- Feature: DM Motorsport’s Mid-Engined V8 Volkswagen Golf GTI
- Nothing Leaves Stock’s One Lap Of America-Winning MK5 GTI
VF-Engineering has been providing complete forced induction solutions for enthusiasts for more than a dozen years, and they are perhaps best known for pairing their centrifugal supercharger kits with GIAC software on everything from R32s, M3s and even 911s. But when VW introduced the 2.0T, VF-Engineering founder Nik Saran saw the obvious performance potential in the motor and decided it was time to dive back into turbos once again. After some research with software partner GIAC it was decided that two unique tuning options should be offered, and work began on the development cars.
Both GTIs utilize larger Garrett turbochargers, each chosen for different power levels. The RSS (street version) car was developed with the intention of selling a kit through a series of VF & GIAC dealers. The more powerful RSR (race version) model was designed to be purchased as a completed unit straight from VF as it requires a complete engine teardown and rebuild with new internals. For this, VF-Engineering developed an engine rebuilding program.
Both cars seen here are equipped with STaSIS suspension systems and brake upgrades. The RSS car uses the Touring suspension package and 13.5-inch front brake upgrade. The brake upgrade utilizes the factory calipers with different carriers and two-piece rotors. The RSR is equipped with a Street Sport Coilover System and 14-inch front brakes. These larger brakes use Alcon Monobloc 4-Piston calipers with the larger two-piece floating rotor and aluminum hats. Both cars ride on 19-inch OZ Ultraleggerra wheels wrapped in Toyo R888 DOT-Legal race tires.
The RSR car received a VF-Engineering Stage 4 ceramic lightweight clutch and flywheel package. To handle the extra power a STaSIS limited-slip differential is also employed. Both cars received VF’s 3-piece engine mount kit to keep movement under control and assure that all that added power gets to the road. While VF’s claim to fame is almost exclusively from their arsenal of forced induction systems, one can only assume that VF knows how to make a car handle the kind of power their FI systems produce. With this in mind, VF-Engineering offers two proprietary Chassis Packages, also available under the RSS and RSR monikers. The RSS and RSR Chassis Packages are comprised of STaSIS brakes and suspension, and a full set of VF Engineering billet engine and transmission mounts. Suffice it to say, you don’t need to be pushing big-turbo power to see the benefits of these Chassis Packages. This is how that car should feel from the factory!
To set the RSR GTI apart from other cars on the road, a Caractere body kit was installed. Consisting of replacement front and rear bumpers and side skirts, it adds an aggressive touch to the visuals of the car. Adding a little extra visual excitement as well as shedding a few pounds, the factory hood was replaced with a carbon fiber piece from DTM Karbon. The center of the hood was left bare carbon to match the car’s grille and the roof was painted black to carry the theme across the entire car. The rear valance has cut outs for dual exhaust pipes, so VF modified the Caracter exhaust rear section to work with their power levels. Once the car is fired up, it is instantly apparent that you are dealing with something far from ordinary.
Under the hood is where the interesting mods really happen. VF and GIAC decided from the beginning that these cars needed to behave like stock in normal driving while providing the maximum performance achievable.
VF looked no further than Garrett Turbochargers as the best option for both kits. Garrett covers a large range of applications and has a history of building top-quality reliable turbos. With the hot side of the factory turbo being cast into the factory exhaust manifold, it was necessary to do some involved engineering. VF designed their own manifold to work with the two different sized turbos. A tubular prototype was built to test for clearance and flow characteristics first. Once a design was decided upon, several prototypes were designed in CAD and a plastic model was made for each design using rapid prototyping equipment. The prototypes were again checked for fitment and then flow-bench tested. The runners are separated to eliminate pulse interference as it enters the turbo. The final production manifolds are sand cast and then CNC machined.
Hanging off the VF Manifold on the RSS GTI is a GT28RS turbo that provides 17psi on both pump and race gas. Once exhaust gasses have spun the turbo they exit through a full turbo-back AWE Stainless Steel Exhaust. The extra boost on both GTIs required more fuel, not the easiest task for some tuners with the new FSI injection, as this fueling system uses many proprietary parts that are not readily available. As well as being an official Kit Engineering house for Garrett Turbos, VF’s accounts with OEM vendors gave access to a new higher pressure fuel “rail pump” and higher flow injectors which are included in the kit to ensure proper air/fuel mixtures throughout the entire RPM range.
The RSR GTI is a much more involved kit. A larger GT2871 turbo was needed to get the 31 psi the car runs on race gas. On pump gas the car still runs an impressive 27 psi. To run that kind of boost safely, a lower compression ratio is necessary. New forged “FSI dish” pistons were designed to replicate the factory dish while lowering compression by a full point, and forged rods are also used for greater strength to withstand the RSR’s neck-breaking power and torque delivery.
While the factory front-mounted intercooler is more than adequate for the RSS, the RSR’s 27-31 psi proved to be more than it could handle. A new front mount intercooler is mounted neatly behind the front bumper and brings intake temperatures down significantly. VF’s cast aluminum end tanks not only look great, but they maximize air flow through the large intercooler core providing maximum efficiency as tested on VF’s in-house flow bench.
On 91-octane California Premium, the RSS GTI spins the dyno to the tune of 300 whp and 281 lb-ft. On 100-octane race gas those numbers are bumped to 336 whp and 283 lb-ft. At just 17 psi, these power figures are an indisputable indicator of maximized efficiency and GIAC’s tuning prowess.
The RSR GTI puts down an astonishing 414 whp and 355 lb-ft on 109-octane race gas and 355 whp and 320 lb-ft on 91-octane pump gas. Like all GIAC equipped cars, the programs are easily changed with the hand held Flashloader.
VF Engineering/GIAC RSS GTI
The sign of a well tuned car is when your first thought is, “Why didn’t the factory build it like this?” It idles just like stock, and boost comes on quick. Once you get above 2500 rpm you begin to realize this thing is fast. Another thousand rpm and you are in the thick of the torque band and the car is pulling like a freight train! Power delivery is factory smooth, and predictable. The larger-than-stock Garrett turbo spools up much quicker than you’d expect, and before you know it you’re in the red! With this kind of power I expected torque steer, but never found it. The combination of sticky rubber and proper suspension tuning really helps keep things under control. Braking is equally as impressive, allowing the driver to wait until the very last second to scrub speed. Turn-in is sharp and neutral with smooth, predictable feedback. Rounding out the RSS Chassis Package are VF’s billet engine and transmission mounts. They do a fine job of keeping engine movement in check, providing the ultimate compliment to these power levels. Hit the gas, and you instantly feel the power being delivered to the pavement- No nonsense here. Modulating the throttle around corners has never been easier- this is “point and shoot” handling at it’s best!
In normal driving the car is slightly louder than stock, thanks to the deep and sophisticated exhaust note provided by the AWE exhaust system. The deeper rumble is complimented by the throaty and intake noise from the VF intake system, which lets you really get a sense of just how much air is being inhaled at full boost. Ride quality is near stock, even with the larger wheels and lowered ride height. There is virtually no downside to any of these upgrades. This is the most fun I’ve had in a GTI in quite some time!
VF Engineering/GIAC RSR GTI
For drivers looking for the ultimate street-legal GTI/weekend racecar or just a racecar-like experience, the RSR is built for you. The lower compression makes itself subtly apparent at rpm, though it is surprisingly easy to drive at low engine speeds. With the larger turbo sitting under the hood, you would expect turbo lag to be more of a compromise for the added power that the RSR produces. Although slightly more pronounced than on the RSS, turbo lag is still minimal. Admittedly, I had some preconceived notions about what it would be like to drive the RSR. What I had in mind was huge power, but a nuisance to drive daily, big turbo lag, sluggish throttle response. If there was ever a time to point out that one should not judge a book by its cover, this is it.
Driving the RSR is a blast! You can measure the caliber of engineering that went into this system by the response of the throttle. Being a Garrett Turbocharger Engineering House has its benefits. Mash the throttle and you almost instantly swing the needle around. Needless to say, things start happening fast. Power comes on smooth once you’re in the boost and it climbs all the way to redline without a hitch. You can feel the boost building gradually and predictable. The car is surprisingly easy to drive, and it seems to have no limits—that is, unless you consider running out of road a limit. It boasts gobs of torque everywhere and near-linear power delivery. The RSR does not just feel like it is accelerating quickly, but rather like it is moving the earth from underneath it. If the RSS pulls like a freight train, this thing is in a whole other world.
Driving the RSR aggressively requires a little more attention. With this kind of power, it is important to know your next move at all times because it comes quicker than you’d expect it to. The STaSIS LSD provides loads of traction, and is necessary to control this level of power. Coming out of corners is effortless under throttle thanks to the combination of high power and loads of grip from the LSD. The end result is the feeling of reeling in the next corner with amazing ferocity. Cornering in the RSR is even further enhanced from the RSS by the STaSIS Streetsport coilover suspension, which boasts favorable dampening characteristics and the ability to corner-balance. The LSD also helps to alleviate some of the understeer, putting power down on corner exit results in a more neutral feel, while lifting mid-corner will rotate the car around.
Even with the larger turbo, the RSR is still completely drivable around town. The idle is factory smooth and even with a stage 4 clutch, take-off is easy. To the average person unfamiliar with a stock 2.0T, they wouldn’t know anything was different on this car until they hit full boost. The exhaust note on this car is louder than the RSS GTI but resonance isn’t an issue.
The RSR may not be for everyone, but that’s the point. VF and GIAC wanted to push the envelope on this one. They estimate that there is still more power left in 2.0T, but more power would require even more extensive modifications to the vehicle. Unless you are looking for a dedicated racecar you won’t need to look any further than this. This is the GTI at its best.
|For more discussion on this story, click on the link to our discussion forums to the left.|