If you own an M113k-powered Mercedes-Benz you know that keeping the intake air charge cool is one of the biggest headaches of the platform. Any supercharged engine will have increased IATs due to the compression of the charge, but the M113K engine suffers more than others because of the size and placement of the intercooler. The intercooler is relatively small, and it sits under the supercharger, in the “V” of the engine. Heat soak is all but guaranteed after each high speed run.
Things get especially bad at the dragstrip because the car spends a lot of time in the staging lanes with no airflow over the heat exchanger, effectively rendering it useless until you start a pass. By then it’s too late and your IAT’s have likely climbed above 90 degrees, which is where the computer starts to pull timing.
There are various ways of dealing with this issue, such as a larger heat exchanger, larger circulation pumps, or methanol injection. I decided to go a different route and use my A/C to cool the intercooler water, courtesy of Kincaid Performance’s Killer Chiller.
Kincaid Performance describes the Killer Chiller as a “refrigerated heat exchanger”. You plumb one side of the KC into your A/C circuit, and the other side into your intercooler circuit. The KC evaporator is very effective at cooling the water as it passes over the core. This allows for lower than ambient intake air temps. After installing the KC, the IAT’s on my car typically run in the low 50 degree range, even on a hot day.
With such low temperatures, the water coming out of the intercooler is usually still below ambient, so running it through a heat exchanger will only add more heat back into the water. You can avoid this by bypassing the heat exchanger with a valve, or removing it completely. I chose the latter, and had a custom front-mount tank made that bolts-in where the factory H/X once lived.
Mounting the Killer Chiller
The typical spot to mount the KC on the E55 is in front of the radiator, sitting on top of the front bumper. It’s a tight squeeze, but it fits. I chose a different location because my car already had the airmatic suspension removed. With no air suspension, I mounted the KC where the factory airmatic pump used to live. I also removed the secondary air injection pump and coded it out in STAR. That leaves plenty of space to mount the Killer Chiler, and it turns out to be a fantastic location as well.
When mounting the unit upside down in front of the driver’s side wheel, the A/C plumbing is a straight shot to the KC. I replaced one of the 90 degree bends that came with the KC with a straight fitting and everything just fell into place.
The KC does a great job of cooling the intercooler water, but there is a problem under full-throttle. The car’s computer will shut off the A/C compressor when the car is at WOT, which will effectively “turn off” the KC. To get around that problem, it is common to put a tank in the circuit so you have a buffer of cold water to use during an extended pull. Since I was going to bypass the H/X anyway, I decided to just remove it and have a custom tank built that will bolt-in right where the factory H/X was mounted.
I had already upgraded to a bolt-in PLM H/X, so I had a fabricator build a tank that matched the shape and size of the PLM unit. Since the KC is mounted on the driver’s side, I designed the tank to have an inlet on that side and an outlet near the pump. This made everything line up nicely and the install was simple.
I also included bleed and drain ports and wrapped the whole thing in self-adhesive neoprene insulation.
This is probably my favorite mod that I’ve done to this car. Before the KC my starting-line IATs were anywhere from 90-120 degrees! Now they are consistently in the low 50’s, regardless of the weather outside. My runs have become much more consistent, and I’ve dropped about .15s off my 1/4 mile ET.