Pontiac GTO Owner’s and Service Manual

Pontiac GTO is about balanced performance: acceleration, handling, steering, and braking. What performance starts with, of course, is power. In elevating GTO to the exalted 400-horsepower realm, engineers trimmed this nimble coupe’s power-to-weight ratio to less than 9.5 lbs per hp. That’s better than every car in GTO’s class* (Mustang GT is saddled with 11.6). It also beats such renowned sports cars as RX-8 6-Speed, Nissan Z, and the BMW 3 Series coupes, including the vaunted M3. Naturally, that massive dose of horsepower and 400 lb-ft of torque is matched with rear-wheel drive and independent front and rear suspension for dramatic performance off the line and through the corners. So while an under-five-second zero to 60 time is a good index of this performance coupe’s capability, it’s just as important that GTO is also capable of .86 lateral Gs. And that its big disc brakes offer formidable stopping performance. Hands comfortably poised at 10 and 2 on the leather-wrapped steering wheel, you feel you can move with a commanding sense of control. Like we said, balanced.

Pontiac GTO Owner’s, Service Repair Manual

Pontiac GTO Owner’s, Manintenance Manual
Power is a function of how much air an engine can pull in through the intake and fire back out through the exhaust in a given time. GTO gets big air with the 6.0 liter aluminum LS2 V8. This fourth generation of the GM “small-block” has been refined by decades of sports car endurance racing, achieving a near-perfect blend of raging performance and go-the-distance durability. The most telling example is that a race-prepared variant of the GTO’s LS-series V8 gave Pontiac the ’04 Manufacturer’s Championship in the Daytona Prototype class of the Grand American Rolex Sports Car Series and is well on the way to wrapping up a second one (see following pages). Like the race engines, the LS2’s block and heads are cast from lightweight aluminum alloys

Pontiac GTO Service Repair Manual
The 90-degree V puts big displacement into a compact package, and the overhead valve design carries its weight low, as much of an asset in a sporty coupe as it is in a racecar. Engineers punched out the bore to a nice even four inches, optimized the engine’s breathing (from a 3.5-inch throttle body all the way back to 2.5-inch exhaust exiting through 2.75-inch tips), and hiked the compression ratio to 10.9:1. Further enhancements such as fitting the lightweight aluminum pistons with floating wrist pins enable a 6500 rpm redline that really pulls in the air. With a resulting 400 horsepower and 400 lb-ft torque, this GTO completely overpowers every car in its class (100 horses and 80 lb-ft more than the Mustang GT.) That’s also more power and torque than the BMW M3 and the Porsche 911 Carrera. Yet with the LS2’s drive-by-wire electronic throttle, all this performance capability is easily modulated by your right foot. Simply press to turn the sound from the low rumble of distant thunder into a 6500 rpm scream.

Pontiac won the Engine Manufacturers’ Championship, our second year in a row. The 500+ hp version of the GTO LS2 V8 overpowered the competition, beginning with a 1-2-3 sweep of the Rolex 24 at Daytona (our second consecutive win) followed by an unprecedented 10 wins and four podium sweeps in the first 12 races, rewriting the record books and leaving the likes of Lexus, Porsche and BMW scrapping for second.

Pontiac GTO Wiring Diagrams
Even with its big-bore horsepower and torque, the LS2 V8’s light weight and compact form help GTO achieve a balanced 55/45 front/rear weight distribution, while a dimensionally precise, welded-steel integral body/frame provides the necessary rigidity for cornering, acceleration, and braking. Leveraging the inherent performance advantages of rear-wheel drive is GTO’s fully independent suspension system. (By contrast, Mustang GT is the only car of 300 hp or more without this important performance feature.) GTO’s track-tuned setup features semitrailing arms at the rear and MacPherson struts up front, with progressive/variable-rate springs all around. The further they compress, the higher their rate of resistance, enabling GTO to ride comfortably in normal driving, yet firm up nicely as cornering forces build. Gas shocks in the rear help maintain consistent damping through sustained performance cornering. To help you chart a precise line through the corners, variable-ratio rack-and-pinion steering communicates just the right amount of feedback to the leather-wrapped steering wheel. The cumulative result is that GTO can generate .86 Gs of cornering force. In other words, as the road starts to twist, your smile begins to broaden.

To help convert the LS2 V8’s force into forward thrust, both the prop shaft which carries power from the transmission to the differential and the constant velocity joints at the wheel hubs are a special high-strength design. A stout clutch-type, limited-slip differential distributes the most torque to the wheel with the best grip, generating a positive, “connected” feel. Under acceleration, GTO’s rear-wheel-drive architecture shifts weight to the rear, increasing available traction for the driven wheels. And the semi-trailing arm independent rear suspension helps keep both rear wheels squarely planted, even on uneven road surfaces. It’s this traction that helps explain why GTO’s zero-to-60 and quarter-mile times were faster than Mustang GT, Infiniti G35, and BMW 330ci Coupe.