That is very cool! Turns your engine into a compressor, ha!
Interesting that the inner ring of the gauge is labelled as "KG"...which would be Kilograms per cubic meter. It's just an interesting scale. Same as pressure in Bar, which would be more common these days in Metric countries (except Canada...lol).
1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995