JTD Performance’s Alfa Romeo Giulia Veloce reached 406 hp at around 6,300 rpm on the dyno, gaining 130 hp over the stock model’s 276 hp. The Dutch tuner achieved the latest increase by replacing the hybrid turbo used during earlier testing with a single-scroll unit. In its final configuration, the four-cylinder engine stays above 394 hp all the way to 6,600 rpm, where JTD set the rev limiter.
JTD Performance pushes Alfa Romeo Giulia Veloce to 406 hp
JTD decided to change the turbo after measuring exhaust-gas pressure in both passages of the hybrid unit and downstream of the turbocharger. The technicians also monitored temperatures to understand what was happening at higher engine speeds, using equipment supplied by Banks Power and a Squadra Tuning data-acquisition system. According to the test results posted on JTD’s Facebook page, the exhaust gases encountered too much resistance before reaching the turbine. That backpressure limited the engine’s ability to evacuate exhaust gases and restricted further power gains.
Switching to a single-scroll turbo combined the exhaust flow into one inlet passage. In the first measurements, pressure upstream of the turbine dropped by roughly 0.5 bar with the same engine calibration. The improvement became especially noticeable at higher rpm, where the engine could maintain its output for longer. At lower engine speeds, however, response became less immediate and peak torque arrived around 500 rpm later than with the previous setup.
The project started with the stock Veloce ECU. The first calibration took the 2.0-liter engine to around 306 hp and 347 lb-ft of torque. JTD then installed a 2263 hybrid turbo along with an additional heat exchanger for the circuit that cools the compressed intake air before it enters the cylinders. The tuner also revised the exhaust system with a 200-cell catalytic converter in the downpipe, plus a three-inch Ragazzon center section and valved rear exhaust.
With those modifications, the Giulia reached 360 hp and 361 lb-ft, placing it within the 355-365 hp range that JTD had set as its initial target. The turbocharger change added another 46 hp and pushed the four-cylinder beyond 197 hp per liter. JTD Performance published the results and a video of the car on its own channels. Development continues, with the tuner now targeting 414 hp, around 8 hp more than the latest dyno run.