An ARM F25 X3 Intercooler upgrade is one of the best modifications you can make to your 28i or 35i X3. One of the F25 X3's most significant weak-points is its stock intercooler. This becomes obvious when tuning the N20/N55 to increase boost with a Stage 1 tune and even more so with a Stage 2+ tune. With a higher boost target the charged air coming out of the compressor is hotter, therefore increasing IAT's. To compensate for the higher IAT's the ECU (DME) reduces boost, timing, and overall power to the engine. This is the exact opposite of what you want for getting your F25 X3 to perform better. In order to keep those IAT's low, a larger and more effective intercooler is needed.
ARM F25 X3 FMIC
The ARM F25 X3 FMIC is the perfect cooling solution for any stock turbo or upgraded turbo N20/N55 setup. With an intercooler core size of 20x11x3" and an overall volume of 660cu in. the ARM F25 FMIC is 235cu.in. or 36% larger than the stock N55 intercooler which comes in at only 425cu in. In addition, the ARM F25 X3 FMIC utilizes an ultra-dense 14 fins per inch external core, giving it the best cooling performance possible.
With a 220sq.in. face the ARM F25 X3 FMIC has a 120% larger frontal area than the OEM intercooler with only a 100sq.in. face, and 55sq.in. or 33% larger than most aftermarket intercoolers for the F-Series platform. Having a larger frontal area equates to more effective cooling compared to intercoolers of similar total volume. In the milliseconds that the ambient air passes through the intercooler it warms up, making the actual cooling less effective towards the rear of the intercooler. Taking the area towards the rear of the intercooler and bringing it towards the front improves the overall ability of the FMIC to cool the charged air on the X3. This is shown in our IAT testing results below.
Our baseline run was performed on a 335i running 16psi of boost with the stock F-Series intercooler. The 3rd gear run started at 93 degrees and ended at 126 degrees, a huge increase of 33 degrees Fahrenheit on 16psi of boost, and certainly restricting the amount of power this N55 could have been making.
After installing the ARM F-Series FMIC there was a massive improvement in cooling performance that resulted in only a 2 degrees Fahrenheit increase in IAT. In this 3rd gear run with boost peaking at 18psi, which is 2psi higher than the stock intercooler run, it starting at 95 degrees and ended at only 97 degrees. This is a 94% improvement in cooling over the OEM F30 intercooler!
Installation of the ARM F25 X3 FMIC upgrade is a basic bolt-on procedure similar to the F30 FMIC installation, but with the addition of trimming one small piece of plastic measuring 1x3", or about the size of a stick of gum. It does not require you to remove the front bumper. It is a direct fit which bolts up into the original stock intercooler location. The CNC connectors will connect to either the stock F30 intercooler piping or to any upgraded intercooler piping that fits the stock intercooler.
BMW F25 X3 28i N20 and 35i N55
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2014 F25 X3 xDrive 28i N20 and F25 X3 xDrive 35i N55
2015 F25 X3 xDrive 28i N20 and F25 X3 xDrive 35i N55
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