If you’re serious about getting more power out of your diesel car then there are a few things that can be done. The first is the obvious; fitting a performance tune to your car’s engine management system. This will provide big power gains in the mid to top end of the rev range.
The diesel turbo tuning gains are however found in increasing the boost pressure that the turbo can deliver. This is achieved by using a bespoke map that alters the engine parameters to allow higher levels of boost.
As a result of this, the combustion chamber can be tuned to produce more power and torque from lower inlet temperatures. This is important as it allows the engine to produce power from a wider rpm range than it can with factory calibrations.
Turbocharged Thrills: Exploring the Art and Science of Diesel Turbo Tuning
There are other things that can be done to improve drivability and fuel economy, such as increasing the air mass that is injected into the engine by installing a bigger induction kit or by fitting a larger bore exhaust system. These should also help to increase drivability in lower rpm bands where the diesel’s naturally low compression ratio really hurts its drivability.
More extreme mods can be used as well, such as compound charging which uses two or more smaller turbos to blow in to the bigger one(s) for drivability and huge boost pressures; sometimes over 100psi! Removing the complex electronic diesel injection system in favour of an older style purely mechanical fuel pump is done on some extreme diesels too.