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2004 Mini Cooper S Twin Turbo - Streetcar

If One Spinning Air Pump Is Good, Two Must Be Better. SPI's Twin-Charged MINI Cooper S Offers Proof

By Chris Knudson, Photography by Henry Z. Dekuyper

"The first thing I get rid of when I buy a new car is the warranty," says Hubie Fuh, of Cliffwood Beach, N.J. We like guys like Hubie.

That's because guys like him are brave enough to explore the unknown, to trade a perfectly fine factory warranty just to answer the question, What would happen if we do this? It's because of people like Hubie that the rest of us can buy off-the-shelf kits for our cars once our precious warranties expire. They're the rolling R&D. We're the benefactors.

As you'll recall, we named the MINI Cooper S to our Eight Great Rides list in 2004, and it was the winner of last year's burnout contest. So to begin with, Hubie started with some decent rolling stock. But Hubie's first impression mirrored our own".

The MINI was amusing at first. It handles great, but it lacked power," he says. Hmm. A refresher course in MINI 101 was in order. One trip to the nearest dealership and the Motoring Advisor's grip on the oh-shit bar confirmed completion of the course. Sure enough, Hubie's assessment was spot on.

After researching the existing OEM supercharger, Hubie came up with the idea of twin-charging the MINI-combining the OEM Roots-style supercharger and a Garrett GT28R turbocharger. He then went about developing a kit that's now for sale through his company, Sharp Precision Instruments.

Hubie wanted to keep the kit as simple as possible, so the two air pumps work in series with the supercharger, augmenting the turbo throughout the entire rev range. Inlet air is initially compressed by the turbo, then routed through the throttle body and into the supercharger, where it's compressed again.

It's then fed through SPI's custom top-mount intercooler and into the engine. The supercharger and the turbo work together; there's no complex sequential pumping and no bypassing of intake air. Full boost of 20 psi is achieved at 6000 rpm, but the kit makes 15 psi by 3500 rpm.

The stock Eaton supercharger bypass valve was removed since Hubie found it caused problems when used with this much boost. Two HKS racing blow-off valves, one for the Garrett and one for the supercharger bypass, rid the system of boost once the throttle is closed. As a result, the MINI now has noticeably better throttle response than its stock counterpart.

The supercharger remains stock, but the plumbing is not, with an upgraded SPI inlet pipe to the supercharger and custom 2.5-inch aluminum piping surrounding SPI's top-mount intercooler. Spent gases work their way through a custom-fabricated stainless-steel tubular manifold back to the Garrett.

In addition to the stainless-steel tubular manifold, the GT28R is held in place by a custom-fabricated stainless-steel downpipe. From there, exhaust gases are expelled through SPI's custom-built 3-inch stainless-steel exhaust and an A'PEXi N1 Turbo muffler.

With this kind of breathing ability, the MINI needed serious help in the fueling department. SPI's 440cc/min fuel injectors do just that, while an A'PEXi S-AFC II allows modified fuel mapping. According to Hubie, the addition of the AFC was by far the most difficult aspect of the project, and the first of its kind in a MINI.

"BMW isn't quick to share its wiring diagrams, so we had to trace every single wire in the harness." But the effort was well worth it, as Hubie tells us this arrangement is good for dyno pulls of 265-wheel hp on a Dynojet chassis dyno.

Even though the twin-charged MINI now produces nearly twice the horsepower and torque of a stock MINI Cooper S, the drivetrain and tranny have been left alone. Hubie is surprised by how well the stock components have held up to the hard launches the MINI now endures regularly.

The suspension, however, received some additional attention to accommodate the increase in power. Turn-in, while already decent in stock trim, has been dramatically improved with the addition of a set of custom-valved, KW Variant III race coil-overs, which drop the MINI's ride height by 2 inches.

Stopping was also given priority in this MINI gone mad. A StopTech Big Brake system does the trick up front with 13-inch slotted rotors, ST-40 four-piston calipers and high-performance street pads. Out back, a set of 10-inch SportStop slotted rotors sit sandwiched by another set of high-performance pads. Hubie replaced the stock rollers with a lightweight set of 18x7.5-inch Volk GT-7s, wrapped in 215/35-18 Hankook Ventus tires. The anthracite finish makes the MINI look as bad-ass as it is.

Clean, minimalist additions to the bodywork begin and end with SPI's carbon-fiber front and rear spoilers. That's it. No unnecessary drama. Together, the subtle changes warn only the more discerning observers that this is no ordinary MINI. According to Hubie, a couple of Supras have already learned this lesson the hard way.

Since the gauge cluster in a stock MINI already looks like ground zero of the great pod invasion, it seemed an ideal platform for SPI to showcase the Dff,fi-Link system. But strap yourself into either of the Sparco Monzas up front, and the only clue that you're not staring at an OEM gauge cluster is the Dff,fi-Link digital display sitting front and center on top of the dash.

In fact, the four Dff,fi BF 60mm gauges are so well integrated into the MINI's existing dash layout, you'd swear they were a dealer-installed option. Mounted alongside the tach on the steering wheel stalk are boost and oil temp gauges. Gone are the two center-mounted vents, and in their place sit 60mm gauges for oil and fuel pressure.

While the car was originally built to be a show car, this new direction has led to a focus on future competition in street class drag racing. SPI also has plans to run the MINI at Watkins Glen later this year to further tune the suspension and toy with the idea of road racing. What began as a platform to display four gauges led to the creation of a monster. Dr. Frankenstein would be proud.

So far this car has won first place in the European Car category at the 2004 SEMA International Auto Salon East show. By accident. "We never entered the car," Hubie says. "We brought it for our booth, and the next thing we knew, the judges were surrounding it." He said their goal was to do something different, to give a Japanese tuning flavor to a European car.

And the warranty? Fawgeddaboutit.

2004 Mini Cooper SEngineEngine Code: W11B16Type: 1598cc SOHC inline four, turbocharged, supercharged and intercooledExternal Modifications: Stainless-steel tubular manifold and downpipe, Garrett GT28R turbo, SPIcustom top-mount intercooler with aluminum 2.5-in. piping, two HKS Racing blow-off valves, upgraded supercharger inlet pipe, SPI custom 3-inch stainless-steel exhaust, dual A'PEXi N1 Turbo mufflerEngine Management Modifications: 440cc/min. fuel injectors, A'PEXi S-AFC II

DrivetrainLayout: Transverse front engine, front-wheel drive

SuspensionFront: KW Variant III Race coil-oversRear: KW Variant III Race coil-overs

BrakesFront: StopTech slotted big brake system with ST-40 four-piston calipers and 328mm rotors, steel-braided lines, high-performance street padsRear: SportStop slotted 259mm rotors, high-performance street pads

ExteriorWheels: 18x7.5-in. Volk Racing GT-7 anthracite with polished lip, +44mm offsetTires: 215/35ZR-18 Hankook Ventus

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By Chris Knudson
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