Track Time Limited due to High CHT

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67Fast_V

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It’s not normal for your car to get that hot so fast. Key words here is so fast
Obviously adding airflow through the radiator will help but you’re treating the symptom, not the issue
In a simple term, you are putting more heat load through the cooling system that it can handle
Is your problem with an abnormal heat load and a normal cooling system or a normal heat load but an abnormal cooling system ?
Obviously the end result in the same but the diagnosis and cure is not
You are right @luc, that I'm working on the premise that there is nothing wrong with my cooling system. I just can't find anything wrong with it. It appears to working as intended. T-stat is opening, no blockage on the condenser, it cools good around town, engine runs great, etc. Maybe the radiator is plugged but it would have to be significant, like30+%. It's brand new and hence not likely.

The Forum experience appears to be that the A10 overheats faster than M6 tranny. Forum member Tundra overheated his A10 GT PP1 on his 1st event as well. Engine, Tranny, and Diff. So maybe its just the sustained high rpm from the Auto that is adding the heat load and lack of airflow through the radiator, combination.

After I make these airflow mods and run again in Nov, I will have more data to help evaluate the situation. But at the moment, I am guessing a bit ... for sure.. Cheers.

 
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67Fast_V

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You are right @luc, that I'm working on the premise that there is nothing wrong with my cooling system. I just can't find anything wrong with it. It appears to working as intended. T-stat is opening, no blockage on the condenser, it cools good around town, engine runs great, etc. Maybe the radiator is plugged but it would have to be significant, like30+%. It's brand new and hence not likely.

The Forum experience appears to be that the A10 overheats faster than M6 tranny. Forum member Tundra overheated his A10 GT PP1 on his 1st event as well. Engine, Tranny, and Diff. So maybe its just the sustained high rpm from the Auto that is adding the heat load and lack of airflow through the radiator, combination.

After I make these airflow mods and run again in Nov, I will have more data to help evaluate the situation. But at the moment, I am guessing a bit ... for sure.. Cheers.
For those that are interested, I wanted to provide a quick update. I will make this short.

I determined the root cause of my cooling issue (CHT from 190 to 250F in 6 mins of track time). The problem was the radiator sealing and the high-rpm heat load afforded by the A10. I'm 90% sure of it.

I ran some air flow calculations. A lot of them. And also heat transfer calcs. I will give you the bottom line. Sealing the radiator increased the airflow through the radiator by 42% and will reduce CHT by 40+ degs F under full heavy load conditions. It's hard to believe, but there are monster opening/leaks in the stock system that seriously hurt cooing performance. You don't see it on the street because the heat load is down and the stock radiator is big. My system (car) was worse than normal (although normal is pretty bad) because I had 1 side seal that was dislodged/non-functional.

Note that what I ran on the track was CHT of 250F but it was still climbing fast. I estimate it would of climbed to 280F+. That's the true SS temp w/ seriously hindered airflow. NASCAR style temps.

I also modified my fan shroud and gained about 7% more flow. That's worth about 7 degs F. So a total increase in flow from my previous track event of 51%, as calculated by my models.

I have a track event on Nov 14 and I will test-out the radiator sealing and fan shroud mods. See if my calcs are reasonable. My pretest prediction is 235F CHT max, fully hammered on a hot day (85-90F). I don't believe I will be off by more than 5 degs but we will see. It's not easy to predict leakage flows. So that would be 240F max.

My last point is this.... if you are interested in tracking your car I would highly suggest that you remove the top cover plate of the radiator (8 push pins/clips) and the undertray and seal up this system. It will take you about 4-6 hrs but well worth it. This should be the 1st step for tracking (okay 2nd step. First step is SRF brake fluid in my opinion and good oil of course).

Okay my real last point. I bought a spare hood and will add a vent/louver to it. This will provide another 5% in airflow, maybe more if the dump pressure of the louvers is significantly different than the pressure under the car.

If you are interested in the details of the flow calcs or heat transfer, then let me know. Thanks for reading.
 

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For those that are interested, I wanted to provide a quick update. I will make this short.

I determined the root cause of my cooling issue (CHT from 190 to 250F in 6 mins of track time). The problem was the radiator sealing and the high-rpm heat load afforded by the A10. I'm 90% sure of it.

I ran some air flow calculations. A lot of them. And also heat transfer calcs. I will give you the bottom line. Sealing the radiator increased the airflow through the radiator by 42% and will reduce CHT by 40+ degs F under full heavy load conditions. It's hard to believe, but there are monster opening/leaks in the stock system that seriously hurt cooing performance. You don't see it on the street because the heat load is down and the stock radiator is big. My system (car) was worse than normal (although normal is pretty bad) because I had 1 side seal that was dislodged/non-functional.

Note that what I ran on the track was CHT of 250F but it was still climbing fast. I estimate it would of climbed to 280F+. That's the true SS temp w/ seriously hindered airflow. NASCAR style temps.

I also modified my fan shroud and gained about 7% more flow. That's worth about 7 degs F. So a total increase in flow from my previous track event of 51%, as calculated by my models.

I have a track event on Nov 14 and I will test-out the radiator sealing and fan shroud mods. See if my calcs are reasonable. My pretest prediction is 235F CHT max, fully hammered on a hot day (85-90F). I don't believe I will be off by more than 5 degs but we will see. It's not easy to predict leakage flows. So that would be 240F max.

My last point is this.... if you are interested in tracking your car I would highly suggest that you remove the top cover plate of the radiator (8 push pins/clips) and the undertray and seal up this system. It will take you about 4-6 hrs but well worth it. This should be the 1st step for tracking (okay 2nd step. First step is SRF brake fluid in my opinion and good oil of course).

Okay my real last point. I bought a spare hood and will add a vent/louver to it. This will provide another 5% in airflow, maybe more if the dump pressure of the louvers is significantly different than the pressure under the car.

If you are interested in the details of the flow calcs or heat transfer, then let me know. Thanks for reading.
Do you have any pictures of what you did to seal? Before and after?
 

luc

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For those that are interested, I wanted to provide a quick update. I will make this short.

I determined the root cause of my cooling issue (CHT from 190 to 250F in 6 mins of track time). The problem was the radiator sealing and the high-rpm heat load afforded by the A10. I'm 90% sure of it.

I ran some air flow calculations. A lot of them. And also heat transfer calcs. I will give you the bottom line. Sealing the radiator increased the airflow through the radiator by 42% and will reduce CHT by 40+ degs F under full heavy load conditions. It's hard to believe, but there are monster opening/leaks in the stock system that seriously hurt cooing performance. You don't see it on the street because the heat load is down and the stock radiator is big. My system (car) was worse than normal (although normal is pretty bad) because I had 1 side seal that was dislodged/non-functional.

Note that what I ran on the track was CHT of 250F but it was still climbing fast. I estimate it would of climbed to 280F+. That's the true SS temp w/ seriously hindered airflow. NASCAR style temps.

I also modified my fan shroud and gained about 7% more flow. That's worth about 7 degs F. So a total increase in flow from my previous track event of 51%, as calculated by my models.

I have a track event on Nov 14 and I will test-out the radiator sealing and fan shroud mods. See if my calcs are reasonable. My pretest prediction is 235F CHT max, fully hammered on a hot day (85-90F). I don't believe I will be off by more than 5 degs but we will see. It's not easy to predict leakage flows. So that would be 240F max.

My last point is this.... if you are interested in tracking your car I would highly suggest that you remove the top cover plate of the radiator (8 push pins/clips) and the undertray and seal up this system. It will take you about 4-6 hrs but well worth it. This should be the 1st step for tracking (okay 2nd step. First step is SRF brake fluid in my opinion and good oil of course).

Okay my real last point. I bought a spare hood and will add a vent/louver to it. This will provide another 5% in airflow, maybe more if the dump pressure of the louvers is significantly different than the pressure under the car.

If you are interested in the details of the flow calcs or heat transfer, then let me know. Thanks for reading.
Thanks for the update
I bet you that the dislodged radiator seal was the vertical plastic seal on the passenger side ….right ?
 


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67Fast_V

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Thanks for the update
I bet you that the dislodged radiator seal was the vertical plastic seal on the passenger side ….right ?
@ Luc ... smart man. yes that's the one. I think the OEM had the "newbie" design that one :).

@ Hana - engine cooling is typically equivalent to 17-22% of the engine HP. Oil is typically 3-6%. A lot of factors drive both of those numbers. Not sure about the tranny heat load but I'm going there soon. After my engine cooling is addressed (hopefully the next event will prove that), I will be working the A10 cooling. I suspect my next event in which I can really go at this, the trans temp will exceed the Flyhalf recommended 230F. Oil cooling will come after the trans (although I need to have a pretty good idea what to do concurrently w/ the trans work).
 

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@ Luc ... smart man. yes that's the one. I think the OEM had the "newbie" design that one :).

@ Hana - engine cooling is typically equivalent to 17-22% of the engine HP. Oil is typically 3-6%. A lot of factors drive both of those numbers. Not sure about the tranny heat load but I'm going there soon. After my engine cooling is addressed (hopefully the next event will prove that), I will be working the A10 cooling. I suspect my next event in which I can really go at this, the trans temp will exceed the Flyhalf recommended 230F. Oil cooling will come after the trans (although I need to have a pretty good idea what to do concurrently w/ the trans work).
I’ve been thinking a good portion of the issue with your the A10 is the ability to keep revs over 6500 more of the time, combined with the added heat load of the automatic.

The amount of heat load generated from 0-6500 is drastically different than from 6500-7250

I think you’ll find as you get faster. Your radiator duct work and hood vents are a good start but not the complete fix.
 

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I think you’ll find as you get faster. Your radiator duct work and hood vents are a good start but not the complete fix.
Besides oil cooler what is the complete fix ?
 

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Besides oil cooler what is the complete fix ?
It took me a Diff cooler, bigger radiator, manual trans air scoop ( shifts still got sloppy at end of sessions—I’m sure I was overheating it). In addition to oil cooler

And even then, it was the ragged edge.

In auto’s case, add a monster trans cooler.
 

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you on stock clutch or ?
Stock clutch. I try to shift with a margin of mechanical empathy, but the shifter would get vague & sloppy.
 
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67Fast_V

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Yes, I have some pics. Let me dig through them tomorrow and find some decent ones and send out.
See attached photo of before and after sealing.

The photos are the left lower corner. Monster openings if you look closely. Can actually see the radiator.

There are hundreds of ways to make these sealing plates. I took the easy route. And will find out soon enough if they hold up. I used cardboard, cut the right shape to fit the opening, wrapped the cardboard with duct tape, and then duct taped it in. Wiped down the sealing surface of the car w/ alcohol and went at it. When possible, I wedged the sealing plate against something to provide mechanical support. I try to avoid the rain but its tough. I run on the street about 4k miles per yr. If I have to replace them, it's not a problem. Proof of concept really ... and well worth it.

Picture1.png


Picture2.png
 

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Unfortunately, these cars do have a cooling problem. Personally, I would have backed off before CHT hit 240 let alone 250. That's dangerous.

Most S550 track guys run hood vents and seal the radiator on the front side so the incoming air can only go through the radiator.
I saw improvement instantly from RaceLouvers hood vent. I will eventually seal the radiator as well but I'm more into Time Attack so a couple laps is all I need.

You could also try a triple pass radiator to bring temps down further
Are those from Racelouvers an exact design replica type of the real GT4?
 

TX-2019-Black_GT

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@67Fast_V I've seen you mention it twice now....DO NOT remove the hood sealers on the rear of the hood next to the windshield. That's a localized high pressure area and if removed, you'll just force more air back into the engine bay rather than evacuating it.

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EDIT- I thought I was at the end when I replied here, but had only read the first of 2+ pages) oops.
Replying to the whole thread in general - I've been going through similar issues and reading tons of forums since Mid-2020. I've got a 2019 GT A10. First track event, noticed the shifts started happening at 5000 rpm sometimes 5500, sometimes 4500 +/-. I'm not using the paddles, just sport+ and Track modes.

1st, I agree with those that said there really must be a problem (with your cooling system, or related). 250F CHT in 6-9 min.! See below for my specific experience.

So, a few key points:
Agreed - do not remove the rear hood seal. High P area.

Side seals? Prob won't make much difference.

Diff - Mine is not the PP Torsen. Mine hits close to 90C max. after 20+ min sessions. Never an issue for me, but is for the Torsen.

Trans temps, never over 215F. Note the gauge is not red until 250+, so not sure why someone said 225 would kill it? (sorry if I remember wrong, I'm not re-reading all to check :-)

Added oil cooler, deleted OEM oil to water cooler, mounted low, plus two fans, and opened up the grill honeycomb a lot. No significant change in oil temp (inferred / calculated, and the one that makes the PCM decide to limit your rpms). Pretty much the same limited rpms due to heat.

So, 11/6 track day, South Texas but high was about 71F. Early session, no overheat, no rpm limit. Later in day, it did limit rpms, sometimes, but just barely and cooled off with just a little 8/10 driving time. My MAX CHT was 235, and my MAX dash-oil temp gauge hit low yellow, which is just over 280F and where it starts to limit rpm.

11/7, today, I used my new hood with Trackspec louvers, big middle vent plus to large side vents. Almost a total of 30X14 inches of wide-open ventilation. Did not have any overheating that limited rpm, but got close. Max CHT about 215-220F. Oil T got close to 'yellow'. But, this was in the cooler morning. I couldn't run again later today because my brake pads wore out to the metal! :-( I won't let that happen again! Spares and better pads. (I also need to remove the engine cover. It pretty well blocks the main center hood vent, so I was not getting their max benefit.)

One last note: I ran 0W-40 this weekend. I dug pretty deep, technically, and as best I can tell, the 'inferred' oil temperature is based mainly on CHT and oil pressure (a function of viscosity and temp, plus rpm, among other things). If I recall correctly, air inlet temp plays into the logic governing the rpm limits. I also opened up the grille for the intake air, and noticed a good improvement in inlet air temp vs. ambient. Bottom line, no matter how you get there, more cooling is needed. From all I've read, hood vents done right are going to make a big difference. Opening the grille is critical, in my view. I just ground off the backside with a proper attachment for an angle grinder while I had the front end off for adding the oil cooler. Ditch the radiator shutters too (had too for the tow hook, but I don't know if the PP cars have them, probably not)

I probably forgot something..... Ask if you have questions. Hope this helps!
 
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TX-2019-Black_GT

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It’s not normal for your car to get that hot so fast. Key words here is so fast
Obviously adding airflow through the radiator will help but you’re treating the symptom, not the issue
In a simple term, you are putting more heat load through the cooling system that it can handle
Is your problem with an abnormal heat load and a normal cooling system or a normal heat load but an abnormal cooling system ?
Obviously the end result in the same but the diagnosis and cure is not
I agree, I believe it getting this hot that quickly is not normal.
 

 
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