Track Time Limited due to High CHT

[Scootsmcgreggor]

Sorry, I don't mean to be a jerk, but I'm not convinced by any of this.

Air flow is dependent on pressure delta between inlet and outlet sides, and restriction (i.e. the fins). Boxing in the radiator may increase inlet pressure, but I think the outlet side pressure is still the enemy if it remains unchanged (and which is probably ambient pressure of ~1 bar).

IMO adding a sufficiently large hood vent will decrease outlet side pressure more than boxing will increase inlet side pressure. If it is located "correctly" (wherever that is precisely) and the large engine cover is removed then it also would be directed over the cylinder head.

I think a better way to increase inlet pressure would be to add double fans ahead of the 3 coolers for a push-pull arrangement. I don't recall seeing this suggestion on the forum (though I certainly haven't read every cooling thread).

A it stands, air exits mostly out the belly pan, and that may help the transmission a little.

Furthermore, we are relying on the OEM dual fans and road speed for air flow. You can still have high RPMs even at lower speeds because of shifting. But the proposed extra set of fans are always running regardless of road speed. Just an idea.

So your theory is that pusher fans in front of the rad will create higher pressure than a boxed radiator? What data or examples do you have to support this?

Sponsored

 

[Twizzty]

It may have been hotter then hell but Thursday was a great track day at Sebring! Good luck with your cooling efforts 67fast_v and I hope you have better luck then when I tried tracking my A10 last year...it led to me getting this 1LE! (RIP Mach1)

 

[gone_n_60]

It may have been hotter then hell but Thursday was a great track day at Sebring! Good luck with your cooling efforts 67fast_v and I hope you have better luck then when I tried tracking my A10 last year...it led to me getting this 1LE! (RIP Mach1)

Awwww traitor! ;-) btw how'd you get that nice motion stop pic? Very nice, and okay ... nice car. tbh I just did my first ever track weekend and being a newbie didn't check stats, just learning to stay on the track, take turns faster that I thought the car could do it (turns out car fine, driver needs more skill) but never had what looks like temp problems. I'm running a 2020 GT pp1 vert, A10 and stock everything. yes after a session under hood hot! but nothing serious.

 

[Twizzty]

Awwww traitor! ;-) btw how'd you get that nice motion stop pic? Very nice, and okay ... nice car. tbh I just did my first ever track weekend and being a newbie didn't check stats, just learning to stay on the track, take turns faster that I thought the car could do it (turns out car fine, driver needs more skill) but never had what looks like temp problems. I'm running a 2020 GT pp1 vert, A10 and stock everything. yes after a session under hood hot! but nothing serious.

lol thanks! Each track day normally has a photographer and they take some amazing pics IMO, Thursday was no exception and they got some great shots for $85.

As far as temps go, as your track experience grows so do the high temps in my experience. A PP1 A10 is good for about 7-8/10's on track but once you start pushing that last little bit it likes to overheat after a couple of laps. I wanted a Mach1 BAD but just couldn't justify the $58k price tag unfortunately...not with 1LE's being $46k.

Enjoy your track experience, every bit of it while we still can and just upgrade or mod as you get faster.

OK one more shameless picture from Thursday...

 

[Angrey]

Velocity across a heat exchanger will improve it's thermal efficiency. The benefits are particularly beneficial at low values.

However, the system is also constrained by the total amount of ambient air that passes through the entire heat generating area.

As posted above, smashing more air into a smaller area isn't going to produce much benefit if the back side is already backed up and not able to flow properly (i.e. squirting a pressure washer at a coffee straw will have similar outcomes as a water hose at it if the back side is already constricted).

This is where I think improving backside flow (i.e. hood venting) will yield much more impactful results. Not only does opening up the hood allow less flow to get traffic jammed on the back side of the exchangers, it helps very much in both keeping under hood temps (and therefore intake temps) lower, but also to actually air cool the entire motor (reducing the load and delta T of the heat exchangers).

By trying to "box in" the the footprint of the radiator, it does indeed increase (to diminishing effect) the velocity across the exchangers, however, the rest of the air that's now disallowed goes over the car and under it (rather than contributing to the overall cooling of the front engine bay area).

At low speeds, this is particularly an issue, for a couple reasons. 1) the fans are most effectual at low speed so the with or without the boxing out, they're pulling air through and 2) at low speeds is where you want to flow as much ambient air through the bay as possible.

This all gets very complicated because under most conditions, low speeds is low engine loading, higher speeds (track speeds) is where the motor is loading most and generating most heat (but there's most flow).

I think if you want to observe some of the practical testing, look at the GT500 development and what they did (vs the GT350). They attempted to reduce fluid friction losses through the grill (narrowing the grill material thickness) and also increasing the size of the mouth to get more flow, recognizing the car will generate more heat. This combined with a large vent above the motor greatly increases the thermal exchange.

I don't think boxing will help under all conditions and without corresponding improvements to the flow of the back side of the exchangers (i.e. the exit paths out of the engine compartment) it may actually be detrimental in some conditions.

In summary, the heat exchangers are important but they're not the only aspect in cooling the hot areas of the car/motor. Air cooling and swap out can and do contribute so the entire system needs to be considered and not just one aspect.

 

[tosha]

I'm sure everyone has seen this, but I'll post it here anyways for the reference:

it's unclear from pictures, but it seems that the rads are reasonably ducted. of course there is this hood vent for heat extraction. ultimately, it seems that #6 and #7 are really critical for this last bit of cooling, after ducting and venting are solved.

@Twizzty , you have a beautiful car and ultimate track weapon. pricewise, it's a no-brainer for the track duty, and I agree with you regarding mach 1 pricing - it's crazy. here in Canada, base Mach 1 with handling package and cloth recaros is $14k CAD over 1SS 1LE. In fact, this mach 1 is almost the same price as base ZL1, and Premium Mach 1 is tapping into ZL1 1LE territory. the problem at least for me is in that camaro design. I prefer to look at the mustang so much more, both inside and outside. and since my car is also my garage queen, weekend toy and daily driver during warm weather, I do want to try to make it work with doing the mods.

 

[EFI]

That fan shroud looks alot more open also. Bigger single fan and every other space around it is flapped for airflow at high speeds. Wonder if that will make any difference in GTs.

 

[tosha]

That fan shroud looks alot more open also. Bigger single fan and every other space around it is flapped for airflow at high speeds. Wonder if that will make any difference in GTs.

several folks in this thread modified their shrouds to be even more open, they can comment first hand on the effects of it.

the screenshots are from this video and there's more interesting stuff on front end aero and cooling of GT500 that they are discussing. sharing as some may pick few good ideas that I might have missed: Ford Mustang Shelby GT500 | Where Does it End? - YouTube

 

[Twizzty]

@Twizzty , you have a beautiful car and ultimate track weapon. pricewise, it's a no-brainer for the track duty, and I agree with you regarding mach 1 pricing - it's crazy. here in Canada, base Mach 1 with handling package and cloth recaros is $14k CAD over 1SS 1LE. In fact, this mach 1 is almost the same price as base ZL1, and Premium Mach 1 is tapping into ZL1 1LE territory. the problem at least for me is in that camaro design. I prefer to look at the mustang so much more, both inside and outside. and since my car is also my garage queen, weekend toy and daily driver during warm weather, I do want to try to make it work with doing the mods.

Thank you and I completely agree with you on the looks of a Camaro vs. Mustang. I'll even go further to say the Mustang does everything better in the DD category and all of the small things are better also like sunglass holder, fitting golf clubs in your trunk without putting your back seat down, button to unlock vs touch, ext. All while looking amazing and that's why I'm sure I'll have another Mustang, S650 most likely. Right now I chose to pocket the $12k and all I can say is it's as fast as it is ugly!!

 

[nbjeeptj]

I was able to drive mine on the road this weekend with aftermarket coolant and oil temperature gauges installed and think after all my mods mine will be fine in reality but the computer algorithm may not think so. The mods are new Mishimoto Radiator, Race louvers in the hood, Watson racing radiator ducting, and a massive series 9, 60 row oil cooler, running water with wetter water. The Temp on oil was never over 212, and 209 on coolant after running the car in 2nd gear at 6800rpm for 3 miles down the road. During this run the head temp did register 235 toward the end, which leads me to believe that even though I should be able to stay well below the danger point in real temperature extremes the computer will still want to cut power. If this is the case I plan to change the table that limits the power to a higher threshold since I am now looking at real oil and coolant temps. I will be able to test this on the track this Friday so I will have much better more accurate numbers to share especially since the highs for the day are supposed to be 97deg.

 

[tosha]

I was able to drive mine on the road this weekend with aftermarket coolant and oil temperature gauges installed and think after all my mods mine will be fine in reality but the computer algorithm may not think so. The mods are new Mishimoto Radiator, Race louvers in the hood, Watson racing radiator ducting, and a massive series 9, 60 row oil cooler, running water with wetter water. The Temp on oil was never over 212, and 209 on coolant after running the car in 2nd gear at 6800rpm for 3 miles down the road. During this run the head temp did register 235 toward the end, which leads me to believe that even though I should be able to stay well below the danger point in real temperature extremes the computer will still want to cut power. If this is the case I plan to change the table that limits the power to a higher threshold since I am now looking at real oil and coolant temps. I will be able to test this on the track this Friday so I will have much better more accurate numbers to share especially since the highs for the day are supposed to be 97deg.

Ooohh, please do. Your car might be a perfect recipe for success . Are you driving MT or AT? I'm guessing it's manual, but would be good to understand.

 

[67Fast_V]

It may have been hotter then hell but Thursday was a great track day at Sebring! Good luck with your cooling efforts 67fast_v and I hope you have better luck then when I tried tracking my A10 last year...it led to me getting this 1LE! (RIP Mach1)

thanks twizzty . I had a rough go on thurs, though. The cooling was actually the best part of the afternoon. The car did not like turn 1 at 90 mph. Was fine at 80 but not 90. Gotta learn to gage speed better.

I feel great about my cooling now. Not sure you have been following the thread but Once the bigger grille goes in, I should have ice 🧊 forming under the hood . And will likely block some holes in the grille during the winter months to improve aero a bit.

If you give the pp1 radiator the proper airflow, it will do just fine ... to summarize 200+ posts in this thread. With 100 sq in of leaks and 100 sq in of grille area, that is a bad combination for track use. Was hoping to keep the stock grille but not in the FL summers, unfortunately. But I bet the M6 guys in a little milder conditions could do it if fully sealed with stock power.

Its kinda of funny that in 2020, I had the opposite experience. I was looking at 1LE and the GT trying to decide which to get. The 1LE is a quicker factory car w/o a doubt but I didn’t want to spend $6k more to get it. Figured I could fix the “passenger” car bit in the GT and get it close in lap times to the 1LE at less cost. Jury is still out, but looks like that was a bad assumption. Currently I’m 5 secs slower at Sebring than the fast 1LE’s. I should be able to bridge 3 secs but the last 2 will be tough. Need a different driver . Will be fun trying, though.

 

[67Fast_V]

Velocity across a heat exchanger will improve it's thermal efficiency. The benefits are particularly beneficial at low values.

However, the system is also constrained by the total amount of ambient air that passes through the entire heat generating area.

As posted above, smashing more air into a smaller area isn't going to produce much benefit if the back side is already backed up and not able to flow properly (i.e. squirting a pressure washer at a coffee straw will have similar outcomes as a water hose at it if the back side is already constricted).

This is where I think improving backside flow (i.e. hood venting) will yield much more impactful results. Not only does opening up the hood allow less flow to get traffic jammed on the back side of the exchangers, it helps very much in both keeping under hood temps (and therefore intake temps) lower, but also to actually air cool the entire motor (reducing the load and delta T of the heat exchangers).

By trying to "box in" the the footprint of the radiator, it does indeed increase (to diminishing effect) the velocity across the exchangers, however, the rest of the air that's now disallowed goes over the car and under it (rather than contributing to the overall cooling of the front engine bay area).

At low speeds, this is particularly an issue, for a couple reasons. 1) the fans are most effectual at low speed so the with or without the boxing out, they're pulling air through and 2) at low speeds is where you want to flow as much ambient air through the bay as possible.

This all gets very complicated because under most conditions, low speeds is low engine loading, higher speeds (track speeds) is where the motor is loading most and generating most heat (but there's most flow).

I think if you want to observe some of the practical testing, look at the GT500 development and what they did (vs the GT350). They attempted to reduce fluid friction losses through the grill (narrowing the grill material thickness) and also increasing the size of the mouth to get more flow, recognizing the car will generate more heat. This combined with a large vent above the motor greatly increases the thermal exchange.

I don't think boxing will help under all conditions and without corresponding improvements to the flow of the back side of the exchangers (i.e. the exit paths out of the engine compartment) it may actually be detrimental in some conditions.

In summary, the heat exchangers are important but they're not the only aspect in cooling the hot areas of the car/motor. Air cooling and swap out can and do contribute so the entire system needs to be considered and not just one aspect.

thanks for chiming in. As discussed in previous posts, the pressure under the hood ie downstream of the radiator is pretty low. I have measured it, as well as the pressure upstream of the radiator. Road test at 80 mph with 2 very accurate gages in my car (plus a barometer) and 4 leads inside the various cavities. Took that data and built a 1D compressible flow model.
The reason for the lower pressure in the engine bay is because the flow is metered at the grille. That is by far the smallest area or restriction in the system. And the largest area in the system is the exit area as the flow escapes the engine bay. Roughly 65-70% of the total available dP is burned across the stock grille. The remaining ~30% occurs across the condenser, A10 HX, the radiator, fan shroud, and engine bay ... combination. So opening up the engine bay with louvers, vents, etc is small potatoes. I have done it and got a ~3 deg CHT reduction. Now if someone goes with an aftermarket grille and doesn’t seal the radiator, then the engine bay exit become a big piece. Cus now the flow is not metered at the inlet and the big leaks need to exit the system.

In summary, To improve cooling, by far the best mod is sealing the system which allows the air that actually goes through the grille to go through the radiator.

I understand that this is not the “conventional” solution and not very elegant for that matter, but it is by far the most effective. And my last Track event with 100F ambient is the support behind this. In the end, I’m just trying to help. Please don’t take offensive to what I’m saying. I’m Just trying to pass along my data and experience ... to help the GT community. Cheers.

 

[Scootsmcgreggor]

Ooohh, please do. Your car might be a perfect recipe for success . Are you driving MT or AT? I'm guessing it's manual, but would be good to understand.

It is the formula. Different brand of radiator and hood vents but ford figured this out for us with the fp350s years ago.

Big aluminum radiator
Setrab 960 (948 will do)
Boxed rad and oil cooler
Hood vents

The problem is some people (understandably so) don’t want to spend that much money or do that much work so they try and come up with another cheaper easier solution and fall short. I have always been that guy, so I know. But man it’s nice to follow the path with results and have it work out first time and not have to redo it and spend more doing it twice.

 

[67Fast_V]

I was able to drive mine on the road this weekend with aftermarket coolant and oil temperature gauges installed and think after all my mods mine will be fine in reality but the computer algorithm may not think so. The mods are new Mishimoto Radiator, Race louvers in the hood, Watson racing radiator ducting, and a massive series 9, 60 row oil cooler, running water with wetter water. The Temp on oil was never over 212, and 209 on coolant after running the car in 2nd gear at 6800rpm for 3 miles down the road. During this run the head temp did register 235 toward the end, which leads me to believe that even though I should be able to stay well below the danger point in real temperature extremes the computer will still want to cut power. If this is the case I plan to change the table that limits the power to a higher threshold since I am now looking at real oil and coolant temps. I will be able to test this on the track this Friday so I will have much better more accurate numbers to share especially since the highs for the day are supposed to be 97deg.

Will be interesting to see how it does on the track. That will be a very hot day. Keep us posted if you have time. Any thoughts on why the big difference (26F) between coolant temp (209F) and CHT (235F)? From memory, your last run showed about 15F ... which is inline w/ OEM calc on my 2020 model (13-14F).

Sponsored