 However, Murray himself has since said that this car, and its successor the McLaren MP4/4, were designed using his original Brabham BT55 drawings as a base (as they were legally his, Murray had brought the BT55's drawings with him to McLaren).The engine was the same 1.5 litre, Porsche built TAG twin-turbo V6 engine that had so successfully powered the MP4/2, but with slight changes in compression and engine balancing, to cope with not only the new reduced fuel limit, but also with the FIA's mandated pop-off valve which restricted turbo boost to 4.0 bar after turbo charging was unrestricted prior to 1987.There were three wins in 1987 with the MP4/3 by Alain Prost at Grand Prix of Brazil, Belgium, and Portugal.