First of all, consider what the purpose of an intercooler is and why you might upgrade the stock unit. An intercooler (or charge air cooler, CAC) is a density machine. Its job is to increase the density of the intake air charge by cooling it, but it must do so without dramatically impacting the pressure of the intake air charge. Air density measurements take both the temperature and the pressure of the air into account. Specifically, to determine if an intercooler is doing a good job, you must compare the ambient air conditions (temperature and pressure) with the conditions in the intake manifold. Any aftermarket intercooler that is worth its salt should improve the air density over the capability of the stock unit, and this can only be evaluated on a live vehicle with appropriate instrumentation while simulated road circumstances in a controlled manner.
We used a 2006 Dodge Cummins truck (with a 2005 build date) and tested it in a variety of conditions. We ran tests under full load conditions (WOT) on a chassis dynamometer held at 2800 RPM for a minimum of 2 minutes until all temperatures stabilized and then evaluated data from the last 20 seconds of each run. A pair of high-powered fans was used at the front of the vehicle to provide 60 MPH of wind speed (simulating road conditions). Each vehicle condition was repeated a minimum of 3 times to ensure repeatability in the data. Our instrumentation list included: Ambient Temp, CAC Cold Side In Temp, CAC Cold Side Out Temp, CAC Hot Side In Temp, CAC Hot Side Out Temp, EGT, Ambient Pressure, Compressor Outlet Pressure, Intake Manifold Pressure, Fuel Flow, Cold Side Air Velocity, Intake Air Flow and Air Fuel Ratio. Some of these measurements are used to ensure consistency and stability in the tests, but the analysis of this data allows us to evaluate the following:
CAC Delta T Hot
- the amount of temperature drop through the intercooler
System Delta P
- The amount of pressure drop from the compressor out to the intake manifold
- The ability of the CAC to reduce temperature as compared to abient, expressed as a percentage
- Evaluation of the density of the air compared to ambient considering both temperature and pressure
Cold Side Air Velocity
- the speed of the air going through the face of the intercooler (lower speeds indicate more restriction to airflow for the radiator and other heat exchangers)
Testing was conducted over a number of days, however ambient conditions stayed very stable during the testing. Ambient temperature ranged between 84.9 and 91.2, barometric pressure ranged between 28.88 and 29.00 in-hg. The stock configuration was tested at the beginning and the end of the test sequence. Also tested were Spearco, BD, AFE and the Banks Techni-Cooler. Each was tested as they are sold.
CAC Delta T Hot
This is the difference in temperature between the inlet side (coming from the turbo) and outlet side of the intercooler (going to the intake manifold). This is one indicator of how well an intercooler is cooling the air. Stock had an average temperature drop of 289.7 degrees F. AFE had an average drop of 294.0 degrees, 1.5% more temperature drop than stock. Spearco was at 291.7 degrees (0.7% more temp drop), Banks was virtually even with stock with a drop of 289.3 degrees (0.1% difference). BD was 7.2% worse than stock with an average temperature drop of only 268.0 degrees F.
System Delta P
This is the difference in pressure between the turbo compressor outlet and the intake manifold pressure. This evaluates the change in pressure over the entire intercooler and inlet system. The more pressure that is preserved through the system, the higher the density will be. Stock had a pressure drop of 2.96 PSI. The Banks system had the least amount of pressure drop at 1.60 PSI (45.9% less pressure drop than stock). BD was next with 1.94 PSI pressure drop (34.5% less than stock), then Spearco with 2.17 PSI (26.7%) and AFE with 2.18 PSI (26.4%).
CAC Effectiveness (Temperature Reduction)
This is the calculated improvement in temperature in relation to ambient temperature expressed as a percentage. This calculation is performed using absolute temperature values (Rankine scale): CAC EFFECTIVENESS = (CAC INLET TEMP – CAC OUTLET TEMP) / (CAC INLET TEMP – AMBIENT TEMP)*100. The stock intercooler has an average effectiveness of 88.9%, AFE 96.7%, Banks 93.4% and Spearco 92.1%. The BD was worse than stock at 84.6%.
This is the measure of improved density and is expressed in comparison to stock. This accounts for both temperature and pressure and is calculated: DENSITY RECOVERY = (AMBIENT PRESS + INTAKE MANIFOLD PRESS) / (AMBIENT PRESS + COMPRESSOR OUTLET PRESS) * (CAC INLET TEMP / CAC OUTLET TEMP). Stock is considered the standard, so the difference compared to stock is evaluated. AFE has 13.7% better density recovery than stock, Banks has +12.7% and Spearco has +7.6%. BD was worse than stock with 4.1% less density recovery.
Cold Side Air Velocity
This is the measurement of air velocity at the face of the intercooler. Lower speed air flow is an indication that the core density might be too great to allow sufficient air flow to the face of the radiator. This can result in engine overheating and if coolant temps reach too high, fuel derating may occur. Stock had an average cold side air velocity of 24.6 MPH (this becomes the standard, 100%). BD had an average air velocity of 23.8 MPH (96.7% of stock), Banks had an average velocity of 22.8 MPH (92.7% of stock). Both Spearco and AFE had significant reduction in air velocity, at 19.2 MPH (78.0%) and 17.3 MPH (70.3%), respectively.
The purpose behind an intercooler upgrade is to achieve greater air density recovery without compromising other critical functions. BD achieves better flow than stock as indicated by a reasonably low pressure drop and they do not significantly compromise airflow to the radiator. But they completely miss the mark on temperature reduction and this results in a worse than stock density recovery. Spearco and AFE do a better job of cooling the air and have a decent density recovery, but they both have an internal pressure drop that is closer to stock and they significantly compromise the cooling flow (this is largely due to the bar and plate core design).
The Banks Techni-Cooler is designed with the intent of achieving greater density recovery by targeting temperature reduction that is comparable to stock while significantly reducing pressure loss. This is achieved as evidenced by the lowest pressure loss of all units tested, without compromising the cooling air flow to the radiator. This test reveals that the Banks Techni-Cooler accomplishes the intended goal.
Intercoolers are available for the 7.3L, 6.0L, and the 6.4L engines. High Ram intake manifolds are included with the 6.0L engines at no extra cost.