kettlekev wrote: ↑Tue Feb 02, 2021 11:14 pm
I see that 300cc injector at 6.6ms = 0.005cc, but what defines the 0.005cc, how do I know my engine needs 0.005cc to generate the HP I want?
You don't, unless you know the
specific fuel consumption of your specific engine setup with specific fuel, and 101 other factors. Specifically.
Seriously, unless you know how efficient your engine (and all supporting parts) are, you can only judge an estimate, as SFCs vary wildly. You can imagine that a '65 Beetle and a '21 BMW will have very different ability to convert fuel to power, and that less-efficient designs will need more fuel to make the same power. Different fuels and blends extend that difference as well.
That said, I'll link to
Eric Fahlgren's Not2Fast site and its
Turbo Calculator page for some mental exercise and relationship building. While still relatively rudimentary, it provides some very interesting information on efficiencies and how changes alter other numbers, including your question of how much fuel for how much power. So, my suggestion is to model an engine in there that is well known to you. It doesn't have to be turbo.
If not boosted, zero the boost and intercooler pressure drop for a normally-aspirated engine.
Model the engine using the power, rpm, and other numbers you know for that engine. See how efficient it is when you change the numbers to make it fit. Try altering the Volumetric Efficiency and the SFC to initially see how those each effect results in power and fuel injector flow. The instructions and other stuff on his site are scratching the surface, but in a way that shows how one parameter or concept can lead to the next.
kettlekev wrote: ↑Tue Feb 02, 2021 11:14 pmI know there is the required fuel calculator that asks for capacity and AFR etc. but what is the maths behind that?
They are standardized calculations, using your entered info to estimate the values similarly to what you see in Eric's calculator. Eric tells how that info is used, or refers to it.
kettlekev wrote: ↑Tue Feb 02, 2021 11:14 pmWill the calculations dash you referenced give me that?
No, but it will lead you to them.