Well we had a chance to start testing products, its been a long time coming. We started off with the Racer X air intake box for the Toyota MR2. We frequently get the obvious question does it make anymore horsepower/torque. For this test we used a mostly stock MR2, it does have a few upgrades but not many. Its current parts are as follows:
Racer X 1 pc hot pipe
Racer X 1 pc cold pipe
Racer X TB inlet
Greddy style side mount IC core
Random fan, not sure of size or brand
K&N 4” x 9” conical filter with 4” intake pipe
OEM CT26 turbo, at 16psi
For the intake comparison we used 3 filters which were:
K&N 4” x 9” conical filter (KNN-RE-0870)
Generic panel filter, supplied with the Racer X air intake box (BCK-042-1446)
K&N panel filter, can be purchased separately for the air intake box. (KNN-33-2017)
For the tests we did 3 dyno pulls for each filter, and the graphs show the best power output for each filter. Although all pulls fell within 1 or 2 horsepower of each other. I have also included the data points, so its a little easier to compare.
K&N 4”x9” conical filter: 192.9 whp / 189.2 ft/lbs
Racer X air intake box, with generic panel filter: 200.4 whp / 194.4 ft/lbs
Racer X air intake box, with K&N panel filter: 204.6 whp / 195.7 ft/lbs
All three runs on the same graph, pulls are within a few hundred RPM of each other. The CT26 is falling on its face right around 6000 rpm, so we did not bother going any higher. I would expect that these gains could be higher with a properly sized turbo.
Data points for the runs, most gains are occurring after 5000 RPM. Again I would expect for this trend to continue if we were not limited by the turbo.
A few notes on the design of the air box, when we started out with the air box we knew that a large velocity stack would be ideal for air flow. The velocity stack opening for the air box is roughly 5” with a bell mouth leading into a taper before starting to the 4” intake pipe. The combination of the air box and large velocity stack makes this transition much easier for airflow and does not require the airflow to turn 90 degrees before entering the intake pipe.
If you were to examine a K&N conical intake filter, you would find a slight radius before entering the 4” intake pipe. Air flow must turn 90 degrees before entering the intake pipe with the conical filter which leads to flow losses and in turn less horsepower.