[Acrova]

Reciprocating engine has 4 cycles. Suck, Squeeze, Bang, Blow.

* Suck - Suck air in. -- turbocharging, AR ratio and its effect, Oxygen control, boost pressure, barro pressure, charge flow, yada yada.

* Squeeze - Compress that air. -- Compression ratio, heat buildup, Start of injection, yada, yada.

* Bang - Fire the cylinder. -- Fuel Air mix, Volatility, Burn Length, Crank Angle, Internal friction, Flame Front, ignition dwell, yada yada

* Blow - Open valves and push out exhaust. -- Exhaust pressures, Turbo AR, Exh. Temps, Heat flow, Manifold flow and temp, exhaust flow and pillow effect, yada yada


-- Then there is the transitional states...

* Transition between suck and squeeze -- Valve closing delay, inrush scavenging, dynamic compression ratio offset, yada yada

* Transition between squeeze and bang -- Compression ratio, fuel air mix, timing advance, yada yada.

* The Bang itself -- When peak cylinder pressure should be achieved (Crang Angle) & how long the fuel should burn (burn length/detonation), controlling internal friction, yada yada

* The transition between bang and blow -- EVO scavenging, exh. gas retension, crank case pressure offsets, piston/cylinder cooling, yada yada


* The transition between blow and suck -- Valve Overlap, Valve delay, exhaust gas scavenging, Inrush shock-wave scavenging, inrush temp deviation, yada yada

-- Then there is external control systems like Intake flow, Turbocharger effeciency and bleedthrough, Charge Air cooling, Exhaust flow control, emission systems like EGR, DPF, DOC, SCR, yada yada

-- Then there is injector design, spray angle, pressures and penetration speed, fuel droplet size, Piston cup design, piston or cylinder volume offset, crank to bore offset, rod angle and friction consideration, yada yada

-- Can't forget about things like the effects having the valve gear-train at the front or rear of the engine. At flywheel end, no offsetting based on tortional load of crank and block, at the opposite end, increased offset and lag per cylinder based on engine load.


-- Then there is the control of those processes by the computer. Diff engine have different control of this.


Properly understanding "Tuning" involves understanding all of the processes i just mentioned in detail and not just part of them. Newer engines have been pushed in design to rely on what is going on between the lines and those transitional states to high precision. Everyone seems focused these days on only  boost, timing, and fueling. That is a very small picture and blind man thinking. - Incorrect control of burn length alone can keep one together or blow it apart, especially if it has high compression, short rods &  no offset bore.

That's a lot to take at ones....
I will love to learn..     no just for tunning but also to be able to properly diagnose.    

Almost any problem in the engine that don't display a code can only be properly repair if all this is understood.

But I gest with the new engines it gets extra complex
....