The hard truth with a compound-turbo diesel is simple: boost pressure is not the same as usable air. If the intake is restrictive, the charge-air cooling is undersized, and there is no intercooling between compressor stages, air density falls off fast. Then you add fuel, the engine smokes, exhaust temperature climbs, and the dyno room fills with what the engine could not burn. That is the real issue here. The parts may be capable, but the air system is not supporting the program. A small filter, inadequate airflow across the air-to-air core, no cooler between turbo stages, and boost leaks all work against the engine. The result is a combination that shows smoke and heat instead of clean, repeatable power. On a diesel, you do not tune by throwing fuel at it and hoping the air catches up. You build the air system first, support it like it will run in the vehicle, and judge the engine by observed power and clean combustion. That is how you make power that can live longer than a short dyno pull.
Gale Banks opens by explaining that his Facebook messages were flooded with requests to watch a video about a fifth-generation Camaro being fitted with an LBZ Duramax diesel and compound turbos in an attempt to reach 200 mph. His immediate reaction is that the target is achievable. He points to Banks' own history, noting that the company put a Cummins inline-six into a truck in 2001 and reached 222 mph. What drew his attention was not the idea of a diesel Camaro itself, but the specific dyno episode people wanted him to evaluate.
As the video begins, Banks recognizes several people involved. He identifies Mike Lefevre at the dyno console, recalling that Lefevre worked for him years earlier in his San Gabriel speed shop. He also recognizes Guy Tripp of SoCal Diesel, whom Banks had previously sponsored in a four-cylinder circle-track car at Irwindale. Looking through the dyno-room glass, Banks immediately starts assessing the hardware. He sees an engine, an intercooler, and a pair of turbos arranged as a compound system, with one turbo feeding the second. He also notes that Edelbrock appears to be involved, which leads him to assume the engine may be using Edelbrock heads. The Camaro itself appears to be a caged 2015 car, and the team says they are pursuing standing-mile speed.
Banks' first technical criticism is the compound-turbo layout and the lack of cooling between compressor stages. In his view, feeding one compressor directly into the next without an intercooler between them risks excessive temperature and can damage the second compressor. He stresses that turbo matching and charge-air cooling are central to diesel performance because the goal is the lowest possible intake-manifold temperature and the highest possible air density. He also notices that the visible intercooler is air-to-air, yet he does not see any meaningful airflow being forced across it in the dyno room. To him, that means the charge-air cooler cannot perform as intended during testing.
He is equally critical of the inlet side. The air filter appears far too small for the airflow demand of a compound-turbocharged engine of nearly seven liters. Banks calls it a major restriction in its own right, arguing that the reduced inlet pressure and density caused by such a small filter would hurt the entire system. In his estimate, the combination has two major restrictions, or "corks": the undersized air filter and the inadequate charge-air cooler. He believes correcting those alone could be worth roughly 150 horsepower, and that adding an intercooler between the first and second compressor stages could be worth another 50 to 100 horsepower.
Banks strongly objects to the way the team talks about fueling and air-fuel ratio. He argues that diesel engines must be approached differently from gasoline engines. In his explanation, a gasoline engine is fundamentally air regulated, while a diesel is fuel regulated: when you want more output from a diesel, you add fuel, but only after ensuring the air system can support it. If the engine smokes, he says, that is evidence of insufficient air. Black smoke is not a sign that things are working correctly; it means the engine is being overfueled relative to available oxygen.
That principle shapes his reaction to the dyno pulls. He sees heavy smoke and interprets it as unburned fuel, elevated exhaust gas temperature, and incomplete combustion. He repeatedly returns to the same point: the engine needs the air before it gets the fuel. In his view, the setup is clearly fuel-rich because the air system is not supporting the program. Rather than demonstrating a well-matched diesel combination, the smoke suggests the engine is starved for air.
Beyond the hardware itself, Banks is alarmed by the dyno-cell environment. He observes what appears to be exhaust lingering in the room and questions whether the exhaust extraction system is functioning properly. At one point he remarks that the engine seems to be "eating its own waste," meaning it may be ingesting contaminated air from the dyno room rather than a clean, cool supply. He also emphasizes again that there is no visible airflow through the intercooler core. For a diesel under heavy boost, especially one using compound turbos, that is a serious problem because charge-air temperature control is essential.
His broader criticism is that the engine should have been tested in a way that replicates how it will operate in the car. That means proper support for inlet air, intercooling, fuel rate, and the rest of the system. In his view, the dyno cell should allow the team to make the standing-mile run in simulated form, not merely produce a short burst of power under conditions that do not resemble the vehicle installation. As tested, he believes the engine is being fed plenty of fuel but not nearly enough air.
Banks also objects to the way the dyno numbers are being handled. He says the team appears to be applying a correction factor that does not belong on a diesel engine. Specifically, he references the old SAE J607 "STD" correction used on gasoline engines, which he says inflates the horsepower number. His position is that diesel performance should be judged by observed horsepower, not by corrected figures intended to produce a larger number. Once the observed number is known, altitude effects can be estimated from there, but the baseline should remain the actual measured output.
He is similarly unimpressed by the level of instrumentation being discussed. When Mike Lefevre says he is watching torque, oil pressure, and boost, Banks dismisses that as inadequate for serious diesel development, saying it is not real data acquisition. He wants more complete information, especially because the visible smoke already suggests the engine is operating in a thermally stressed condition. He specifically asks about exhaust gas temperature, arguing that any time an engine is making that much smoke, elevated EGT should be assumed and monitored closely.
The dyno session produces several notable figures. Banks hears one pull described at 1,385 lb-ft of torque and 967 horsepower, which he acknowledges is substantial output. He notes that standing-mile racing is tougher than many people assume, but those numbers are already in the range where a 200 mph attempt is plausible. He also identifies another result around 912 horsepower with torque in the low- to mid-1,300 lb-ft range, occurring at roughly 3,400 rpm. Later discussion in the video references 60 psi of boost versus 90 psi, and Banks emphasizes that the difference between those boost levels is enormous.
What concerns him is not simply the absolute numbers, but how they are being achieved. As the team adds fuel and raises rpm toward about 4,200 rpm, he sees more smoke and hears that the engine is making less horsepower despite more boost. To Banks, that is a warning sign. More boost should not coincide with worsening combustion quality and falling power unless the system has serious inefficiencies or leaks. He interprets the smoke increase as further evidence that the combination is not using the added boost effectively.
Eventually the team identifies major boost leaks, with leakage described as coming from multiple places, including the wastegates. Banks agrees that the leaks need to be fixed, but he also sees them as part of a larger pattern: the combination has the right major parts in the wrong arrangement, along with several supporting components that do not match the goal. Even before the leaks are addressed, he questions whether the engine would survive a full standing-mile pull. Dyno runs of only a few seconds do not answer that question. A standing-mile pass from a dead stop requires sustained load for much longer, and an engine that is already smoking heavily on short pulls may not live through the full event.
His concern is essentially that the setup behaves like a time-delay fuse. If the engine is overfueled, undercooled, and thermally stressed, then the issue is not whether it can make a big number briefly, but whether it can survive long enough to use that power in the real run. That is why he keeps returning to air density, intercooling, and combustion quality rather than celebrating the peak dyno figures.
Banks closes with a mixed assessment. He clearly enjoys seeing familiar people and acknowledges that the project has serious potential. He does not dispute that the goal of 200 mph is within reach. However, he believes the dyno setup and air system are fundamentally flawed. In his summary, the build contains the right parts in the wrong combination, plus a few parts that simply do not support the program. He singles out the intake system used on the dyno as inadequate and says the intercooling strategy "totally sucks," especially without an intercooler between compressor stages and without proper airflow across the main core.
To underline his point, he compares the project to a stock-displacement L5P in Banks' own dyno cell, saying they make 912 horsepower on a single turbo with no smoke and are working toward 1,000 horsepower. That comparison is meant to show that the smoke and thermal behavior seen in the Camaro video are not inherent to diesel performance; they are symptoms of a poor setup. His final message is directed at viewers who care about doing diesel performance correctly: he intends to keep explaining the proper approach, centered on airflow, charge-air cooling, realistic testing conditions, and measured observed performance rather than inflated corrected numbers.