Radiator Purchase

There was an article in one of the Model A magazines,maybe from the 70's,by somebody that made a tool to dimple the fins with out of a pair of duck bill pliers.They just filed away one jaw and left a nub sticking up in the middle,then filed the other jaw leaving a place for the nub to stick into.Pretty simple,but not something I'd bother with. A radiator guy told me years ago that dimples,bends,and kinks were put in the early radiators to keep the thin fins from vibrating like a blade of grass in the wind.I understand the theory,but I don't know if it amounts to anything in the real world.Probably not as everybody went to straight fins.I've hauled quite a lot of sheetrock and lumber over the years.If I ran my straps down to the trailer in perfect flat runs,they would vibrate,buzz,and self destruct in no time.If I put a couple of twists in them,no noise,and no fraying to destruction.
 
I made a pair of pliers into a tool to fix the bent dimples on my Studebaker radiator many years ago. Straightening all the fins was time consuming, but worth it for the good looks.
 
I remember reading somewhere, maybe here, not too long ago about the dimples in the fins of the 30-31 radiators. It was said that they served some purpose in cooling. My homework with model A's over my lifetime tells me that there is no noticeable improvement. The 28-29 radiators that I have and have seen all have flat fins. The three heavy duty 30-31 radiators that I have bought, all from different vendors, all have flat fins and cool really good. I have an original dimpled fin radiator on my speedster. It may not be a fair comparison . the original radiator was boiled out in 1977 and I run it for years on the coupe. When I redid the coupe I installed a heavy duty new radiator and the original dimpled fin radiator ended up on my speedster, it still works good. I think the dimpled fins are more important for show cars that need to appear exact original or lose points.
 
Yes, that was my angle for the question, just for aesthetics and judging. It would be tedious to do manually with the pliers mentioned, but really... when has that ever stopped us in our hobby?
 
ctlikon0712 said:
Yes, that was my angle for the question, just for aesthetics and judging. It would be tedious to do manually with the pliers mentioned, but really... when has that ever stopped us in our hobby?
Click to expand...

Quote taken from Brassworks radiators:
The dimpling process tumbles the air and minimizes the impact of Laminar Flow Theory. Air has viscosity and by disrupting the boundary layer with dimples we improve cooling.

Is this something we all buy into? At 6 dimpled fins per inch (original) vs. 10 fins per inch (some reproduction), where is the trade-off (--or equal) in efficiency??
 
BRENT in 10-uh-C said:
Quote taken from Brassworks radiators:
The dimpling process tumbles the air and minimizes the impact of Laminar Flow Theory. Air has viscosity and by disrupting the boundary layer with dimples we improve cooling.

Is this something we all buy into? At 6 dimpled fins per inch (original) vs. 10 fins per inch (some reproduction), where is the trade-off (--or equal) in efficiency??
Click to expand...
I think we should get NASCAR to put some Model As in the wind tunnel they use for testing air flow on the spoilers & we can find out about our radiators !! :eek::rolleyes:
 
Yes, as quoted above, I really don't care about the minute differences in efficiency. I just want to replicate the look. Brent, as a judge, would you say that the 30-31's without an original radiator (rare) are judged more favorably if they have the dimples? If I'm not mistaken you get half the points deducted for a repop part even if it's correct........
 
Perhaps you've already checked local shops, but when I did, I found an enthusiastic guy who recore my '28 radiator for $150. Its been running cool for years now. So it is possible to have the work done by someone outside the hobby.
 
My local guy in New Milford says that he can't find a source for cores for A radiators... he knows about Berg's, but they will not sell cores to local shops... only complete radiators...
 
ctlikon0712 said:
Yes, as quoted above, I really don't care about the minute differences in efficiency. I just want to replicate the look. Brent, as a judge, would you say that the 30-31's without an original radiator (rare) are judged more favorably if they have the dimples? If I'm not mistaken you get half the points deducted for a repop part even if it's correct........
Click to expand...

Well, I cannot comment specifically on "judged more favorability" because I have never judged Area 3 Cooling, however I have attached a copy of my spreadsheet that replicates the regular judging sheet so you can see how the points in that area is broken down.

Your last sentence is a little confusing to me however let me just say it this way based on my own experiences. Rarely does it say specifically how much a judge should deduct for a reproduction part therefore I have found consistancy in scoring to all over the place. Theoretically in the case of a reproduction radiator you could receive as little as 2 or 3 point deduction (out of 40 points) ...or maybe a 30+ point deduction for a "repop part" just depending on how the Team Captain views the item.

I will tell you the Brassworks 30/31 dimple-finned radiators I have used on two vehicles have scored without any deduction. The Brassworks 28/29 radiators have received deductions however when Gery Bergbower used original tanks and straps on his cores, they scored without deduction.

Hopefully this has answered your questions???
 

Attachments

i wonder what a replacement radiator would have cost in say 1930. we now pay more for a radiator than the car cost when they were new.
 
BRENT in 10-uh-C said:
Quote taken from Brassworks radiators:
The dimpling process tumbles the air and minimizes the impact of Laminar Flow Theory. Air has viscosity and by disrupting the boundary layer with dimples we improve cooling.

Is this something we all buy into? At 6 dimpled fins per inch (original) vs. 10 fins per inch (some reproduction), where is the trade-off (--or equal) in efficiency??
Click to expand...

BRENT in 10-uh-C ................
I don't know what the Laminar Flow Theory is, but I'm thinking that the dimples might keep the air from flowing through the tubes, too fast, to do much good. ?????
MIKE :)
 
FL&WVMIKE said:
BRENT in 10-uh-C ................
I don't know what the Laminar Flow Theory is, but I'm thinking that the dimples might keep the air from flowing through the tubes, too fast, to do much good. ?????
MIKE :)
Click to expand...

I dunno either but something we learned back in the mid 90's while we were GreatRace-ing is that when we were traveling through the desert, the vehicles tended to overheat on long pulls because of the extremely dry air passing through the radiator. The trick the veterans taught us was to mount the "nozzle end" of a bug sprayer onto the backside of the headlight bar, and run a length of hose to the reservoir (pump end) and mount a little valve inline into the supply hose. All it took when climbing those hills was to mist a tiny amount of water in front of the radiator and the engine coolant temps would drop something like 20 degrees. The reason we were told this worked was because the fins could dissipate the heat better into the moist air in lieu of the arid air which was passing through the radiator. Ironically this did not seem to make any difference on the same car as we pulled mountains around here while prepping the car for the race.


31TouringRD.jpg
 
I am of the opinion that the boundary layer that is most near the surface (fin) is sublect to some small amount of friction and thereby travels slower. In addition, the air that flows between the boundary layers travels faster, but is not near the fins, so it's ability to transfer heat is minimized.

The little dimpled lip acts as a spoiler and similar to a 'gurney lip' found on open wheel car rear spoilers, it creates a small amount of turbulence and make more of the air get in contact with the metal surface and more heat will be transfered and moved away.

The small amount of this additional turbulance will also cause a minor drop in air pressure at the exit side of the radiator and that will slightly increase air flow. That is also what I believe makes the engine pans work. The rear of the pans is lower in the rear and air passing underneath it has to pick up speed as it passes underneath, and it works just like a carb venturi. As the air increases in speed, it developes a lower pressure and that draws the air above the enging pan away from the motor. I have seen this as a 1/16" to 1/8" drop on the Motometer temperature indicator, after adding the engine pans.

Just a thought!
 
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Yes, that answered my question Brent, Thanks! :) I think I got that from a discussion about the repo A Ford batteries. One entrant in a MARC sanctioned show only received half points for a $300 dollar battery and wasn’t happy. Rockhillwill, I think you hit the nail on the head. That all makes sense, great discussion guys!
 
Thanks Carl.

Each time I loose some hair, apparantly some skills go with them, and typing is most willing to leave. LOL
 
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