2007 Volkswagen GTI
It's a well known fact that when VW released the Direct Shift Gearbox (DSG), it changed the world's perception of what an automatic transmission was capable of. Suddenly it wasn't a paradox using the words "sporty" and "automatic" in the same sentence. But while impressive, DSG is a major control freak that spends every millisecond contemplating ways to keep the engine's power and torque in check, but not in a good way. We were originally informed by the manufacturer that this extremely advanced piece of technology could only handle about 258 lb-ft of torque. So they installed a torque limiter in the transmission's computer that would cause the transmission to disconnect if the torque limit was exceeded. The power struggle goes on virtually unnoticed because chip tuners found ways around this, manipulating torque numbers that the ECU lets the transmission see. While effective in preventing disconnect, it still doesn't address the fundamental problem with the overprotective DSG computer. Symptoms could include excessive timing retard, loss of power, and listlessness. While these symptoms can be attributed to other factors, the most likely condition is an agitated DSG computer.
Engine: 2.0-liter I4, dohc, 16-valve, FSI direct injection, turbocharged and intercooled
Transmission: Six-speed Direct Shift Gearbox (DSG) automated manual
VF/GIAC RSS-20 big turbo kit, VF front mount intercooler, VF Milltek 70mm turbo-back exhaust with 200 cell metallic HJS catalytic converter
Ambient temp: 72°
Test gear: Third
Test octane: 91
Peak power: 265 hp @ 6400 rpm
Peak torque: 247 lb-ft @ 4700 rpm
Temperature: 75° F
All horsepower and torque numbers are SAE corrected and quoted at the wheels.
Performance programming stage 2
Peak power: 268 hp @ 6700 rpm
Peak torque: 283 lb-ft @ 3900 rpm
Max power gain: 20 hp @ 5600 rpm
Max torque gain: 55 lb-ft @ 4000 rpm
Installation time: 30 minutes
• Increases the transmission torque limiter from factory limit of 258 lb-ft to 368 lb-ft
• Increases the transmission rev limiter to 7150 rpm; actual rev limiter is still controlled by the vehicle engine control unit
• Launch control activated on vehicles that did not come equipped with the feature from the factory
• Launch control maximum rpm raised to 4750 to better utilize torque curve
• Recalibrates upshifting and kickdown features in both M and S modes to optimize the driving experience
• Adds gear indicator in the instrument cluster next to the P-N-R-D-S icons
• Eliminates automatic shifting feature in S mode
• Progressive shift response uses a scaling effect to improve the shift response between gears to eliminate clutch slippage and reduce clutch wear on (D)rive, (S)port and (M)anual mode (tip-in throttle 1/3 faster than factory, 50% engine load or wide open throttle 2/3 faster)
• Elimination of the automatic shifting feature in S mode
Because we didn't have the patience to wait for the schedule HPA had set up for its distribution network in the U.S.,HPA techs were gracious enough to fly down to Los Angeles from Canada to flash the DSG software. However, this prevented us from performing the after-test the same day, so we preformed test two days and about 100 miles later. The peak power and torque gains listed illustrate gains in the normal rpm range of 6400 rpm. The software gave us access to power that was limited by the transmission rev limiter, so technically we did record a peak gain of 268 hp at 6700 rpm.
When we first tested the VF/GIAC RSS-20 turbo kit on this 2007 GTI, it was immediately obvious that the DSG computer's internal rev limiter was preventing the Garrett GT28RS turbo from reaching its full potential. The original purpose of this Proven test was to demonstrate the power that could be gained by increasing the rev limiter in the transmission. We figured that the other features would be a subjective evaluation, but after a few dyno runs the HPA programming exposed something that was not readily apparent in DSG-equipped vehicle tests we have done in the past: the extent of the DSG's computer control on the rest of the rpm range.
It's my opinion that the torque limiter is responsible for the result. It's all about control. It seems like the transmission is constantly monitoring the engine torque trying to keep it below the torque threshold, and when it detects that it's getting close to that limit it starts retarding the engine's fuel and timing to reduce output. For those of you who own a modified DSG and find the 258 lb-ft number a bit confusing, the reason that your vehicle can produce higher torque numbers is because software tuners manipulate the torque data coming from the ECU to keep it right below the 258 lb-ft mark. This prevents the DSG computer from disengaging the transmission, but the problem is the computer starts to get involved when the torque numbers exceed 207 lb-ft.
The HPA software increases the torque limiter to 368 lb-ft, which effectively eliminates the DSG computer's meddling, allowing the engine computer to do its job with no ill effects. And overall, the HPA DSG/S-Tronic Performance Programming Stage 2 completely transformed the vehicle. Don't get me wrong, the vehicle was amazing before, but it was frustrating knowing peak power was just out of reach. The HPA programming solved that problem but did so much more than access hidden power. It also provided increased control.
Let's break down the key features. The Progressive shift points are designed to reduce the number of milliseconds it takes to change gears, (honestly though, how can one even feel a millisecond?) but the transmission seemed to transition between gears more quickly and smoothly than before the upgrade. The GTI already had launch control, and after using it twice we never used it again. Besides making lots of noise, there never seemed to be much use for it. The torque and rev limiter increase was the key to making more power. It would be interesting to see if, with less interference from the DSG computer, the engine software could be optimized for more power.
As for eliminating automatic shifting in S mode, I fell into a love-hate relationship. When you're focused, driving the canyons or on the track, it's perfect. The problem becomes apparent when driving around town. However optimized, D mode still lacks the power and snap found in S mode. But in certain situations while using S, the revs stay so high in range that engine noise stays at a constant pitch and becomes annoying. The ultimate upgrade would be eliminating D entirely and allowing two S modes: one with automatic shifting and one without.