The K04 framed turbo was commonly fitted to the cars which were considered the higher performance versions of the 1.8T range such as the Leon Cupra r and the Audi S3. There are 2 different variants of this turbo found on transverse engines. These are the k04-022 and the k04-023 with the difference being the 023 having a egt probe boss and the 022 not.
The K04 is the “bigger brother” of the K03 turbo found on the large majority of 1.8t’s. The came on cars with a base power level if 210bhp and 225bhp.
K04 vs the smaller K03
The K04 turbo will range in power when remapped, with a simple stage 1 remap taking power to around 250bhp. With full stage 2 hardware and supporting mods the typically power can range from around 265bhp-300bhp. (figures are based on being mapped on UK 99RON fuel)
With the K04 framed turbos, the best method to extract power is the ensure that you can get as much cold air into the turbo as possible, and ensure it also has a good exhaust system to remove the exhaust gases. Air flow is crucial for these small framed turbos, and the easier and more efficiently you can get the air flowing through the turbo, and across the engine cylinders the better.
Some of the best mods you can do is fit a oversize silicone intake pipe from the likes of R-tech, Badger 5, SFS hoses. Be wary of the Non supersize versions found both on eBay and from the likes of companies such as Forge motorsport, as their diameter is very small and can end up causing a restriction, especially when compared to the larger versions.
As with all small framed turbos when you start to up the boost pressure you also get a increase in the heat produced. A small turbo that is boosting to the max will have extremely hot air coming out of it, which needs to be cooled down before entering the engine. A Front Mounted Intercooler is required for a good stage 2 setup as the stock Side Mount Intercoolers simply cannot cool the air down sufficiently enough. Check our Intercooler section for advice on choosing the right intercooler setup.
The k04 turbo also comes with a extremely restrictive manifold. Changing this manifold for a more efficient setup can make a huge difference whilst mapping at the stage 2 level.
To view our full guides follow the links below!
- Stage 1 K04 Tuning
- Stage 2 K04 Tuning (coming soon)