Complex sentence: On one hand, the Alfa engine program helped the team to survive the increasingly professional turbo era; on the other hand, the heavy, unreliable and thirsty machines contributed to the team's lack of competitiveness.
Split into simpler sentences: On one hand, the Alfa engine program helped the team to survive the increasingly professional turbo era. On the other hand, the heavy, unreliable and thirsty machines contributed to the team's lack of competitiveness.