Track Time Limited due to High CHT

[GTP]

https://www.motorsportandperformance.com/blogs/blog/mustang-gt-oil-cooler-failure

For last time the OEM oil cooler has a very thin aluminium plate between the oil and the coolant that because of heat have a tendency to break. And as we know mixing oil and coolant is not great idea for any motor. So if you can get rid of that thing better do it.

Thanks for that link. I read it. I'm still listening and learning.
I suppose I could start with the sandwich plate over the OEM cooler for my next track day. Then remove the OEM cooler if it has not improved sufficiently. But then I would likely need a larger cooler than I would have purchased originally. You know?

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[NeverSatisfied]

Thanks for that link. I read it. I'm still listening and learning.
I suppose I could start with the sandwich plate over the OEM cooler for my next track day. Then remove the OEM cooler if it has not improved sufficiently. But then I would likely need a larger cooler than I would have purchased originally. You know?

I'd strongly consider getting all the oem stuff out of there and out of the way. Jam a 948 in front of the condenser and Then move on to trying to figure out how to get your A10 to stay cool.

 

[Scootsmcgreggor]

I'd strongly consider getting all the oem stuff out of there and out of the way. Jam a 948 in front of the condenser and Then move on to trying to figure out how to get your A10 to stay cool.

This.

 

[TeeLew]

I get what you are saying.

What I learned in heat transfer class is that heat flow is a slow process but it always flows from the higher temperature to the lower one.

So yes, the heat flow is from the oil to the water, and that heated water gets cooled back down by the radiator, when the heat flows from the hot water to the cooler air.

Let's not forget that water has a much higher heat capacity, and specific heat, than air, meaning it takes more energy to heat water than it does to heat air. Water has a specific heat of 4.186 J/g degreesC, versus air, which has a specific heat of 1.005 J/g degreesC.

The question is how much extra load is the OEM oil cooler on the coolant system? If it is not all that much compared to the engine, then I will try it with the OEM oil cooler and install an auxiliary aftermarket oil cooler. Still deciding which one, where to mount, etc.

You're going down the right road here.

We get the biggest bang for our cooling real-estate buck on the water side. You want to pull as much heat out of the water as possible. As you do, you'll also pull heat out of the oil, because we're talking about global heat rejection, not just water or just oil. The truth is, we run way too hot on both of them. We tend to react to the oil temperature because that's what throws the car into limp mode first, but, by that point, the car is already well over-heated on water & oil.

A Ford mod/Coyote V8 (Eco's are very similar) should run about 185* for optimum coolant temp and about 210-220* for optimum oil temp. Once you take these numbers into account, you start to see we're about 50+* too hot on oil and 35+* too hot on water. A big oil cooler is a nice start to *a* solution, but it is not *the* solution.

Another thing to take into account is stacking heat-exchangers. For the most part, this is a really bad practice. It's bad because you end up feeding the trailing cooler hot air, but it's biggest issue is what you point out concerning cooling air in general. Air doesn't have much heat capacity, so we need a lot of it. When we start stacking coolers, we end up restricting the air to *both* heat-exchangers in the stack. Because of this, we end up with both being oversized, inefficient coolers. We're much better off to get a little more clever with our air routing and keeping coolers single stacked.

 

[Scootsmcgreggor]

My biggest concern with putting the oil cooler outboard of the frame rails is damage in a minor off that could starve and kill the engine. I really wanted to put my oil cooler forward of one of the wheel wells but this concern for damage and the fact that I’d need to downsize and run one in each corner to get enough cooling capacity steered me away from doing so. Running two oil coolers also increases pressure drop from all the extra lines and fittings. But indeed if you can avoid stacking coolers that is by far the best option.

 

[GTP]

You're going down the right road here.

We get the biggest bang for our cooling real-estate buck on the water side. You want to pull as much heat out of the water as possible. As you do, you'll also pull heat out of the oil, because we're talking about global heat rejection, not just water or just oil. The truth is, we run way too hot on both of them. We tend to react to the oil temperature because that's what throws the car into limp mode first, but, by that point, the car is already well over-heated on water & oil.

A Ford mod/Coyote V8 (Eco's are very similar) should run about 185* for optimum coolant temp and about 210-220* for optimum oil temp. Once you take these numbers into account, you start to see we're about 50+* too hot on oil and 35+* too hot on water. A big oil cooler is a nice start to *a* solution, but it is not *the* solution.

Another thing to take into account is stacking heat-exchangers. For the most part, this is a really bad practice. It's bad because you end up feeding the trailing cooler hot air, but it's biggest issue is what you point out concerning cooling air in general. Air doesn't have much heat capacity, so we need a lot of it. When we start stacking coolers, we end up restricting the air to *both* heat-exchangers in the stack. Because of this, we end up with both being oversized, inefficient coolers. We're much better off to get a little more clever with our air routing and keeping coolers single stacked.

Yes, my other concerns I have not yet posted about are what you say.

1. Grille area is only half the HX stack area
2. Airflow restriction due to HX's covering each other
3. The accepted practice of keeping the HX's close to each other (no gaps)
4. Airflow losses due to side leaks
5. Loss of the water/oil HX requires large oil HX, which covers up the stack thus causing more flow restriction.

#1 can't be helped without a different bumper. (non starter for me)
#2 can't be helped without nixing the condenser (also non starter)
#3 is an issue because the gap between rad and cond is too small for standard thickness coolers. So we put a big oil HX in front of the stack, which leads to problem #5.
#4 can be addressed.
#5 has no clear solution.

The solution to one issue always seems to exacerbate a different one. Argh!

My current thinking is to choose a wide oil HX and mount it vertical and low in front of the condenser. So that's 3 HX's in the lower half of the stack, but with a 2" gap between condenser and rad. (And 3 in HX's still in the upper half). If oil cooling is solved, but trans remains a problem, then I would upsize the OEM trans cooler to a Setrab SLM to fit in the narrow gap.

Regardless, I just can't give up the AC.

I can't shake the feeling that Mach1 owners will be complaining about insufficient cooling next year.

 

[67Fast_V]

My biggest concern with putting the oil cooler outboard of the frame rails is damage in a minor off that could starve and kill the engine. I really wanted to put my oil cooler forward of one of the wheel wells but this concern for damage and the fact that I’d need to downsize and run one in each corner to get enough cooling capacity steered me away from doing so. Running two oil coolers also increases pressure drop from all the extra lines and fittings. But indeed if you can avoid stacking coolers that is by far the best option.

Very valid point, Scoots. Thanks. Didn't think of that. There is a risk there for sure. Reminds me of a friend in his C7Z did a little grass mowing at 70 mph. Punched a hole in the aux cooler in the front. Just have to drive slow and avoid off roading

 

[GTP]

...

1 x 12an double swivel 45*
1 x 12an double swivel 60*

I used these to route my lines between the top of the subframe and under the sway bar, pointed outboard to route the lines around the drivers side of the radiator. If your lines are resting on the subframe, the sway bar even at full compression is an inch away from -12 lines with fire sleeve on them.

@Scootsmcgreggor , a few more details from your build:

1. Did you choose the 45 & 60 double swivels so as to spread them apart and gain wrench clearance?
2. Are you saying that your routing scheme will not risk pinching by the swaybar?
3. Did you add fire sleeve for peace of mind?

 

[Ewheels]

Grille area is only half the HX stack area

That's not actually a problem. Ideally you don't want equal areas.

Airplanes do this, F1 does this, and racers with good fab skills do this.
You want 30% opening compared to the radiator area. The increase in area in front of the cooler will increase pressure and then leaving the cooler after, the decrease in area will decrease pressure. So you'll have high pressure in front and low pressure behind the radiator, helping to push air through.
Granted this only works if it's all correctly ducted. Need smooth transitions

Here's another picture to help show

 

[GTP]

Right, and I also just realized that the fins reduce the cross-sectional area of the air by quite a bit.

 

[Scootsmcgreggor]

@Scootsmcgreggor , a few more details from your build:

1. Did you choose the 45 & 60 double swivels so as to spread them apart and gain wrench clearance?
2. Are you saying that your routing scheme will not risk pinching by the swaybar?
3. Did you add fire sleeve for peace of mind?

The 45 and 60 put the hose outlets around the same place and angle once attached to the sandwich plate as I have it angled.

Correct as I have it laid out it cannot be pinched by the sway bar. Shocks bottom out first with room to spare. Note this is with my coilovers you should check the stroke on whatever shocks you have and cycle the sway bar to confirm.

Fire sleeve is for added protection in case of a fire of course but also abrasion resistance. The silicone outer layer of the raceflux fire sleeve gave me confidence to use their lightweight hose which is less abrasion resistant than typical stainless braided hose.

 

[GTP]

Another idea I had was to source a cooler that matches the lower grille area, mount it vertical above the belly pan, and then shroud it before and after, with the exit forced down and through a cutout in the belly pan. I bet that would have good airflow through it. But then I worried that the upper grille area remains the only source of air to feed the AC/Trans/Coolant stack and that it might not be enough.

 

[paulm1]

With the oil coolers mentioned in this thread that i've seen.....you're bringing a knife to a gun fight trying to cool 10 quarts of oil from a wet system imo. Check out the size of this oil cooler, its as big as the radiator and located behind it. https://www.fluidyne.com/products/nascar-spec-cooling-module

 

[TeeLew]

Another idea I had was to source a cooler that matches the lower grille area, mount it vertical above the belly pan, and then shroud it before and after, with the exit forced down and through a cutout in the belly pan. I bet that would have good airflow through it. But then I worried that the upper grille area remains the only source of air to feed the AC/Trans/Coolant stack and that it might not be T.

I really think starting with either a GT350 or GT500 front bumper & fenders makes things so much easier. There just isn't enough real-estate on the other noses to really keep things cool. Yes, you can start shooting air under the car, but you probably don't want it there for lift reasons. At the end of the day, you probably want to shoot the cooling exhaust out of the sides or back if you can. The side nose intakes of the 350/500 make this much easier. Pull through the front and exit though fender vents. For the center rad, you exit though hood vents. You don't really want heated air to go around the greenhouse, but this is kind of a take-what-you-can-get scenario.

 

[TeeLew]

With the oil coolers mentioned in this thread that i've seen.....you're bringing a knife to a gun fight trying to cool 10 quarts of oil from a wet system imo. Check out the size of this oil cooler, its as big as the radiator and located behind it. https://www.fluidyne.com/products/nascar-spec-cooling-module

Please, stop.

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