Air-to-air intercooler for Mercedes-Benz C-Class W205 / E-Class W213,C238,A238 / SLC R172 / GLC-Class C253,X253 with M274 engine code — TA Technix

The turbo compresses the air, and compression generates heat: at the compressor outlet, the air can exceed 150 °C. It is then less dense, meaning it contains less oxygen, and it causes knock — which the ECU corrects by retarding the ignition, reducing power. The intercooler cools it before it enters the engine.

The benefit is therefore less about top-end power than consistency: a saturated stock intercooler lets power collapse on the second lap of a circuit or during the third acceleration. Beware of automatically choosing the biggest one: excessive volume takes longer to fill and dulls response. The right intercooler keeps temperatures under control throughout actual use.