Radiators and cooling problems my observations

[jerthemost]

I recentlyy had a thread on here about cooling problems on my 68 mustang after some fairly heavy performance upgrades. I have partially solved the problem and in doing so have some observations to offer as follows:

I bought a 25 x 16 4 core aluminum radiator and installed it along with 2 - 9" electric fans pushing in the front of my a/c condenser. I left the mechanical 18" 6 blade no clutch fan on with the plastic shroud. Anytime the car is moving it is fine, 165 on the highway, 175 to 185 in town while moving at least 25 mph. But when i stop the temp will fast start rising and get to 200 or more if i let it. This is with a/c on. If i turn a/c off it will still creep up but not as fast. The 2 elec fans are on a thermostat at about 180 degs so they are on when ideling. Now all of this is with osa temp of 100 to 107 here in Houston.

I read all the stuff about 4 core vs 2 core and thought the 4 would be better because it had more fin surface to conduct off the heat. I am an old mech and elec engineer and was going by my old a/c days and thermo i learned in college. But now i think i made a mistake. I think it would be better to go with the 2 core because i think the 4 core has too much resistance to air flow. If you look at todays cars they all have very thin radiators and electric fans. I looked at a sherrif's crown vic the other day and that's what it had and idles in traffic or stopped sometimes for hours.

I tried an experiment the other day. I drove home from town about 20 miles and left the car running in the yard with a/c off and was running about 195 with hood open a few inches. I put a fan i have on my porh in front of the grill and turned on a/c and the temp went to 200 but stayed there for several minutes. So obviously the problem is airflow.

With my 3 fans i should not have a problem but i really think that 4 core is just too thick. By the way i do have a trans cooler in front of rad so that is also adding some heat.

In summary i am happy with 4 core but wish i had gone 2 - 1" core instead. I am going to put a lincoln fan on before next summer and i feel sure that will take care of it.

So anyway if you are considering a new rad try a 2 core 1 " instead of the 4 core. I hope this helps someone.

 

[Rmoore45]

I was having problems cooling my mild 289 w/ ac, I installed the 2 core aluminum radiator (with 1" tubes) from engineered cooling products. I have the mechanical 18" 6 blade fan, no clutch, with the plastic shroud (that has some pieces missing lol). I using a mechanical Sunpro temp gauge with a 180 thermostat and so far with a/c on the results are (I live in the Houston area and its HOT)
180@65mph
180@40mph
180@25mph
190@15mph

It slowly creeps up to 190 while setting at a light but once moving it cools down. I let it run in the driveway for probably 15-20 minutes and got up to 200, but that's it. Only problem I could see is waiting in traffic for a long time, but I can cycle the a/c and rev the engine up to 1200rpm to cool it down. I think a couple of electric fans in combination with the fan would solve my problem completely but I pretty much have the problem fixed. The radiator works great and I polished it up and clear coated it so it always looks good.

 

[jerthemost]

thanks for your input

from what you described above it would appear that there is noot too much difference between our situaions but enough that the 2 pusher fans would probably help you quite a bit since you have a less restrictive rad.

i have been doing a lot of research on this subject and have enountered others who tend to validate my theory about the 4 being to restrictive. and shouldn't we really get more cfm from the meh fan at least at around 1000 rpm? i cannot find fm figures anywhere but it does seem like we would. so with that in mind how about going to a 7 blade flex fan?

my shroud is also made such that it sets off of the rad about 1/2" on the sides so maybe stopping up that hole would help. Also the position of the fan is such that it fita farther into the shroud than it should so maybe changing the fan spacer and moving fan back a little might also help. or maybe have someone build me a custom aluminum shroud. i am going to look into that before next summer. the flex fan being mechanical should pull better aginst the high static of the rad than an electric fan would. and i believe that the flex fan unloads at higher speed doesn't it?

 

[Hack]

How many CFM do the electric fans move? Do the electric fans have shrouds that force the air from the fan to go through the radiator? If they have shrouds, are they sealed to the radiator, or is there clearance between the fan shrouds and the radiator? I have seen a lot of threads through the years where people with electric fans have cooling problems. I'm not sure why, but I think that there isn't always enough air going through the radiator. All fans are not created equally, and the diameter of the fan doesn't tell you everything.

Possibly you are correct that a thinner radiator would work better, but I doubt it, unless there's something else wrong in the system that the thin radiator could band-aid. Yes, cars that make 150-250 hp are going to use thinner radiators than you will need.

Another side issue you could look at is verifying that the A/F ratios and timing are spot on, because those are possible sources for cooling problems.

 

[horseballz]

I may be wrong about this and would appreciate some correction, if so. The way I understand the functioning/purpose of a "flex-fan" is that as RPMs increase, the centrifugal force makes the blades flatten out to reduce horsepower consumption and the downside is that when the blades have flattened they make kind of a wall/dam impeding the air flow created by the forward motion of the car, thus creating a different set of cooling issues, I.E. reduced air flow at high RPM?
Just My $.02,
Gene

 

[PoppyMod]

Hi,
Enlight of your ambient temps of 100+, I don't regard the 200 deg as a problem. I do think you should drop that tranny cooler down, as to not add to the heated air stream. Yes, having a condenser in front, as well, adds to your incoming heat. But, this is the price to pay for AC.
Are you running a coolant recovery system to maximize your coolant levels? What T/S are you running?

 

[jerthemost]

goog points

Hi,
Enlight of your ambient temps of 100+, I don't regard the 200 deg as a problem. I do think you should drop that tranny cooler down, as to not add to the heated air stream. Yes, having a condenser in front, as well, adds to your incoming heat. But, this is the price to pay for AC.
Are you running a coolant recovery system to maximize your coolant levels? What T/S are you running?

yes 200 would not be bad except that when ideling it would not stop there with a/c on. It would keep going. And yes i am looking at dropping tranny cooler down under the front, i am just concerned about rock damage etc. so will have to come up with a rock sheild of some sort, maybe a piece of wire of some sort. No recovery system yet. My level stays about 1/2 " below top of rad. 160 deg stat

 

[jerthemost]

How many CFM do the electric fans move? Do the electric fans have shrouds that force the air from the fan to go through the radiator? If they have shrouds, are they sealed to the radiator, or is there clearance between the fan shrouds and the radiator? I have seen a lot of threads through the years where people with electric fans have cooling problems. I'm not sure why, but I think that there isn't always enough air going through the radiator. All fans are not created equally, and the diameter of the fan doesn't tell you everything.

Possibly you are correct that a thinner radiator would work better, but I doubt it, unless there's something else wrong in the system that the thin radiator could band-aid. Yes, cars that make 150-250 hp are going to use thinner radiators than you will need.

Another side issue you could look at is verifying that the A/F ratios and timing are spot on, because those are possible sources for cooling problems.

the 2 elec fans are pushing mounted against a/c condenser so air has to go thru both cond and rad whih is not best setup but best i can do. There is a space between cond and rad and i have thought about moving cond out if possible and put fans between so fans would be right against the rad. That would make a world of difference. I don't know the cfm of the fans each is 80 watts and they do put out quite a bit of air.

The mech fan shroud is not sealed against rad as i described above. I can fix that.

I know the timing and a/f could be a problem just have not been able to get timing cheked yet. I am running rich i know my plugs and tail pipes are black. But isn't it usually lean that makes it run hot? A frind who is very good on restomods told me to set timing by feel instead of timing light what do some of you guys think about that?

 

[robbz28]

I concur that you definately have a flow problem...but I still can't make the math work to where a 4 row has more tube to fin contact per row than the 2.....heres my math, someone please correct me if im wrong: the 4 row has 3/8 rows x 4 = 1.5" of area for tube to fin contact. the 2 row has 1" rows x 2 = 2" of area for tube to fin contact. The 2 row has 1/2 inch more surface area per row (1" more if you count the top and bottom of the tubes) for the fins to contact to draw out the heat. Provided the radiators are the same dimensions and have the same amount of rows.

 

[Hack]

I know the timing and a/f could be a problem just have not been able to get timing cheked yet. I am running rich i know my plugs and tail pipes are black. But isn't it usually lean that makes it run hot? A frind who is very good on restomods told me to set timing by feel instead of timing light what do some of you guys think about that?

Yes rich = cool.

Setting timing by feel is a joke to me, but then I'm a fairly anal guy and I like numbers and equations. Yes ideal timing will be different for different engine configurations, but I like knowing what the number is and knowing I'm in the ballpark. Timing lights don't cost very much; IMO they are a great investment.

 

[PoppyMod]

yes 200 would not be bad except that when ideling it would not stop there with a/c on. It would keep going. And yes i am looking at dropping tranny cooler down under the front, i am just concerned about rock damage etc. so will have to come up with a rock sheild of some sort, maybe a piece of wire of some sort. No recovery system yet. My level stays about 1/2 " below top of rad. 160 deg stat

OK. Adding a coolant recovery system will increase the coolant volume. This will come via the coolant system "burping" that 1/2' layer of air and replacing it with coolant. I don't say this is the "end-all", but, it does insure the coolant system is at max volume.
Continued good luck!