 The Porsche-TAG engine featured an updated Motronic 1.7 engine management system, and now produced in race trim and up to in qualifying.Although a number of teams, notably Benetton with their Ford V6 turbo and Arrows with their 4 cyl Megatron turbo (formerly the BMW turbo), encountered problems with the pop-off valve during 1987 when it would often come in lower than the 4.0 bar limit thus giving less horsepower, McLaren got around this by generally setting their TAG's turbo limit at 3.6 bar in 1987.This also allowed McLaren the advantage of better fuel economy.