Nerd’s Eye View: LA Autoshow 2015 – BMW

Nerd’s Eye View: LA Auto Show 2015 – BMW

by Khiem Dinh

I have mentioned it before, but I will say it again, BMW has gone all-in with turbos. Some may say (ahem, me), that BMW has gotten a little soft, literally in their suspension tuning. But don’t fret, the engineers at BMW still know how to make cars that can hustle around a road course. Exhibit A, the BMW M4 GTS.

The engine in the M4 GTS has had its power bumped up to an even more stout 493hp from an already impressive 425hp in the base M4. BMW installed a water injection system to allow for the higher power output. The improvements helped the M4 GTS lap the ‘Ring in 7:28. There are two air boxes, one to feed each turbo. This increases the air filter area which should minimize pressure drop. I bet having the two mass air flow sensors helps with the resolution helping drivability too. As we have seen before, the two turbos feed the single air-to-water intercooler where the flows combine to enter the intake manifold. The benefit of the air-to-water intercooler is short routing to improve transient response.
To shave weight, BMW dug into its carbon fiber capabilities (they built their own carbon fiber plant to provide enough of the stuff to build the i3 and i8) to make the hood. The ‘M’ shaped under hood structural element is fitting. The vent is functional of course.
The vent in the hood is located near the front which is a lower pressure area to help suck the hot air out of the engine bay. You can see just how forward the vent is as you can see the carbon fiber brace through the vent. The vent location is similar to that of the Porsche GT3RS.
A big front splitter (for a street car) balances out the downforce of the rear wing. When you watch the video of the M4 GTS on the ‘Ring, you can see it’s quite stable. Go back in time and watch the video of the C6 Z06 Corvette (around year 2008) and it’s much twitchier. Of course, heat exchangers occupy both corners of the car along with the horizontally mounted cooler in the middle. It also appears those two openings between the splitter and front bumper are brake ducts.
The design of the heat exchanger outlet is the most elaborate I have seen to date on a production car. As one would expect on a car designed to go fast, the bottom of the car is pretty smooth and flat.
It is a bit hard to make out, but I believe that is a brake duct scoop mounted to the lower control arm in front of the black sway bar.

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