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The 996 GT3 is heralded as the best version out there, with a sparser list of features and comforts than the 997. It has a unique sound and feel, and for some, is the ultimate track tool. So in keeping with it’s original factory philosophy, how do you improve on it?
Musante Motorsports has just completed the first true 4.0 liter 996 GT3. From the factory, the 3.6 liter motor is an amazing power plant, with an 8200rpm redline and rock solid reliability. Musante Motorsports started with a clean sheet of paper to design what they thought would be the ultimate upgrade path for those looking for more power. Custom pistons and oversized cylinders allowed displacement to be increased from 3.6 to 4.0 liters without the need to change the crankshaft or rods.
Musante Motorsports also has a 4.3 liter street kit and a 4.3 liter racing kit that is available in July. Among other items, this kit features a billet crankshaft, rods and pistons of the same design used in the 4.0 liter. All 4.0 and 4.3 kits are available for the 997 GT3.
All of these parts work in harmony due to Musante's investment in time and precise CNC equipment that can bore the cylinder block and case as a single assembly to one ten thousands of an inch (.0001"). This process gives the cylinder support not only in the water jacket, but in the case as well, allowing for oversized bores to remain round and true. This assures longevity and no problems with blow-by for a clean running engine.
A fairly conservative 12:1 compression ratio was selected to allow for daily drivability on 93 octane pump gas, while a set of custom camshafts was designed to work with the larger displacement and 8200 rpm redline. These details come together to make a smooth running car that is at home on the track or the street, with the low-end pulling power out of the corners that the stock motor simply doesn't have.
After hours of dyno tuning and street/track testing. Musante worked with EPL to create custom ECU calibration files for both 91 & 93 pump gas, and 100 octane . Musante had the car on their in house Dyna-Pak and also on EPL's Mustang dyno. Using conservative and realistic correction factors, both the EPL and Musante dyno agree that this is an honest 450 HP (at the crank) street kit. The exciting part is the car eagerly revs to 8200 but makes close to peak power at 7150 RPM. With a curve like this, the average useable power eclipses that of any tuned 997 GT3 making for a fun, driveable and fast car that still retains the feel of the original race bred GT3 engine.
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"The GT3 4.0L was delivered in early February to the Sebring race track in Florida for an arrive and drive program with Musante Motorsports. I did not know exactly what to expect as I had not seen or driven the car in several weeks. I strapped into the six point race harness, turned the key and the car started immediately and idled smoothly with a deep purposeful sound. After warming the tires on the Sebring track, I gradually pushed the car and was amazed at the smooth and rapid acceleration. Each gear had to be shifted at a much faster rate to avoid hitting the rev-limiter and I had to use the brakes more extensively at the end of the straights due to the increase in speed. The sound of the 4.0L engine was awesome, deep and throaty, but not excessively loud as the Fabspeed mufflers were left on the car for the event. As the tires warmed up and my comfort level with the new engine and components increased I was out accelerating 996 Turbos, 997 GT3's, and even some Cup cars.
Especially impressive was the acceleration out of the corners due to the increase in torque coupled with the Hoosier tires. Since the Sebring event I have been able to drive the car on the highway and around town and it certainly gets a lot of attention, both visually and audibly. The car is a complete joy and I am very impressed with the performance and drivability that this conversion has offered."
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