Good tuning is the key to unlocking the potential of any engine. OE manufacturers spend ungodly amounts of time, money and research fine-tuning engines to run as efficiently as possible at all times, under any conceivable operational conditions. Simply put, if your engine is stock, it's unlikely you can get a better overall tune than the one it came with. Make a few changes though and things can change rather quickly.
An internal combustion engine is basically like a big air pump. As it comes equipped from the factory, it will flow a set amount of air based on things like engine speed, load, etc and is tuned accordingly. When changes are made to the things that regulate the amount of air that gets into an engine (cams, header, intake, forced-induction, etc.), changes need to be made to the engine management to compensate. This entails adjusting fuel and/or ignition timing, at minimum if the engine's potential is to be realized.
Basically, when airflow is increased, fuel delivery must be increased accordingly. The goal is to get the fuel and the air into the engine in the correct ratios. But don't be fooled into thinking that tweaking the air/fuel ratio (AFR) is the only thing that needs to be addressed when making serious changes--it's not that simple.
Getting more air and fuel into the engine means that there is a bigger explosion happing, which means higher temps and pressures in the combustion chamber, which can dramatically increase the chance of detonation and engine damage. As such, ignition timing often must be adjusted as well.
While comprehensive tuning involves more than just tuning the fuel delivery and ignition timing, they are 90 percent of the equation. Also, if these two things are in order and set conservatively, chances of engine survival are good.
Just like everything in life, tuning is about compromises. The key to getting the best tune is to balance maximum power and engine safety, without running the car on the threshold of destruction. Twenty years ago, tuners relied primarily on their eyes, ears, noses and timeslips to tune, which required years of experience. Today, thanks to modern fuel injection systems, we have a mess of sensors under the hood, which makes things a lot easier.
- Check out the following pages for more engine tuning info!