Jaguar has developed a new V8 powertrain with the support of predictive design analysis techniques. This paper describes some of the work performed during this programme to ensure low frequency powertrain refinement.The concept of the engine was to produce a lightweight 4.0 litre engine with class leading specific torque and power, while satisfying customer aspirations for vehicle refinement.To meet the refinement objectives, an understanding of the structural dynamic performance of the powertrain was required. This understanding would be essential in developing the design from initial concept through to production intent. To support this requirement a programme of predictive work was included within the design plan.In the predictive work, low frequency modes of the powertrain and order tracked mount vibration were used to characterise the influence on in-vehicle refinement. Comparison with measured engine vibration confirmed the predicted effects of design changes.The result of this focused approach is a lightweight 4 litre V8 powertrain with first bending mode frequencies exceeding 200Hz, fundamental torsion over 400Hz and low vibration levels at the mounts.