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Intro to Tuning
The automotive community is one which has many labels. One such label that is often applied to import owners is “tuners” which came about because these cars pioneered new technology involving tuning. Wrenches have been replaced by a single laptop and a mouse when it comes to adjusting how a vehicle works.
Still, how many people labeled as “tuners” actually tune their car?
If you’re interested in tuning, understanding how it works and what goes on inside your engine is absolutely critical. Some professional tuners will say what they do is beyond the grasp of an average owner, or some kind of voodoo magic. The truth is that tuning is very possible with an understanding of math, physics, and a little bit of patience.
So how do you tune a car? There are various methods but they all require tweaking of your Engine Management System or EMS.
An EMS is defined as “a device or module that, through the use of a graphical or mechanical interface, controls the combustion process of an engine, through manipulation of the basic fuel delivery and ignition timing.”
As in the definition, there are two parts to tuning. First is tuning for an air/fuel ration and the second is the ignition timing of the motor.
First, let’s deal with the physics. Without going too specific the simple reasoning is that a leaner mixture of air and fuel results in more power. In a perfect system it takes 14.7 parts of air to combust 1 part of gasoline. However, there are many factors which influence this such as coolant temperature, barometric pressure, combustion chamber temperatures etc. As a result, when your engine is under heavy load it requires a richer mixture of fuel to prevent detonation.
Detonation is when fuel ignites in the combustion chamber incorrectly or at the wrong time which can result forcing the piston/rotor in the opposite travel direction or damage other parts of the motor. The fuel’s temperature is risen to such a point that it detonates without the assistance of the spark plug.
There are various terms referring to detonation including knock, ping, and pre-ignition. These are all the same thing but knock and ping refer to two types of noises heard in piston motors when detonation occurs. Pre-ignition is detonation which occurs specifically before the spark occurs.
When tuning for air/fuel or timing, detonation is something that must be avoided because the end result is a damaged or destroyed motor.
When tuning for air/fuel the tuner’s goal is to find the best mixture that yields the most power. This usually results in leaning out the fuel mixture from the stock configuration. In regards to vehicles with forced induction the optimal air/fuel occurs between 11.2:1 and around 12.5:1. With naturally aspirated vehicles the range from 12.5:1 and 13.5:1 is optimal. Now, these are all based on characteristics of the motor itself as well as mods etc.
Adjustment of timing is adjusting when the spark fires and the duration. Advancing timing results in the flame front starting earlier and often results in more power. Still, advancing the timing increases your risk of detonation so it’s a balancing act. Optimal timing is dependent on the characteristics of the motor but the standard practice is to advance timing as close to detonation as possible and then back it off for safety. Forced induction requires much more careful tuning as even slight detonation could cause major engine damage.
In the opposite direction, reducing timing lowers the octane fuel requirements so it’s possible to allow a premium fuel only car use 87 or 89 octane with reduced performance.
All these aspects of tuning are accomplished via the EMS system which can use various different interfaces from 3d graphs to simple text and spread sheets. A trend which has been occurring for the past 10 years has been to start using the OEM provided EMS systems instead of installing complex and often expensive aftermarket management systems.
This gives the tuner greater access and control over the individual vehicle. The trade off is that these stock computers have to be reverse engineered which takes time and resources.
Common aftermarket EMS such as AEM, Motech etc. can be used in a wide variety of platforms and professional tuners usually have lots of experience with these devices.
This is a very brief overview of the tuning process and there are many more variables which are vehicle specific that are not listed here.
With research and proper education you can develop the skills to tune vehicles but I would highly suggest having a professional do most if not the entire tune. However, knowing what is happening under your hood and being able to understand the tuner’s adjustments will go a long way to preventing a disaster with your motor.
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