For anyone with a T-Bird, there is an erratum put out by Ford many years ago covering how the hood intake affects airflow through the radiator. At highway speeds there is enough air forced into the top of the engine bay to reduce flow through the front. I've never tried it, but Ford recommends blocking the intake over summer to help with cooling.

I had a customer that had a 455 Olds in a Firebird. He had a place in Palm Springs that was over 110 degrees in summer.He liked to drive fast to get there quickly. It had been to a few other shops  that upgraded radiator, shroud, fans and air ducting. The problem continued for over 3 years.
I installed an engine oil cooler, overheating problem solved.

Lovely and refreshing for a change to listen to someone who actually understands auto sciences.

Nice videos, keep them coming.  I'm from Australia and like to share my experiences,  I have a 406 SBC,  642HP , AFR headed.  runs 10.52@130MPH in 3600lbs car.  Mine is very well behaved temp wise.  Can sit in 38C deg traffic and will sit on 185 to 190F.  I run a 180 deg thermostat with 3 x 4mm holes around the outside.  I found with a 160 high flow the water travelled to fast to cool down.   sat on 200F.   Thick thin radiator, runs the same with both, had a 1inch , went to 2 inch. ran the same.  Runs a 1985 Camaro radiator.  2 x electric fans that come on at 173F.  I find if water starts to cool in radiator before thermostat opens it's much better controlled. My thermostat hardly ever opens as it sits around 170F most of the time.  With pulley size when I had mechanical water pump.  I fitted a serpentine set with a larger bottom pulley,  lost 1.2mph over the qtr.   Put a smaller puller on the bottom and got mph back. You can lose 13HP with over drive pulley.  Now run an electric water pump.   I run 24 initial timing and 33 total.  Just sharing what works for me.  Cheers from Australia.

The reason why people use coolant restrictors, is to keep the coolant in the radiator longer, therefore the the returning water is cooler. But you should use a thermostat as the restriction. You should also mount the radiator on a 3 to 5 degree angle so radiator itself restricts and catches the airflow, holding the incoming air between the radiator tubes longer.

U can just wire a relay to your electric fan with a temp probe and never have to worry about switching the fan on again.

Great videi! Also, couple things may be to add. For heat transfer, its flow X specific heat X deltaT. Specific heat is 4184 j/kg K for water, but will be less based on the glycol mix percentage.

Also, pulley ratio should be 1.2 to 1.3 to the crank for AC vehicles, or 1 to 1 for non-AC vehicles for vehicles operating in normal driving rpm ranges. Also, apart from higher pressure radiator caps getting more heat transfer, they can offer benefits to reduce caviation which can cause hot spots due to air pockets.This is important for vortec heads bc they lack the internal bypass, so a bypass hose is needed if the vehicle doesn't have a heater core as a bypass. The Tstat should also have a small hole drilled in the Tstat to bleed off trapped air.

Lastly, it may sound stupid, but test your sending unit with boiling water even if its new and the same one you've used before prior to install. Plus make sure its the proper one. I chased what I thought to be a overheating issue on a new build with a brand new sending unit, but turned out it was just a bad sending unit and resistance range was off despite it being new and the correct PN.

Always enjoy watching your videos and seeing how others with a ton of experience do things. While I do some things differently, thank you for taking the time to share with us. This old dog learned a few things!

Excellent video. Worked on a 1930 Packard years ago that would overheat. Big heavy luxury car. Had adjustable timing by driver on the fly. Owner didn’t realize timing was off and caused it to run hot.

Nice to see Alan!

I think I listed points that I always address when fixing a heating problem, in a comment on one of your videos a while back.

Most recently I put those points to use helping someone with their big block 496 cutlass. Brought engine temps from 230 and higher to a steady 170-185. The factors were under driven water pump, top rad hose higher than the rad cap, poor quality water pump, low fan air flow, no coolant expansion/recovery tank, rad core not sealed to the radiator support, and low ignition timing, including no vacuum advance. With everything fixed, it still ran hot on the highway. Adding vacuum advance dropped highway temps 30 degrees, making it 170-185 all the time.

Tell your son depending on the core size of his race car, look at Proform brushless fans. They work great. Or some OEM type fans. Dorman 620039 works great, and is 24x19 with the mounting tabs cut off (30x21 with them) and 4.5” thick.
It pulls an honest 4-4300 cfm measured through the core. About 20 amps per fan.
It also comes with brushless motors, dorman 620039XD.

Ensure the wiring is proper, with proper gauge for the amp draw and run of the power AND ground for the fan motor added together. The power circuit is power and ground so you need to add their lengths together.
I use this chart all the time.

https://jascoautomotive.com/automotive-wire-amperage-capacity-chart/

I also always use EMP Stewart thermostats.

Remember, when the car used to overheat, we turned the heater on to call the motor cause you got more water volume,
So we did we tapped into the heater and ran into the front area, in front there’s always space in a muscle car. with 5/8 hoses 6 feet
long going and coming attached them to heater cord and that thing runs great If you still wanna run water to your heater, just put a LT plastic adapter and you still have extra extra water if need be.

South ga summers will put any cooling system to the limit.

I live in tucson and often find myself dealing with the anxiety of being stuck in traffic while my temp gauge creeps past my comfort zone. And those hot 112°+ days always seem to be the ones that I'll catch every red light in town.

Racers I knew used restrictors to control flow rate in the engine. An open thermostat accomplishes that, but racers tend to worry about component reliability. A thermostat can fail at any time and stay closed.
The ID of the restictor is determined on track by watching the coolant temperature. If it is running a little cooler than desired, a smaller ID may be required. Conversely if it is running warm then a larger diameter may tune it.

We have to put in the account that hot air is still being trapped in the engine compartment. Old engines do get hot very fast because of the design. My 07 Ram Hemi I put an electric fan on it because I was doing a fuel mileage experiment with a manual switch. I didn't need to turn that fan on while moving. I couldn't let anyone use my truck because of the switch because I did forget to turn it on a few times while idling in the drive way.  I person could get a nice hood to let the hot air out, Trans Am cars had them built into the fenders.

Took me 2 months of playing around to get my 12:1 iron headed solid cam 427 in a '64 Chevelle to finally not overheat in 30+C weather.. 16" 2500-3000 cfm puller and pusher fans (on relays of course) custom 1" fan shroud (1" from surface spacing) covering every inch of the radiator surface, bigger jets to run a little richer than needed, hottest thermostat I could get my hands on (not that it makes much difference when it's open after initial warm up..). Pulled back the timing as much as I could without loosing too much power and ran good fuel with octane boost. Swapping to 3" exhaust pipes and lower restriction mufflers. The result was 200-206 in the hottest weather, at the very most. Products such as water wetter can only do so much. The next step would have been waterless coolant but I figured things out before going to that, which is a rather expensive deal. You can get there you just need to keep tuning and testing.

have another drink

Thanks AG. Always learning something. Alot of the things I forgot.

On small blocks where the water outlets are blocked off on the firewall end of the engine. Drill and tap for 1/4 pipe plugs. Run two hoses to the thermostat housing below the thermostat. Use 3/8 hoses at least. Some one makes a kit to install these.

great video...Thanks