TIA
In: 639
There are lots of things that can be changed, but the most common is managing the fuel map.
Basically, there is a giant table in the ECU of load in one dimension, RPM in another dimension, and things like temperature in other dimensions.
It takes air flow or some other RPM parameter as an input and outputs fuel. That controls the EFI to tell it what to do.
From the factory, the tables are designed with emissions controls in mind. Typically, they are not optimal for power – they are lean to reduce NOx.
If you modify airflow outside of the parameters the engine was designed to handle, and/or are going for power, then you can tune the fuel maps to be richer, maximizing power/response.
For example, I tuned my Indian Scout (RIP Nov 2022) after doing baffle-less slip-ons, and then again when I added an intake. From the factory, the bike was smooth, but slow to rev and very mild feeling.
After doing airflow mods, without the tune, the bike was very lean and the cylinders were imbalanced. It would surge idle, stall on throttle blip, lots of decel popping, and run hot.
The tune richened the low load/low throttle a lot, balanced cylinders, then richened the mid/top ends a little bit kept it running cooler, gave it enough fuel to handle throttle blip, smoothed idle, and dramatically increased its ability to respond to throttle input as it had some excess fuel to react to sudden air increase.
And, even more, it had enough fuel to respond to the new intake opening up on the top end, so while before the engine would fall flat at the top under WOT, with the intake full open and resonating, and fuel maps working right, it would keep pulling, even pulling harder with a torque bump kinda like you might have seen with old VTEC.
Both an audible and palpable difference on the intake side, and a big difference in behavior.
“Tuning” is making the engine work as close to the best it can. Kind of like adjusting a guitar string slightly to get it to vibrate at the perfect (desired) frequency, a multi-cylinder engine like those in cars will have some “best” timing to the cycle of firing pistons. Old time mechanics (way long ago) would literally “tune” a car by ear, by listening to how the pistons were firing and identifying the one, or few, that weren’t firing when they should, and fixing it, until the car engine sounded just right (if they were good mechanics, of course). They did not have electronic tools to measure the system functioning. They did it by ear, and by eye too (looked for unwanted vibrations).
Tuning is making that “Best” timing come to be, as close as you can. Each piston fires in order, one after the other, then back to the one that started it all, doing it again. Tuning is making the pause between each piston firing be the same (or when it needs to be, which might not always be the same for every step), so they always push on the drive rod (the engine cam) in their own turn at just the best time to keep the rod spinning at the same rate without differences between the input from each piston. However, you also need to link in the positions of each piston, which move up and down, so they all hit top and bottom of their individual movement at exactly the same time that the spark is being made, and also according to the same pause length between each piston. And finally, the piston movement is linked to letting gas in and, on the other side, pushing exhaust out, and that has to be made to work the same in each piston, as best as you can get it.
You want all of these different pistons to do each of those steps at exactly the same place in cycle, each and every time. So, you might have to adjust the piston positions, the spark timing, and the gas+air injection (and amount) to get it all to go how it will be the best you can. Each piston moves the same way but in its own turn, perfectly when it should.
Sort of like a multi-man canoe, say. All the paddlers want to be paddling at the same frequency and strength or the canoe will not go straight and smooth and will not get the most from the work of each paddler. Car engines need to do about the same thing, as a general idea: work all together smoothly.
Modern cars have electronic ignition (computerized firing timing) and fuel injection, so there isn’t a lot that can be done to actually tune the car, except maybe adjust the pistons a bit. Don’t really need to “tune” a modern car, but you do need to change spark plugs or maybe clean the system once in a while, so if you get a tune-up these days, that is mostly what is done: check the plugs, check that the computer is doing the job the way it ought to, and make sure there isn’t a lot of gunk accumulating in, or wear happening to, the pistons. In old cars, there were mechanical systems that could be (had to be) physically adjusted for each of those aspects, and they would wear out or vibrate out of place with use, and need to be put back into the ideal condition, every so often.
What about the Italian tunning?
It changes the ECU (engine computer) settings to be more aggressive and extract more performance from the engine by making turbocharger work harder among other things.
From the factory, an engine is often not at max performance capacity for a variety of reasons, chief among them, reliability. It’s better for a manufacturer to detune the ECU and put less strain on the engine so that components will last longer.
Say you’ve got a Gallo 12 in your car. You go to Gallos and ask them to tune it. When you get your car back. Your car will be rippin like a Gallo 24.
Ok.. for the 5 year olds:
Most cars that truly get tuned have a turbo charger which helps the engine make more power.
When they make cars the computer controls how much power the engine makes. They don’t want cars to break down so they don’t give it too much power.
When people tune cars they tell the computer to let the engine make more power even if it means it won’t last as long.
When people tune cars that don’t have a turbo they are usually putting on some fancy looking parts that don’t make it faster in any noticable way.
For the 16 year olds.. these are things like a really loud muffler, a cold air intake, lowering springs and giant wings on the back.
Latest Answers