still be intact at lower engine speeds, allowing for better performance across the entire speed band and a broad, flat torque curve around the crossover point. During rising engine speed, a slight lurch can occur at the crossover point and an experienced driver will be able to detect the shift in performance. Production of the first-generation engine model lasted until May 1987. Second Generation "Red & Black Top" (Late Bigport) The second-generation 4A-GE produced from June 1987 to May 1989 featured larger diameter bearings for the connecting-rod big ends and added four additional reinforcement ribs on the back of the engine block, for a total of seven. The T-VIS feature is retained, as well as the MAP sensor (MAF sensor in the US-market). It is visually similar to the first-generation engine (only the upper cam cover now featured red and black lettering) and the US-market power output was only increased to . The first- and second-generation engines are very popular with racers and tuners because of their availability, ease of modification, simple design, and lightness. Third Generation "Red Top" (Smallport) The third-generation appeared in June 1989 and was in production until June 1991. This engine has the silver cam covers with the words only written in red, hence the nickname "red top". Toyota increased the compression ratio from 9.4:1 to 10.3:1. To correct the air-speed problems of the earlier generations, the intake ports in this cylinder head were re-designed to have a smaller cross-section, and hence it has been nicknamed the "smallport" head. This change in the intake ports negated the need for the earlier twin-runner intake manifold and it was replaced with a single-runner manifold. Additional engine modifications to extend life and reliability included under-piston cooling oil squirters, thicker connecting rods and other components. Also of note, the pistons were changed to utilize a fully floating gudgeon pin unlike the pressed-in pins of the earlier versions. Other internal revisions were made to the pistons. They were slightly modified to make space for the under-piston cooling oil squirters found in this engine version. In addition to this, the piston ring size were changed to (top ring), 1.5mm (second ring) and (oil ring), this change in size made it difficult to obtain as compared to the earlier 16 valves versions of the 4AGE (top ring), (second ring), (oil ring). All non-US market 4A-GEs continued to use a MAP sensor, while all