How hot does the engine get? If the radiator tubes are completely clean and the water pump vanes are not worn, then it should stay within operating limits. If not, then an oversized radiator would probably be your best bet if one is available. I would first start by determining that the cooling system you currently have is operating properly and that the actual engine temp is, in fact beyond its design operating limits.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record