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Recipe for Horsepower: Installing Whipple’s 3.4L Supercharger on the S197 Mustang GT

By - April 1, 2008 – 8:17 pmOne Comment | 6,385 views

It seems that some will never be satisfied in their quest for horsepower. The S197 Mustang GT’s 300-horsepower will quench that desire for the majority of owners, but there are also those that will have as much horsepower as their checkbooks will allow. ST Motorsports of San Berndardino, CA is never one to shy away from setting new boundaries of performance with the Mustang, and for this article we will go over a custom supercharger setup for a Mustang GT owned by one of their horsepower-hungry customers as the components necessary to achieve the amount of horsepower being produced.

Whipple 3.4L W210AX Supercharger

For those wanting to make serious horsepower with their Mustang, Whipple’s 3.4L W210AX twin-screw supercharger is the answer. At 210 cubic inches it’s the largest displacement blower on the market and is capable of producing nearly 30 lbs of boost to produce insane amounts of horsepower. It is normally intended to be applied to the Shelby GT500’s 5.4-liter V8, but this particular owner thought it would be better suited under the hood of his Mustang GT. Since Whipple doesn’t offer a package for the GT, ST Motorsports took on the duty of fitting it to the 3-valve V8.

A side by side comparison with the standard Whipple 2.3L supercharger shows the massive displacement of the 3.4L unit. In addition to the ability to produce higher boost, the 3.4L unti is also more efficient. Back-to-back testing done by ST Motorsports on another vehicle showed a gain of 100 horsepower when switching from the 2.3L to the 3.4L supercharger.

Internal Strength – Forged pistons, connecting rods, and crankshaft

Even lower displacement superchargers can surpass the limits of the rotating assembly of the 3-valve engine, so upgrading these components is a must. For this particular build ST Motorsports installed Scat forged steel H-beam connecting rods, custom JE forged aluminum pistons, a Kellogg forged steel crankshaft, and Tri-metal bearings.

The connecting rods are generally the weakest link when it comes to the 3-valve engine, and this side-by-side comparison with a Scat H-beam rod shows exactly why.

Increased Airflow

While the Whipple 3.4L supercharger has the ability to compress a ton of air, the intake system can still restrict airflow into the engine. According to ST Motorsports, the stock throttle body becomes restrictive at 12-13 lbs of boost above 5400 rpm. To prevent this, they have come up with a custom intake system utilizing a Black Diamond “Big Mouth” 1900cfm throttle body and custom 4-inch intake pipe and intake manifold fabricated from sheet metal. Separate testing has shown a 25 rwhp increase at 13 lbs of boost using the larger throttle body, and even higher numbers with the complete intake.

A side-by-side comparison between the Black Diamond 1900cfm throttle body and the stock throttle body.

A detailed look at the custom sheet metal intake manifold:

The custom 4-inch sheet metal intake pipe leads to an open-element air filter in the right fender well.

Additional Modifications

In addition to the components listed above, the following modifications were also added to the car:

  • GT500 duel fuel pumps
  • Dual Kenne Bell boost-a-pumps
  • 60lb fuel injectors
  • GT500 oil pump
  • Cometic head gaskets
  • ARP head studs
  • HP valve job
  • Livernois springs
  • Manley valve upgrade
  • Kenne Bell 8 rib kit (due to time constraints this was modified into a 7 rib until gets the right offset is machined on the blower pulley, although this will eventually be an 8 rib)
  • Ford Racing intercooler pump
  • Fluidyne heat exchanger
  • Clutchmaster Stage 4 clutch
  • Custom fabricated ST Motorsports tensioner dubbed the “frankentensioner”

Test and Tune

With all the modifications installed, it was time to get the car on the dyno and see how much power it would make. Adam Montague, owner of ST Motorsports and tuning wizard, worked his magic with a DiabloSport Predator. With a 3.5-inch pulley and timing set at 23 degrees, the Mustang netted a best of 636 rwhp and 594 rwtq running 20.5 lbs of boost. The addition of a full exhaust system, ported heads, and a more aggressive camshaft would undoubtedly add much more horsepower.

Adam of ST Motorsports using a DiabloSport Predator to tune the Mustang

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