Keeping Engine Cool With AC

[fishinman78]

Just finished a build on a 76 Ranger

I have built several Broncos over the years but we wanted this one to have AC so I bought a kit from Classic Auto Air.

Drove the Bronco around without AC with success keeping it cool (granted not in 98 degree weather). Now that I have the AC finished it's running Hot. At least hot for my liking. Temp was 98 yesterday here and while steadily moving at 50mph I could keep the temp around 205 with the AC nice and cold. At a stop light temp would creep up depending on the amount of time. Stop and go traffic seems to maintain 210-215 but as soon as it sits and idles temp climbs. Got it home and let it sit for a few minutes after a drive and shut it down at 221

Specs:
Rebuilt factory engine with RV cam
192 degree thermostat
Factory cast iron manifolds
2 Bbl sniper EFI factory iron intake.
C4 with remote cooler. (Not running through the radiator)
Explorer Serpentine with metal fan and the 46049 heavy duty fan clutch 1/2" of the fan is out of the shroud
Toms offroad reverse rotation aluminum radiator with Ron Davis Full circle fan shroud
75% water /25% coolant mix
The condenser pretty much takes up the entire opening in the core support

I have an airdam installed between core support and grill as well as rubber air dams on both sides of the radiator and one at the top to seal it at the grill.

Not really sure what else I can try...

I have a set of pederated fender skirts so I am considering cutting out the inner fenders and using them but not excited about it.

Also considering a condenser fan set-up similar to the attached picture but don't want to waste time and money

Any help or suggestions would be appreciated.

 

[1969]

Not sure how much it would help but you could drop the coolant/water to 50/50 mix instead. Water is much better at cooling than antifreeze.

 

[73azbronco]

I think you have done everything you can.

I went through this 15 years ago, trying 3 different AC unit ideas. None would work in 115. And I have some serious insulation on the body and firewall and roof.

Best advice I had, if you want your knee cap cooled, install A/C. So I didn't.

You have the best airflow you can through the radiator/condenser that you can get. Unless you go to a larger condenser, sperate fan on the condenser, i don't see you running cool unless it's 80 outside.

Agree with the 50/50 mix idea, i never run more than that, or lets say, i only use what I need for freezing or highest expected temp, say 240. But in reality, all you do is delay the heat soak that will occur as the radiator cannot remove the heat fast enough.

Fun fact, a car v8 makes about 20,000 BTU, so thats what the radiator cools. An AC condenser can pull 20,000-40,000 BTU off the AC coolant lines. Thats why your radiator can't keep up, it's trying to cool, 3 or 4 V8s worth of heat.

The only option I found for the EB, remote mount the condenser under the EB with it's own fan. Which of course, is mostly unrealistic for a 4x4 going offroad.

 

[Slowleak]

What fan blade are you running? The difference between a stock 5 blade and a 7 blade flex is huge, particularly at idle when the blade has the most pitch.

 

[fishinman78]

Not sure how much it would help but you could drop the coolant/water to 50/50 mix instead. Water is much better at cooling than antifreeze.

I already have 75% water and 25% antifreeze

 

[fishinman78]

What fan blade are you running? The difference between a stock 5 blade and a 7 blade flex is huge, particularly at idle when the blade has the most pitch.

Running explore metal fan with clutch

 

[fishinman78]

I think you have done everything you can.

I went through this 15 years ago, trying 3 different AC unit ideas. None would work in 115. And I have some serious insulation on the body and firewall and roof.

Best advice I had, if you want your knee cap cooled, install A/C. So I didn't.

You have the best airflow you can through the radiator/condenser that you can get. Unless you go to a larger condenser, sperate fan on the condenser, i don't see you running cool unless it's 80 outside.

Agree with the 50/50 mix idea, i never run more than that, or lets say, i only use what I need for freezing or highest expected temp, say 240. But in reality, all you do is delay the heat soak that will occur as the radiator cannot remove the heat fast enough.

Fun fact, a car v8 makes about 20,000 BTU, so thats what the radiator cools. An AC condenser can pull 20,000-40,000 BTU off the AC coolant lines. Thats why your radiator can't keep up, it's trying to cool, 3 or 4 V8s worth of heat.

I guess I should have elaborated more. Running 75% water 25% antifreeze now

 

[fishinman78]

You have the best airflow you can through the radiator/condenser that you can get. Unless you go to a larger condenser, sperate fan on the condenser, i don't see you running cool unless it's 80 outside.

I don't see having the room for a larger condenser. One of the reasons I was considering the two smaller fans was to help keep the condenser cool

 

[Slowleak]

My stock ‘77 with A/C never gets over 200 even in 90 degree weather. It has a stock Ford 7-blade flex fan, no clutch, stock radiator, and a wide parallel flow condenser. No air dams or any of that stuff. I would look into options for fan blades that might pull more air at idle. You can also mess around with different size pulleys to give your fan and waterpump more speed. My temps used to creep up like that with the old non-flex fan.

 

[1969]

You could try using a 180 degree thermostat? How old is your water pump?

 

[Timmy390]

With a 192 stat you should be seeing temps of around 200-210 in normal driving. I don't have A/C and with a 195 stat I hold 210 and in stop and go I see 215-220 which is normal. My ECM controls my fan and it kicks on high at 220.

Tim

 

[fishinman78]

You could try using a 180 degree thermostat? How old is your water pump?

Water pump is new. I tried a 180 first and then went to a 192 hoping for better cooling .

Engine operates at about the same temps for either thermostat

 

[fishinman78]

With a 192 stat you should be seeing temps of around 200-210 in normal driving. I don't have A/C and with a 195 stat I hold 210 and in stop and go I see 215-220 which is normal. My ECM controls my fan and it kicks on high at 220.

Tim

I might just be worrying too much. Never had a Bronco that ran this hot

 

[jckkys]

Right now it's 107 here, and that's not unusual for Tucson. The EBs have many things working against them also. The area of the radiator is tiny to fit between the frame rails, and the radiator has little room in front of it. So for me; open windows is the strategy. With the dry air we don't suffer too much. But then I drove a UPS truck here for 21 yrs. and that was much worse than the EB. I got out and stood in the sun to cool off !! As the original owner of a '73 that was replaced by my '77, I decided that no AC is the only choice for me. If I have to cool off, I go to the mountains.
I'd rather drive with hot dry air moving over me, than sitting on the shoulder waiting for the engine to cool down. For 9 months of the year, and or 15 hrs. a day/night the heat isn't a problem.

 

[73azbronco]

Right now it's 107 here, and that's not unusual for Tucson. The EBs have many things working against them also. The area of the radiator is tiny to fit between the frame rails, and the radiator has little room in front of it. So for me; open windows is the strategy. With the dry air we don't suffer too much. But then I drove a UPS truck here for 21 yrs. and that was much worse than the EB. I got out and stood in the sun to cool off !! As the original owner of a '73 that was replaced by my '77, I decided that no AC is the only choice for me. If I have to cool off, I go to the mountains.
I'd rather drive with hot dry air moving over me, than sitting on the shoulder waiting for the engine to cool down. For 9 months of the year, and or 15 hrs. a day/night the heat isn't a problem.

This^ so i moved north of Payson

 

[Broncobowsher]

There is one thing I see that could help. You state 1/2" of fan out of shroud. Trim the shroud back about an inch. The fan not only flows axially, but radially as well. A little more blade exposed can add a little centrifical airflow.

What is the gap between the fan and shroud? This can get sketchy. The more that gap closes up, the better the fan works. But too close and the rubber mounted radiator moving on the rubber mounted body that flexes around itself, can run into the fan that is on rubber motor mounts. Lots of layers of flex that stack up. So there has to be clearance.

While thinking of things. Look at the fan blades. The concave side. Facing the engine? If yes, you got it right. If not, don't do anything else until you flip the fan over. The fan will only move a fraction of the air if the concave side faces forward.

 

[1969]

What about cutting part of the inner fender well out and possibly a hood scoop to increase air flow?

 

[fishinman78]

A quick update. I added some VP Racing "cool down" just out of curiosity (similar to water wetter), 2 bottles and it did in fact lower the operating temp under most conditions. I drove the Bronco to Dallas, Oregon with the AC cranked. This drive is mostly back roads driving 45-55 mph, and the temp stayed around 195 consistently, outside temp was 97 degrees.

I did find that the temp crept up while driving in stop and go traffic. Saw temps around 205-210. If I was able to get up to any speed consistently in town, the temp would hover around 200.

I think I am going to try the two small fans mounted to the condenser and see what happens. They aren't horribly expensive, and keeping the condenser cool with enough airflow seems to be the ticket. I will report back in a few days

 

[Tricky Dick]

Maybe a remote oil cooler could shed some load too?

 

[joebronco73]

There is one thing I see that could help. You state 1/2" of fan out of shroud. Trim the shroud back about an inch. The fan not only flows axially, but radially as well. A little more blade exposed can add a little centrifical airflow.

What is the gap between the fan and shroud? This can get sketchy. The more that gap closes up, the better the fan works. But too close and the rubber mounted radiator moving on the rubber mounted body that flexes around itself, can run into the fan that is on rubber motor mounts. Lots of layers of flex that stack up. So there has to be clearance.

While thinking of things. Look at the fan blades. The concave side. Facing the engine? If yes, you got it right. If not, don't do anything else until you flip the fan over. The fan will only move a fraction of the air if the concave side faces forward.

I'm a mechanical engineer that works in HVAC design and I would caution against this - the shroud is meant to direct air through the radiator. Yes, Bowsher is correct that the fan can spin air off radially, but the system is designed to pull air over the coils inside the radiator, which is where your engine cooling takes place.

It would seem the best alternative is an electric fan that isn't modulated by engine speed (slows at idle or traffic speeds).