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Freightliner Cascadia - Birth Of A Super-Turbo

Diesel Racing On A Gigantic Scale

Oct 7, 2013
Photographers: Trevor Reed
Gale Banks gets excited when he talks about the Super-Turbo Detroit Diesel engine setup he designed alongside his engineers for use in Mike Ryan’s Freightliner Pikes Peak race truck. Banks didn’t worry about taking on the project of reinventing the truck’s powertrain less than three months before the race. Instead, he jumped at the chance to put his team’s work on display for the whole world to see at the 2013 “Race to the Clouds.”
Last year, professional racer and stunt driver Mike Ryan piloted his Freightliner Cascadia to the summit of Pikes Peak Raceway in record time. Even after a brake failure led to a spinout that added about 30 seconds to his finishing time, he still made it to the top of the mountain in the fastest time ever for a semitruck. While Banks and his team had a solution in mind for the braking system (high-pressure water sprayers), they also had plans to dramatically increase the power output of the Detroit Diesel Series 60 engine with a new supercharger and turbo combination.
Photo 2/31   |   The Super-Turbo system uses a twin-screw-style supercharger mounted at the rear of the engine and feeds directly into a large, 95mm-inducer turbocharger. The supercharger is driven by an adjustable pulley system and the turbo is spun by exhaust pushed through equal-length headers.
Pikes Peak International Hill Climb has 156 turns over just 12.42 miles, with an elevation increase of 4,710 feet between the start and finish. So, the Super-Turbo setup was chosen because it would allow the 5-ton truck to accelerate quickly out of steep corners. Even with the sequential two-turbo setup used in the 2012 race, the truck still needed to build exhaust energy before the power could be poured on. With the supercharger spinning at multiples of the engine speed, this turbo lag is eliminated and manifold pressure builds starting low in the rpm range. This also allows the use of a larger turbo since the supercharger handles boost duty until the turbo kicks in when there is enough exhaust pressure. Add to that multiple stages of water-methanol injection, water sprayers for the intercooler, water nozzles built into the brakes, custom tires, off-road shocks, and a cabin customized for racing, and you have this year’s version of Mike Ryan’s Pikes Peak race truck. Here’s how it all came together in less than 80 days at the Banks Power headquarters.
The Supercharger
Taking cues from both racing and marine engines, the team at Banks decided to use a Whipple supercharger. The large, polished twin-screw compressor has an 8.3L displacement and looks like it would be at home sticking out of a dragster hood. It is spun by a driveshaft that’s attached to a custom adjustable pulley system at the front of the engine that multiplies the rpm by a ratio of 4.31:1. The supercharger was mounted at the rear of the engine block to minimize the distance between the outlet of the supercharger and the intake of the turbo. This required the fabrication of multiple large, solid-aluminum brackets, which were also used to mount the pulleys and the driveshaft. A large blow-off valve regulates how much pressure is created between the supercharger and the turbo.
Photo 3/31   |   The supercharger gets the first two stages of water-methanol injection from four nozzles that can spray a total of 70 gph. The stages begin to kick in sequentially when the outlet temperature reaches 120 degrees, with the StraightShot controller ramping up the output of the 300 psi so the fluid delivery is as consistent as possible. The nozzles are directional and are aimed to spray directly into the inlet of the supercharger.
The Turbocharger
A custom-made boost tube takes pressurized air from the triangular outlet on the supercharger to the inlet of the BorgWarner S510 turbo. The big turbo has a 95mm-inducer diameter and uses a twin-scroll turbine housing. A large blow-off valve keeps the system pressure limited to about 60 psi, even though the Super-Turbo setup is capable of creating up to 180 psi of peak pressure. Since the intake pressure is limited, the Freightliner is able to reach its optimum intake pressure at relatively low rpm. Custom brackets and stabilizer bars allow it to sit in perfect position to meet up with the racing-style exhaust system.
Photo 4/31   |   A large BorgWarner S510 turbocharger is a water-cooled and oil-lubricated unit with a twin-scroll turbine housing. It is mounted using a custom Heim joint array that connects to the frame and the engine block, and a metal plate also attached to the block.
The Exhaust
You don’t often see headers on a diesel engine, but this is no ordinary project. Since the Freightliner would spend a lot of time in the low rpm range while pulling itself out of corners, maximizing the effectiveness of the turbo could provide significant gains during the race. Like a drag race car, the Detroit Diesel engine is fitted with six equal-length headers that feed into two collectors, which are then merged directly into the turbine housing. The headers are made with 2.5-inch tubing that’s as big, or bigger, than the tailpipe on many passenger cars. The same size tubing is used for two giant wastegates that release excess exhaust pressure to prevent the turbo from overspeeding once the maximum intake pressure has been reached.
Photo 5/31   |   The angle-cut exhaust tips for the turbo outlet and the dual wastegates are bound together with solid aluminum brackets. The main exhaust is 5 inches in diameter, and the wastegate exhaust tubes are 2.5 inches each.
Water-Methanol Injection
Four stages of water-methanol injection are used throughout the Super-Turbo design, starting with injectors that spray directly into the supercharger inlet. The first two stages are run through four directional 10-gph nozzles that are aimed to spray into the teeth inside the supercharger. The other two stages occur across six 5-gph nozzles that are mounted next to the intake runner for each cylinder. The tips on these nozzles are positioned to spray directly into the cylinders. The injection of the 50/50 water-methanol mix is operated automatically by the new Banks StraightShot system with multiple controllers. The first two stages are based on the supercharger outlet temperature and kick in beginning at just 120 degrees, while the other two stages are activated when the manifold reaches a pressure of 30 to 50 psi.
Photo 6/31   |   Water-methanol nozzles, rated at 5 gph, are mounted on the intake manifold as close to the cylinder intake ports as possible. A StraightShot controller starts distribution of the 50/50 mix into each of the six cylinders once the intake pressure reaches 30 psi.
Water-Chilled Intercooler
A large version of the high-flow Banks Techni-Cooler is mounted under the Freightliner’s hood. In front of it are five 14-gph nozzles aimed to spray a thick fog of water directly onto the cooling fins and keep the intake charge as dense as possible. The water delivery is also controlled by the StraightShot system and is operated in two stages that begin when the intake charge reaches just 100 degrees.
Photo 7/31   |   The water sprayers for the Techni-Cooler intercooler under the hood were placed close enough together so the 14-gph nozzles can create a thick fog that won’t get blown away while the truck is at speed. The water delivery is controlled by the StraightShot system that initiates two stages of spray beginning when the intake charge temperature reaches 100 degrees.
Water-Cooled Brakes
During the 2012 Pikes Peak race, Mike Ryan suffered a brake failure that caused him to spin out and hit a guardrail during a hairpin turn. Recovering from the accident added a full 30 seconds to Ryan’s race time, so the Banks team paid special attention to improving the truck’s braking ability. Spray nozzles are mounted where they can distribute water directly into the heat extractor vents of the discs whenever the brakes are activated. The entire braking system was improved with 17.1-inch Bendix rotors up front and 15.1-inch rotors in back, and Meritor four-piston air-over-hydraulic 75mm calipers at each corner.
Photo 8/31   |   Nozzles are mounted where they can spray water directly into the center of the brakes’ rotors and have it ejected out of the heat extraction vents as the wheels spin. The water delivery is activated whenever the brakes are applied during the race.
The Freightliner Race Truck
The rest of the vehicle is just as unique as the drivetrain it supports, with a body made completely from fiberglass and carbon fiber. Even with that lightweight body, the truck weighs in at 10,000 pounds (the engine itself weighs more than 2,600 pounds!). The suspension uses huge 3.0 King coilover shocks, similar to what you might find on a truck built to race in Baja, along with custom support links and limit straps to keep the suspension stable. The rear tires are custom hand-cut versions of the Michelin XDA-HT High Torque tires that normally cost more than $1,000 each.
Photo 9/31   |   Banks Super Turbo Freightliner Race Truck
It requires a couple of steps to climb up into the semitruck cabin, but the inside looks just like a conventional race car. The dash is covered with instruments, including the displays for all the StraightShot systems that control the water-methanol, water sprayers, and a Banks iQ that operates everything. There is a speed shifter for the transmission mounted at dash height that’s next to a hand brake used for drifting the Freightliner around corners. Mastercraft 3G racing seats with five-point harnesses, a removable steering wheel, a helmet ventilation system, and safety netting contribute to the NASCAR-style appearance. The truck also got a new black-over-red-and-gray, Banks-style paint scheme.
The Race
Less than three months after the Freightliner arrived at the Banks facility, it was ready for the debut of the new Super-Turbo drivetrain on the track at Irwindale Speedway in Irwindale, California. After the engine fired up, we told Gale Banks that it “sounded angry,” to which he smiled and excitedly replied, “It sure does! It sounds nice and angry.” The sounds emitted by the truck are unique to say the least and are created by the supercharger rotors, the belt pulley system, and the turbo with its direct outlet. After two days of shakedown runs at the raceway, the truck was shipped to Colorado for the 2013 Pikes Peak International Hill Climb.
Photo 10/31   |   World-famous stunt driver and racer Mike Ryan roasts the rear tires of the Banks Super-Turbo semitruck on the infield of Irwindale Speedway. The public debut of the truck was used to show it off to the press and give it a real-world shakedown. This allowed engineers to adjust the engine programming, supercharger pulley ratio, and water-methanol injection tuning before the truck left California for Colorado.
Race fans, officials, and even other competitors flocked to the Freightliner during the tech inspection. Then, spectators were treated to thick clouds of white smoke when the truck boiled its rear tires on a drifting demo course designed for import cars. Practice runs up the mountain were successful and included a 200-foot burnout at the starting line. Unfortunately, the infamous Pikes Peak weather brought snow, hail, and lots of rain down on the mountain by the time Mike Ryan was scheduled to race. After some discussion, Banks and Ryan decided he should take it easy due to the weather hazards. Caution paid off when the truck encountered washed-out sections of the road littered with mud and granite pebbles. Even with the truck not being pushed to the limits, Ryan managed to finish with an impressive time of 12:49:211, which was just 10 seconds more than his record-setting run from the year before.
The Future of Super-Turbos
In addition to the Freightliner chasing the record again at next year’s race, the developments involved in the creation of the Super-Turbo truck could some day make it into the hands of civilians. Like the auto manufacturers, the team at Banks is known for using race vehicles as testbeds for new technologies. Who knows if someday we’ll see Super-Turbo setups become common, but if it means more diesel power, then count us in!
Base Vehicle: Freightliner Cascadia
Driver: Mike Ryan
Base Engine: Detroit Diesel Series 60 (DD60)
Configuration: Inline-six
Displacement: 14.0L
Bore and Stroke: 5.24 x 6.62 inches
Horsepower: 2,400 hp
Torque: 5,000 lb-ft
Maximum Engine Speed: 2,700 rpm (fuel cutoff)
Engine Weight (stock): 2,640 pounds
Turbocharger: BorgWarner S510 with 95mm compressor
Supercharger: 8.3L twin-screw with 4.31:1 ratio
Manifold Pressure: 180 psi (maximum) / 60 psi (operational)
Injection: Four-stage water-methanol
Intercooler: Air-to-air with two-stage water cooling
Exhaust: 2.5-inch equal-length headers and 5-inch main outlet
Wastegate: Dual 2.5-inch
Transmission: ZF 5 HP-500 five-speed automatic
Suspension: Solid axles with multi-link
Shocks: 3.0-inch King coilover shocks
Wheels: 22.5-inch 10-lug
Front Tires: Michelin XZU 2
Front Tire Size: 305/70R22.5
Rear Tires: Michelin XDA-HT High Torque (hand-cut)
Rear Tire Size: 445/50R22.5
Brake Calipers: Meritor four-piston 75mm
Brake Rotors: 17.1-inch (front)/15.1-inch (rear) rotors with water cooling
Curb Weight: 10,000 pounds (approximate)


Gale Banks Engineering
Azusa, CA 91702
Pike's Peak International Hill Climb
Mike Ryan Motorsports