Tanud Kri­wei cribs

New Zealand Classic Car - - Technical Feature - Words: Con­nal Grace Pho­tos: Adam Croy

Chances are that, at some point in your life, you will have en­coun­tered a ve­hi­cle over­heat­ing. How of­ten you come across such a prob­lem is an­other is­sue al­to­gether. If you’re the type to just buy a car and drive it, all is prob­a­bly well; if you own an older clas­sic, its cool­ing sys­tem may not have been de­vel­oped with mod­ern traf­fic is­sues in mind; and if you pre­fer to pull your mo­tors out and hot them up — no pun in­tended — then you’ve prob­a­bly dealt with about as many cool­ing prob­lems as en­gines.

The prob­lems arise be­cause in­ter­nal com­bus­tion gen­er­ates heat, and en­gines built for per­for­mance will, by de­fault, gen­er­ate more heat. The heat is a by-prod­uct of the com­bus­tion events that keep the mo­tor run­ning and the fric­tion be­tween mov­ing parts that re­sults when a typ­i­cal au­to­mo­tive en­gine is op­er­at­ing — of­ten at many thou­sands of rev­o­lu­tions per minute.

To dis­si­pate the heat gen­er­ated, most en­gines are wa­ter cooled. The cast­ing process for en­gine blocks, heads, and in­take man­i­folds will al­most al­ways in­cor­po­rate wa­ter chan­nels to al­low coolant to cir­cu­late through the ar­eas most ex­posed to ex­treme tem­per­a­tures, to dis­si­pate any heat that is gen­er­ated. The coolant mix­ture is com­monly an eth­yl­ene gly­col–based so­lu­tion that ex­pands as it heats up, in­creas­ing pres­sure, which, in turn, lifts its boil­ing point to be­yond that of plain wa­ter. Even so, the coolant it­self still needs to be cooled con­tin­u­ally in or­der to dis­si­pate heat prop­erly.

This is where the ra­di­a­tor is comes in. The wa­ter pump pushes coolant through the wa­ter chan­nels, and the heated mix­ture even­tu­ally cir­cu­lates through the ra­di­a­tor, which is po­si­tioned for max­i­mum ex­po­sure to ‘cold’ air. The flow of cold air through the ra­di­a­tor re­duces the tem­per­a­ture of the coolant by dis­si­pat­ing the heat to the at­mos­phere, and the coolant is then re­cir­cu­lated through the sys­tem to ab­sorb more heat.

While the en­tire cool­ing sys­tem rep­re­sents the ef­fec­tive­ness of a fun­da­men­tally ba­sic con­cept, there is quite an art to how the ra­di­a­tor core — where the magic hap­pens — ac­tu­ally works and is as­sem­bled. We were lucky enough to visit Auck­land-based Adrad Na­tional Ra­di­a­tors to ob­serve first-hand how it all hap­pens, and here’s what we found out.

The gen­eral au­to­mo­tive ra­di­a­tor ‘CT’ core con­tains a large num­ber of finned, nar­row coolant chan­nels, giv­ing a high sur­face-areato-vol­ume ra­tio. The re­sult­ing con­vec­tion ef­fect al­lows rapid heat dis­si­pa­tion. How­ever, there is a process in­volved in turn­ing a stack of raw ma­te­ri­als into a ra­di­a­tor core, and, look­ing at the ma­te­ri­als in­volved — rolls of cop­per, lengths of brass tub­ing coated in sol­der, and brass sheets — it can be tricky to see how it all goes to­gether.

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