midnight wrote:There is alot more than just displacement that goes into figuring out cooling.
How lean does a motor run
How effective is it at cooling it's cylinders.
How high does it rev
How much cooling is done by the oil.
But mostly it's cost at the end of the day. One radiator for all models.
The 6l ss motor can pull the tb alot easier and with less work that the i6. And the 5.3 is the middle child. So make one that over cools the i6 and the 6l and then just right for the 5.3.
Power also plays into it... The amount of fuel burnt, and the amount of heat made is directly related to the amount of power (work, HP) output... Yeah, the I6 is smaller in displacement than most of the truck engines of the past, but puts out close to 300HP... Even the Vortec 350 only put out, what, 260?
Though, I think the 6L is probably harder on a cooling system than the 5.3L... Load also plays into cooling... You'll notice that the SS isn't rated any higher on towing than the 5.3L, even though it has more power, a (theoretically) stronger transmission, and a stronger rear end... Day to day cooling, lots of people run e-fans on the SS, 5.3L, and I6 TBs... The problem shows up when doing high throttle for extended periods, and expecting the fan to do the work... Guys say "I've got a 600HP SS on an efan on the stock radiator, and it's fine"... Yeah, but 5 seconds after you use that 600HP, you're going 60+ mph, and the fan isn't doing the cooling any more, anyway...
These are guys (the designers, bean counters, execs at GM) who would give their left nut for 1mph fuel mileage increase on a vehicle that counts toward their CAFE numbers... They sold a blue million of the GMT360/370 platform, and the ~1mpg city and highway that the efans would have bought them would have done them WORLDS of good in their CAFE numbers... The fact that they went with mechanical fans on these vehicles, in the first place, says that any of these vehicles WILL NOT cool themselves in the desert, in the mountains, towing rated load, with efans.
Mike