Dayyan got hold of us in 2016, during 'Project Free Tune' a short initiative we had to assist 1.8T owners that had been having bad luck getting advice and a good custom tune. Specs as follows:

Model: 2007 VW Polo 9N3 GTi

Engine: 1.8T 20VT 4-Cylinder Port Injected (BJX)

Transmission: 5 Speed Manual (02J)

ECU: Bosch ME7.5

Location: THANAS CPT

when he brought his awesome Polo GTi through he had already equipped it with some decent 'Cape Town stock' hardware:

• 63 mm Downpipe
• Beijing BOV (Blow-off Valve)
• 3.5 bar Fuel Pressure Regulator
• Off-the-shelf ECU software
• Forge Silicone TIP
• 86 Auto Front Mounted Intercooler kit

As with most of the off-the-shelf tunes that vehicles we tune arrive with, it was experiencing excessive timing retard (knock), unstable boost curve and choppy/jerk part throttle. After throwing the BOV over the wall, we built a custom ECU tune for the vehicle, making the following adjustments:

• Correctly adjusted torque-load tables
• Ignition advance / timing tables appropriate for pump fuel
• Our developed 3-Part knock suppressive fuelling strategy
• Smoothed part throttle and calibrated boost PID
• Correct injector scaling for the 3.5 bar fuel pressure regulator
• Exhaust crackles sprinkled on top (Nusr-et style)

The vehicle then went off the dyno where it made a very respectable:

Power: 168 kW / 225 hp

Torque: 334 Nm

While that is a very decent stage 2 power on pure pump fuel, as we all know, the only amount of boost that is enough, is:

MORE BOOST - Borat, 2010

More power requires either a larger turbo, more cooling or higher octane (+ more fuel), and with the K03s not going anywhere for the forseable future, we set about upgrading the octane, cooling and fuelling. The Stage 2+ mods were added as follows:

• Bosch EV14 550cc Injectors
• EV14 Plug adapters
• WMI Kit
• Throttle body space plate

We then remapped it again taking into account the better cooling, octane and increased fuelling. The injectors were scaled in to ensure a smooth idle, great part throttle and good consumption, Bosch quality FTW!

With that done, we were back at the dyno, and this time managed a slightly improved, and still respectable:

Power: 170 kW / 225 hp

Torque: 360 Nm

Not the results we were hoping for, we wanted more, and after some digging, we found an issue with the WMI system, the nozzles were not atomising the WMI properly, most of the spray was hitting the walls of the spacer plate and there was a substantial boost leak from the other nozzle fitting. Back to the drawing board.

At this point it was decided to remove the WMI system, after countless leaks and maintenance issues. We instead moved over to an E20 fuel blend, 25% E85, and 75% normal 95 Octane fuel. We adjusted the fuelling, and after another logging and revision session, went back to the dyno and this time we made the progress we had hoped for:

Power: 183 kW / 245 hp

Torque: 372 Nm

That's more like it, at 73 kw and 132 Nm above stock, now we were starting to make some decent power! But at that very moment Dayyan received a message from Cell C telling him that his car was slow.

I guess we're gonna have to forge this bad-boy and full-send it - Dayyan 2017

Thanks for reading, next up, the forged build and K03s record!