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Turbo GSX600 Project
This project started from a desire to better understand the limitations of pressure and flow-rate control within forced induction applications. GSE wanted to expand its knowledge of fluid dynamics for the purpose of exploring the design of a small external turbofan as a supercharger (similar to US patent #6450156). However it quickly became a much larger educational and fun experience.
Specs:
Dimensions and mass
Engine
Driveline
Chassis
Electrical
Capacities
Stock Performance
Upgraded Performance
The Process
Starting with a severly abused, but running, 1996 GSX600 (CA model 14,000 miles) [stearing head bearings growling, front stablizer plate broke, chain ready to fall off, original spark plugs], for the low price of $500 the bike was stripped bare and the motor torn apart.
Compression checked out okay, so the head was pulled in order to check the cylinder walls and perform a valve job. Suzuki builds some pretty good equipment, as the valves showed only minor wear and lapping compound cleaned up the seats sufficently. The valves were all adjusted by swapping out little spacers that sit between the rocker and valve. The local bike shop was willing to swap what we had for what we needed.
GT12 Turbo Sizing
The GT1241 is the smallest turbo Garrett makes and is rated for up to 130 horsepower, which is due to its maximum flow limitations.
Selected for this application the turbo will be spinning as hard as it should be spun and pushing air flow velocities to their
limits in terms of efficiency. Doubling the horsepower is a good start. A GT1544 would have allowed more horsepower room, but spool up would
have suffered, as would the wallet.
Handy turbo sizing tool (http://www.squirrelpf.com/turbocalc/)
O' The Plumbing
The exhaust manifold came first. Creating a mockup of the bike after making some measurements proved the easiest way to build the exhaust manifold. In fact, I've never built anything so fast! It took a couple hours at most, as making everything fit wasn't the chore of weld, check, weld, verify, check.
The finished product, complete with pyrometer bung. The header was then wrapped to keep as much heat in the exhaust gas to both power the turbocharger and to keep from heating up the nearby intercooler.
Almost a perfect fit the first time around. One tube needed a little heat to adjust its angle a few tenths of a degree in order to ensure it would seal properly. The output of the turbo was easy, a 90 degree bend of 2" pipe welded to a steel flange.
Intercooler Build
Knowing we were going to run high boost pressure it was necessary to run an intercooler, however finding one of the right dimensions was bit difficult. All the motorcycle intercoolers were quite expensive and all the inexpensive intercoolers were too large. The solution was in taking a 3 core 1G DSM intercooler and using a bandsaw to cut it down to a single core. Once the single core was cut off, it was only a matter of TIG welding up covers over the upper and lower tanks to create an intercooler that fit our size need.
Some TIG welding with T6061 aluminum J-bends from Burns Stainless built the rest of the intake plumbing.
Intake and Throttle Bodies
The eBay deal of the century was had on these throttle bodies, a whopping $42.01 was paid. They came off a 2002 GSX-R600, and actually had two sets of throttle blades. In the 2002 bike, one is manually controlled by a operator and the other by the computer to curb and apply power in an effort maintain maximum intake velocity. After disassembling them for my application I was left with a spare TPS sensor and an interesting servor motor.
Instead of trying to fabricate up my own intake, I opted to start with a blank from Mr. Turbo, as they didn't have any already cut to fit my application. Some milling and TIG welding were spent getting the intake together. One odd item that was required which isn't directly pictured is what technically would be the intake boots between the throttle bodies and cylinder head. Suzuki makes then out of hardened rubber and they're specifically offset for the original carbs. A set of hard plastic reducers were cut up on the lathe to adapt the much larger throttle bodies to the existing intake boots. No porting of any type was done (heads, intake, exhaust).
Oil Lines, Oil Pumps and Oil Messes
As the bike is oil-air cooled, oil temperature was used for a temperature sensor reading. Setting up the sensor in an aluminum block between the cylinder head and an oil pressure line was straight forward. Although the oil routing for the turbo proved to have some problems.
The first oil design for the turbo pulled oil from the pressure side of the oil cooler lines into the turbo, then returned it through a check valve. It was quickly discovered that although the turbo was getting oil, it could not get rid of the oil fast enough and started pumping it out the exhaust. Pressure was also a problem, and a bolt was threaded into one of the oil line fittings, then drilled out with a 1/16" hole to minimize the flow (and pressure) of oil the turbo was receiving. The final design incorporated an oil scavenging pump from RB Racing, as the turbo was too low [height] to drain oil back into the oil pan in a consistent way. The oil scavenging pump design solved the problem completely.
Megasquirt Fuel Injection
At the heart of this project is the Megasquirt fuel injection system. Locations for the MS and the relay block were pretty slim to choose from. An aluminum plate that bolted between to the bottom of the battery tray and to the frame cross member just below the intake. This provided a protected shelf to mount the MS case. The relay block was simply mounted to the left hand side of the bike under the left rear ferring. The stock fuse block resides in this location on the other side of the bike. The stock spark box was moved to behind the battery opposed to in front of it.
Configuring the Megasquirt for the application was straight forward, with the exception of realizing both the bike's tach signal and either coils' signal [coil signal used] would only be 1/2 the bike's true RPM. The MS was setup with '2' cylinders instead of four to compensate for the 1/2 coil signal and used a req fuel of 4.8 to start tuning. The MS was also loaded with the MSnS code in order to use the 12x12 tables for higher resolution tuning and have AFR tables to better control fuel under heavy boost. Also, the Innovate LC-1 wide band O2 sensor controller was mounted on top of the MS case.
Fuel Pumps
The first attempt a high pressure fuel pump was a stock GSXR 1100 intank pump, used externally. That failed, as most intank pumps are not meant to be used externally (pressure return venting, etc). Instead of cutting the stock tank to install an intank pump, we chose a MSD high pressure and Malloy high pressure regulator. This solved the fuel problem (after working through a fuel cavitation problem due to heat), but did cause an excessive amount of hose routing and AN-6 fittings to be used. The stock fuel tank on/off valve was replaced with an aluminum block to provide similar funcationality. The first block was cut wrong, as the measure twice rule was forgotten.
Results
So with all the pieces together, the bike runs very well. With the turbo wastegate hooked up (5 psi) the bike pulls substancially harder than its stock counterpart, but its nothing extreme. With the turbo wastegate disconnected, letting the turbo make full boost (up to about 18 psi) the 1996 GSX600 is extreme, exploding to life when the boost needle moves beyond 7 psi (at about 6000 rpm). Keeping the front wheel on the ground is a problem. We've yet to dyno the bike in its fully modified form, but that is one of the next items on the list.
Thanks to all those who made this project possible. Bowling and Grippo for Megasquirt, RB Racing and Mr. Turbo for letting us talk your ears off and especially my grandfather John for a good portion of the machine work.
Generic Solution Engineering LLC
info@genericse.com