2007 Ford Mustang GT 500 - Twin Screw Supercharger Kit - Too Much!

It's a shame the air filter,... 

   

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It's a shame the air filter, mass air meter, and tubing cover the 2x75mm throttle body of the Stage 3 kit. It's so pretty.

When reviewing any dyno data, note the correction factor used. On chassis dynos, the two correction factors commonly seen are SAE and STD. The SAE is from the Society of Automotive Engineers; It's the more widely accepted correction factor in engineering and serious tuning circles. The STD, or Standard, reads a percent or so more power, so it's more fun for casual tuning and more helpful to the average dyno shop engaged in the endless knife-fight of the unregulated, self-promoting hot-rod world. At the 800hp level, the difference between SAE and STD is around 15 hp, with the STD number larger. All Kenne Bell tests use the SAE correction factor and WinPEP 6.03 data acquisition software on their '96 Dynojet 248.

Note: Stage 1 is the blower; Stage 2 adds an air filter and a MAF; Stage 3 adds a 2x75mm throttle body. Bold denotes highest power available with 91-octane pump gas. Best power with 93 octane and Stage 3 calculates to more than 700 rwhp, assuming the electronics are tuned for it; KB can provide this tune. Power increases on equal fuel among kits are due to increased blower efficiency because of freer-flowing inlet air. Boost is measured after the charge cooler. All power and torque figures are at the rear tires as measured on Kenne Bell's Dynojet. An SAE correction factor is used. Kits will likely come with 3.00-inch pulleys, others can be substituted or additionally purchased

Kenne Bell makes low and high... 

   

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Kenne Bell makes low and high internal-pressure ratio blowers. Everything is identical between the two configurations except the outlets, as seen here. The high-ratio blower has a smaller exit, effectively lengthening the rotors, giving them more time to compress the air charge. At high boosts, this is more efficient. Below approximately 15 pounds of boost, the low-ratio blower is more efficient. H- and L-blowers deliver the same volume of air and the same boost, the difference is that the H-blower takes less horsepower to drive at high boosts. All KB GT 500 kits use the 2.8H, as they are designed to range from 12 to 24 pounds of boost.

So what was that we mentioned about 1,000 hp? It's what the engine is actually producing to make a Dynojet read 810 rwhp.

To put numbers to it, 810 rwhp is 932 hp at the flywheel if you use the industry standard 15 percent driveline-loss figure. Jim Bell further guesstimates-and he's surprisingly accurate in his guesstimates, as we've learned throughout the years-the 2.8H Twin Screw needs 70 hp to drive it at 24 pounds of boost. Adding it to the 932 flywheel horsepower, we get 1,002 hp. That's what the crank, rods, and pistons inside the GT 500 engine are experiencing-3 hp per cubic inch. Incredible!

We'd all love to try megapower, but it's different. We've hinted at the driving technique required with such huge power and how a less-enthusiastic combination could easily be faster in a typical zero-to-hero street blast that tops out at 65 mph or so. Something else to noodle is all those driveline parts downstream of the engine.

One consideration Kenne Bell ran into was what to do with a bent two-piece Ford driveshaft after it relieved itself under the stress of being caught between the underhood gorilla and the Dynojet drum. That's right: The driveshaft didn't hit anything, and it wasn't shocked with dragstrip gear changes-it simply yielded under the torque it was transmitting on the dyno. A single-piece Ford Racing driveshaft was the answer.

But there'll be plenty more parts quivering when this monster hits the asphalt in anger. For example, the transmission wasn't designed to input 600 lb-ft of torque at 2,000 rpm; we wouldn't bet on axles or U-joints.

In the short term, wheelspin is the savior. As long as the tires go up in smoke, almost everything else ought to live. But when the slicks roll onto a glued track, the budget needs to provide for a fully prepped rear axle and chassis reinforcements at the least.

Max power on the dyno was made with the air filter laying up and out of the engine compartment. It seemed to gain horsepower, maybe a single digit. Production kits will have an air dam or fence built around the filter, but getting cool air to S197 engines remains an issue. Ford didn't leave large enough air paths to the left-front corner of the engine compartment. Car owner Earl Moorehead is planning on cutting a scoop into the side of the front fender-just outboard of the headlight-to feed his orange monster. It ought to help.