What limits tuning?

[voon]

I'm a tuning noob, since we can't do that here in Switzerland much anyway. But I wonder:

1. In theory, I assume bringing up the power is simply pushing in more fuel and air. And that's it. More explosion, more power.

2. The limit is the mechanical parts or the air you can shovel in through the turbos. Does any rod, wheel, the entire casing, the gearbox etc contort or blow up with the extra power applied etc.

Is that tuning in a nutshell?

 

[eflyguy]

Dynamically adjusting air/fuel ratio and also ignition timing. In vehicles with variable valve timing and other controllable components, it can leverage those as well.

If you want to know more, I suggest looking at the Engineering Explained channel on YouTube - he has some great information on air/fuel, ignition and tuning - as do many others, but he also describes things well.

 

[robz32]

That is a very simple way of putting it. However there are more variable that com into play when properly tunning an engine.
You mentioned two key components, air and fuel. The more of those two you get into the combustion chamber the better. However how you get it in there and how the explosion is made also determines the amount of extra power you will be able to extract.
The most common limiting factors when tunning any car are, fuel (proper octane to prevent detonation), injectors (injectors have a max flow capacity, that will be a restriction when trying to achieve high HP), engine internal component (every engine is manufactured differently and their internal components are manufactured to withstand a certain amount of torque and power. Now keep in mind that these components are always over engineered and that is not by accident, manufacturers do this to achieve a certain level of reliability, that's why we are able to tune the Stinger for a higher HP, however in return we are effectively reducing the expected usable life of the factory components), heads (this is one of the variables that if manufactured properly will net the most gains when tunning, heads allow air flow inside the combustion chamber, at the same time they allow the left over gases from the combustion process to be evacuated via the exhaust system), exhaust (another important component which will net big gains when tunning, here the less restrictions/bends the piping has the better, as the gases can escape easier), and drivetrain (same principle from the engine internal components applies to the drive train, transmission, differential, driveshafts, axels, etc have been over engineered for the same reason).

Phew....those are the most important components that help tunning any gas power engine more or less efficient and also the limiting factors when tunning. I may have left some out, feel free add them.
Hope this helps @voon

 

[Kazz]

1) The internal combustion engine is a glorified air pump. Getting more air through the engine is the goal. Fuel, spark, and air mix to make the pistons, etc. move.

Removing air restrictions is usually a first step (intakes, exhausts, etc.). In a forced induction setup (turbo), where air is compressed and then shoved through, temperatures become more of an issue as well. So a cooler "charge" (body of compressed air) is desired and that's where intercoolers come in. From there, higher compression of the air and increasing the flow beyond just removing restrictions (larger bores on intake manifolds, engine blocks, exhaust components) come into play.

Mind you, doing these things can quickly render the spark (coils, plugs, even amps) as well as the fuel delivery system (fuel pump, fuel pressure, injectors) inadequate. And the programming of the car's computer (ECU, ECM) needs to be changed to keep up with timing and fuel delivery.

Oh! And then there is getting the power to the ground - clutch, flywheel, transmissions, differentials, driveshafts, etc. all need to be able to handle the additional power as well. A car needs adequate and quality rubber in order for all that twisting power, even once it gets all the way to the wheels, translated into moving the car forward instead of spinning uselessly in place.
It can all be very much like chasing one's own tail unless these changes have been tested, proven, and shared.

2) Yes, engines and transmissions can blow up from bad tunes, programming, too much power, etc. One of the current concerns with the 3.3TT Stinger relates to the driveshafts. Maybe the engine and trans in the GT can handle the power, but it must be able to get to the ground dependably, efficiently, and provide adequate grip.

 

[eflyguy]

My explanation may be simple (I'm a simple man) but I read his question as wondering what you can do with an ECU and what are the limitations.

The air pump analogy is a good one, anything you can do to get more air, and hence fuel, will produce more power. The stock components can't be manipulated by the ECU to accomplish this.

 

[miltonjackson]

I'm a tuning noob, since we can't do that here in Switzerland much anyway. But I wonder:

I am from Basel, and i never heard of this. Can you elaborate why we can't tune i Switzerland?

On a side note, i am back to Basel in August and i am looking forward to buy a stinger. Could you be so kind to give a rough estimate on what i would need to pay in tax/insurance every year?

 

[voon]

No we can tune, but only within tiniest limits .. unless you want to go and do a separate homologistaion of your car, which costs thousands. Insurance will be about 2000ish CHF, depending on your options and taxes depend extremely on where you live ... I pay around 700 CHF in Solothurn. But I read cantones ask from 500 to 2000 for the same car (not the stinger .. was another car, but just shows how different it can be), depending on power or displacement etc.

 

[miltonjackson]

Awesome. Thank you for your reply. Exactly what i was looking for. See you on the road