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This is the first of many dyno tests to come to show how performance parts add horsepower to the C8 Corvette.

Our performance testing here at Paragon takes place on our in-house DynoJet enclosed within a dyno cell. We specifically chose a DynoJet for our shop for the purpose of being able to provide consistent data and results that are easier to compare to other results produced on other DynoJet dynos across the world.

We carefully monitor and control the dyno cell conditions as well as provide fresh airflow to the radiators and airbox. During our testing, we constantly monitor engine parameters using the HP Tuners logging software. Despite being unable to tune the C8 engine control module (ECM) at the time of this writing; we can still monitor quite a bit of data so we know exactly what the ECM is doing with fueling and timing. We can also see the airflow (MAF) that the ECM is reading as well as the fluid and air temperatures.
After warming up the engine, we do a number of control runs to settle the power into a consistent baseline number that is repeatable from run to run. The purpose of this is to eliminate the power advantage that can be seen on the first couple runs before an engine has been fully heat soaked even if it has reached normal operating temperatures. During the testing, we adequately cool down the car between runs and start each run from the same fluid and air temperatures to ensure consistent results on each run. After each mechanical change, we get the car back up to normal operating temperature and do a new set of runs from the same starting fluid and air temperatures until we establish a new, repeatable result. By following this process, we eliminate comparing one-off best case runs against one-off worse case runs which can show false results. We only compare the results that we deem to be valid and repeatable.
Air Filter Results: We did no less than 50 dyno runs during our air filter testing as we compared a brand new OEM air filter to three different replacement air filters we sell here at Paragon. The aftermarket filters included the aFe Magnum Dry S and Pro 5R (oiled) filters as well as the Attack Blue filter. In addition to testing the filters, we even tested the car without any filter at all. The purpose of that test was to determine if having a filter creates a measurable restriction. Interestingly, we found running with no filter actually produced a loss of 5-6 horsepower.
The cause of the lost power is likely due to increased air turbulence as air enters the throttle body. After establishing this, we ran the car with each aftermarket filter and compared the results to the stock air filter. The data showed that all the filters performed slightly better than stock and all produced peak numbers within less than one horsepower of each other and 5-6 horsepower above the stock filter. On the average we found the Attack Blue performed the best when we examined the area under the curve.
+6HP on average for the Attack Blue
The Attack Blue air filter is the only one that contains an internal divider inside the filter that mimics what the OEM filter has. In theory, this divider is designed to straighten airflow and reduce turbulence as air is rammed into the airbox through the side ducts and is probably the main reason for it's better overall performance.

+5HP on average for the aFe Magnum Dry S
+4HP on average for the aFe Pro 5R

Between the two aFe filters we tested, we found the dry filter slightly outperformed the oiled (Pro 5R) filter on average but both offered very similar horsepower gains over the stock filter. After combing through the data and evaluating all the results, our conclusion is this.

GM designed a good air filter that offers very little restriction but as is common with the nature of something produced for an OEM vehicle, the filter material is perhaps not quite as free flowing as other materials which our testing showed. These aftermarket filters may not produce a big power gain on their own but you can rest assured they do not lose power and in fact do offer a slight increase in power which when coupled with other modifications will support overall larger power increases.

Next up in our series is full intake replacement shootout. Give us a month or so with the holidays and will have that data out as well. Preliminary testing puts them all fairly equal as well.