What is Spec E46? Well, in the simplest terms, Spec E46 provides drivers with an intermediate step between low budget entry-level spec series like Spec E30 or Spec Miata and much more expensive less restricted racing series. Spec E46 does this by utilizing a modern chassis and drivetrain and specifying quality components that result in a fast, lightweight, and agile car that is able to be set up, adjusted, and dialed in for nearly anyone’s driving style. The BMW E46 chassis is perfect for this because it was sold in great numbers, it’s relatively new so many examples can be had in good condition, it’s old enough to have reached the nadir of its depreciation curve and so it is relatively cheap, and parts are readily available and of a high quality. These traits come together to make an ideal rear-wheel drive platform on which to base a road racing car.
All Spec E46 race cars start as non-ZHP 330i sedans or coupes with either the 5-speed or 6-speed manual transmission. All sunroofs must be removed and covered. Interiors, excluding the dash, and any ancillaries that are unnecessary for racing (such as airbags or HVAC) can be stripped for weight savings. The shifter and linkages can be modified or replaced, as can the engine and transmission mounts so long as they remain in the stock location. The clutch and flywheel can be upgraded, the rear end can be swapped for a limited slip differential, and there is a spec custom ECU tune that helps to maximize both power and reliability. The exhaust system that has been speced is a special unit that has been co-developed
The BimmerWorld/MagnaFlow racing exhaust that has been speced is highly indicative of the thinking that went into the rules for the series. It is extremely high quality and it is purpose-built for racing. The system’s 3-inch diameter would be less than ideal for a street-driven vehicle, but because race car engines are operated almost exclusively at the upper end of the rev range, any loss of torque at the low end is negated by the larger gains nearer to red line. The system includes both a resonated at a straight-pipe center section which should allow drivers to meet maximum sound requirements at restrictive tracks such as Lime Rock Park or Laguna Seca. Changing the center section is very easy as the entire exhaust has been designed to use V-band clamps which make removing the whole system extremely quick and easy. The BimmerWorld/MagnaFlow system is also available with an optional Y-pipe designed to mate exclusively to the specced catless E36 exhaust manifold which facilitates ease of installation without the need to cut up your stock E46 parts!