On an engine dyno, fuel filtration has to do two jobs at once: remove dirt and separate water without choking flow. That matters even more with modern diesel fuel, where lubricity additives can let tiny water droplets stay mixed in the fuel as an emulsion. If the filter media is not up to the job, water and contamination can get through, or restriction can climb enough to affect the fuel system and the data. That is why we use a serious Parker Racor fuel filter/water separator upstream in the dyno fuel supply. The point is high capacity, low pressure drop, and media designed to catch fine contamination while pulling water out of the fuel. In our setup, that protects the fuel measuring equipment, lift pump hardware, and the final filtration ahead of the engine. Just as important, it helps make sure the fuel supply system does not imprint itself on power or fuel-efficiency results.
The video focuses on a major upgrade to the fuel systems that support Banks' engine dyno cells. With several engine dynos in use, the team is rebuilding the fuel supply arrangement from scratch, and the next critical component is filtration. Rather than using a typical vehicle-mounted aftermarket filter, the goal here is a serious, facility-level diesel filtration and water-separation system designed to support controlled testing with minimal restriction and long service life.
The filter chosen for the job is a Parker Racor S 3207 T, configured as a 10-micron fuel filter and water separator assembly. Gale emphasizes the size of the unit, noting that it is much larger than the kind of filter most people would bolt onto a truck. At roughly $400 each, these are not casual purchases, so the discussion centers on what justifies the cost.
The primary requirements are straightforward but demanding: remove dirt, remove water, provide high contaminant-holding capacity, and do it with very low pressure drop. These assemblies are rated at 250 gallons per hour with only 1 PSI of pressure drop. Using a pair of them for each dyno cell gives a combined capacity of 500 gallons per hour while maintaining very low restriction and substantial filter life.
For dyno work, filtration cannot become a variable that affects test results. The fuel system must deliver clean fuel without imposing enough restriction to influence engine power, fuel efficiency, or the behavior of the supply hardware. That is why low pressure drop is treated as a core design requirement rather than a convenience.
In this setup, the filters are intended to protect everything downstream: fuel measuring equipment, lift-pump equipment, and the final filtration stage before the engine. The final engine-side filtration will be in the 5- to 7-micron range, which Gale expects to work well with both Bosch and Denso high-pressure pumps and injectors. The Racor units therefore serve as the primary filtration and water-separation stage, taking the bulk of the contamination load before the fuel reaches more sensitive components.
A major part of the explanation concerns why modern diesel filtration became more difficult. Around 2007, diesel particulate filters, or DPF systems, were introduced broadly on diesel vehicles. Because DPF systems do not tolerate sulfur well, the fuel industry had to remove sulfur from diesel through hydrotreating.
That change created a secondary problem. Hydrotreating removed sulfur, but it also reduced the fuel's natural lubricating quality. To restore lubricity, the industry added chemicals known as surfactants. Those additives solved one issue but introduced another: surfactants allow liquids that normally resist mixing to combine as an emulsion. In practical terms, that means water can exist in diesel fuel as extremely small dispersed droplets rather than separating cleanly out.
According to Gale, this is the dirty little secret of the newer fuel chemistry. The lubricity additives make it easier for water to remain blended into the fuel in very fine particles. As a result, older filter test methods and older media designs were no longer adequate. Filtration technology had to evolve to remove both fine particulate contamination and emulsified water without sacrificing flow.
Gale credits Parker Racor's advantage to the filter media inside the canister. In his view, the technology in the media is what separates these assemblies from ordinary filters. To explain that, the video includes comments from Christine Stanfill, chief engineer of global filtration media at Parker Racor.
Stanfill describes Racor's media development work as highly diverse, including programs focused on chemical treatments that give specific chemical reactivity to media surfaces. That is especially important in fuel filtration when the objective is to separate fuel from water. She explains that the industry has moved from particle fibers on the order of a micron down into the micro and now nanofiber region. As filter dimensions decrease, the demands on the paper become more extreme, so the solution has been to move toward composite media.
The example she shows is a four-layer media structure. It includes a structural support layer that provides both mechanical support and fine-particle filtration, composited with melt-blown synthetic layers. Each layer is designed to work with the others so the finished media can hold dramatically more dirt than base paper alone. The key is not just finer filtration, but combining fine capture with durability, capacity, and water-separation performance.
The central engineering principle is surface area. Gale summarizes the concept bluntly: if you want to remove contaminants down to 10 microns and also separate water while maintaining decent flow, you need a great deal of effective media area inside the canister. Stanfill makes the same point in more technical terms, explaining that coalescence media can provide hundreds of square meters of surface area between the dirty, wet upstream side and the clean, dry downstream side.
She goes further, saying the coalescence media they have developed offers thousands of square meters of surface area per square inch of media for that separation task. That enormous internal area is what allows the filter to capture fine contamination, encourage water coalescence, and still support high flow rates. Gale reacts to that figure as almost mind-blowing, because it explains how a physically compact assembly can perform at industrial flow levels without becoming excessively restrictive.
To put the filtration scale into perspective, Gale explains the size units involved. A micron is one one-thousandth of a millimeter, and a millimeter is about 0.039 inch. A nanometer is one one-thousandth of a micron. His point is that the media technology is operating at an extremely small scale, far beyond what most people picture when they think about a fuel filter.
That matters because the challenge is not simply catching visible debris. The filter must deal with very fine particulate contamination and water dispersed in tiny droplets throughout the fuel. The move into micro- and nanofiber media is therefore directly tied to the real-world chemistry of modern diesel fuel and the need to maintain both cleanliness and dryness at high flow rates.
These Racor assemblies will be installed in the fuel shed as the primary filtration stage on the vacuum side of the system. Fuel will first be pumped from the storage tank into a gravity-feed holding tank using an air motor, specifically to avoid any chance of sparks in the fuel shed. From that holding tank, fuel will gravity-feed through a pair of Racor filters to each dyno cell.
The assemblies will collect any water that may be present in the diesel, with the separated water accumulating in the bowl for draining. Gale does not expect large amounts of water, but the system is designed to remove it if it appears. The expectation is that the outlet from these filters will provide clean, dry fuel to the rest of the dyno fuel system.
Once installed, the entire system will be instrumented. Banks plans to measure and log pressure drops, or pressure gains, throughout the fuel path so the supply system does not imprint itself on measured power or fuel-efficiency results. All of that data will be fed into the iDash data system for analysis. The filtration upgrade is therefore not just about protecting hardware; it is part of building a repeatable, measurable fuel-delivery system for accurate dyno testing. Gale closes by noting that the installation and operation of these filters will be part of the next episode of Killing a Duramax.