Hi Bernardo.

The same effect (cs727_smoke) is used for each engine, but the coordinates for each is different:

[SMOKESYSTEM]
smoke.0=-33.00, -8.50, 1.00,  cs707_smoke - Engine 1 (z = 33.00, x = -8.50, y = 1.00)
smoke.1=-36.00,  0.00, 1.00,  cs707_smoke - Engine 2 (z = 36.00, x = 0.00, y = 1.00)
smoke.2=-33.00,  8.50, 1.00,  cs707_smoke - Engine 3 (z = 33.00, x = 8.50, y = 1.00)

Engine 1 is left of centre (-8.50)
Engine 2 is further back AND centred (36.00, 0.00)
Engine 3 is right of centre (8.50)
And all 3 engines are the same distance above the centre of the fuselage (1.00)