| K&N | 240.2 hp @ 5300 RPM |
| Injen | 238.7 hp @ 5700 RPM |
| Stock/Learned | 237.3 hp @ 5500 RPM |
We also see that the K&N system, tuned for high RPM operation, is able to sustain its horsepower advantage between 5200 - 5700 RPM. This is most likely due to the inertia of air, which increases with engine speed, allowing for more air to force itself into the engine. Interestingly, based on readings from the stock MAF sensor, we have the following peak airflow characteristics for the above horsepower readings:
| K&N | ~173 g/s @ 5300 RPM |
| Injen | ~186 g/s @ 5700 RPM |
| Stock/Learned | ~188 g/s @ 5500 RPM |
What the data is telling us here is that the highest horsepower recorded was with the K&N intake, which the ECU believed to be flowing the least amount of air. Further illustrating this is an apples-to-apples comparison of the intakes at the same engine speed (5300 RPM):
| K&N | 240.2 hp @ ~173 g/s |
| Injen | 234.7 hp @ ~177 g/s |
| Stock/Learned | 236.2 hp @ ~184 g/s |
Looking at the averaged performance dyno charts for each intake, the K&N short intake makes the most high RPM power, assuming its on account of the higher resonance frequency of the shorter intake. But if we look at the power relative to the MAF rate, the stock intake performs best.
Torque
Ignoring the red stock curves, the maximum torque outputs again are close to each other, with the spread between top and bottom being about 7 lb-ft. The long, cold-air intake from Injen performed best as the tuning principles imply, followed by the medium-length stock system, and finally by the short K&N system:
| Injen | 279.5 lb-ft @ 3720 RPM, ~127 g/s |
| Stock/Learned | 277.1 lb-ft @ 3760 RPM, ~137 g/s |
| K&N | 272.6 lb-ft @ 3740 RPM, ~131 g/s |
The advantage of the long pipe length with the Injen system is seen in the range of its torque output. The Injen system starts to differentiate itself from the other systems at about 3500RPM and maintains its torque advantage up to about 4500 RPM. As we found out in the horsepower investigation, we see that the highest overall torque was achieved with the lowest airflow reading. Again, comparing systems at the same RPM (3720 RPM), we have:
| Injen | 279.5 lb-ft @ 3720 RPM, ~127 g/s |
| Stock/Learned | 275.8 lb-ft @ 3720 RPM, ~135 g/s |
| K&N | 272.2 lb-ft @ 3720 RPM, ~130 g/s |
Looking at torque, the Injen intake, with its longer length, shows its advantage at lower engine speeds, resulting in higher torque. According to the data, the stock intake is still the most efficient at delivering air to the engine.
So far, the dyno results follow simple intake tuning concepts - take advantage of the pulsating flow in order to have a "ram" effect. For peak power, a short intake system is best since the resonant frequency (when the pressure peaks constructively interfere with each other) is at its highest (at a high RPM where peak power is made) where as for peak torque, lower in the RPM range, a longer intake system results in a lower resonant frequency/RPM.