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Project Audi S4: Part 4

Putting the car to the test

Pablo Mazlumian
Nov 18, 2002 SHARE

In Part 3, Project S4 acquired a substantial power upgrade to its 2.7-liter turbocharged V6. APR stepped in with its Stage 2-plus setup, increasing boost from the stock 7 psi to an astonishing 1.0 bar--just over 14.5 psi. On my first test drive with the 100-octane setting, Project S4's acceleration felt on par with ec's Project M3 when it's run at an 8 to 9 psi boost level, delivering over 300 hp to the wheels.

To confirm my mind-blowing experience, Project S4 went to GT Motorsports for some dyno runs. GT Motorsports' new facility in Rancho Cucamonga, Calif., has it all--a million-dollar machine shop, a four-wheel Dynojet 248C, a handsome retail store and a large shop with eat-off-the-floor cleanliness. The company reported it will soon acquire a Mustang load dynamometer for greater tuning capabilities.

GT Motorsports specializes--well, maybe that's the wrong word--let's say has expertise in cylinder-head porting and polishing, flow-bench and dyno testing, valve jobs, custom engines and engine swaps, body kits and suspension modifications. It does service on a variety of vehicles as well. We were thrilled about finding a four-wheel Dynojet 248C, because it spits out similar numbers to our McMullenArgus Tech Center's inertial Dynojet 248C, which is only for two-wheel-drive vehicles. Most four-wheel-drive dynos are a load type and provide different numbers because of the different calibration methods.

One of the main concerns I had with this car prior to dyno testing was the evident power loss after repeated runs. Step on the gas the first time and the car runs great. But after the fourth or fifth consecutive full-throttle run, Project S4 begins to lag. I asked GT Motorsports' dyno technician Sam Safley to do repeated runs, one right after the other, with the stock boost setting. Sure enough, with only 1 minute between runs, Project S4 lost over 16 hp and 31 lb-ft of torque by the second run, and an additional 12 hp and 14 lb-ft of torque by the third run.

In any case, 222.4 hp at 5700 rpm and 265 lb-ft of torque at 3100 rpm are respectable numbers. Keep in mind, this was with APR's full Stage 2-plus exhaust--you'll probably see lower numbers with a stock exhaust, especially in low-end torque. For the Level 2 setting (14.5psi), I tried to mimic 93 octane by mixing in a few gallons of Sunoco's 100-octane race gas to the equation. At this level, the car skyrocketed to 256.8 hp at 5500 rpm and a whopping 318.5 lb-ft of twist at the wheels at only 3250 rpm. The car's ECU was pulling back a little bit of timing in some areas, but nothing looked to be raising a red flag--it's a good thing the S4 came equipped with forged pistons! But, until APR comes out with its 91-octane program for the 2000 S4, California residents are not recommended running the Level 2 setting with straight 91 octane fuel. To remedy, mix three to four gallons of Sunoco's 100 octane in a full tank, and it should do the trick.

Now came the moment of truth--how much power can Project S4 really make with this setup? To find out, we ran Project S4's tank dry and filled it with Sunoco GT 100-octane unleaded gas we got from one of its main distributors, Down's Commercial Fueling. After a short cool-down, the car went through its first Level 3 run--285 hp at 5200 rpm and an incredible 363 lb-ft of torque at 3500 rpm. These SAE-corrected numbers told the true story of why the car pulled so incredibly hard with this race-gas setting (STD numbers revealed over 290 wheel hp). With far more advanced timing from APR, Project S4 spun the dyno drums hard enough to threaten your new E46 M3 or Porsche 3.6 Carrera. Additionally, the curves in Level 3 were smoother than at Level 2, even though we're talking about much more aggressive timing and almost 30 more peak horsepower. That's the magic behind race fuel.

With this setup, the car's powerband for street use is incredible, leaving the need to make a downshift for quick passing a rarity. But if even more horsepower is what you're after, APR should have its Stage 3 setup available by the time you read this, featuring the use of a couple of Audi RS4 turbos (and hopefully something to keep the car running cooler as well). To monitor Project S4's boost level, Supreme Power Parts installed a very unique, custom-designed A-Pillar gauge kit, which houses a VDO boost gauge. Although the boost gauge is mounted on the A-pillar, it's not as noticeable from the outside by unsuspecting vehicles. In its gauge kits, SPP also blends the gauge into the pillar so that a gauge pod is not visible, and it ends up looking like a factory original.

One of the minor complaints of some S4 owners is the car's inability to release boost quickly enough when the clutch is depressed, causing a temporary "lag" in turbo spool-up when a quick upshift has occurred. To counteract this hesitation, Stratmosphere sent out a set of its Forge bypass valves for Project S4. These valves are a direct O.E. replacement and were a relatively easy half-hour install.

After the valves were installed, I took Project S4 out for a test drive, waited for the oil temperature to warm up, and hammered it in first gear. Watching the tach needle reach 6000 rpm in a violent hurry, I shifted to second gear as quickly as I could. In the middle of that instant, I witnessed the SPP VDO boost gauge register 15 psi to vacuum to 15psi again in the blink of an eye (the VDO gauge is a tad optimistic), and the hesitation was dramatically reduced. For a little over $500, the Forge valves and SPP gauge kit are must-have upgrades if you demand a smooth and quick transition of power from your S4, and are concerned about monitoring your turbos' performance. These compromise-free components simply pick up where the Ingolstadt engineers left off.

Audi Performance and Racing (APR) LLC.
1027-B Opelika Rd.
Auburn, AL 36830
(334) 502-5181
Fax: (334) 502-5181
E-mail: apr@goapr.com
www.goapr.com

Downs Commercial Fueling Inc.
1296 Magnolia Ave.
Corona, CA 92879-2098
(888) 810-3835
Fax: (909) 272-3369
E-mail: alan@downsoil.com

GT Motorsports
8220 Masi Dr. # A
Rancho Cucamonga, CA 91730
(909) 989-2278
E-mail: info@gtmotorsports.com
www.gtmotorsports.com

Stratmosphere
28 Boulder Creek Drive
Rush, NY 14543
(866) 533-1777
E-mail: contact@stratmosphere.com
www.stratmosphere.com

Supreme Power Parts
1025-B Ortega Wy.
Placentia, CA 92870
(714) 632-1951
Fax: (714) 632-9249
E-mail: info@supremepowerparts.com
www.supremepowerparts.com

Sunoco Performance Products
(800) RACE GAS (800-772-3427)
www.racegas.com

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By Pablo Mazlumian
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