Engine setup

- 70cc MHR Team 7T (tuned exh.198°, transfers 130°)

- 19mm Team carburetor

- Everything other that goes with an high-end setup

Exhausts tested

- Stage 6 R1400

- Yasuni C21

- Malossi MHR Team

- Roost Sprint Type ('09)

- Roost Sprint Type HR ('09)

Testing

The exhausts were tested in such sequence; Sprint Type HR, R1400, C21, MHR, Sprint Type. On each exhaust we done 4 runs, of them the best result was taken for the graph above. The engine temperature at the beginning of each test was about 45°C.

Results

Interesting comparison between some of the high-end commercial exhausts. The lower rpm making, MHR exhaust, was the less powerful exhaust on the test, but with good and a clean torque output. The R1400 performed better at high rpm. It is a peaky exhaust, it's power falls sharply after top power rpm. The C21 had more or less the same results as the R1400, had a little less power at lower rpm but with a wider rpm range. The Sprint Type (green line) was the best performing exhaust in the test, having the highest power and torque of all. The Sprint Type HR (blue) made almost the same peak power as the Sprint Type, the power range was a little wider.

Probably the three highest revving exhausts could have had better results if a bigger carburetor was used.

Scores