What is the Valvetrain of the Diesel Engines Model?
CREATE TABLE "2011" (
  "model" text,
  "engine" text,
  "displacement" text,
  "valvetrain" text,
  "fuel_system" text,
  "max_power_at_rpm" text,
  "max_torque_at_rpm" text
);
SELECT "valvetrain" FROM "2011" WHERE "model"='diesel engines';