The second tool I think deserves its own post. It's a spreadsheet that is a helper in figuring out safe boost levels if you have a compressor map. Everything I've seen out there is a bit crude, and though it works, the reason why its crude is because psychrometrics can be hard and most don't have the working knowledge of mathematics or handy calculators to deal with running those calculations.
This sheet has spots for 4 surge-to-top-speed lines of whichever turbos you wish to input. I've left space for a user defined turbo and you can replace the data of any of the existing ones there. I used the open source software
Engauge Digitizer to trace and output CSV data I used from existing turbocharger compressor maps that are out there.
In order for this sheet to work properly, you need to know the volumetric efficiency of your engine. I did my own tests on this
way back when so I didn't have to used a constant, estimated value. Please note that the 5000 RPM value is an interpolated one at this time since I haven't retested., but I digress...
Back psychrometrics. You can define your ambient temperature in °F or °C and altitude in feet or meters as well as relative humidity. The default is via Imperial, but the math is run from the metric output
. You can define two sets of atmospheric parameters and they will be averaged for the final computation.
You can define 15 individual RPM bands to be explored with this sheet. For each of these RPM bands the pounds-per-minute of air mass that *could* flow through the turbocharger is the first output, with the light yellow highlight on all values below the surge line or max speed line. Since a ripe portion of compressor maps are in pounds-per-minute of airflow, this is the mass flow used for this output and for plotting RPM bands vs compressor maps. Next to it will be a the respective MAF output in milligrams per stroke with a few highlights for limitations.
Limitations. In order to know the ingested air, you also need the cylinder geometry and the MAF limits, diagnostically and absolutely. These two are separate and you need to know the size of housing in the MAF. for the 1Z/ALH, the absolute [stock] limit is 460 kg/hour and the [stock] diagnostic limit is 1275 mg/stroke. On the RPM band graphs, you'll see a green highlight for all values up to 95% of this limit and orange for 95%-100%. Additionally, mostly in the higher RPM bands with the higher PRs, you'll get a red strikethrough when the absolute limit is exceeded.
You can change the PR values on the far left of the table cluster to whatever you wish if you want finer resolution.
An example output with a raised MAF diagnostic limit of 1530 mg/str,
click to embiggen:
Turbocharger - Boost & MAF.xlsx