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Finally had heat management problems :/

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#1
This past weekend I finally ran into the heat management issues, went on a back road run with a buddy and after a decent amount of miles i looked down and saw the temp gauge was pegged full hot. Didn't go into limp mode but it was more than likely on the edge of going into limp mode. Now the question is Mountune or Mishimoto radiator?
 


jeffreylyon

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#2
... or an oil oiler? I don't like the idea of running oil temp. higher than coolant temp. An oil cooler give you extra heat rejection and cooler oil.
 


TDavis

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#3
This past weekend I finally ran into the heat management issues, went on a back road run with a buddy and after a decent amount of miles i looked down and saw the temp gauge was pegged full hot. Didn't go into limp mode but it was more than likely on the edge of going into limp mode. Now the question is Mountune or Mishimoto radiator?
I had the same question and this will probably answer yours

http://www.fiestastforum.com/forum/threads/17216-Mishimoto-Radiator-OR-Mountune-Radiator

... or an oil oiler? I don't like the idea of running oil temp. higher than coolant temp. An oil cooler give you extra heat rejection and cooler oil.
Radiator is what people recommend first and probably what most people only need is a radiator because the oil cooler uses coolant to cool it so an upgraded radiator will help the oil as well.
 


Woods247

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#4
The mishimoto radiator solved my consistent overheating problems on track. Oil temps have been acceptable after just the radiator upgrade. I’ve had no temp related limps since the radiator upgrade.
 


jeffreylyon

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#5
Radiator is what people recommend first and probably what most people only need is a radiator because the oil cooler uses coolant to cool it so an upgraded radiator will help the oil as well.
Does anyone know if the stock oil cooler has a thermostat or if it's just "balanced" with the heat rejection of the radiator?
 


D1JL

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#6
Believe it or not,

When ever you do spirited or track driving, with a newer model street type car, you should always keep the air conditioner on.
Your request for AC also turns on the high speed radiator fan and this is a good thing.
At the same time your request for performance (wide open throttle) causes the AC to turn off, but not the fan, so no loss of power.

Just a thought.


Dave
 


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Thread Starter #7
Part of me wants to go all out and get the Mountune radiator, mishi oil cooler or comparable if not better brand, and then get a tubular crash bar and shave the grille to open up a little more air flow. But the wallet does not agree right now so i may have to save up and go one by one down the list.
 


BRGT350

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#8
oil cooler has a thermostat and oil temp should be higher than coolant temp. Target is usually around 195'F coolant and 225'F oil. That can vary depending on a number of factors, but pretty close for most cars.
 


alexrex20

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#9
Mine was full hot yesterday after tooling around on the street with 95F ambient. AC was of course on and didn't help. Time to get a Mountune rad I guess. :/

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alexrex20

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#10
Shaving the grill is pointless. The crash bar is behind it and blocks the airflow.

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BRGT350

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#12
I would consider adding heat extraction vents in the hood before altering the crash structure. Fox Mustangs are terrible when it comes to cooling, so I created an aluminum shroud that sealed the radiator to the opening in the bumper cover. The goal was to completely box in the radiator and seal it so all the air goes through the radiator. The next step was going to be adding extractor vents in the hood since all the air that goes through the radiator needs a place to exit. The problem was that the shroud worked too well and the engine won't heat up. I had to block half of the bumper and 25% of the radiator just to get it close to operating temp.

The Fiesta has some decent shrouding, but could still be sealed better to make sure no air can find a way around the radiator. Adding a set of extractor vents above the radiator will take advantage of the low pressure above the hood and draw out high pressure hot air from the engine compartment. Usually what happens is that air gets trapped in the engine compartment or doesn't flow out as fast as air is flowing in. This creates a high pressure and actually starts to push air away from the front of the car. It also lifts the front of the car too. Giving an exit for the air removes the high pressure. The flap under the radiator/bumper cover is designed to create a low pressure under the front and pull hot air down from the engine compartment. Hot air likes to rise, so it really has to work hard to get it to work. This is one reason why the flap is so large. If you open up the grille and make more air come in without adding an area for the air to exit, you could easily create an even higher pressure in the engine compartment and make cooling more difficult. Air in needs to equal air out.

Or just buy a bigger radiator to increase surface area and volume.
 


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#13
Mine got pretty hot a few weeks ago and went ahead and ordered the Mountune radiator. With the current sale going on and a coupon code I found online, it was under 430 shipped.


Actually just showed up today.
 


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#14
I would consider adding heat extraction vents in the hood before altering the crash structure. Fox Mustangs are terrible when it comes to cooling, so I created an aluminum shroud that sealed the radiator to the opening in the bumper cover. The goal was to completely box in the radiator and seal it so all the air goes through the radiator. The next step was going to be adding extractor vents in the hood since all the air that goes through the radiator needs a place to exit. The problem was that the shroud worked too well and the engine won't heat up. I had to block half of the bumper and 25% of the radiator just to get it close to operating temp.

The Fiesta has some decent shrouding, but could still be sealed better to make sure no air can find a way around the radiator. Adding a set of extractor vents above the radiator will take advantage of the low pressure above the hood and draw out high pressure hot air from the engine compartment. Usually what happens is that air gets trapped in the engine compartment or doesn't flow out as fast as air is flowing in. This creates a high pressure and actually starts to push air away from the front of the car. It also lifts the front of the car too. Giving an exit for the air removes the high pressure. The flap under the radiator/bumper cover is designed to create a low pressure under the front and pull hot air down from the engine compartment. Hot air likes to rise, so it really has to work hard to get it to work. This is one reason why the flap is so large. If you open up the grille and make more air come in without adding an area for the air to exit, you could easily create an even higher pressure in the engine compartment and make cooling more difficult. Air in needs to equal air out.

Or just buy a bigger radiator to increase surface area and volume.
Everything I’ve read indicates the top of the hood is a high pressure area. So vents there won’t help without large spoilers to create a low pressure area behind them and disrupt the boundary layer. If you look at the WRC cars you will see the vents on the side extremities of the hood for that reason.
 


TyphoonFiST

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#15
Everything I’ve read indicates the top of the hood is a high pressure area. So vents there won’t help without large spoilers to create a low pressure area behind them and disrupt the boundary layer. If you look at the WRC cars you will see the vents on the side extremities of the hood for that reason.
What about the use of NACA Ducts? I have used these with success in the past and a lot of Race operations and aeronautics utilize them! [thumb]

Heres a very similar piece of what I have used......

https://cdn.shopify.com/s/files/1/0...-b1b2-9d3f70e10762_1024x1024.jpg?v=1504750864
 


Last edited:
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#16
What about the use of NACA Ducts? I have used these with success in the past and a lot of Race operations and aeronautics utilize them! [thumb]

Heres a very similar piece of what I have used......

https://cdn.shopify.com/s/files/1/0...-b1b2-9d3f70e10762_1024x1024.jpg?v=1504750864
They are very good at getting flow into an area but in this case BRGT350 wants to get flow out of the engine bay.
Centre hood vents can work, but they need a larger spoiler on the leading edge to disrupt flow, so might not look the best. I’d expect the WRC teams had many hours in wind tunnels to work out the most effective and efficient placement of vents.
 


alexrex20

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#17
Top of the hood is and always has been low pressure. A vent works well at extraction. If you want induction you need a scoop that's tall enough to get above the dead air directly above the hood.

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BRGT350

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#18
Everything I’ve read indicates the top of the hood is a high pressure area. So vents there won’t help without large spoilers to create a low pressure area behind them and disrupt the boundary layer. If you look at the WRC cars you will see the vents on the side extremities of the hood for that reason.
Yes, however, the pressure isn't constant across the entire hood. The underhood pressure is still greater than the pressure over the hood, therefore, the flow would still be from a high pressure to a lower pressure, even if the pressure over the hood is higher than other areas of the exterior. For the most part, the overall hood can be considered a lower pressure area. There are some good CFD images showing how the pressure is different over the hood, and that difference will change from car to car based on the design. It has been awhile since the last time I read over my aerodynamics book on underhood air flow, but this is how I recall the information. To help promote a low pressure area, most hood vents have a flap on the leading edge to break up the boundary layer and create a localized lower pressure. I also think the WRC cars have underhood ducting that takes the heat from the radiator and isolates it until it gets to the hood vents. They also have a lot more room in the engine compartment to run ducting. If you look at the last few decades worth of WRC cars, it is interesting to see how many different types of heat extraction vents have been used. The 2003-2005ish Focus WRC had the radiator mounted almost flat and ducting going into the radiator from the bumper, a set of twin fans in a shroud on top of the radiator, and then a boxed section on the hood that sealed the radiator to the extraction vents. Subaru has done similar things with their radiators and it works well with the boxer engine being so much lower in the chassis. For a street car, adding a set of hood vents with a leading edge flap would still be effective. I have seen a number of Fiestas use the MkII Focus RS vents. They look great on the car and work as well.

You are 100% right on the NACA ducts. They bring air in, not air out. Not many people get that one, so I am impressed.
 


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