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Diesel tow tunes and towing considerations.

Updated: 5 days ago

Tow tunes are obviously something TechTune Performance specialises in. Being at the heart of Western Australia, Perth, we receive numerous questions and inquiries about improved towing performance. Our research and tune development on the engine side has been extensive over the last decade, driven by the popularity of touring, camping, and boating in Australia.

Exhaust Gas Temperatures

Performance tune maps designed for all-out performance are not suitable for heavy loads over extended periods. With diesels, exhaust gas temperatures (EGTs) need to be controlled by typically running much leaner than gasoline vehicles. Where diesels have cooler EGTs when running lean, gasoline vehicles achieve cooler EGTs when running rich.

EGT monitoring during research and development with tuning must be considered in all cases, closely monitored by an EGT probe before or after the turbo, and a wide-band O2 sensor to monitor air-fuel ratios.

We typically control EGTs by adding more turbo boost pressure in some areas, among other minor tweaks.

If you have an aftermarket EGT probe installed, which you can monitor with a gauge, and you see temperatures of 730-760 degrees Celsius or more, you typically don't want to linger in this area for too long.

It's also important to consider emissions control systems such as the diesel particulate filter (DPF). Too rich air-fuel ratios throughout the power range can severely affect soot accumulation, regeneration burns, fuel economy, and the longevity of the DPF filter.

Additionally, carbon buildup on the intake side can reduce the flow of fresh air into each cylinder, increasing the stress on components and raising cylinder temperatures. A well-maintained vehicle is going to be much more reliable heat-wise and needs to be considered when tuning.

Sustained Power and Heat Rejection

When towing, it's all about sustained power and heat rejection. The longer you're pulling, the more heat from your exhaust will soak into the engine head, subsequently affecting your internal components.

Another point to note is your engine oil temperature, which is ultimately going to protect your pistons from destruction. We have seen many issues with oil temp sensors blown out from aggressive tunes and other faults, where things have gotten too hot and ruined their day. Vehicles tuned like this, with rich air-fuel ratios, need to be monitored, and the driver needs to have a good understanding of their vehicle's condition during these wide-open throttle pulls.

Controlling Heat

How can we increase heat rejection? Firstly, the remapping needs to be sufficient to control the heat for the vehicle's intended use. Secondly, there are plenty of aftermarket modifications for your cooling stack to aid in cooler running and heat rejection. An aftermarket inter-cooler, being the first part of this stack, often sits in front of your radiator. The cooler the incoming air into the engine, the more oxygen available in the combustion chamber, allowing for cleaner, leaner burning. Then comes the radiator, and in most cases a transmission cooler built into the radiator or mounted externally. We have installed many aftermarket upgrades for both.

A free flowing exhaust is another inexpensive modification that can improve heat rejection.

It's not always essential to upgrade these, as we can tune to within safe parameters for your vehicle's stock components.

Bull-bars and winches really do not help the situation. They are there for protection of this cooling stack, not to aid performance. This is something else that needs to be seriously considered.

Transmissions and Driving

Transmission heat and shifting need careful consideration. In most cases, automatic transmissions can remain in 'D' if you're towing flat, but sometimes it's beneficial to switch down a gear in manual mode. This locks the torque converter and provides the correct amount of power to the drive-line and prevents constant gear changes, which creates more heat. Heat is the enemy. Whether driving a manual or an automatic, listen to and feel your engine; sometimes it may be safer to select a lower gear instead of staying in overdrive or top gear. This keeps the engine in the optimal torque range, where the turbo is providing sufficient air for fuel combustion, and lower gears are generally stronger and designed to handle more stress.

Our Tow Tunes

Other than our regular performance tuning, we design tow tunes specifically for purpose. Our approach ensures that power gains are optimised for the appropriate areas, maintaining enough airflow to keep the engine cool while pulling your load. We avoid over straining the diesel engines at higher rev ranges, which is generally unnecessary for towing. We also consider your vehicle's age, mileage, and modifications. Our tuning includes many subtle trade secrets that you might not notice, but they are crucial in ensuring your engine performs optimally and lasts longer.

Some vehicles come with automatic transmission maps that can be enhanced for better towing and overall performance. However, many models we examine are already well-tuned, with manufacturers' engineers having done an excellent job.

Have any questions or queries? Send us an inquiry about your tow rig, or come down and visit us in Wangara.

Disclaimer: The information provided in this blog is for general informational and educational purposes only. We make every effort to ensure that the content is accurate and up-to-date, but we recommend consulting with a professional technician or our experts at TechTune Performance before making any significant changes to your vehicle. Actual results may vary based on individual vehicle condition, usage, and other factors. TechTune Performance is not responsible for any damages or issues that may arise from the application of information found on our site. Always drive safely and within the mechanical limits of your vehicle.

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