Diesel Performance – Is There a Safe Way to Chip-Tune a Common Rail Diesel?


Car Tuning chip

“How can I – safely – increase diesel performance in my common rail ride?”

One common question we get at BDG, both at the shop and on our Facebook page, as well as on the forums, has to do with increasing diesel performance by chip-tuning your ride. Is there a safe way? Without getting into the weeds of how Diesel engine combustion actually happens (that is a whole post in itself, coming soon), here is what you need to know.

The only way to increase performance – add more fuel.

The only factor that determines the amount of diesel performance you get out of any given engine is the amount of fuel dumped in the cylinder. With the common rail diesel, you have two basic choices of how to accomplish this.

  1. Increase rail pressure
  2. Hold the injector open longer

So which is the better option? Honestly, there are pros and cons to both, not considering the price. Here is what we know.

Diesel performance chips that increase rail pressure.

The Good: When correctly set and tuned, these chips will give a decent boost to mid-range performance (+/- 2800 RPM), as well as some gains in efficiency. These chips will not really affect top-end performance. These chips are readily available, fairly safe, and (reasonably) cheap. (If you are paying more than $500, you are paying over the odds – Matt.)

The Bad: If these chips are incorrectly tuned for your ride, you will start throwing code after code. The higher pressures wear out the injectors faster – this is a common-sense fact. Higher diesel performance > higher fuel pressure > more wear > shorter life span. At the end of the day, there is no way to pinpoint exactly how much faster your injectors are wearing out, but again, it is common sense. Better performance and fuel economy are the Holy Grail for every car company. If just increasing rail pressure delivers better diesel performance, why do they not just increase it? Reliability and lifespan of the injector.

Diesel performance chips that hold open the injector longer (and add boost pressure).

The Good: These chips give you a lot more capability to tune, and inflict a bit less wear on the injection system. The added ability to tune (each injector is metered out to the microsecond) means more horsepower and top-end performance, but not better fuel economy.

The Bad: These chips are more expensive. More expensive to buy, and more expensive to install and tune correctly. The higher sophistication and tuning flexibility means much smaller margin of (and greater likelihood of) error, so know and trust your installer/tuner.

It is worth mentioning here (and covered in more detail in a future post) that any increase in diesel performance also increases the forces exerted on the pistons, rods, bearings, etc. Whilst 1KD + CRD tuning is relatively new, the blocks put up with a stupid amount of abuse. These engines inject after TDC, which means that pressure is building inside the combustion chamber as the piston is already on the down-stroke, causing less strain on the rods and bearings than a petrol engine, which combusts at the top of the stroke.

Bottom line: If you are after more than just some mid-range increases and better economy, choose a chip that holds the injector open longer and increases boost pressure as well. Choosing the right shop to install and tune this chip to your ride is a key. End of the day, if you want more power, and take steps to minimise the risk, tuning can be the way to go. If outright reliability is more important to you than increased diesel performance, then stay away.

As a side note, one critical aspect of increasing diesel performance and tuning your CRI vehicle is making sure the replacement parts you install are up to the task. High performance does you no good if it delivers you an injector failure. Click here to learn about the new BDG next-generation DLC injectors for your Common Rail diesel vehicle.