Originally Posted by buggy4crossfires
Just took my car in for an oil change before the weather starts getting nasty and I don't get it out that much. When I got home I decided to open the engine compartment and make sure everything was in order and no damage had been done. I couldn't believe how hot the engine cover and intake tubes had gotten (mind you this is the replacement MB SLK 320 Cover). I had only driven home about 5 miles over about 15-20 minutes since the oil change. I left the car in the garage and forgot about it. About 2 hours later I went down to the garage to check on things and the cover was still pretty hot so I removed it for closer examination in the house next to the Crossfire cover. The 2 covers are virtually (other than cosmetics) identical. I thought perhaps the MB cover was using a more restrictive filter which might cause the temps to climb but EVERYTHING is identical to the XF cover. I reinstalled the MB cover and figured I'd ask the experts. Mind you I have nothing to compare this to. I've never checked the engine bay immediately after driving for anything let alone to see how hot the cover was getting so this may be entirely normal. Anyone know for sure? Thanks in advance.
The stock cover/air filter assembly does get VERY hot after a run due to heat soak. On the face of it this would appear to be very bad for performance, which it is to a certain extent, but when moving at speed the intake air temperature drops considerably. I've logged it via the OBD and the IAT is not much above ambient when cruising. The stock setup really is a cold air intake and a lot better than people think; certainly better than the systems that hang a couple of filters in the engine bay. As another exercise I have tapped a hole either side of the one of the filters to measure the pressure drop (if any) across it.
For information here's a pic of the temp I measured on the underside of the airbox cover after a short run - 78.2 Celsius (173 F).
