The real limit on a hard-running 6.7L Cummins is often the intake elbow. Most designs have to dodge the stock number one injector line, so the inlet gets flattened, chopped up, or pushed into a compromised turn. That costs airflow right where the engine needs it. Our Banks Monster-Ram Intake and Killer Grid Heater Upgrade takes a different path. We use a proprietary fuel-line solution so the elbow does not have to be crushed to clear the line. That lets us keep a larger, cleaner inlet and a more direct path into the head. The outlet is symmetrical, the flange surface is properly machined, and the ports are positioned to support added sensors or water-meth nozzles with a more useful spray angle. On the flow bench, that design change mattered. The 3.5-inch Monster-Ram posted a 474 CFM gain over stock, and the 4-inch version reached a 576 CFM gain, the best result in this comparison. Just as important, the airflow gain came with strong value per 100 CFM. If you are trying to make power, improve spool, and stop the intake side from becoming the choke point, this is the elbow design that gets out of the engine’s way.
The video presents the results of Banks' 2017 6.7L Cummins intake elbow comparison. Testing was performed on a SuperFlow SF-1020 flow bench. Each elbow was tested at the same inlet pressure: 10 inches of water, which Gale describes as roughly 3/8 psi. The elbow was installed on the bench, the target pressure was set, and the bench automatically increased airflow until the pressure drop through the elbow reached that value. The resulting airflow was then recorded, eliminating operator adjustment as a variable.
The stock intake elbow served as the baseline and flowed 432 CFM. From there, each aftermarket elbow was compared by its absolute CFM gain and percentage increase over stock. The discussion also emphasizes that this is not just a shape comparison; it is intended to show how inlet geometry, outlet symmetry, flange quality, injector-line clearance, and auxiliary port placement affect real airflow.
The first elbow discussed is the H&S unit. Like several competitors, it is shaped to clear the stock number-one injector line on the Cummins. According to Gale, that packaging requirement forces a severe deformation of the inlet section, flattening and chopping the passage in a way that restricts flow. He characterizes the internal path as blowing into a wall and then forcing the air downward, which creates substantial loss. In testing, the H&S elbow improved airflow by 110 CFM over stock, a 25% increase.
The BD elbow, which was not physically present during filming because it had been returned to its owner, performed better than H&S but still fell short of the top results. Gale notes some disappointment given BD's long history in turbocharging. Its measured gain was 266 CFM, equal to a 62% increase over the stock elbow. The implication is that while BD improved the airflow path, it still did not overcome the compromises imposed by the stock injector-line clearance and overall elbow geometry.
AFE's elbow is presented next. Gale describes AFE as relatively new to this specific kind of engineering compared with long-established turbocharging specialists, and he criticizes what he sees as a marketing-driven feature set. Their "Blade Runner" concept includes an internal blade intended to help the air make the turn. Even with that feature, however, the elbow still suffers from the same heavily chopped and gouged inlet area needed to clear the fuel line. This version uses a 3.5-inch inlet and produced a gain of 355 CFM, or 82% over stock.
Glacier Diesel Power's elbow also lacked one of the mounting bolts in the example shown. Gale points out that although it uses a locating pin, there is no bolt applying clamping force at that point to press the flange against the cylinder-head intake surface. The tested sample also had a pronounced groove in it, which he nicknames "Scarface." Despite that, the GDP elbow gained 366 CFM, an 85% increase over stock. Gale finds it notable that this elbow, without any internal "Blade Runner" feature, outperformed the AFE piece, reinforcing his view that the blade is more of a marketing element than a true airflow advantage.
The Pusher elbow is described as a "muffler shop elbow" with a 3.5-inch inlet. Gale compares its geometry to an old NACA study he says he has relied on since 1956, specifically the kind of turn shape he tries to avoid because it does not manage airflow efficiently. In his view, the design does not fully take advantage of the available outlet area, and the sample shown also has a significant gouge in it.
He spends additional time on the placement of the water-methanol injection ports. On this elbow, one port appears to direct flow mainly into a single runner, while the other sprays toward the divider between passages. The TMAP sensor sits beneath that area, and Gale questions whether water-methanol dripping onto the sensor would be good for sensor durability or accuracy. In flow testing, the Pusher elbow gained 394 CFM, which corresponds to a 91% increase over the stock elbow.
Banks then moves to its own Monster-Ram design. The 3.5-inch Monster-Ram uses a symmetrical outlet, which Gale highlights as a major distinction from some competing elbows that effectively "cheat" the bend by skewing the outlet rather than maintaining a square, centered flange transition. He argues that the Banks design sends the air almost straight down into the head after the turn, promoting a more uniform distribution.
The water-methanol injector nozzles are also deliberately canted and aimed based on Banks' cylinder-head work so that the spray cone enters what Gale calls the sweet area of the elbow. The goal is improved evaporation time, cooling time, and more uniform delivery into the cylinder head. He contrasts this with competitors whose nozzle placement appears less controlled. Gale also criticizes one competing flange for being ground on a disc sander rather than machined flat, arguing that a dead-flat machined surface is important if the engine will see very high boost pressures.
A key part of the Monster-Ram story is that Banks avoided the usual design compromise by developing an injector line that clears the elbow properly. Rather than reshaping the elbow to fit the stock line, Banks changed the line. Gale says this line is produced by a major OEM fuel-injection supplier rather than fabricated informally. Both the 3.5-inch and 4-inch Monster-Ram versions include provisions for every early and late 6.7L Cummins sensor and mount, and they also allow additional sensors for users who want to monitor pressure or temperature with their own instrumentation.
The 3.5-inch Monster-Ram improved airflow by 474 CFM, which is a 110% increase over the stock elbow. That places it ahead of all of the other 3.5-inch competitors discussed in the video.
The 4-inch Monster-Ram delivered the highest result in the comparison, gaining 576 CFM over stock for a 133% increase. Gale presents this as the payoff for eliminating the injector-line interference problem and preserving a cleaner, less compromised airflow path. In the context of the test sequence, the Banks elbows are positioned not only as the highest-flowing parts in the group but also as the designs with the most complete sensor and nozzle integration.
Banks gives pricing for both Monster-Ram sizes. The 3.5-inch version in natural aluminum is priced at $339, and the required injector line to clear it is $60. The 4-inch version in natural aluminum is $369, with the injector line also priced at $60. Paint is available for $24 on either version. Banks also offers powder coat, and for customers running a 4-inch elbow with a 3.5-inch boost tube, there is a hump hose adapter available. Gale notes that the 3.5-inch Monster-Ram will accept any boost tube that fits the stock setup.
He also frames the comparison in terms of durability and sealing. Missing bolts, poor flange finish, and compromised geometry are presented as concerns for engines that may see very high boost pressures. Gale mentions future operating conditions in the range of 50, 100, or even 150 psi, emphasizing that when airflow and boost rise to that level, flange integrity and sealing become much more important than they may appear in a simple visual comparison.
The final part of the video compares not just purchase price, but cost per 100 CFM of airflow gain. Gale argues that this is the more meaningful metric because the buyer is fundamentally purchasing airflow performance.
Using online pricing, H&S is listed at $329 with a 110 CFM gain, which works out to about $300 per 100 CFM. For BD, Banks estimates roughly $250 for the casting alone, excluding the extra boost tube included in BD's package; at that level, the cost is about $94 per 100 CFM. When the mandatory 3.5-inch boost tube and the adapter hose to 4 inches are included, Gale says BD rises to about $143.80, rounded to $144, per 100 CFM.
AFE is listed at $390 online, which yields about $110 per 100 CFM gained. Glacier Diesel, configured with five ports, is priced at $359 and comes out to about $98 per 100 CFM. Pusher, with two ports standard and another two available for an additional $20, is treated as a $369 package in this comparison; with its 394 CFM gain, that works out to about $94 per 100 CFM.
For the Banks Monster-Ram, the 3.5-inch version with four ports and the injector line included comes to about $84 per 100 CFM. The 4-inch version in the same configuration drops to about $74 per 100 CFM. Gale then gives an apples-to-apples casting-only comparison, excluding extras such as the injector line, where the 3.5-inch Monster-Ram works out to $72 per 100 CFM and the 4-inch version to $64 per 100 CFM. His conclusion is that Banks offers both the best airflow performance and a highly competitive overall price, with especially strong value when measured by airflow gained per dollar spent.