is limited above that temperature to protect the engine. So 230-250 coolant temp sounds fine to me.

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[fatbillybob]

boiling point of pure water is about 250F at 15 psig.

Keeping the oil below 280F is important, and power is limited

So 230-250 coolant temp sounds fine to me.

This is a track forum so pure water (with water wetter) is what should be used because antifreeze is slippery when spilled on track.

Your theory is sound but not in practice. Temp at the sensor is lower than at the cylinder wall. If you get microbubbling at the walls AKA cavitation you will suffer liner damage. We see that in high compression diesel motors and rarely on gas motors but it does happen. When it does happen in gas motors it is with extremes of operation. I don't want to see any coolant temp >230F because I know it is hotter elsewhere and will boil then cavitate. You also do not want 215 coolant with 280 oil. Radiator.cooler need to be sized complementary so you might have 215 coolant with 240 oil. This way your motor has better survival.

 

[TeeLew]

I'm not sure that's right.

I am. Find me a racecar that runs engine temp over 100*C and we'll talk. Most run between 80-90*C. By the time you get over 105*, you're way down on power.

 

[Flyhalf]

This is a track forum so pure water (with water wetter) is what should be used because antifreeze is slippery when spilled on track.

Your theory is sound but not in practice. Temp at the sensor is lower than at the cylinder wall. If you get microbubbling at the walls AKA cavitation you will suffer liner damage. We see that in high compression diesel motors and rarely on gas motors but it does happen. When it does happen in gas motors it is with extremes of operation. I don't want to see any coolant temp >230F because I know it is hotter elsewhere and will boil then cavitate. You also do not want 215 coolant with 280 oil. Radiator.cooler need to be sized complementary so you might have 215 coolant with 240 oil. This way your motor has better survival.

Unfprtunately our engine especially gen 3 works very hot.
Couple of consideration.
1. We measure CHT. So 235 cht is probably less in water temp ( wich i think is calculated also. )
2. I have a real gauge and the temp are a little...off in the green /yellow %red calculated one. With a eal cooler theynwill be lower but not much.
Our cars runs betweem 240-280f for oil temp. That is why is fundamental having the right oil on track (mobil ow40 is a great compromise for price /quality).also with some friction reducer (i use motorkote since the beginning of my race car journey) .helps tomreduce wearing and friction (=heat)

3. Main issue for 2018+ are the absence of the side pockets where to put coolers.
So in case of additional coolers we will trasmit heat from the coolers to the radiator. A downward spiral.
4. Agreed 100% l.pure water (or 90% at least) and water wetter. Safe for the other drivers and cooler than the mix)
5. Boxing/ducting is the most effective thing to reduce temps. (Better if with hood vents. )

Unfortunately our cars are PERF PACK cars..not track pack.
Ford waited 7 years to "understand" or better listen to the track guys saying do like the SS 1LE and put coolers.
Now they are saying the "mach1 is most capable 5.0 on the track!" What did they do? Put coolers (really?) And the 350 brakes (really?!?)
I wonder how they will keep the A10 to work on travk..im at my 3rd.
Alex

 

[TX-2019-Black_GT]

This is a track forum so pure water (with water wetter) is what should be used because antifreeze is slippery when spilled on track.

Your theory is sound but not in practice. Temp at the sensor is lower than at the cylinder wall. If you get microbubbling at the walls AKA cavitation you will suffer liner damage. We see that in high compression diesel motors and rarely on gas motors but it does happen. When it does happen in gas motors it is with extremes of operation. I don't want to see any coolant temp >230F because I know it is hotter elsewhere and will boil then cavitate. You also do not want 215 coolant with 280 oil. Radiator.cooler need to be sized complementary so you might have 215 coolant with 240 oil. This way your motor has better survival.

Yeah, you're right. I posted before finishing my homework, or thinking it through completely, plus I later saw the ECT vs. RPM limit tables and they do kick in above 240? (from memory).
I wasn't suggesting 280 oil and high coolant temps were GOOD, but I did think what TeeLaw said, "By the time coolant gets to 245*, something has already destroyed itself." was a slight exaggeration. Maybe not, at least not is those temps are frequent and for a lengthy time.

 

[TX-2019-Black_GT]

I am. Find me a racecar that runs engine temp over 100*C and we'll talk. Most run between 80-90*C. By the time you get over 105*, you're way down on power.

OK, so I admit I was guessing out loud, I really don't know what coolant or head temps are 'best' for these engines on 30 min track sessions, both with respect to engine durability and power production. I know if the temps are higher, then power loss will occur because things like ignition timing need to be retarded to prevent detonation. Turbos and superchargers would have to cut the boost too. IAT affects this also. And there are other factors....

So, I did a quick Google, and this made me laugh!
"The temperature inside a NASCAR V-8 engine can reach 2000 degrees Fahrenheit and the pressure can reach 1500 psi, or more than 100 times the normal air pressure we feel around us every day."
So there's your racecar engine over 100C!

Now a more serious note: apparently, plenty of racecar engines run at well over 100C. From a 2012 story - In NASCAR, up to 240 is OK / normal, but they can run at 245 up to 260-265: https://www.autosport.com/nascar/news/99367/temperatures-a-concern-at-talladega

And this interesting article (May 2019) quotes Stephen Papadakis stating that NASCAR engines run around 290F. (this appears to contradict the info in the previous linked article, but note the dates - new technology now vs 2012)
https://jalopnik.com/the-fascinating-reason-why-nascar-engines-run-so-hot-1835071544

I know, we are not driving NASCAR cars or engines, and I realize not much of the linked articles relates to us, but you asked me to show you a racecar that runs over 100C.

The 2nd linked story includes a cool YouTube about NASCAR Tech that's worth a look. The first 90 seconds talks about engine temps and cooling. Spoiler - 75 psi cooling system.

 

[TeeLew]

You're talking about highly unusual conditions. A Cup car qualifying where the nose is all taped up for aerodynamics is not typical of their racing life.

But, by all means, run the F'in thing at 500 degrees for all I care.

 

[Flyhalf]

I 've missed somenthing.
Where do you guys see the coolant temp in gen 3 mustang?

 

[fatbillybob]

I am. Find me a racecar that runs engine temp over 100*C and we'll talk. Most run between 80-90*C. By the time you get over 105*, you're way down on power.

?? 100c is just 212F. Engines are over that all day long.

 

[fatbillybob]

Unfprtunately our engine especially gen 3 works very hot.
Couple of consideration.
1. We measure CHT
Alex

here is something to consider...After reading this stuff I cannot figure out to any numbers coming off my dash are true. I know any gauge I buy is also not calibrated or certified so you cannot rely on those numbers either. We also have no operational temps from the factory to my knowledge. We also have none from the factory race cars fp350s using same motor. So sounds to me like we are all guessing.

what I know is even with giant coolers of oil and A10 I cannot over cool the system so I’m just going for it. We will see how long the motor And A10 lasts.

 

[TeeLew]

?? 100c is just 212F. Engines are over that all day long.

Not if you're racing, you're not.

Here's some information of which I'm certain. When Yates was building a 5.0L Ford V-8 for Daytona Prototypes (DOHC), they ran at 90*C. When Aston Martin ran a Ford V8 (a 281, Huffacker built in US) in GT4, it ran at ~83*C. When a Mazda-badged, naturally aspirated version of the EcoBoost engine was used in IMSA Lites (for over a decade, Elan as the engine builder), it's operating temp was ~85*C. Presently, an unbadged, naturally aspirated version of the EcoBoost engine (Elite as engine builder) is used in the IndyCar Indy Pro Series. It's operating temp is 82*C. Do we all see the trend here?

Now, by all means, run your engine at whatever temp you want to run...IDGAF. However, unless you know more about your specific engine than the people above, their numbers are probably a smart place to start. The problem with this information has nothing to do with it's validity. It has to do with the fact that no one wants to hear what I have to say or to do the work necessary to keep their car cool.

 

[TeeLew]

I 've missed somenthing.
Where do you guys see the coolant temp in gen 3 mustang?

We think we're seeing it on the OBDII.

 

[fatbillybob]

Not if you're racing, you're not.

Here's some information of which I'm certain. When Yates was building a 5.0L Ford V-8 for Daytona Prototypes (DOHC), they ran at 90*C. When Aston Martin ran a Ford V8 (a 281, Huffacker built in US) in GT4, it ran at ~83*C. When a Mazda-badged, naturally aspirated version of the EcoBoost engine was used in IMSA Lites (for over a decade, Elan as the engine builder), it's operating temp was ~85*C. Presently, an unbadged, naturally aspirated version of the EcoBoost engine (Elite as engine builder) is used in the IndyCar Indy Pro Series. It's operating temp is 82*C. Do we all see the trend here?

Now, by all means, run your engine at whatever temp you want to run...IDGAF. However, unless you know more about your specific engine than the people above, their numbers are probably a smart place to start. The problem with this information has nothing to do with it's validity. It has to do with the fact that no one wants to hear what I have to say or to do the work necessary to keep their car cool.

many street tstats kick in at around 180f about 82c? engine cumbustion temp is at the cylinder or oil temp is then way higher. Any racer will see easy 240f and higher oil temps on our converted street cars. In fact if we can keep oil under 250f we are quite happy. We ran our vettes as a group in the 240-280f oil temps all day long. We were no where close to the 215f or so we see with street driven vettes. I don't have enough time in the s550 with the lying temp guages to know what they run at but I suspect the oil in 240-280f range Ideally on track.

 

[Flyhalf]

We think we're seeing it on the OBDII.

I know for sure that is also calculated. There is not a real coolant temp sensor.

 

[TeeLew]

Oil and water temps are different topics. Let's not confuse the two. Previously, I was speaking only of water temperatures. Now it seems on the Eco's oil temperature is this 'inferred' hand-waving type thing which takes X, Y & Z into account and then guesses at oil temp. If that guess is over 280*F, then it pulls a bunch of power. Cool the oil all you want, it will still infer it's hotter than reality and pull power. Because of this, we _have_ to get water temp under control. Anything north of 100*C on-track is not controlled enough, IMO.

Modern synthetic oil can be pretty damned hot and still maintain film strength and lubricating qualities. Our issues with oil temp is actually more a product of the engines. With AL blocks and a steel crank, you have a difference in thermal expansion. As the temps climb and these blocks expand, the bearing journals allow more and more clearance which lets the oil leak out and reduces oil pressure. Sooner or later, you don't have enough oil to keep the crank floating and the journal touches the bearing. Do that enough and you'll spin the bearing for sure. Now, yes, racing engines can often run crazy high oil temps, in the range of 300+ degrees F in extreme situations. Can we?

Not really. These engines running super high oil temps are warmed to ~60*C prior to starting. This warming allows the block to expand and provide bearing clearance prior to even idling. We can hit the starter on our cars at -40*. It might protest a bit, but it will start up an not hurt a bearing. If you tried that with one of these racing engines, the starter wouldn't be able to turn the engine over, because the bearings would be clamped solid on the crank. If you did fire the thing, you'd spin the bearings immediately.

I don't doubt you've ran oil at 240-280*F consistently. Yes, that's hot, but it's still in the realm of reasonable. I think you're better off keeping it a bit lower (220-240*F), but that's not crazy. It's not hot enough to radically degrade the oil or effect the operation of the engine, so you're pretty much good to go. I would change the oil when I got home, just because it lived a rough life.

Water is not the same story. When you get the water as hot as is being reported, you're much more likely to get localized pockets of boiling around the combustion chambers which will cause all sorts of detonation and pre-ignition. This problem is in addition to the thermal expansion problem mentioned earlier. The ECU should be able to back out the timing and/or reduce boost to keep things in one piece, but you'll be giving away a ton of power. That Cup engine that ran so hot also has a high pressure water system. Wonder why? It's damn tough to get localized boiling when you're running that much pressure in the system. Don't think you can just stick a big pressure rad cap on your car (you can probably add a cap up to 25 psi safely). They're running radiators that cost $10-15k which are build to hold those pressures. Trying that with a standard rad core would balloon the tubes and close off all the airflow.

I'm really confused as to why I'm getting such push-back on the subject of temperatures. I know it's not the answer that everyone wants (i.e. It's just fine), but it's not. In the same way stock brakes or suspension settings are not suitable for the track, neither is the cooling system. There will be places where it's tough to keep the car cool. If you're in a desert with 100*+F ambients, it will be tough. The track in Utah is particularly difficult, because it's in a desert *and* at altitude (thin air). It's a whole lot easier if you're running in Mid-Ohio in the spring or Brainerd in the fall, but those aren't the norm. If you're going to be hitting the track, you have to make some serious upgrades to the cooling system.

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