The Effect of Dimpling and Intake Enlargement on Engine Performance 2019-01-0766
Some engine tuners claim that the dimpling of the inner surface of engine intake ports may improve engine performance. However, it is difficult to find scientific evidence of this outcome. Therefore, the objective of the present work was to assess the potential improvement provided by such modifications in terms of flow, torque and power.
The work was based on a 1.6 L S.I. engine where four different engine stages of intake port tune were evaluated:
1. Original port (stock engine), with original valve seat;
2. Enlarged port, with original valve seat;
3. Enlarged port, with enlarged valve seat;
4. Dimples machined over the enlarged port, with enlarged valve seat.
The different engine head configurations were flow tested using an engine flow bench to account for steady-state improvements for different intake valve openings ranging from 1mm to 12mm.
Also, three head configurations (1, 3 and 4) were dyno tested on an actual engine, in order to evaluate the potential power increase of each level of tune.
Flow bench results show that for the range of conditions tested, the flow rate can be improved up to 40% with the combination of port enlargement and dimpling. However, the contribution of dimpling in this improvement seems to be marginal. On the other hand, dyno results show an increase in power output of up to 7% between 6500 and 7500 rpm due to the dimpling of the inner surface of engine intake ports.
Adriano Sousa, Jorge Martins, F. P. Brito, Tiago J. COSTA