I'm running 14psi right now on my custom 17x7.5x2.75" FMIC, and it seems small compaired to alot of the FMIC's I've seen. I'm looking to go much higher than 14, but I've got a few things to do before I get into that. Intercooler size has recently came to me as a possible problem before I get there. I have a datalogger and can log my intake temps, but I don't know what exactly I'm looking for and I honestly dont feel like going through past posts right now to find the answer.

What are your intake air temps at full boost?

-"Easy Mac"
05 Mazda RX-8 (RR8 #88)
99 Eclipse RS 398whp & 372lb-ft

Just watch your intake temperatures... If it gets more than say, 30-40 degrees above atmospheric then you probably need a bigger intercooler. On a hot day, like 85 degrees I see tempatures around 100-105 degrees at the intake manifold. With my old sidemount with the same boost pressure it would be near 150!

Also after a dyno run or a long 4th gear pull stop and feel the intercooler. It should be slightly warm on one side and cooler on the other. If the whole thing is on fire, or "heat soaked" then you're trying to flow too much hot air. The sizing of an intercooler is also pretty dependent on what kind of turbo you have, the larger the compressor wheel the more efficient it will be and the less heat it will create for a given airflow.

As long as it’s bigger/better than one of those Starion FMIC’s, I’m sure you’ll be fine.

2016 WRX STi Limited (current)
2001 A4 1.8tqms (donated)
1991 GVR4 #1933 (sold)
old.dsmregistry.com/detail.php?carid=218 (dismantled)

I would worry less about the size and more about the effiecncy of the IC. Mine is 18*6*3.5 and in comparison to my starion at 15 psi I saw a decrease of about 30 deg on average. One time on a hot day (80-83) I saw intake temp of 161(max)deg on the starion on a long long long pull. Now on a hotter day (92-94),same stretch of road my max was 123 deg. All of my pulls down the drag stip lately have been with temps not going over 112 and its now about 80 deg here. Anyway you should find out how much cfm it flows and what its efficency is at.
IMO my starion looked way better, but it is just a fact this one works better.

Kevin
The old:


The new:

I'm going to the track today, I'll log my temps and see what the deal is. I'll let you guys know what I come out with.

Smaller intercooler usually means less of a pressure drop, which in turn means a turbo not having to work harder than it needs to.

It's not a matter of how much boost you can run on an intercooler, it's about how much flow. When the flow is too much for the intercooler to handle is when it gets heatsoaked and your intercooler is too small".

Often companies will substitute horsepower for airflow (as they are related, but not directly). My 25"x7.5"x2.5" FMIC claims is rated to be efficient to 400 hp. Testing by your IAT (in the intake manifold) is not acurate to see how well of a job your intercooler is doing, because you could be inducing heat in the upper IC piping from underhood temperatures, and intake manifold itself. The simple test you should do is like what Nathan said, just touch the cold side, and if it's ambient temp after a hard pull, your intercooler is working at 100% efficiency (never will be w/ air to air, but it can be very close), if not compare the hot side temp to the cold side temp to figure the effiency.

If you're really serious, you put temporary temperature probes immediately before and after the IC to find the efficiency.

You'd be suprised at how much of a difference ducting (either partial, or full) will increase the intercooler efficiency.

Anyone looking for buying an intercooler should aim for short runners, and as large of a frontal area, and as thing as you can go for the frontal area you can use.

Longer the tubes = greater pressure drop

Each inch of thickness only increases the efficiency by a very small fraction. Think large front displacement, thin as possible (for your flowrate @ your front displacement) intercooler.

Joel Baldridge, ASE Certified Master Technician, Audi Certified Expert Technician

I took it for a spin and got it spooling up pretty good on a local road, up to about 2 or 3 times and immediately got out and felt both sides and the cool side was pretty damn cool compaired to the hot side which I could only keep my fingers on for a few seconds before they started to burn. The cool side was a bit warm but significantly less than the warm side, so I'm going to assume it is efficently doing job. I didnt get to log intake temps yet.