Everyone loves an underdog. At least we do, and we suspect it's one of the main reasons so many people hang onto older VWs and continue to drive them well after they can afford something more exotic. Sure they handle well, look cool and are economical, but at the end of the day it's just plain fun to line up against a more expensive car and blow its doors off.
Meet Dave Graf, owner of the Aberdeen, MD based VW/Audi shop New German Performance - better known as NGP Racing. He obviously feels the same as we do because as a long-term enthusiast whose first car was a Rabbit GTI when they were nearly new, he's the man behind the clean Mk5 Rabbit 2.5 five cylinder turbo you see here.
The idea wasn't just to champion the underdog, but to prove a hunch that the new VAG straight-five was a great motor for forced induction and not just an entry-level option.
"It has lots of torque and as far as I was concerned, the 2.5 had plenty of potential as long as the engine was built enough," he began.
He picked up the phone and dialed Chris Collier at C2 Motorsports, a company NGP has regularly worked with over the years, and discussed the possibility of working on the project together.
"We have a long term relationship with C2 and respect its ability to tune VAG cars," he continued. "We felt it would be better that they develop the basic kit, and then we'd go down the road of custom-building a higher horsepower version, because that's one of NGP's specialties."
The prototype parts were delivered a short time before last year's H2Oi, and they began the mad scramble to build the car for the show. Head technician Ron Weaver retained the exhaust manifold and T3/T4OE hybrid turbo from the stage 1 C2 turbo kit and custom fabricated the rest of the parts needed.
A modified Eurojet Racing side-mount intercooler from a Mk4 application was then chosen to both keep the front end clean and the competition guessing.
After a brief experiment with nitrous over the summer, Dave was aware that the stock pistons weren't suitable for the boost levels he had in mind.
"There were questions over the strength of the stock pistons at higher boost levels. It was up in the air; at this point you can run up to 13-15psi on the stock pistons, but above that would be an issue," he explained.
JE Pistons produced a forged set of pistons with 9:1 compression and a turbo-friendly ring design. They were matched to a set of forged Pauter rods before the 2.5 was buttoned up.
A large diameter intake draw pipe was fabricated and fitted with a K&N cone filter. They also manufactured a 3" stainless downpipe. A high-flow cat and 3" APR cat-back exhaust then finished off the system. One of the few headaches in the process involved squeezing all the parts into the tight engine bay, while keeping the bends smooth for adequate flow.
"It's a little tougher to accommodate the downpipe on the 2.5 because you have to make a 180 turn out of the turbo to get down the transmission tunnel," Dave said.
Jeff Atwood, the head programmer and co-owner at C2, created a custom program for the prototype stage 3+ kit based on what C2 had already learned with its test car. A set of "green giant" Bosch 415cc injectors replaced the puny stock parts, and ensure the engine won't run lean.
Unfortunately, a number of teething problems have kept the car off the dyno and from obtaining solid horsepower numbers, but it is estimated at over 300 to the wheels.
Based on the stage 1 numbers, this seems reasonable. However, a problem with over-boosting on the original internal wastegate design led to an external 38mm Tial wastegate. This improvement has also been incorporated into the production C2 stage 1 kit.
Dave assured us the car is a blast to drive and the performance is fantastic. "The car is amazing. The C2 software retains stock drivability and the power delivery is smooth and linear. The configuration of the T3/T4, the side-mount and the custom piping has worked out great, giving it great torque and great mid-range, and it pulls hard to redline," he enthused.
Surprisingly, the only change to the transmission was a stage 2 Spec clutch and B&M short shifter. Dave mentioned he likes to find the limits of the stock parts before he upgrades. "It's not always the smart thing financially, but from a business aspect its allows us to know what it will handle, what it can do and what the problems are going to be," he explained.
Externally, Dave combined parts from FK and Abt Sportsline, topping them off with custom body mods to create a smooth, aggressive look. FK Silverline Plus X coilovers bring the car almost 3" closer to the tarmac, while Autotech sway bars keep it flat through the bends. The brakes are currently upgraded with performance rotors but a big brake kit is under development.
Working with Joe Klitzsch at RH Wheels, a set of meaty ZW1 alloys were custom fitted. Measuring 17x8.5" front, 17x10" rear and matched to Yokohama ES100 rubber, they fill the arches without rubbing.
Leather Corbeau CR1 seats replace the stock units, mated to Corbeau arnesses, Sparco pedal covers and a Momo shift knob to round out the interior changes.
With the turbo spinning under the hood and the free-flow exhaust allowing the unmistakable five cylinder burble to escape from the rear, Dave has found little reason to upgrade the stereo.
"I was driving it today, thinking about how good it sounds," he exclaimed. "The exhaust note is so deep, and with the 3" exhaust it sounds awesome."
With the final tuning and dyno runs around the corner, Dave's excited to get the kit into production and plans to offer the kits with or without the forged internals, allowing customers to upgrade the parts (and the boost) as funds permit.
"Our stage 3+ kit will be for the enthusiast who's looking for the ultimate 2.5 turbo kit," he concluded.
It would appear that with the addition of these turbo systems from NGP and C2, the 2.5 is an underdog no more. But we still love it anyway.
It's estimated the NGP stage 3+ kit will cost $6995 (including pistons and rods). See www.ngpracing.com for more details.
C2 Motorsports, based in Louisville, KY, is one of the top tuners for forced induction VWs. After an inspirational conversation with Dave Graf about a joint venture on the Rabbit 2.5, Chris Collier and Jeff Atwood (owners in charge of business and product development, respectively) jumped in head first.
The result of their cooperation has yielded a range of products, from intakes and chip upgrades to a complete line of mild to wild turbo kits.
The stage 1 kit utilizes the stock cat and exhaust, engine internals, compression and has no intercooler. However, it does get the stainless exhaust manifold and downpipe, 3" cone filter, 415cc injectors and theC2 software, of course.
Although the stage 1 kit on C2's white Rabbit was running the stock air box, the production version will use a draw pipe based on NGP's design. At a modest 9psi, the same T3/T4OE hybrid turbo cranks out a smooth 220hp and 237 lb-ft at the wheels on 93-octane.
With an estimated price of $3499 for stage 1, it should prove to be a deadly weapon in the armory of drivers who chose the 2.5 over the more tunable 2.0T.
Stage 1 should be in production now, and will initially be available exclusively from NGP Racing or C2 Motorsports.
Testing has yet to be done on an auto tranny, but this is planned, as is a stage 2 kit running the same boost but with the addition of an intercooler and upgraded software. A modular pipe design will make this an easy upgrade on cars already equipped with the stage 1 kit (www.c2motorsports.net).
2006 VW Rabbit
Owner: Dave Graf
Location: Aberdeen, MD
Occupation: Owner of NGP Racing
Engine: 2.5 liter 20v five cylinder with Pauter forged rods, 9:1 compression JE forged pistons, NGP stage 3+ T3/T4OE hybrid turbo, C2 Motorsports 304 stainless steel exhaust manifold, custom C2 Motorsports 42# injector/ECU package, APR R1 diverter valve, APR 3" Race cat-back exhaust, 3" high-flow cat, NGP 3" downpipe, draw pipe and intercooler piping, modified Eurojet Racing Mk4 side-mount intercooler, modified battery tray with Odyssey compact battery
Drivetrain: stage 2 Spec clutch, stock flywheel, B&M short shift
Suspension: FK Silverline Plus X adjustable coilovers with Koni shocks, Autotech adjustable sway bars
Brakes: Autotech cross-drilled and slotted rotors, brake lines, Pagid pads
Wheels & Tires: 17x8.5" front, 17x10" rear RH ZW1 wheels, 215/40 R17 front, 235/45 R17 rear Yokohama ES100 tires
Exterior: FK badgeless grille, FK eyebrows, Abt Sportsline chin spoiler and hatch spoiler, functional NACA duct in hood, badge notch shaved, GTI rear bumper with smoothed and painted lower trim, hatch smoothed and shaved, FK angeleye headlamps with black surrounds, smoked NGP side markers, FK N-Look mirrors
Interior: black leather Corbeau CR1 seats and four-point harnesses, modified OEM seat brackets, rear seat removed, Momo Race Airleather shift knob, New South Performance ColumnPod with Indigo boost gauge, Sparco pedals
Thanks: Ron, Chad and Jessie at NGP (410/994-0000, www.ngpracing.com), Chris and Jeff at C2 Motorsports (www.c2motorsports.net), Joe at RH Wheels, FK Automotive