Pontiac Firebird Turbo Installation - Subterranean Turbo System
If you've been following this nut-and-bolt turbo install on an '00 Formula through the first three installments, then you know the Squires Turbo Systems kit is unlike others marketed for '98-'02 LS1 F-bodies. The turbo bolts on where the muffler used to be, offering an almost invisible installation and 5 psi of boost. An optional methanol injection kit can even add more punch to the already potent package by allowing boost to be increased to 7.5 psi without worry of detonation.
We covered the hows and whys of the system already in past stories. This time, we will finish the methanol system install, upgrade the injectors, install boost and fuel pressure gauges to properly monitor the actions of the fuel system and turbo, and finally see what it's all worth on the dyno.
According to Rick Squires, owner of Squires Turbo Systems (STS), "Although this kit can be installed by the enthusiast with average mechanical skills, we highly recommend you work with one of our factory-trained dealer/installers to maximize the potential of your Firebird or GTO and ensure that the system is properly tuned for safe operation. Variability in the fuel injector size that GM provided on the Firebirds and the mechanical condition of the vehicle play a large part in how the car performs.
"We prototyped the system on a stock '99 LS1 vehicle with low mileage, and after a performance PCM tune by Nelson Performance, the car maintained a safe air/fuel (A/F) ratio of 11.5:1 and has been a paragon of reliability. Unfortunately, an almost identical Firebird may not fare as well and could severely damage the engine, if not properly monitored.
"After system installation, we recommend that the PCM be tuned and the car be monitored with either a scan tool such as Autotap or a wide-band O2 sensor equipped chassis dynamometer. Under no circumstances should the owner go out and start ripping on the car before verifying the engine will maintain a safe A/F ratio. If A/F ratios lean out beyond 12:1 on the base kit, either the tune isn't appropriate or the vehicle isn't receiving enough fuel.
"Rather than bundle a generic PCM tune and larger injectors into the base price of our kit, we choose to warn the enthusiast that careful monitoring of the system is paramount to success. Including larger injectors in a kit necessitates a custom tune, but what if the injectors aren't necessary for safe operation or the larger injectors aren't sufficiently sized due to the car starting out with serious modifications to begin with? The base kit provides the foundation for some serious horsepower, and the enthusiast should utilize the resources that our company and dealer-trained installers provide in order to maximize the horsepower and safety."
Follow along as we complete installing the STS rear turbo system on an LS1-equipped '00 Formula WS6 at Real Performance Motorsports and DuSold Designs, both located in Lewisville, Texas. Texas Rear Turbos of Arlington is a factory trained distributor and full-service installer of STS turbo systems. so its employees performed the turbocharger installation. Allen Nelson of Nelson Performance assisted with the methanol injection system and provided expert PCM tuning and vehicle diagnostics.
Testing: On The Street
After completing the installation, Allen Nelson of Nelson Performance downloaded a custom tune using his HP Tuners software suite. Here's what he had to say:
"The STS-equipped LS1s are tuned for a target air/fuel ratio of between 11.5:1-11.8:1. I have found this to be the middle ground for boosted applications for maximum horsepower and safety. Extra horsepower can be achieved by leaning the car to 12.0:1 or 12.1:1, but I have found that in hot conditions, running it on the edge will cause timing to be pulled, thus wiping out the small horsepower gains of tuning it leaner. With Billy May of Texas Rear Turbos piloting the Formula and my HP Tuners software hooked up to record the pertinent engine monitoring functions, we set out for some initial testing.
"The smaller 26.4-pound injectors installed on '00 models ('99s and '00s used 26.4-pound injectors, while 28.8-pound injectors were used in '98s,'01s, and '02s) caused this low-mileage car to lean out. I recorded O2 sensor values of 620s, which are dangerously lean and translate to a 14.9:1 A/F ratio. Had the run not been monitored and aborted before reaching the redline, the engine may have incurred damage.
"Upon returning to the shop and discussing the setup with Billy, we decided that a fuel-system upgrade was necessary. In order to make the car safer until upgrades were performed, I revised the tune to allow only 4 degrees of timing at wide-open throttle and told the owner not to take the car over 4,000 rpm. For comparison purposes, the factory tune on a stock vehicle is set between 26 and 28 degrees, and my target for the STS-equipped Firebirds is 16 degrees.
"After discussing the test data with Rick Squires of STS and the owner, Rick asked that the owner provide some scan readings by using their Autotap software. Even with only 4 degrees of WOT timing, the car was leaning out above 3,500 rpm and showing A/F ratios upward of 13.5:1. In both testing scenarios, the small 26.4-pound injectors were showing that they were being severely overloaded. A good rule of thumb is that the injectors shouldn't be pushed beyond 80 percent duty cycle, and this car was running over 115 percent duty cycle. Bottom line, the fuel injectors couldn't supply enough fuel to the engine at WOT.
"After doing the calculations, we determined that at a minimum, the car would require a set of 37-pound injectors. Since the cost and tuning ability of the Delphi 37- or 42-pound injectors are a push, we chose to provide a bit of margin and selected the 42-pounders (flow 48.8 pounds at 58 psi versus the 37-pound injectors that flow 43 at 58 psi). After installing the 42-pound injectors and a custom tune, I was able to meet my goal of an 11.8:1 A/F ratio at WOT.
"It would have been very helpful to have the Auto Meter gauges installed before the retune, but they weren't available then. The Formula started to lean to around 12.5:1 above 4,500 rpm, but I was able to adjust the fuel-injector pulse widths to maintain the safe target. No knock retard was noted after the final tune, and the inlet air temperatures (IAT) were very reasonable given that the testing occurred at an ambient temp of 90 degrees. With the 5-psi boost level, I logged a maximum IAT of 150 degrees, with only 118 degrees noted with the methanol injection flowing.
"Since only one PCM tune can be installed in the car, the system was optimized for the base 5-psi kit. When the electronic boost controller was flipped and the car ran 7.5 psi of boost, the Formula ran a bit richer at 11:1. After Texas Rear Turbos installed the fuel pressure and boost gauges, the fuel pressure was observed falling off to 42 psi while under boost. Additional monitoring showed that the car was still operating safely, but any degradation in the fuel system operation would be dangerous.
"In order to correct the fuel pressure and volume deficiencies, additional fuel-system upgrades and monitoring are necessary to make sure the car operates safely. My recommendation is that the Formula be upgraded with an aftermarket high-volume fuel pump. Once this is complete, I can revise the tune to match the upgraded fuel delivery and would strongly suggest that a wide-band O2 gauge be installed to monitor the A/F ratio at all times."
Testing: On The Dyno
In stock configuration-other than a skip shift eliminator and Exedy twin-disc clutch with flywheel-the Formula put down 308.2 hp and 318.2 lb-ft of torque. According to Wade Wells, technical assistant at RPM, "The Formula produced good power numbers considering it registered an average A/F ratio of 11.8:1. The vast majority of stock F-bodies run leaner air/fuel ratios of 12.8 to 13.0:1."
For the dyno session with the STS turbo system installed and a Nelson Performance custom tune, the 5-psi boost setting put out 392.6 hp, or an 84.4hp increase over stock. Torque followed right along, registering 401.7 lb-ft, an 83.5 increase. The air/fuel ratio registered at 11.7:1 on average-perfect for a boosted application.
After a cooldown, the methanol injection switch was flipped on and the Formula was fired back up. When the rollers stopped spinning, max horsepower of 446.9 was recorded, which is a 54.3hp jump over the base 5 psi pull and an outstanding gain of 138.7 hp over stock. Torque showed even better results with 472.6 lb-ft, which is a 154.4 lb-ft increase over stock and a 70.9 lb-ft increase at the higher boost levels.
Since the tune was configured for the 5-psi level, it wasn't surprising to see the A/F ratio richened up when utilizing the methanol. According to Wells, "During the 5 and 7-1/2-psi pulls on the Formula, I logged 2-3 degrees of knock retard on our Tech II scanner. The combination of extreme heat and substandard atmospheric conditions contributed to the engine pulling timing to combat the spark knock. Although the A/F ratio average stayed safe on each of the boosted runs, the A/F ratio did richen up to approximately 11:1 as soon as the car reached 5,000 rpm. With some cooler ambient temps and some added octane, the Formula could have easily netted an additional 20 hp with similar torque gains."
Dyno Results
Key Engine Parameters: Air inlet temperature (AIT) maximum values are noted unless otherwise stated. Average horsepower and torque are dyno pulls recorded between 3,300 and 6,000 rpm for the naturally aspirated pull and between 3,300 and 5,900 for the boosted runs.
Stock (Exedy)72.6308.2318.2 268.3304.511.8STS 5 Psi107.9 392.6401.7 336.8370.211.7STS 7½ Psi109.3446.9472.6 369.3425.711.0
Testing of the '00 Formula WS6 was performed at Real Performance Motorsports in Lewisville, Texas. RPM has a Dynojet Model 248C dyno that is capable of measuring up to 1,800 hp, and is optioned with the above-ground kit and the Commander wide-band 02 sensor so air/fuel ratios can be charted.
The barometric pressure, air inlet temperature and SAE correction factors for the runs are listed below. Correction factors use a standardized SAE calculation, which include reference temperatures of 77 degrees Fahrenheit, and a barometric pressure of 29.23 inches of mercury.
Stock: Modifications include an Exedy twin-disc clutch and flywheel
Test parameters: Air inlet temperature 72.6 degrees Fahrenheit, barometric pressure 30.38, vapor pressure 0.23 in. HG, correction factor 0.96
STS 5 psi: Modifications include an Exedy twin-disc clutch and flywheel and STS rear turbocharger system set at 5 psi
Test parameters: Air inlet temperature 107.9 degrees Fahrenheit, barometric pressure 30.03, vapor pressure 0.7 in. HG, correction factor 1.03
STS 7.5 psi: Modifications include an Exedy twin-disc clutch and flywheel and STS rear turbocharger system set at 7.5 psi, with an STS sequential methanol injection system delivering a 50/50 mix of methanol and water
Test parameters: Air inlet temperature 109.3.6 degrees Fahrenheit, barometric pressure 30.03, vapor pressure 0.72 in. HG, correction factor 1.03
Recommended ToolsMetric socket set
Metric wrenches
Standard socket set
Standard wrenches
Electric drill
1/4 -, 5/8-, and 21/64-inch drill bits

Recommended Parts and SuppliesAntiseize compound
Silicone grease
Thread tape
Scan tool

Photo Gallery: Pontiac Firebird Turbo Installation - High Performance Pontiac

Read More | Digg It | Add to del.icio.us