The air inlet pipe is installed...
The air inlet pipe is installed onto the compressor housing with a 3-inch silicone hose and two 3-inch clamps. Each clamp is tightened using a 5/16-inch socket or a flat-bladed screwdriver.
"Smaller A/R housings spool up quicker than larger A/Rs but are more restrictive on top-end flow and horsepower. Too large a housing A/R will give you turbo lag, too small an A/R will suffer top-end power. Sizing the A/R correctly is based upon engine displacement, rpm range, and--what most of the world forgets about because in the traditional turbo location, it isn't really a variable--exhaust gas temperature.
"A front-mounted system for the LS1 would typically be designed utilizing a 0.96 A/R housing. In order to compensate for the minimal loss in thermal energy conversion as the exhaust travels to a remote location, an 0.81 A/R housing works great for a rear-mounted turbo system. The factory exhaust manifolds and Y-pipe do an excellent job of retaining the heat and allow a high exhaust gas velocity. By running the intake tubing underneath the car and using HPC coating on the charge pipes, we see a 52 percent reduction in temperatures between the compressor housing outlet and the temperature of the air as it enters the intake with far less pressure drop than a typical intercooler.
"The cooling properties of pulling in cool air from underneath the car and then using it to cool the charge pipes, effectively provide a natural intercooler effect (Passive Charge Cooling), eliminating the need for an expensive air-to-water or air-to-air intercooler core and plumbing. Turbo lag isn't an issue as once the exhaust is up to temperature, the specially matched turbo spools quickly. On a typical LS1 F-body, boost is all in by 3,000 rpm and, depending on load, comes in as soon as 2,000 rpm.
The exhaust pipe is mounted...
The exhaust pipe is mounted to the inlet of the turbine housing and secured with a 3-inch V-band clamp using a 1/2-inch box-end wrench. We didn't completely tighten the clamp, as we'll want to adjust the orientation of the pipe where the exhaust pipe exits.
"By relocating the turbo to the rear of the vehicle, the turbocharger itself doesn't contribute to heat-related problems seen in conventional placement systems. Air is constantly flowing over the turbo when the vehicle is moving, so the housing stays cooler, eliminating additional expense for items such as turbo timers. Many F-body customers have reported gains of 2-4 mpg, at least those who can resist the urge to keep their right foot from constantly being planted on the floor."
Now that you know the premise of this product, follow along as an STS rear turbo system is installed on an LS1-equipped '00 Formula WS6. STS' sequential methanol injection kit will be added to allow the base turbo boost pressure of 5 psi to be raised to 71/2 psi. Installation was done at Real Performance Motorsports and DuSold Designs, both located in Lewisville, Texas, by technicians from Texas Rear Turbos, an Arlington, Texas-based factory trained distributor and full-service installer of STS turbo systems. In Part I, we will introduce the components of the bolt-on kit and dive into the installation.
The spray nozzle is installed by drilling a 21/64-inch hole in the air intake tube that connects from the MAF to the throttle body. A 1/8-inch NPT tap makes threads, and Teflon tape is put on the nozzle's threads before it's carefully tightened. The methanol injection is introduced into the system after the MAF, but before both the IAT sensor and throttle body. The 50/50 mix of methanol and water that is run will significantly reduce the intake temperatures, and we need the computer to recognize that, thus the placement before the IAT sensor. Needless to say, spraying any liquid into the MAF will quickly stop the engine from running and may damage the delicate electronics.
Recommended Tools
- Metric socket set
- Metric wrenches
- Standard socket set
- Standard wrenches
- 5/8-inch plug socket
- Prybar or large screwdriver
- Plug-gapping tool
- Electric drill, 21/64-inch drill bit
- 1/8-inch NPT tap
- Sawzall
- Die-grinder
Recommended Parts and Supplies
- Antiseize compound
- Methanol
- Die-grinder deburring stones
- X-Acto knife or razor blades
A banjo fitting is threaded...
A banjo fitting is threaded into the wastegate and tightened with a 10mm wrench. Then a length of rubber hose is routed to the nipple on the compressor outlet and pushed on. This reference line provides the wastegate with boost pressure so it can regulate the boost. Also note the wastegate was mounted so that when it bypasses exhaust gasses to the atmosphere, the hot gasses don't vent toward the turbo or surrounding hardware.
The turbo assembly is completed...
The turbo assembly is completed and ready to be mounted to the car. Note that the compressor and turbine housing bolts weren't tightened. This is because the turbo will be rotated during trial fitting under the car to mate up with the factory exhaust system and provide as much ground clearance as possible.
More on turbo assembly later...
More on turbo assembly later as the factory after-cat exhaust has to be altered in order to continue with the installation. In the majority of cases, the factory unit is removed while it still resides on the car by cutting the I-pipe as close to the muffler as possible, allowing the muffler and tailpipes to be taken off. Because of the rarity of this WS6 Formula, it was recommended that a used replacement factory after-cat exhaust, including I-pipe, be purchased, thus allowing the owner to store the original. In order to remove the stock exhaust, the rearend must be dropped down low enough to pull the exhaust out in one piece. Here Keith Lohse and Brian Boccafusso of Real Performance Motorsports carefully extract the exhaust.
The replacement after-cat...
The replacement after-cat is laid out and the exhaust pipe leading into the muffler is cut 1 inch before the muffler body with a Sawzall. The pipe where the cut was made is deburred with a cutting stone, and the replacement I-pipe and after-cat (minus muffler) is reinstalled onto the car.
Moving under the hood, the...
Moving under the hood, the upper section of the airbox has to be removed in order to relocate the mass airflow sensor (MAF), so the band clamp that joins the airbox to the throttle body is unscrewed. The intake air temperature (IAT) sensor is unplugged from the airbox along with the MAF harness and air pump hose, which is retained with a plastic clamp.
The lid is unlatched from...
The lid is unlatched from the lower airbox and the two plastic rivets that attach on each side of the baffles are removed. Pulling back on the airbox separates it from the throttle body, and it comes out as a complete assembly.
Now that the airbox and MAF...
Now that the airbox and MAF assembly are free, the clamps that attach the MAF to the airbox and the air tube to the throttle body are removed so that the MAF can be pulled out...
...and relocated to the STS-provided...
...and relocated to the STS-provided 31/2-inch diameter by 3-inch-long silicone hoses. A 4-inch hose clamp is used at each end of the MAF and tightened with a 5/16-inch socket or flat-bladed screwdriver.
Next, the adapter that will...
Next, the adapter that will attach the STS piping to the exit side of the MAF is mated to the hose via the 4-inch band clamp. We made sure the arrow on the MAF was pointed toward the throttle body, or the airflow will be measured incorrectly, causing severe driveability problems!
The portion of STS pipe that...
The portion of STS pipe that attaches from the MAF to the throttle-body section contains the provision for the IAT sensor. In order to remove the IAT sensor from the stock airbox, we gently pushed the sensor out of its rubber grommet. (If the sensor refuses to come out, rupture the integrity of the rubber grommet by using a fine-bladed X-Acto knife or razor blade to get the sensor out undamaged.) The STS pipe has a new IAT sensor rubber grommet, so we gently pushed the sensor into the pipe.
Before installing the pipe...
Before installing the pipe to the MAF and throttle body, the provisions for spraying the methanol injection into the engine will have to be handled. STS' sequential methanol injection kit comes complete with a pump, tubing, and all of the connections necessary to install it. Not pictured is the supplied tank, as the windshield washer reservoir on our Formula will now be tapped to provide the fluid reservoir.
The spray nozzle is installed...
The spray nozzle is installed by drilling a 21/64-inch hole in the air intake tube that connects from the MAF to the throttle body. A 1/8-inch NPT tap makes threads, and Teflon tape is put on the nozzle's threads before it's carefully tightened. The methanol injection is introduced into the system after the MAF, but before both the IAT sensor and throttle body. The 50/50 mix of methanol and water that is run will significantly reduce the intake temperatures, and we need the computer to recognize that, thus the placement before the IAT sensor. Needless to say, spraying any liquid into the MAF will quickly stop the engine from running and may damage the delicate electronics.