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Ask AJ Hartman - Aero Questions

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cholmes1

400lb Gorilla
350
216
Denver, CO
Thanks. The side planes between the wheels seems to be a easy place to start as they are already relatively flat and easy to mount upon.

I also agree that attempts to use a single sheet of aluminum or ABS on the front clip will likely lead to overheating if special accommodations aren’t made. Perhaps louvers as heat extractors could be the path.

I most interested in a functional rear diffuser and believe it would sell well but how large to make it is always the question. That and most everyone’s rear end varies in terms of exhaust and rear axle setups.

I look forward to seeing your progress and photos.
 
2005 mustangs have a issue where the hood flutters at speed. I noticed some people putting a belly pan from a 2010 on the first get s197’s. Curious on your thoughts if it would actually do anything.

378AA5E4-0AA2-4B06-8104-0103625DB520.jpeg
 
2005 mustangs have a issue where the hood flutters at speed. I noticed some people putting a belly pan from a 2010 on the first get s197’s. Curious on your thoughts if it would actually do anything.

View attachment 12995
I would do hood louvers. Air out the top of the hood is much less detrimental then dumping air under the car.
 
Hey AJ,

I watched all your Videos on the flat floor, I know you will see some airflow to the trans but I would be surprised if it is enough and by closing off the tunnel you will be trapping a large amount of heat in that airspace with little fresh air movement. I would plan on a pump and cooler or if the rules allow swapping to the Tremac with the internal pump or even a Magnum.

I tried all kinds of cooling solutions for the MT82 even without the flat floor to keep it cool and it was not uncommon for it to hit 260*F even on short 25 min sessions. You are pushing as hard if not harder than me and it will get hot on you for sure. Even the Ford Performance air scoop trans cooler that is in the undercar air stream and direct all the air to the fins on the trans is barely enough to drop the fluid temp in to the 240-245*F range. If you are going to rely on air cooling I would add a catch can to the MT82 vent or extend it to above the valve covers in the engine bay to prevent it from puking trans fluid down the tunnel.

By the way enjoy the vids and your work.

Dave

IMG_6359.JPGIMG_6360.JPGIMG_6361.JPG
 
Hey AJ,

I watched all your Videos on the flat floor, I know you will see some airflow to the trans but I would be surprised if it is enough and by closing off the tunnel you will be trapping a large amount of heat in that airspace with little fresh air movement. I would plan on a pump and cooler or if the rules allow swapping to the Tremac with the internal pump or even a Magnum.

I tried all kinds of cooling solutions for the MT82 even without the flat floor to keep it cool and it was not uncommon for it to hit 260*F even on short 25 min sessions. You are pushing as hard if not harder than me and it will get hot on you for sure. Even the Ford Performance air scoop trans cooler that is in the undercar air stream and direct all the air to the fins on the trans is barely enough to drop the fluid temp in to the 240-245*F range. If you are going to rely on air cooling I would add a catch can to the MT82 vent or extend it to above the valve covers in the engine bay to prevent it from puking trans fluid down the tunnel.

By the way enjoy the vids and your work.

Dave

View attachment 55846View attachment 55847View attachment 55848

Thanks for the advise. I mention in the video why I opted against a pump at this time, but not saying its wrong. Keep in mind that the exhaust now runs down the side of the car along the rocker panels. So there is very little heat trapped to begin with. Plus a nice clean airflow of cool air due to very little exhaust heat, or engine/radiator air making it to my cut in vents, the cut in vents probably flow much better than dirty, hot air making it to the air scoop you mentioned. I could be wrong, but it was about 95* at Lime Rock the other weekend and all went well, but one race weekend isn't a huge measure of success.
 
I added the scoop to my first build in an effort to avoid the eventual trans swap on all subsequent builds. I was not really ever thinking about trans temps with all the known issues of diff temps getting too high. While the diff does run hot and heats up quicker at higher speed tracks the trans is not far behind. I am sure that is can be influenced by the OEM exhaust path and airflow through the engine bay which you have addressed by your setup but I was shocked at how hot it got and how quickly it would heat up when I added a temp sensor to the drain plug in order to measure fluid temps. I was seeing rapid increases in temps over a 25min session and even with a hour wait time between runs not much heat was shed between runs so it was always running with fluid temps in the 250-255*F range and would spike to 260*F. The FP trans scoop sits quite low under the car and should scoop up quite a bit of air and it just did not drop the temps that much. It was not ideal for long sessions but probably enough if you change the fluids more often.

Now I run a 10 row Setrab trans cooler mounted out front with the Tremac trans and internal pump. Fluid temps are in the 160-180*F range under all conditions. By the way let me know if you need any spare MT82s, I have a stock pile of them and will trade for cool light weight carbon bits if you are interested.

Dave
 

Fabman

Dances with Racecars
6,519
8,155
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
I added the scoop to my first build in an effort to avoid the eventual trans swap on all subsequent builds. I was not really ever thinking about trans temps with all the known issues of diff temps getting too high. While the diff does run hot and heats up quicker at higher speed tracks the trans is not far behind. I am sure that is can be influenced by the OEM exhaust path and airflow through the engine bay which you have addressed by your setup but I was shocked at how hot it got and how quickly it would heat up when I added a temp sensor to the drain plug in order to measure fluid temps. I was seeing rapid increases in temps over a 25min session and even with a hour wait time between runs not much heat was shed between runs so it was always running with fluid temps in the 250-255*F range and would spike to 260*F. The FP trans scoop sits quite low under the car and should scoop up quite a bit of air and it just did not drop the temps that much. It was not ideal for long sessions but probably enough if you change the fluids more often.

Now I run a 10 row Setrab trans cooler mounted out front with the Tremac trans and internal pump. Fluid temps are in the 160-180*F range under all conditions. By the way let me know if you need any spare MT82s, I have a stock pile of them and will trade for cool light weight carbon bits if you are interested.

Dave
This is something I haven't addressed. So far I haven't burned anything up but that's not much of a metric.
Any idea what the delta between the fluid temp and the case temp might be?
A temp gun is a lot simpler than routing yet more gauges into this thing.
Just a thought, I know we have some smart engineers on site...anybody venture to guess?
 
16
6
Exp. Type
W2W Racing
Exp. Level
20+ Years
Denver, CO
Do you have a video or an article somewhere where you go over how you make your wings?

Do you start with a foam core and then layers on top of that?
 

Mad Hatter

Gotta go Faster
5,237
4,227
Santiago, Chile
I added the scoop to my first build in an effort to avoid the eventual trans swap on all subsequent builds. I was not really ever thinking about trans temps with all the known issues of diff temps getting too high. While the diff does run hot and heats up quicker at higher speed tracks the trans is not far behind. I am sure that is can be influenced by the OEM exhaust path and airflow through the engine bay which you have addressed by your setup but I was shocked at how hot it got and how quickly it would heat up when I added a temp sensor to the drain plug in order to measure fluid temps. I was seeing rapid increases in temps over a 25min session and even with a hour wait time between runs not much heat was shed between runs so it was always running with fluid temps in the 250-255*F range and would spike to 260*F. The FP trans scoop sits quite low under the car and should scoop up quite a bit of air and it just did not drop the temps that much. It was not ideal for long sessions but probably enough if you change the fluids more often.

Now I run a 10 row Setrab trans cooler mounted out front with the Tremac trans and internal pump. Fluid temps are in the 160-180*F range under all conditions. By the way let me know if you need any spare MT82s, I have a stock pile of them and will trade for cool light weight carbon bits if you are interested.

Dave
Lol, me too, went through five of them suckers!! added a Setrab 915 cooler with a pump and temps went from 300 to 180-200, That was with a extra big cooling duct under the car. Finally got fed up and added a Calimer stage 3 Mt82 and temps went down to 180 with out the pump.....
 
100
109
Utah
Aj:

Aero question related to S197 Mustangs and cold air intakes. Generally cold air intakes work and some work better than others. My goal is to get the coolest air I can into the S197 throttle body. The coolest air available is always the ambient air and not air in the engine compartment or air from the fender wells, etc. This may seem a crazy or stupid but I will ask anyway. The s197 normal throttle body is located at the front of the intake manifold. The normal S197 cold air intake system is norrmally located in the left front corner of he engine compartment. Now completely remove that normal cold air intake. Then Cut/insert a NACA duct in the center front of the hood with the NACA duct exit in front of the throttle body which has an airfilter in front of the throttle body. The air into the NACA duct will not have any ram air pressure at all but will be cool ambient air going nearly directly into the throttle body.

Note: The NACA duct for combustion air may be a problem during rain. Regardless, this Mustang is a tracked car only, NASA TT3, always slicks so no rain because no rain tires. Just a fair weather tracked NASA TT3 Mustang so rain entering NACA duct to throttle body is a non issue in this case..
 

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