I am trying to figure out the best intercooler for my needs, more or less looking for reassurance. Right now I will be sticking around stock boost pressures, but I am sure I may consider to increase them later; to what extent I am not sure.

The two I have been considering is:
12.8x8x3.5 (Bar and plate) CFM 700
15x10.5x 2.87 (tube and fin) CFM 900

Which is better bar and plate or tube and fine?

Where and how can I find out the CFM of the 13BREW and with count of the boost? I assume since i may consider to increase the boost I would be better off with the larger one, but I am not sure if I would be scarficing performance/flow with going with the larger. Although with the smaller I will be able get better direct airflow to the IC which should improve cooling. I am trying to go after the most effiecient setup possible.

Thanks for the help!

 

The search button is your friend.

 

That debate will probably go on forever.

You wrote that you were trying to go after the most efficient setup possible. The above statistics have nothing to do with thermal efficiency, which is what "efficiency" usually means in the intercooler world. See if either of those manufacturers quote efficiency numbers, which may be shown in the format of Thermal Efficiency %, ET, Delta-T, T2-T3 / T2-T1, Charge Side Efficiency %, etc.

The CFM rating shown by most manufacturers is usually the airflow rate at which the intercooler experiences a target pressure loss, as specified by the manufacturer. For example, Spearco bases their CFM rating on a 1.5psi pressure drop across the core. Any CFM above the rating would be more than 1.5psi, and any flow rate less than the CFM rating would be less than 1.5psi. This has nothing to do with the maximum CFM the intercooler can flow, nor efficiency, but you can use this number to target the intercooler to your flow rate to keep from incurring a heavy pressure drop. If your above examples were made by Spearco, the "900 CFM" intercooler would have less pressure drop across the core. Not all manufacturers use the same criteria, so be sure to ask what the numbers mean.

BTW, for those who don't quite understand pressure drop, it is the amount of boost lost due to restrictions, drag, etc. Example of pressure drops at various locations:

20psi compressor output
-.2psi tubing
-.2psi intercooler end tank (inlet)
-1.2psi intercooler core
-.2psi intercoller end tank (outlet)
-.2psi tubing
= 18psi manifold pressure (as read on the boost gauge)

As for sizing:
1) A more square intercooler generally works better than a more rectangular intercooler. A rectangular intercooler usually works best when the end tanks are on the longest sides as opposed to the shortest sides.
2) A larger intercooler will take longer to pressurize and to react to changes in engine air requirements, but will generally have better efficiency and less pressure drop. Choose your poison.
3) All physics aside, the most inportant aspect of an intercooler is that it must fit in the car. Don't stess about all the techno stuff.

The engine CFM remains the same, assuming that you ignore the changes in volumetric efficiency due to the variations in efficiency of the turbine wheel. It is the density (pressure and temperature) of the air charge that changes in a boosted engine.