3 Core vs. 4 Core Radiator

[JKH67302]

My stock radiator is shot and will need replacing. I have made the decison to go copper only for the longevity and repairability. So the question is high-efficiency 4 core or stock 3 core. Does anybody have some good tips on which is better. Reading through threads many people comment on having problems with 4 cores. I don't know why this is but maybe someone could shed some light.

 

[SteveL]

bc 3-core. The 4-cores spring leaks where they are mated up to the 3-core ends. You might be able to get one built with your radiator to the BC specs at a local shop otherwise I've had the best luck with his. I just run his standard 3-core to cool a 351w in both broncos with no problems driving in LA traffic and heat.

 

[broncnaz]

I've had better luck with 3 row radiators. One of the problems I feel 4 rows have is its harder to pull air through them due to there thickness which in the nbed doesnt help cooling.

If your 3 row was working fine you may as well stick with what works.

 

[jimyJack]

No problems with my 3 core and I run an electric fan and the clearence is tight.Dont want a 4 core.

 

[RIbronco]

I bought a 4 core from JBG only to have it fail in multiple locations along where the end tanks meet the core. As SteveL pointed out, they use end tanks from a 3 row and put a 4 row core in between. Due to the parts not truly fitting together correctly, the solder joint is not as strong as it should be. I also questioned the build quality related to the soldering, but that's another topic all together.
There is also the airflow that broncoaz mentioned. True, the will be less cfm pulled through a 4 row vs a 3 row (assuming the fin pack is the same).
Also, you have to take heat transfer into consideration. By going from a 3 row to 4 row will not pick up 33% more heat rejection. By the time air gets to the 4th row, it has already been heated beyond what the exit temperature would be for a 3 row (less cfm, so more time in the radiator to pull heat = higher temperature) This hotter air will not be as effective at pulling heat from the fins of the 4th row. I'm not about to do the math on this, but I would expect less than a 20% increase in capacity. There are a lot of other variable to take into consideration, like coolant flow, ambient temperature, altitude, etc....

Bottom line. Unless you have a properly functioning cooling system that is not capable of keeping the engine cool with a 3 row radiator, there is no need to go with a 4 row radiator.

 

[Viperwolf1]

I once bought a 4 row radiator and found it didn't cool any better than the old 3 row.

 

[Rockin69er]

I once bought a 4 row radiator and found it didn't cool any better than the old 3 row.

Same here..........

 

[JKH67302]

Thanks a lot for the good info. I have heard the same thing about flow being harder through a 4 core. I will begoing with the 3 core.

 

[JKH67302]

Have any of you ran the stock high efficiency radiators from Toms?

 

[Z Bronco]

Just to be a Devils Advocate. I have had the same 4 core radiator in my bronco for 23 years, the fin design is straight compared to the curved fins I have seen in many. My radiator has performed great with no problems. That being said the builder of mine went out of business years ago, plus I agree that a properly functioning cooling system is a must regardless of radiator used and that I feel is the key. Just thought I would speak up for the 4 core people.

 

[00gyrhed]

Wow you guys have had some intersting experences.

I would like to know how you verified that the CFM through the radiator dropped or did someone just tell you that. I deal with heat transfer equipment for a living and it would very hard to get an accurate REPEATABLE measure of CFM through a radiator mounted in a Bronco.

Just because exit air temp went up does not mean CFM went down. That is only true if the rate of heat transfer did not change and by definition it HAD to change the heat transfer area changed. You would expect the temp to go up based on the extra surface area. Why do think it matters what the leaving air temperature is anyway. As long as it is less that entering water temperature you are still doing work.

As to the construction problems, I just took my old three row the a local radiator shop and he let me look through several core types. I fianlly picked one an he put my tanks on it. I Haven't had any issues and the bronco certainly runs cooler while wheeling in 105 degree conditions.

Not sure what type of core you guys are comparing but genrenally when stepping up to a 4 row core water flow increases slightly (good thing), HT area jumps anywhere from 20% to 35% dependant upon the fin arrangement, Air flow is only restricted when a dense fin count is used. In my case I am pretty sure my airflow went up. I actually measured velocity in front of the radiator in several places before the change and again in the same places after the change. (I had heard these facts) I can tell you that in those spots the veocity increased. If you know anything about measuring air flow though that is not a gaurantee CFM actually increased. But it is a good indicator. More air, more water, more area, Higher airside temperature differnece, mean only one thing MORE HEAT TRANSFERRED.

 

[broncnaz]

While CFM probably didnt change it is harder to pull air through 4 rows of fins then it is 3 rows. Less restriction means more air flow in most cases but then again you add a 4th row and its closer to the fan and the area its pulling air through has decreased so it stands to reason that you might actually see a increase in veocity. Had the 3 row been just as close would have it seen the same increase? There's a lot of factors involved.
But a lot of people have had good luck with 4 row radiators. Some are good some are bad I also had issues with the tanks on my 4row. it had 4 row tanks but they were just made to thin in my opinion and would flex due to heating and cooling and leak at the seams. I can flex the tanks with my fingers thats how cheaply they were made. The 4 row worked to good in the winter and not very well at all in the summer it ran hotter and would eventually start leaking again.. Went back to a 3 row from BC because I got tired of fixing the seams in the 4 row and I havent had a issue in years.

 

[JKH67302]

Gyrhead...what specs did you go with on the re-core? Was it still 3 core or a 4 core?

 

[Oatmeal]

Fin count plays a big role in the radiator's ability to shed heat not just number of rows. I had a K-Bar-S (remember them) 4 row years ago and it wasn't that impressive as far as cooling was concerned....it was thicker (my fan ate it) flowed a lot of coolant but, never cooled any better than my original radiator. Did a little research and found that my HD 4 row only had 11 fins per inch. After the fan dining on my radiator, I had my old one recored with a high efficiency Modine 3 row core with 14 fins per inch and never had any more cooling problems after that---------Hans

 

[NYLES]

Im good n confused now! I know my 4 row dont get it done, seriously thinkin Aluminum.

My 4 row will not cool at creepy crawly speeds, stock fan and ele pusher, hit road speeds cools off in just a min????

 

[00gyrhed]

Im good n confused now! I know my 4 row dont get it done, seriously thinkin Aluminum.

My 4 row will not cool at creepy crawly speeds, stock fan and ele pusher, hit road speeds cools off in just a min????

Contrary to the people that seel these fans say, an electric pusher does not always mean more air flow and often times it means sigficantly less. They can easily restric airflow. Hard concept to explain but many a young mechaical engineer has been burned by not properly designing fan entrance and exit conditions.

Also what he said above is true. Fins increase the airside surface area and the air side is the hardest side to drive HT. The HT coeff of air is much lower than water that is one reason a well made 3 row might exhibit better HT than a 4 row.

The basics of good bronco cooling are as follows.

1. just because the temperature gauge says its doing 250 DEG F doesn't mean it is. Check and verify that the temperature gauge is correct before you spend a lot of money chasing a problem you do not have. Take it out and dump it in a boiling pot of water it had better read 212 at sea level and whatever water boils at you elevation. Also check another position at say 150 or so.
2. If you are not boiling water out of the radiator you are NOT damaging the engine. Even a 50-50 mix with a 16# cap will not boil out until like 250-260 DEG F and that engine will be fine with a 250 DEG F water temp.
3. Run at least a 190 DEG thermosatat. AT LEAST.
4. Make sure your radiator is clean inside and out. If there is scale on the inside of the tubes go get a new core. stock 3 or a 4 row will work and you do not need a high dollar aluminum radiator, unless you have somereason your engine needs to reject more heat.
5. Shroud, shroud, shroud, shroud.
6. just in case you didn't understand you NEED a shroud in a bronco. The shoud needs to be relatively tight or even sealed to the tanks of the radiator. the fan end shoulD NOT extend more than half way across the fan blades. Because there is an engine right behind the fan the fan MUST be able to sling the air out, but you need at least half the fan covered to get the air to flow well into the fan. A bald fan sittting behind the radiator reciculates air from the engine side without forcing it through the radiator. Hang a cigar down there near the inside of the radiator sometime.
7. Rare but I have seen it make sure you water pump impellors are intact. Not on a bronco but I have seen these wasted away to almost nothing.
8. Body lifts help as do opening up the fenders.

Personal experience. I have a 71 302 with EFI. 2" body lift, nothing particualy special at least these days anyway. When I first put the EFI on it I had one of those high efficiecy 7 blade prop fans with no shroud and a new 3 row rad I think BC sells the fan and if all else fails it does move a lot of air. That EFI engine ran 225 deg F on the highway all the time as well as off road. (accurate gauge and the same gauge used for all these measurements) I ran a mesquite branch as big as my arm up through the radiator and destroyed it. I had a four row core installed with my tanks and ran it with the same unshrouded fan. the ran 205 on the highway but still crept up to about 220 offroad on hot days. That 7 blade fan scrubs off a lot of HP so I built a nice tight fitting shroud and bought a hastings 6 blade fan and fan clutch to give it a try. The difference in torque in that engine is noticeable and it is much quieter to boot. The hastings fan does not move nearly as much air but OH WHAT A DIFFERENCE A shroud makes. Idleing in TX heat, offroad in 106 DEG temps, cruising at 75 MPH that same gauge reads 200-205 all the time. And thats with LESS fan.

200-205 is where the thermostat is controlling so the cooling system is doing all it needs to and then some for. I also gained some horses to boot with the clutch and the less aggressive fan.

 

[cgbexec]

Yup! OOgyrhead explained it very well! Thanks for the lesson.