It's in (your games folder)\steam\steamapps\common\il-2 sturmovik cliffs of dover\manual, there are separate PDF files for each supported language.
The engine handling section starts with the Spit on page 83, the 109 is on page 89.
Also, keep in mind that not all aircraft are mentioned but you can use the values for the Stuka and Ju-88 in the He-111P as it has the same engine type. The 110 and Ju88 also have clearly marked limits on the instruments for both RPM and manifold pressure.
The 110 is running slightly lower values than the 109, the markings on the instruments are
d for maximum continuous settings
30 for the 30 minute climb/combat limit and
1 for the 1 minute emergency power setting.
The Ju88 instruments use a green mark for the continuous setting, a yellow one for climb power and a red one for emergency/never exceed settings.
Finally, the Spit and Hurri use the same values as they both run merlin engines, the boost setting for level flight (which is a safe bet to assume it's continuous) is clearly marked by a red arc with a white triangle in the middle on the instrument face but the RPM gauge doesn't show any (keep it at 2650 RPM for continuous power, 2800 for a bit extra, the never exceed value is 3000 RPM).
The ones that are completely missing and can't be inferred from another type are the Blenheim, Br.20 and Fiat G.50.
Hope it gets you started, cheers
