The Baja Bomber with its Cummins turbodiesel engine needs to breathe cool, pollutant-free air for optimal performance and reliability. Unfortunately, the dusty silt beds of Baja California, for which this rig is being tuned, provide little more than fine baby-powder dust, which quickly clogs most OE air filters. These bottomless beds of powder are also known for caking dirty grime to any exposed fluid or residue present under the vehicle. In this segment we will tackle these issues.
Everyone knows that increasing the amount of filtered air available to the engine can result in increased horsepower and torque. However, for a turbodiesel engine the benefits of such upgrades are increased because the turbo is compressing the air on its way to the intake manifold. This creates a vacuum effect at the filter element. So it makes sense that by increasing the surface area of the inlet filter, one can expect better turbo performance.
A larger inlet filter will result in quicker turbo spool-up and cooler intake-air temperatures. This is a good thing because less heat means the compressor wheel is compressing more air with each rotation. In effect, the difference in pressure from the negative side of the turbo to the positive side is decreased. That's called turbo efficiency, as it relates to the cold or precombustion side of the turbocharging process.
Modification 1 This is the...
Modification 1
This is the Bomber's stock inlet system. Restrictive and bulky, it was in dire need of help. So we decided to replace our stock air filter with the Scotty Air II from Scotty Air Systems. This unique intake replacement provides all '94-'01 Dodge Rams with roughly three times the filtering surface of the OE unit, as well as a working cowl induction system. It was easily installed in about half an hour.
Once the stock airbox was...
Once the stock airbox was removed, we cut a hole in the cowl using a drill with a 411/42-inch hole-saw bit. This perforation into the cowl will allow positive air pressure from the sloping windshield to dump into the Scotty Air intake plenum. This hole may seem like a drastic measure for better airflow. We surely thought so until we cut it out and realized the large cavity that existed behind was an untapped void full of pressurized cool air when the truck was moving forward.
After installing the system,...
After installing the system, the spool-up response time seemed like it had been cut in half. We also noticed lower exhaust gas temps, which confirmed this was a beneficial modification. The only thing that seemed like it might have a negative affect was the noticeable difference in the intake/turbo sound. With the Scotty Air II installed, the interior had a strange new noise that sounded like someone was running a vacuum cleaner under the hood. We spoke to Scott Presak, who invented the Scotty Air system, and he suggested we try a Turbo Air Guide, or TAG, to silence the noise.
Modification 2 A Turbo Air...
Modification 2
A Turbo Air Guide (shown above) is a simple device that installs right before the turbo inlet. Diesel Power Products of Pasco, Washington makes these units for all domestic turbocharged trucks. A TAG is designed to straighten out the laminar airflow as it enters the turbo compressor wheel. The principle is simple: By aligning the flow as it enters the turbo, each passing vane of the compressor wheel is able to capture more air per rotation. In other words, by limiting air turbulence, a TAG increases turbo efficiency and allows the air to flow smoother and faster. This sounds great, but does it actually work? On the dyno the tag had no affect on horsepower whatsoever. What it did do, however, was silence our mystery vacuum cleaner.
Modification 3 The last...
Modification 3
The last modification we decided to try on our intake extravaganza was a system that solves a problem all Cummins owners hate: The crankcase oil vent that dumps out above the steering box and front differential. It's the source that coats every part under the truck with a grime-grabbing film of motor oil. Walker Engineering of Sun Valley, California has solved this annoying problem. The company builds a bolt-on kit, called an Airsep, which connects to the Cummins crankcase vent and returns the oil vapor to the oil pan where it belongs.
The Airsep system is simple...
The Airsep system is simple to install with standard handtools. The installation took us about three hours to complete. When used with the stock airbox, the kit comes with everything you need to create a closed-loop system out of your Cummins crankcase vent tube. The system replaces your factory intake hose with a specially molded plastic tube (left), which allows for the additional space required by the filter element. The filter itself is a canister with two connection ports-one for suction and another for drainage.
The unit installs between...
The unit installs between the air filter box and the turbo inlet. The drain at the bottom directs oil down to the oil pan via a return line.
Once installed, the Airsep...
Once installed, the Airsep had no noticeable affect on performance, but completely stopped our little oil leak at the front of the engine. We pressure-washed the Bomber's undercarriage, and now it stays clean and free of dirty grime. One added bonus of this system is that it actually draws a slightly negative pressure on the crankcase, which should help preserve gasket life. This is the finished product. Now we can hit the dusty trails of Baja without worrying about the Bomber's air intake.