Injection Timing/Flow/duration discussion

[soutthpaw]

I was thinking this weekend and have some questions that should lead to quite an interesting and lengthy thread. My main goal is to get a better understanding of the injection theory applied specifically to the 7.3's. I don't expect Bill or anyone else to cover all the questions in one reply either... Maybe taking one point at a time as we can work through it.
My question is basically this. we know that we can regulate several factors of the compression stroke on the diesel: which I will list below.. add other factors if I miss any. How do changes of each of the parameters affect the HP, torque, and MPG performances of the engine.

• Injection Timing= when during the exhaust/compression stroke do we start putting fuel in the cylinder
• Injection duration= how long do we keep putting fuel in the cylinder during the compression stroke
• Volume= the total amount of fuel we put into the engine controlled by Pressure applied to the injector as well as the duration
• Airflow= How much air and at what pressure we put into the engine... I really wanted to leave this out to focus on the Injection (fuel) side of the equation but just in case its needed for discussion I added it.

Questions

• What effect does each parameter above have from a tuning perspective? Why would changing one over another parameter be advantagous and in what ways.. IE: one paramater works better for towing another for performance and another for MPG
• How changing other non-tune parameters such as Injectors, HPOP etc. can alter the above factors and to what extent.
• Can u add larger injectors and still get and equally good MPG's (say with a Fuel Sipper base tune): I am thinking yes as the injection duration could be shortened to make up for higher flow due to larger volume
• What are the Factory settings for these parameters
• Does any fuel get injected during the combustion stroke or only during compression..