Radiator Construction - Brass/Copper vs. Brass/Brass

[packardresto]

Does anyone know if a ribbon cellular type construction for a radiator core would reject heat differently if it were contructed using brass for the water passages and brass for the cooling fins?

I have a reproduction radiator that was made to replace one in a 1932 Packard model 901 with a 320 C.I. staight eight. This engine has a 3 3/16" bore x 5" stroke, the rated H.P. is 110. The radiator core size is 21" wide x 22 5/8" high x 2 3/4" thick. The core design is ribbon cellular, Auburn type.

Here's the issue, the original core was made using brass for the water passages with copper cooling fins between the cooling pasages. The replacement core was made using brass for the water and cooling fins.

Since the thermal conductivity of copper is 401 W/mK vs. 110 W/Mk for brass would the use of brass for the cooling fins reduce the amount of heat the radiator would reject?

The copper and brass material used in both radiators, the original and reproduction are both 0.012" thick.

Thanks for any advice.

 

[MikeHalloran]

The thermal conductivity of the boundary layer of air over the fins is _way_ worse than that of either metal.







Mike Halloran
Pembroke Pines, FL, USA

 

[Fabrico]

If the copper finned unit kept up with no problems, the brass version should be OK.

 

[Metalguy]

>"I have a reproduction radiator that was made to replace one in a 1932 Packard model 901 with a 320 C.I. staight eight. This engine has a 3 3/16" bore x 5" stroke, the rated H.P. is 110."<

If the new rad. needs help, I've found that increasing airflow via more/faster fans works well-if that wouldn't be detrimental to the authenticity of the car.

BTW, by 1948-49 Buick also had a 320" straight 8 (Fireball) with a bore of 3 7/16" and 4 5/16" stroke. They rated it at 150 HP and 280 ft. lb. torque. It had overhead valves, and I suspect your engine is a flathead. In 1953 Buick suddenly changed to a V8, 322" and 4" X 3.2". Unfortunately they had to make it very narrow, so all valves were vertical, resulting in tiny exhaust valves and horrible ports.

"When the Eagles Fall Silent
The Parrots Start Jabbering".

W. Churchill

 

[packardresto]

Metalguy,

Yes, you're right, the '32 is a flathead, updraft Detroit Lubricator carburetor, 4spd manual, roller rockers, vacuum operated automatic chassis lubrication, and adjustable ride control on all four shocks, full floating rear axle, hypoid gears, all stock.

I'm sure the volumetric efficiency is not the best with the carb / intake port design but the engine does have some interesting features.

Some interesting comments concerning my question. If a brass/copper design doesn't offer an improvement vs. brass/brass I wonder why 90% of the automotive radiators I've seen use brass/copper construction.

 

[Metalguy]

One possible reason might be that because Cu has better corrosion resistance than brass, the very thin fins might not last too long when exposed to rain, road salt, etc.

Roller rockers back in 1932, wow! Doesn't Jay Leno collect Packards?

"When the Eagles Fall Silent
The Parrots Start Jabbering".
Winston Churchill

 

[patprimmer]

A 1902 Oldsmobile has roller followers.

It's easy to tell, because the cam and follower are outside the crankcase in the open air.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MikeHalloran]

I've only worked on a few radiators, all made after 1957, and all brass/brass. I think Detroit went to brass/brass in the Fifties, maybe earlier. While copper has a theoretical advantage in heat transfer, the difference is small, and likely overshadowed by other issues, e.g.:

- brass is stronger, hence:
- brass shears cleaner and produces smaller burrs
- brass is less likely to be distorted by impact, as in:
- incidental impacts during manufacture
- gravel impacts on the road

If you desire absolute historical accuracy, I guess you could demand brass/copper. If you just want a good replacement radiator, you've probably already bought one.



Mike Halloran
Pembroke Pines, FL, USA

 

[patprimmer]

And when they are both painted black, you won't see a difference.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.