I'm no forced induction expert on by any means, but I was researching a replacement for my ATI 4.5" twins and found they support much more than people think. They can handle upwards of 850 hp with no problem.

Be careful about following the crowd as far as intercooler selection goes. There are two things that you have to looks for: Total surface area (in2) and flow (CFM). Buying an intercooler based solely on looks alone is a roll of the dice.

Surface area - Determines the level of cooling it can achieve.
Flow (CFM) - Determines how much power it can support.

Crossflow Intercooler - 16 passages

The big crossflow intercoolers that are so popular create a restriction on high horsepower engines because of their design. All the air has to go through only 16 passages. One thing they have over a similar dimension vertical is more surface area to cool down the intake charge. Another plus is that they are sometimes easier to install because of the location of the inlet and outlet. But you have to ask, will this intercooler limit the total power output?

Verticle Intercooler - 48 passages

The vertical design has 3X the passages for the air charge to flow through than the crossflow. This means they support much more horsepower than a crossflow of the same dimensions. The downside is that they have to be deeper to achieve the same cooling surface area as a crossflow. If you're already running meth injector or E85 then that isn't much of a concern.


Consider ATI and TTi include vertical intercoolers in their kits. Look at their high horsepower 1000+hp race intercoolers. They are just very deep (6") verticals with big inlets and outlets (4"). More depth also creates more surface area and flow.

Thanks for reading! Opinions and rants welcome...

Dan

 

I know there are many cars that have made big power and good times with twin 4.5's (don't know what IAT's typically are with the twins).
For me, I choose to go with a 31x12x4 FMIC with 3" inlet and outlets. I'm sure that will be more than enough cooling for me.