Trask Performance Turbo, Part 1
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.
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.
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.
Lucky for us Ron doesn’t mind experimenting with different power upgrades on his bike. So while we are going to start off with the Trask Turbo, other hopups, such as larger cams and possibly an increase to 103 ci, are likely to occur shortly down the line. With that being said, and the fact that Ron can get pretty wild when it comes to riding his bikes, the decision was made to tear the engine down, split the cases, and beef up the lower end. While it’s not an absolutely necessary step when adding a Trask Turbo to a bike, Nick was made aware of the additional power modifications and suggested that reinforcing the lower end would be a smart move. There are a couple modifications that can be performed on the TC’s lower end that will make it more robust, sustainable to high horsepower/higher loads, and help prevent potential internal catastrophe.
The first of which is converting the straight roller bearing in the engine’s left-side case to a more durable tapered Timken roller bearing setup. As the TC engine gets hopped up and makes more and more power, the high-speed flexing of the crankshaft can put additional stress on the stock roller bearing which can cause the bearing’s outer race to fracture and disperse broken metal throughout the lower end causing major havoc. JIMS Machine and H-D’s Screamin’ Eagle line both offer a Timken bearing kit along with a Timken bearing sleeve that allow you to install the bearings without having to machine the case. The sleeve is precision machined and made from high-quality steel that is much stronger than the stock bearing setup. The sleeve and dual tapered bearings make for a more durable setup.
Another modification that can be done to further beef up the lower end is to weld the crank. The stock crank is a three-piece, pressed-together assembly with the crankpin “hard” pressed into the flywheels. While under normal circumstances this setup is usually OK, once again as power significantly increases the additional stress and load can cause the crank assembly to twist. This twisting can cause the assembly to become out of true and can lead to a wobbling pinion shaft. A wobbling pinion shaft can lead to major or catastrophic problems. The solution is to true up the assembly to within 0.001 inch and then weld each side of the crankpin to the flywheel halves. With each side adequately welded, the assembly is then re-trued to within 0.001 inch.
In this article we will first look at some of the components that make up the Trask Turbo kit for this ’11 Dyna. We will then show you some of the precautions we spoke of that Anaheim-Fullerton Harley-Davidson took to make sure the lower end of Ron’s Dyna would be prepared for the other power upgrades that get thrown at it. HB
Source:
Anaheim-Fullerton Harley-Davidson
(714) 871-6563 | harleyfullerton.com
Harley-Davidson
harley-davidson.com
Trask Performance
(623) 879-8488 | traskperformance.com