Tuning MG A-series engines for drivability

Part 2 of 2

It is quite amazing that, even though BMC’s A-series engine first appeared in the Austin A30 some seven decades ago, expert tuners are still finding interesting and innovative ways to squeeze more performance from this well-loved, cast-iron, in-line, four-cylinder engine. We are still finding ways around its inherent design weaknesses, such as the three-main-bearing crank, by using new design techniques or re-working tried and tested methods.

The range of tuning options for the A-series and A+ used in MGs is extensive and engine specialists are spread across the globe. There is a diversity of options that include making an MG’s A-series an outright track monster to improving torque and driving responsiveness for the road. It is the latter that we address here in this tuning guide.

Air filters

There are several different designs of air filter that were originally fitted to the various A-series-engined MGs, with a wide range of efficiency. To produce a given power demands a given volume of air irrespective of the engine but, when producing maximum power, a 948cc A-series engine demands less air than a 1275cc. Filter choice impacts differently between different engines. The other aspect is under-bonnet look, as some MG owners will want to retain an original appearance.

Some aftermarket filters look attractive but are often far from efficient and are sometimes less efficient than standard. Essentially you have to look at the total surface area of the different filter media and assess whether the replacement offers any advantage over an original factory part. Take the