Emissions compliance comes down to one thing: proving a part does not make the vehicle dirtier or defeat the factory emissions system. That is where CARB Executive Orders matter. A CARB EO gives a clear path to 50-state emissions legality, while EPA expects a documented reasonable basis showing the product stays compliant. The hard part is that testing is expensive and not every product change should require a full round of emissions work. When the engineering is understood and prior data supports the application, that evidence should count. When it does not, chassis dyno or engine dyno testing becomes necessary. The regulated outputs are not just smoke. Labs are measuring hydrocarbons, particulate mass, NOx, carbon monoxide, methane, and related values at very small levels. There is also a clear line between legal performance work and defeat devices. If a tuner removes or disables EGR, DPF, catalysts, or other emissions controls, it is not going to pass compliance review. That is why delete tuning keeps drawing enforcement. The right way to build performance parts is to understand the system, document the results, and make the power without turning the truck into a smoke machine.
This episode of Speed School opens with Gale Banks interviewing Peter Tride, now SEMA's director of emissions compliance. Their connection goes back to 1992, when Peter's father, a dental X-ray technician in Glendale, happened to meet Gale and passed along Peter's contact information. At the time, Peter was working at Esslinger Engineering, where he had started in 1986 while still in high school.
Peter described Esslinger as his real introduction to engines. He began sweeping floors and cleaning machining chips, then gradually learned to use drill presses and lathes, port cylinder heads, assemble engines, run the dyno, and support race efforts. Esslinger specialized in Ford four-cylinder racing engines, particularly the 2.0- and 2.3-liter Pinto-based engines. Through that work, Peter became familiar with Gale Banks through magazine ads and articles, especially Banks' reputation in marine engines and diesel performance. When Gale eventually hired him, it was nominally as an engine builder, although Peter's role quickly expanded into many other technical and managerial functions.
Gale used Peter's background to revisit the early days of Banks diesel turbocharging. In the late 1970s and early 1980s, Banks had already been deeply involved in turbocharger development for marine engines and land-speed projects, so applying turbocharging to naturally aspirated diesel truck engines was a logical next step. Gale explained that Chevrolet first asked him to evaluate the 6.2-liter diesel as a twin-turbo marine engine intended to compete with Caterpillar's 3208. Although the twin-turbo setup could make enough fuel to destroy the engine, it was ultimately pump-limited and not a viable contender in that marine application.
The truck application was different. Banks received pre-production Chevrolet diesel trucks, including a 135-horsepower half-ton with a floor shift and a 145-horsepower dually with a three-speed automatic. Neither had much performance in stock form, so Banks developed his own turbo systems. According to Gale, simply forcing air into the intake manifold transformed the engines: performance improved, smoke dropped, fuel economy increased, and exhaust gas temperatures fell. He argued that turbocharging a diesel produces benefits across the board, whereas naturally aspirated diesels offer few advantages in comparison.
The discussion also touched on Ford's naturally aspirated 6.9- and early 7.3-liter International Harvester diesels. Banks still sells turbo systems for some of those trucks, and Gale noted that their medium-duty-engine origins make them exceptionally durable. In pickup use, 500,000 miles is routine, with seats and transmissions often wearing out before the engine does.
Peter joined Banks in 1992 and stayed for roughly 20 years, aside from a one-year break when he worked as a youth pastor. Gale said he often created positions for talented people rather than waiting for openings, and Peter credited that approach as one of the distinctive features of Banks Engineering.
Although hired as an engine builder, Peter's work ranged widely. He recalled rebuilding a naturally aspirated 6.5-liter diesel in a Hummer after Banks had developed a turbo system for it. Packaging that kit was difficult because air conditioning and many other components had to be relocated, but once sorted, the system worked well. During testing on Cajon Pass, the engine failed a piston. When Peter tore it down, the team discovered flaws in the GM pistons, and even replacement pistons from new boxes showed the same defect.
Over the years Peter held multiple roles, including engineering manager, oversight of technical service and customer service functions, and extensive training work. He and Gale conducted dealer seminars, product training, and technical presentations explaining how Banks systems worked. Those seminars brought in dealers from around the country for multi-day sessions and became memorable enough that attendees still mention them years later.
One of Peter's major responsibilities at Banks became emissions compliance. He had to learn the California Air Resources Board process largely on his own, although Banks was already the industry leader in Executive Orders, or EOs, which are the documents CARB issues to certify that an aftermarket product is emissions legal. Gale emphasized that Banks had been involved in the creation of that framework long before Peter arrived.
The origin story centered on a turbocharged Pontiac Sunbird project in the late 1970s. Pontiac wanted a dealer-installed turbo package for a front-wheel-drive four-cylinder car, with the parts shipped in the trunk and installed after delivery. That approach worked in 49 EPA states because the vehicle was considered to have entered interstate commerce when it left the factory. California, however, considered the car under state control until the dealer delivered it to the customer. That distinction forced Gale to confront a regulatory process that did not yet have a practical path for aftermarket manufacturers.
Gale and Rayjay chief engineer Hugh MacInnes met with CARB staff at the Haagen-Smit Laboratory and were told that certifying the turbo Sunbird would require essentially the same elaborate and expensive process Pontiac itself would use. For a small speed shop in San Gabriel, that was unrealistic. The Pontiac deal was eventually lost, but the effort helped drive the development of California Vehicle Code section 27156, which became the basis for aftermarket emissions compliance. Gale credited people such as SEMA attorney Russ Deane and technical advisor Jim McFarland with later helping shape the relationship between the aftermarket and regulators.
The conversation broadened into the history of SEMA itself. Gale recalled that the organization originally stood for Speed Equipment Manufacturers Association before later becoming the Specialty Equipment Market Association. That evolution reflected the industry's expansion from pure speed parts into wheels, tires, and many other specialty products, but Gale stressed that SEMA's roots were firmly in performance equipment.
He described two forces behind SEMA's formation. One was intellectual property, as toy makers were reproducing hot rods with aftermarket brand logos without permission. The other was financial survival. Manufacturers such as camshaft companies were being exploited by dealers who would buy on credit, fail to pay, then move on to another supplier. Because racers and manufacturers saw each other regularly, they began comparing notes and realized they needed an organized trade association.
Gale also recalled that early SEMA meetings were held in attorney Eric Grant's insurance office on San Gabriel Boulevard, and that Ed Iskenderian, the first SEMA president, remains one of the foundational figures of the industry. Gale described Isky as the first person ever to sponsor him and praised both his creativity and humility. These stories framed emissions compliance not as an isolated bureaucratic issue, but as part of a much longer struggle by the aftermarket to organize itself and defend its legitimacy.
Peter explained that Banks' diesel pickup and RV products naturally pushed the company toward emissions-compliant engineering. These were not race vehicles; they were tow rigs and work vehicles where reliability mattered, and most owners wanted legal, durable performance rather than deleted emissions systems. In that environment, emissions compliance was not an afterthought but part of the engineering envelope.
He said the compliance process often requires manufacturers to educate regulators. Aftermarket companies understand their products, the vehicles they fit, and the technical mechanisms involved, but agency staff are not always equally technical. As a result, obtaining an EO can involve presenting engineering data, prior test results, and detailed explanations to show why a product is compliant. Sometimes emissions testing is necessary, but Peter argued that agencies can default to testing simply because they do not understand the product well enough to evaluate it analytically.
That matters because emissions testing is expensive. Peter said one of SEMA's goals is to ensure that manufacturers are not subjected to unreasonable or unnecessary testing demands. CARB has sophisticated facilities and is investing heavily in new labs, including in Riverside, but Gale questioned whether the agency can consistently staff those operations with engineers capable of making fair technical judgments. Both men expressed concern that some decisions are increasingly arbitrary rather than grounded in engineering.
Peter distinguished between compliance and enforcement. At CARB, one group handles EO applications and screens products for legality, while another focuses on enforcement against defeat devices such as deleted EGR systems, removed DPFs, or tampered catalysts. EPA, by contrast, does not operate a comparable aftermarket compliance department. Historically, manufacturers were expected to maintain a "reasonable basis" for emissions compliance, but EPA did not clearly define what that meant.
For years, a CARB EO effectively served as the industry's gold standard because EPA would generally accept it as evidence that a product was 50-state emissions legal. Banks even sent emissions data directly to EPA as part of its due diligence, although at one point an EPA contact reportedly told them simply to keep the records on file rather than mailing them in.
Peter said EPA has recently clarified its expectations around reasonable basis, and SEMA has responded by creating the SEMA Certified program. This program documents procedures that satisfy EPA scrutiny and gives aftermarket manufacturers a clearer path to demonstrate compliance even when a CARB EO is not involved. SEMA has also built a new emissions laboratory in Plymouth, near Ann Arbor, to support that work. Peter described it as a world-class certification lab comparable to OEM facilities, dedicated specifically to the aftermarket and serving roughly 500 manufacturers.
The lab measures the regulated pollutants relevant to light-duty and medium-duty vehicles, including hydrocarbons, particulate mass, oxides of nitrogen, carbon monoxide, methane, and formaldehyde. Carbon dioxide is also measured, although it is not currently regulated in the same way. For chassis-dyno testing, standards are typically expressed in grams per mile, while some heavy-duty engine-dyno standards use grams per horsepower-hour. Peter noted that the numbers being measured are becoming smaller and harder to quantify, which increases both the technical challenge and the cost of compliance.
The discussion then turned to Banks' own emissions-testing history. Before building more sophisticated in-house capability, the company used five-gas analyzers, opacity meters, and later an AVL Micro Soot Sensor. The opacity meter was a simple light-beam device mounted at the tailpipe to estimate smoke density as a percentage. Peter recalled that Banks used 15 percent opacity as a practical target, while some older diesel standards tolerated much higher values, around 40 percent. In extreme cases, heavily fueled trucks could produce 80 or 90 percent opacity.
Banks later acquired more advanced equipment, including chassis dynamometers and emissions measurement systems originally purchased from states such as Texas after IM240 inspection programs were canceled. That equipment helped the company build its own emissions lab. The Micro Soot Sensor proved especially useful for diesel development because it allowed Banks to quantify soot output before it reached the diesel particulate filter. That mattered because crude aftermarket tuning often increased fueling to the point that DPFs would load rapidly, regenerate too often, create excessive backpressure, and even damage the substrate.
Gale contrasted Banks' approach with tuners who simply add fuel to make more power. He argued that such calibrations often ignore DPF backpressure, regeneration frequency, fuel economy, and overall system durability. Peter said CARB and EPA are primarily concerned with defeat devices and obvious emissions tampering, and that social media has made enforcement easier by giving regulators visible evidence of deleted diesel trucks rolling coal. In his view, many of the most aggressive enforcement actions in recent years have been directed at those blatant offenders.
Gale closed the main interview by connecting emissions work to current Banks engine programs and future propulsion concepts. He described Banks' military versions of the Duramax-based D866T engine used in the Joint Light Tactical Vehicle built by Oshkosh. Tactical military vehicles are exempt from normal emissions equipment requirements because the armed forces prioritize simplicity, reliability, and survivability over the complexity and failure modes of full emissions systems. Even so, some European customers want cleaner engines, roughly at a Euro 3 level.
Gale said Banks was able to substantially beat that standard on NOx without using EGR, while also retaining performance and fuel efficiency. Independent confirmation came from Ricardo, now called E-xcel Engineering, in the Detroit area. Banks sent an engine out for baseline testing, then correlated the results with its own AVL-based test cell and refined the calibration. Gale emphasized that this was not easy because the goal was to preserve both performance and efficiency while reducing emissions. He also noted that Banks recently won the next phase of the JLTV engine competition against formidable competition, including Caterpillar, with production for the A2 version expected to begin in 2024 and continue for about a decade.
From there, the conversation shifted to future powertrains. Gale expressed little enthusiasm for hydrogen internal combustion because of the energy required to produce hydrogen, the storage challenges, boil-off losses, and poor practicality. He cited his experience evaluating BMW's hydrogen V12 sedan, which used both hydrogen and gasoline injectors in each intake port and stored liquid hydrogen in a cryogenic tank. The car could lose its hydrogen charge simply by sitting, and Gale considered the overall energy balance deeply unfavorable.
By contrast, he was enthusiastic about hybrids, especially diesel hybrids. He described P0 and P2 motor-generator layouts, with P2 placing the motor on the same axis between the engine and transmission. That arrangement can provide torque fill during acceleration, reducing the need for enrichment while improving either fuel economy or performance. Gale said Banks had just begun a hybrid program and wanted to run a hybrid diesel at Pikes Peak. He also mentioned recent Toyota diesel injection patents aimed at improving oxygen availability in the center of the combustion chamber to reduce smoke. In his view, internal combustion still has substantial room for improvement, especially when paired with hybrid assistance.
After the interview, Gale answered two viewer questions. The first concerned intercooler heat rejection and whether a bare aluminum core or a painted core performs better. Gale framed it as a radiation question: color affects thermal radiation. He said that if the core were painted white, bare aluminum might be preferable, but if painted black, the black surface would radiate heat better. In that sense, a black-painted intercooler can improve heat rejection.
The second question asked about centrifugal superchargers for racing engines. Gale compared them with turbochargers based on a past test on a Mustang V8 where he evaluated a single-turbo system against a centrifugal supercharger on the same engine. He found that a properly matched, wastegated turbocharger delivered better engine response than the belt-driven centrifugal unit. His criticism was that a centrifugal compressor produces little boost at low rpm and then comes on abruptly, and because its speed is tied directly to engine speed, it cannot escape that narrow operating range.
For drag racing, where an engine may stage and launch at 6,000 rpm, Gale said a centrifugal supercharger can make sense. Outside that narrow use case, he prefers either a positive-displacement supercharger or a turbocharger, especially because a turbocharger offers a broader power band and better real-world response. He dismissed centrifugal units as effectively belt-driven turbochargers and made clear that, for his applications, they are not the preferred solution.