MINI Cooper S intercooler upgrades
Rob Hawkins visits MJR Minimatt to find out how to uprate the intercoolers on the supercharged R53 and turbocharged R56 Mini Cooper S using Uk-manufactured components from Forge Motorsport.
Fitting the supercharged R53 and turbocharged R56 with bigger intercoolers.
The first-generation of the Cooper S (known as the R53 from 2002) that was manufactured by BMW featured a supercharger, whereas the next version (known as the R56 from 2006) was equipped with a turbocharger. In both cases, the air fed into the petrol engine was air-cooled by a large radiator (intercooler) mounted on the top of the engine at first, but later fitted behind the front bumper’s lower grille. Air travels through the intercooler, just like a coolant radiator, but with the intention of cooling the air inside that’s being force-fed into the engine. Cooling this induction air is an important aspect of improving the performance of an engine. The cooler the air, the greater its density, which in turn means it contains more of the oxygen that is one of the essential ingredients for combustion.
Forge ahead
There are several solutions for improving the performance of an intercooler, such as spraying water over it, or making it larger so that it has a greater cooling capacity. Forge Motorsport has adopted the latter and in the case of the first-generation Cooper S, their uprated intercooler features 14 rows instead of the standard 11. They have calculated their intercooler offers a 29% reduction in induction air temperature over the standard intercooler. As Luke Amon of Forge Motorsport explains, “On the road you will often hear a slight increase in induction noise, accompanied by an increased enthusiasm for the engine to pull more strongly, especially in the higher revs. This is where the OEM intercooler loses its cooling efficiency.
In fact many customers have reported that the unexpected increase in top-end power has initially caught them out and they have found themselves hitting the rev limiter whereas previously the tail off in power at the higher revs, experienced with the OEM intercooler, has forced them to change gear early.”
The intercooler on the R56 Cooper S has more potential for improvement due to its location. Forge’s uprated intercooler for this model has a 250% larger surface area and a 125% thicker base core. Their testing revealed a reduction in intake air temperature of 9°C with an increase in power output of 18bhp.
The work involved in changing the intercooler isn’t particularly complicated, but is completely different between the two models of the petrol engine Cooper S. On the first-generation, the top-mounted intercooler is easy to access and can be removed within halfan-hour. On the later model, the front bumper has to be taken off and the lower grille needs to be swapped for a modified version from Forge, or you can trim the existing one, as we have shown. So set aside three or four hours for this job.
All the following steps were completed at independent BMW and MINI specialist MJR Minimatt in Shropshire.