The growing popularity of rearwheel dynamometers is a very positive development for performance consumers. In addition to being able to perform precise tuning more easily than in the past, there is another important benefi t which is often ignored. Rearwheel dynos also allow you to easily perform baseline testing prior to installation of a power adder such as a supercharger. This baseline testing not only allows you to determine the actual performance gain you receive, it also allows you to ensure that the engine is healthy prior to stepping up the power.

Certainly other diagnostics such as a leakdown and compression test are wise for ensuring a healthy engine, and track testing is also helpful for determining baseline power and performance gains. However, the additional time and expense for baseline dyno testing is minimal, and the benefi ts are large.

Remember that dyno testing does have its potential flaws. You need to ensure that conditions on the dyno are representative of real world use, including stabilized operating temperatures and adequate airflow across the intercooler. Additionally, three dyno pulls should be performed for each test, with the results averaged. Such testing will provide meaningful and repeatable results.

Finally, when calculating performance gains, also ensure that “before and after” tests are performed in similar environmental conditions. This is very important at the track, and equally important on the dyno. Dyno room temperature and humidity can vary dramatically, beyond the coverage of correction factors. Additionally, the correction factors utilized in dyno software deal primarily with air density and cannot account for changes in combustion dynamics experienced by forced induction applications subjected to widely varying atmospheric conditions. Similar “before and after” conditions help ensure meaningful test data for comparison.

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