In case you hadn’t noticed, Mercedes moved the turbo to the backside of the engine and placed an air-to-water intercooler on the front. The benefit of moving the turbo to the rear is a shorter exhaust path from the turbo to the cat for better emissions. Plus trying to fit a big downpipe and cat underneath the engine isn’t required which allows the engine to sit lower for a better center of gravity. Also, the turbo and manifold are relatively heavy, so the move places them closer to the center of the car for a reduced polar moment of inertia. Of course, the Evo X did this back in 2008 and Honda moved their header on the K20 to the backside in the early 2000s. Anyway… In case you haven’t noticed again, many of the OEMs have transitioned to air-to-water intercoolers for short intercooler piping for better throttle response among other reasons.
All the OEM intercoolers these days use plastic end tanks (something like PA66GF-30) clamped onto the intercooler core. The orientation of the end tanks on this intercooler with the flow coming in and making a 180 degree turn out is the best for even flow distribution across the core. Check out the inlet side tank and it’s shaped a bit like the catalytic converter entry in order to get more even flow across the core. My S2000 intercooler concept is not too dissimilar. The coolant connections to the intercooler have quick connect fittings and the flow should be in a counter flow arrangement with the airflow to get maximum cooling. The big cooler on the transmission has the same quick-connect coolant fittings. AWD transmission and transfer case need cooling to stay reliable at the power levels the M139 puts out.
The engine cover looks to have a duct attached to it to direct cooling air to the top of the engine. The big silver pipe on the right is from the compressor outlet of the turbo. The big round duct above the pipe goes to the compressor inlet. When making over 200hp/L, restrictions have to be minimized everywhere.
The path between the turbo compressor outlet and intercooler inlet is short and fat for minimal pressure drop. A compressor bypass valve is connected to the turbo outlet pipe and the compressor inlet pipe. It’s the little black cylindrical thingy on the right. A slight manufacturing observation, it looks like they screw in two massive loops on the top of the engine to lift the engine around easily. In the bottom of the picture, the black fitting with the yellow cap is the female end of the coolant quick connect. It just snaps onto the male fitting and the metal retaining clip locks the fittings together. There’s an o-ring inside the female fitting which creates the liquid-tight seal. On the male side, the callout for surface roughness is critical as too rough of a surface will not create a seal with the o-ring. And that’s probably more than most of you wanted to know about fluid quick connects.
The high-pressure fuel pump for the direct fuel injection system is run off the intake cam. A roller is used at the interface of course to reduce friction. None of that old cam follower stuff like on the old Audi 2.0 engine that has high friction and wears out.
The Mercedes AMG M139 engine has employed the basic tuner concept for going big turbo on a small displacement engine which is a twin-scroll and ball bearing turbo. Ball-bearing turbos have been largely absent from production cars. Sure, a couple of the 90’s Nissan cars had Garrett ball bearing turbos. But they haven’t shown back up again until recently as the people have demanded more power while the OEMs have to meet mileage and emissions targets. Ball bearings can also be relatively noisy compared to plain journal bearing turbos, but that’s not a concern on these performance cars with their loud exhausts. The airflow piping is big diameter and the catalytic converter is massive to minimize restriction as much as possible. As is the current trend, an air-to-water intercooler makes for tidy packaging, short airflow plumbing, and likely more consistent intake air temps too. Will we see 250hp/L engines in the future? Maybe…. E-turbos are coming.