Having ordered one of the very first UK cars to arrive in the UK we were very quick to realise the many abilities – and opportunities – that lay untapped with the engine.
We always like to live with a new car for a few weeks before we tune it in earnest. Having previously owned and thoroughly enjoyed the M235i we had already done a lot of groundwork on the N55 engine, meaning that certain tasks could be developed very swiftly.
Back in 2014 we received our M235i and begun working on a more powerful and safe ECU calibration. This remapping work even saw our M235i successfully take part in a world record setting high speed run.
We were delighted to see that the same basic ECU architecture was retained for the M2 – saving months of work. This meant packages could be developed for both OEM and aftermarket exhaust options that delivered respectable power increases in a safe, drive able manner, leaving all of the factory boost and safety parameters firmly in place.
An engine producing more power usually needs better breathing but despite testing numerous induction kits we have yet to test a kit, on the dyno or on the road, which can handle heat as well, or flow as much air at the standard air box with a good quality air filter.
Dyno tuning the M2 showed a significant improvement over the original power and torque figures. We have spent considerable time developing our Stage 1 remap which will lift power from the original 370bhp to 400bhp and torque increased smoothly to 385lbft from the original 343lbft. However this only tells part of the story as the power delivery is more progressive and predictable with the engine revving more freely throughout the rev range. We have also added some more character to the engine note as it pops and crackles more on the overrun in Sport modes. Our remap also removes the BMW Speed Limiter.
Although we can produce more than 400bhp we found that the intercooler was starting to become saturated and if we ran the car hard on track you could see the safety trims subtly pulling power from the engine as the temperatures increased with sustained use.
The natural next step was to test an improved intercooler and from what we had learnt with our M235i Forge Motorsport have an excellent direct replacement. This intercooler requires no trimming or adjustment to the surrounding area and significantly improved both the temperature reduction and the pressure drop through the core.
We had already proven the benefit of installing a free flowing exhaust with the best coming from Akrapovic. The exhaust alone produced another 9bhp and 5lbft so when combined with the consistent temperature drop of the new intercooler we were able to find a comfortable 420bhp and torque increasing to a solid 400lbft.
Having tested the car at the Paul Ricard Circuit and on the road we decided this was more than enough power. When we installed a higher powered versions of the map you could feel the chassis starting to struggle to put the power down and it became less fun to drive. We found the same on our M4 tuning although we could produce considerably more torque than we offer as the car just didn’t perform as smoothly and you end up just producing unnecessary heat and stress for the driveline without improving the driver enjoyment.
We have plenty of chassis work planned for the M2 so keep an eye out for another Blog post….