Fins on flatheads?

Seem like almost every aftermarket flathead head since the beginning of time has been finned. Why is that? Is it purely cosmetic? Do the fins actually help cooling an appreciable amount? What's the scoop? Thanks for the input.

 

i need a set for a 59ab if any one has them.

 

For the same reason brake drums ended up with fins on them. More surface area for air to pass over equals greater heat dissapation.

 

Aluminum is one of the best heat sinks out there. The fins transfer heat to the air, much like a radiator. Whether or not it's a big amount, I don't know.
However, I have done testing on finned aluminum trans pans, and there was a difference.
Everyone knows about finned aluminum brake drums, but heavy duty or sever duty iron drums (cop car and taxi) were frequently finned steel.
Car amplifiers, computers and other electronic equipment employ finned aluminum heat sinks as well, and they usually don't have fans on them, indicating (at least to me) that the heat transfer to the surrounding air is suffecient enough to keep the component from overheating.
-Brad

 

But they look so cool!

 

A couple years ago there was an in-depth tech discussion on the fins on flatheads... I think the conclusion was that the fins did more to add strength and rigidity than they did to add heat dissapation.

But then again, ford didn't think he needed fins on his 21 stud heads.

 

Fins do pretty much nothing for cooling on a flathead V8. They'd have to be much thinner and more of them to be effective (think motorcycle or VW/Porsche w air colled engines). Aluminum is the difference whether finned or not - it conducts and dissipates heat at least 4 times better than cast iron, which is great at storing heat. For anyone who cooks, you'll notice a big difference in the way aluminum pots and pans heat up (fast) compared to cast iron (slow, but holds heat much better). Fins sure do look spiffy though!

 

Fins in general certainly can aid cooling but it is dependent on a number of factors. Material, fin height, fin thickness, spacing, etc., as well as the nature of the flow across them. More surface area is better, obviously, but there is a thermal efficiency associated with a fin's geometry.

I'll have to get some dimensions from a finned head and figure this out. I would think there would be a small increase in heat transfer but it depends what the definition of "appreciable amount" is...

 

Thanks for the info. "Appreciable amount" for me in this instance means are they worth having for non-asthetic purposes. I'm designing a new head, and the cost savings in aluminum for a non-finned head is quite a bit.

 

Sounds like a polished smooth aluminum head is the way to go.

I always thought the main reason for the fins were for looks. If the fins were there for cooling, why not make them much deeper since fins need area?

Neal

 

A satin finish will also radiate heat better than polished

 

A polished surface is absolutely NOT the way to go. On that trans pan testing I did, we tested a polished aluminum pan, steel pan, chrome pan, raw finned aluminum and thermal coated finned aluminum. The polished and the chrome pan tested the same, and they held heat longer than any of the others, including a stock steal pan.
Polished surfaces reflect the heat back into the fluid.
-Brad

 

I reacall reading years ago an article regarding aluminum's ability to shed heat. The part that seems relevant was that the greater the surface area of an item the more heat it was able to dissapate. Now this of course is simple physics. But the article went on to say that this surface area not only was not confined to major things like cooling fins but the finish of the piece as well. Basically, the smoother the item, the less its ability to shed heat. Even the texture left by sand casting added significantly to the surface are of the item and therefore, their ability to transfer heat.

Now, think about the extra surface area afforded by fins. Take a flat sheet of paper, say 4" x 10". You have 40 sq. in. of surface area. Now take a sheet 8" x 10" and fold it like a cheap Chinese fan so that it's outer dimensions are 4" x 10". You now have the 8" x 10" surface area in a 4" x 10" space, doubling the surface area and heat transfer capacity.

Since this is a cylinder head in question and heat, either hot-spot or across the whole combustion chamber is the root cause of detonation, I'd welcome any advantage that fins may offer. And since the combustion chamber is the most immediate source of heat saturation in an engine, having that extra bit of heat sink and radiant transfer capacity right at the source may be more beneficial than just looking pretty.

Off course, the real question is does this affect cooling in an appreciable manner on an old Ford Flathead? I dunno - but it certainly can't hurt. If these new heads are performance oriented I'd take a look at factoring in all the advantages I could. Radiant heat loss can be substantial in certain cases. Ever reach under a car and pull yourself close to that catalytic convertor? Radiant heat transfer can be a bitch and you'll have the scars to prove it if you get close enough.

Real world here - fins may not offer enough of an advantage vs. $$ in your case here, but I wouldn't be quick to dismiss the impact they may have. You'll need a more experienced head than I've got to answer this one, but here's something to think about. They can't hurt, they may help more than realized, and if you ever want to sell some of these new heads, you know we guys are suckers for cooling fins, functional or not.

Good luck. I'm curious to see if anyone can answer - scientifically- how effective cylinder head cooling fins really are.

 

Good point. I really think the reinforcement offered would be beneficial as well. And it would look trick.

I should elaborate on my earlier comment about fin efficiency. It's intuitive that more surface area equals a greater rate of heat transfer. But, say we increase the surface area of the head by adding fins.

The actual surface area may have been increased, but the effective surface area for heat transfer will not be increased by the same amount. More is better, but it's not a 1:1 relationship. This is due to the efficiency of the fin, which is dependent on geometry. This will enter in to any benefit vs. cost comparison.

I also agree with the earlier comments on the polished finish. A polished finish tends to "insulate" the surface, as does paint. A raw cast finish would be better for heat transfer by radiation.

 

I had never given it alot of thought about which cools better, polished or not. I do know that polished looks better.

My thought is that it probably is not that important. If a cool combustion chamber is important, the coolant in the head has more to affect it than the outer surface of the head. How the coolant is brought into the head, the volume of coolant, etc. will have more influence on the temperature.

I have a set of 59a style heads setting here that were made without fins. Do not remember who made them but are polished and look good. Just different than what you usually see.

Neal