Understanding the function of the "engine-to-transmission ratio" is essential learning for any automotive enthusiast. The ratio can be tweaked to achieve optimal performance results by modifying how the vehicle’s engine and transmission are paired together.
In fact, two vehicles with the same engine and the same transmission can vary significantly. Depending on the owner’s intended use, adjustments made to the engine/transmission ratio will dramatically impact the behavior of two identical vehicles.
Some manufacturers will alter the engine/transmission ratio of a series in order to meet certain guidelines and requirements. Recently, we saw Jeep break new ground with its factory-modified Gladiator Mojave.
The modified Gladiator, already accustomed to driving in extreme conditions, is singled out among the brand’s other liveries. Jeep revised several components, but more importantly they adjusted the engine/transmission ratio. In doing so, they equipped the Gladiator Mojave with the prowess to navigate the most unforgiving 4x4 terrain with ease.
What does the engine/transmission ratio mean?
The engine/transmission ratio determines the variable relationship between the input speed (to the motor) and the output speed (to the drive shaft).
To put it another way, a vehicle's engine produces energy that is transferred to the drive wheels via its transmission, transfer case (T-case) and differentials. These three elements transform the rotational speed of the engine into torque by means of gear systems.
Depending on the manufacturer’s specifications and the owner’s expectations, the gear ratio can be tweaked to improve and customize performance. This is what Jeep did with the Gladiator’s new “Desert Rated” Mojave series.
Let's take the example of the Gladiator Mojave and the Gladiator Rubicon. Wonderfully versatile, both vehicles possess exceptional off-road capabilities. They house the same 285 horsepower 3.6L V6 engine delivering the same 260 lb-ft of torque. In appearance, the engines are mechanically identical.
Given this, Jeep engineers set the engine/transmission ratio for the Gladiator Mojave at 2.72:1. This means the vehicle moves quickly and more easily when shifting to "4-Low" mode. The modification allows owners to run their Jeeps in unpredictable environments, like ploughing through deep snow or sand dunes. The vehicle’s performance is managed by alternating to “4-Hi” mode for low traction highway surfaces.
When it came to the Gladiator Rubicon, Jeep selected a 4.0:1 gear ratio. The advantage the Rubicon has over the Mojave is a considerably greater towing capacity, regardless of the condition of the terrain its owner is driving on. This is a configuration often used by pickup truck manufacturers.
Two seemingly identical vehicles behave differently by modifying how the engine/transmission ratio is configured.
Whether geared towards improving off-road or racing capabilities, tuning enthusiasts are known to modify their vehicle’s engine and transmission ratio to unleash its full potential. Some drivers are looking for a powerhouse on bumpy running, while others are looking to take speed and handling to new levels.
Tuning gear ratios on your own is never recommended. Customization is increasingly popular, but keep in mind that doing it yourself can come at the expense of safety —yours and others. These types of modifications require considerable knowledge and a background in mechanics. Your local dealership or mechanic shop is the best place to seek advice.
