Chrome Fan Shroud Question

[craigvwdude]

Yep, what Glenn said!

[aussiebug]

Chrome on the fan shroud won't make any difference to the cooling system. The DESIGN of the shroud will make a difference though - VW spent around $1million US in the late 60s redesigning the shroud for the twin port engine, with the doghouse oil cooler (that was a LOT of money back then). This shroud has more guide vanes inside than previous shrouds, and a complex air path for the oil cooler air - and all to get better cooling even though the 1971 twin port 1600 had just 3 more hp than the 1970 1600sp engine with the older shroud design.

A lot of aftermarket chromed shrouds (and black ones too) have few or no quide vanes inside, so the air just spills around is not guided where it needs to go - these DESIGNS are very poor and will affect the life of your engine - but chrome v black shrouds won't make a jot of difference.

But chrome on OTHER areas can affect the cooling.

For example, in the 60s, VW supplied an "arctic kits" for cars which had to live all the time in super cold conditions, and it included chromed valve covers, to help keep heat IN the engine - to prevent over cooling! So why did this help? The oil inside the engine comes into direct contact with the inside of the valve covers (which are insulated from the head itself with cork gaskets) and so the covers become a useful part of the oil's cooling system - both through convection (air under the car passing over the covers); and more importantly, through radiation - the hot black covers radiate heat away from the engine better than hot shiny chrome ones. Shiny chrome radiates less heat, so the engine oil will run hotter with chromed valve covers.

Bob Hoover (VW Guru and sadly not with us any more) also stated that if you wanted to remove heat from the cylinders a little better, a THIN coat of stove-pipe black paint or similar would help radiate heat away from the cylinders. The heads were a different matter - they run hotter than the cylinders and might bubble any paint applied to them, and the passages through the heads are more complex, making it difficult to get an even coat anyway, so his recommendation was to leave the heads uncoated.

So the best wisdom with regards to cooling and chrome is - if it is touched by engine oil, leave it black or it's stock natural finish. If it's only a visual effect and not touched by engine oil, then chrome it if you want to - fan shroud, tinware, fan pulley and so on are just fine. I say that even though chrome isn't my preferred finish.

[aussiebug]

Regarding black paint, one thing to keep in mind, that when the deck lid is closed, the black paint isn't any different than any other colour and won't radiate heat better (although probably better than thick chrome). There is no colour spectrum in a closed environment without light. That's how the German's did just fine with brown and green paint on war-time Beetles and Kubels...

Not quite right Neil. When it's dark inside the engine bay you are only talking about VISIBLE light, but heat is affected by radiant surfaces even though you cant see it - it's just a different (non-visible) part of the electromagnetic spectrum. Under the engine lid is quite visible in the heat spectrum range. Chrome will still radiate heat worse than a black surface - even in the dark.