what chapter are the formulas in? i only found this part about placement/ducting. Technically about intercoolers, but heat exchangers anyhow:
Ducts.
A duct is in a large sense, a form of streamlining of the core. The ducts present the air molecules with no alternative but to go on through the core. Do not underestimate the ability of a duct to improve the efficiency of the intercooler I would suggest that an improvement of 20% is possible, good duct versus none.
When constructing ducts, it is decidedly worth the extra effort to insure that the air molecules have no alternative hut to go through the core. That is, seal all edges, corners, and joints.
It is not necessary for the duct inlet, to be as big as the frontal area of the IC cure. A rule of thumb is that the duct inlet should be at least one-fourth the core area. This rather strange situation is brought about by the fact that less than one-fourth of the air molecules would get through the core with little or no attention to ducting.
Core streamlining.
Streamlining represents the ease with which ambient air can get through the core. Certainly, the easier the air moves through the core, the greater will be the rate of flow and, hence, the greater the cooling ef¬fect For example, if the charge air tubes in the core present a rounded edge to incoming ambient air, the rate of flow is likely to be somewhat greater. An en¬gineering factor missing from all core data published is an ambient air drag co¬efficient.
Placements of the intercooler.
The place to put an intercooler so often boils down to finding available space for a big enough unit. That doesn’t take much science. A few rules, however; should receive some forethought. Try hard not to put an air/air intercooler in the same compartment as the engine. Placing it behind the cooling system radiator is also out.
Consider that air having passed through the cooling system radiator is generally 40°F or more, hotter than am¬bient and therefore does a lousy job of trying to cool anything.
Indeed, the turbo, in low boost ranges, may not heat the intake charge up to the temperature level of the underhood air that is being asked to cool the in¬take charge. When this happens, the intercooler becomes an “interheater” not a good turbo part. When the boast rises to the point that the temperature of the charge exceeds the underhood temperature, the IC will begin doing some work but will forever suffer from a severe efficiency loss. Not what we want. Underhood radiation of heat to the IC can also be a problem. Insulation and ducting can help these problems, but, fundamentally, the engine compart¬ment is no place for an intercooler.
** RULE: Always be on the lookout for the villain called the “interheater”
oddly enough it also says a thinner core is more efficient. I could have sworn I’ve read otherwise elsewhere. I’ll have to look up and find out who it was.