Photography by Derek Bartolo
As you crank the boost the air intake temperature that is headed into your manifold rises with it. Some factory intercoolers are completely undersized junk that heat-soak immediately, while others are fairly decent like those found in the Mitsubishi Evo and Dodge SRT-4. However in the case of BMW’s twin turbo rockets, the factory units are small and restrictive. There are only a few companies who tried to build a better unit but the space constraints were so tight that it proved near impossible to engineer an upgrade.
The BMW experts over at the HorsepowerFreaks (HPF) were relentless in perfecting heavy duty intercoolers for the 135i and 335i. We talked with HorsepowerFreaks owner, Chris Bergemann and he says the intercooler upgrade should be the third step in your upgrade path after the intake and the exhaust.
The first thing you will notice about the HPF intercooler is its incredibly thick core. In fact it is thicker than it is tall to amount to some serious volume. The highly efficient bar and plate core measures 20.25x5.75x7-inches of depth for a grand total of 815 cubic inches! By the numbers, that is 87% more volume than the factory unit. The end tanks are durable cast construction with the HPF logo raised along the side. The entire unit is high polished and clear-coated to a mirror-like perfection you can fix your hair-do in.
The end-tanks also retain the factory style billet connecting clamps, so there is no need to convert over to silicone tubing and clamps. The factory C-clip couplers provide a positive connection that will not flake under high-boost conditions either. The design of the intercooler also allows for adequate pass-through so as not to interfere with the radiator airflow. The HPF intercoolers also utilize the factory mounting points making it the easiest on the market to install. The secure mounting points also use the sway bar mounting tabs which provide a positive connection without shifting. Installation on the 335i was totally complete in about an hour and required only minor trimming but no cutting, drilling or major modifications to make it all work with the OEM front bumper.
After the install, the car was street tested to see if there was any noticeable lag. When you add more volume, it is a challenge for the turbo to fill it all with compressed air and provide the same response. Despite being rated up to 650whp, the HPF intercooler felt the same with all of the impressive snappy throttle and instant-on power you expect from a 335i. And the dyno numbers back up the seat-of-the-pants meter, because the results at only 11psi were impressive.
The 335i laid down an extra 22whp horsepower over its pre-HPF runs to push over 400whp with 412lb-ft of torque! The 335i is supported by only an intake, chip and still uses the stock exhaust, which would have netted even more with the HPF intercooler. The resulting drop in intake temperatures did well for the car and the nonexistent lag means this intercooler is fine for daily drivers. The bonus of having this intercooler handle up to 650whp of airflow is a huge plus, meaning it is future-proofed for substantial turbo and ECU upgrades. Next logical step would be to add the HPF intercooler piping kit and HPF is also releasing an innovative new blow-off valve to manage the boosted air - stay tuned for a full install and review!
BMW 135i & 335i Intercoolers