As the rules go, Porsches are built for speed and Mercedes are built for luxury. It seems no one ever explained the rules to Steffen Leitgeb of MKB Motorsports. MKB is located in a small peaceful town in Winnenden, Germany. Steffen is the public relations director at MKB and is fortunate enough to drive this '99 E430 Mercedes on a daily basis. MKB is a pure Mercedes hop-up shop that houses some of the meanest Mercedes-Benz in Germany. This E-Class is actually owned by MKB but Steffen has the pleasure of testing out new products on the vehicle. One of the main products he is testing out is an MKB-built powerplant flexing its latest engine performance upgrades. Though this car looks fairly stock-with the exception of the wheels and tires-it is capable of running flat-out over 180 mph on the street.

With less than 1500 miles on the engine, MKB decided it was time to give the Benz a power transfusion. What was once an OEM 4.3-liter V8 is now a custom-built creation displacing 6.0 liters. An extensive amount of time and money was put into the engine, testing MKB's new stroker kit encased in the 4.3-liter aluminum block. MKB punched out the factory sleeves and replaced them with ductile-iron models. The new sleeves now house eight 11.0:1 compression KS-Racing pistons. The 100mm pistons are 10.1mm over the 89.9mm factory issue slugs. A change in stroke was also needed to obtain the 6 liters of displacement MKB desired. The factory stroke is 84 millimeters, and the current stroke on the Benz now 94.8mm. The longer stroke was accomplished utilizing a custom MKB crankshaft and rods. The bottom-end 4.3- to-6.0-liter crossover was made possible using all MKB Motorsports one-off parts, which are soon to become over-the-counter affairs.

One of the key issues the MKB crew faced was designing the cylinder heads to hold up to the high-rpm demands that would be placed on the V8. To accomplish this feat, MKB decided to scrap all the existing valvetrain parts for rpm-friendly hardware. Once the valvetrain was disassembled, Steffen had the MKB engineers modify the ports and combustion chambers to create the extra airflow needed. This was accomplished by hogging out the stock exhaust and intake ports as well as reshaping the combustion chambers.

The redesigned head now houses a set of MKB polished and under-cut valves as well as a set of MKB valve springs and rocker arms. The factory bumpsticks were reground to a more race-spec design. Fuel compensation comes by way of two "very large and loud" Bosch fuel pumps with bigger injectors. Judging by the way Steffen filled out our tech sheet, we can tell he wanted to keep the fuel delivery in the Benz a secret. Under injector size he wrote, "Big, Ha Ha." Other than the pumps and injectors the only other modifications to the 180-plus mph Benz is a custom-programmed MKB ECU and Beru spark plugs.