Trask Performance Turbo, Part 1

01. Here is the Trask Turbo kit ($4,995) that was ordered for Ron’s bike. The kit is designed for carbureted or EFI ’00-later Softails and ’99-later Dynas. This kit came in a sinister black finish and some of the main components include: an exhaust manifold and exhaust pipe with heat shields, turbo housing, plenum, a boost gauge, billet breathers, an air filter, a Zippers two-bar sensor, a billet cam support plate, and a Barnett high-performance clutch spring.

01. Here is the Trask Turbo kit ($4,995) that was ordered for Ron’s bike. The kit is desi

Last issue in “Dyna Suspension Upgrade,” we introduced you to Ron and his ’11 Dyna. In that article we mentioned that Ron likes to ride hard and push his bikes to the limit, which was the reason for upgrading the rear suspension with the Progressive 970 series shocks. Not one to tread lightly, Ron also likes to beef up his bikes with added horsepower and torque and he’s had it all, from big bore kits to strokers. So when it came to hop up his new Dyna, he figured why not try a different route and start out with a power-adder like a turbo from Trask Performance.

Ever since he moved to the US from New Zealand, Trask Performance Owner Nick Trask has been continually developing his line of turbo systems to put out dependable, streetable power that will result in significant performance gains. While we’ve covered the installations of a Trask Turbo on several occasions over the years, we figured we would give those of you unfamiliar with turbo systems a little background on its basic principles and then delve into some of the major components that make up a Trask Turbo kit.

02. Here’s the heart of the kit, a modified Garrett turbo. The turbo is comprised of three main housings. On the left side is the turbine housing (red arrow) where the exhaust gasses enter and spin the turbine wheel. In the center is the housing for the common shaft and its bearings/bushings, which are fed with oil via the fitting up top (yellow arrow). Then on the right side is the compressor housing where the charged air is created and then sent to the intake via the tube coming off the top of the housing (blue arrow). On the front of the turbo unit is the waste gate assembly, which controls boost pressure via an actuator assembly and a calibrated 8-pound spring in the cylindrical housing (green arrow).

02. Here’s the heart of the kit, a modified Garrett turbo. The turbo is comprised of thre

The first thing to remember with a Harley engine (or any internal combustion engine for that matter) is the key to making more power is stuffing more air into the cylinders. More air means more fuel and a bigger combustion creating more energy pushing down on the pistons and more power output at the crankshaft. Hence the reason why the simple addition of a larger air cleaner can easily add 5 horsepower. A normally aspirated engine depends on atmospheric pressure (14.7 psi at sea level) and the vacuum created by the downward stroke of the pistons on the intake stroke to draw in air. However, a stock engine doesn’t completely fill the cylinders as it cycles. The addition of a turbo system and its ability to create pressurized, charged air, and flow more air into the cylinders than atmospheric pressure alone would, means the volumetric efficiency (percentage of quantity of fuel and air that enter the cylinders during induction to the actual capacity of the cylinder under static conditions) can easily reach more than 100 percent. Boost (increase in manifold pressure above atmospheric pressure) is the measured amount of charged, pressurized air coming out of the turbo. Boost is measured in pounds per square inch (psi). More boost means more air will be forced into the engine creating more horsepower.

03. Looking into the right side of the turbo you can see the compressor wheel. As the wheel speeds up it creates the charged air. A high-flow filter gets fitted over the front of the compressor housing.

03. Looking into the right side of the turbo you can see the compressor wheel. As the wh

So how does the turbo create the pressurized, charged air? Exhaust gasses. Within the turbo housing are two impeller blades (a turbine wheel and compressor wheel) with a common shaft running between them. An exhaust manifold directs the spent gasses from the engine’s exhaust ports to the turbo housing. The velocity of the gasses spins the turbine wheel, which turns the common shaft and compressor wheel connected at the other end. As the compressor wheel spins faster and faster the air becomes compressed, charged air. The charged air exits the compressor housing at a higher velocity and then finally makes its way to the intake and stuffs the cylinders with more air. More air, a little more fuel, and you can create more power.

The Trask Turbo system is designed as a bolt-on system that will create 8 psi of boost and will provide a significant power increase without having to dive into the engine—that is if you keep the engine mostly stock.