Until someone gets round to successfully altering the necessary Java for damage calculations, here's a viable expedient that effectively makes P-40s less easy to have their engines knocked out. In short, the engine-related hit boxes have been reduced in size, making it about twice as hard to kill the engine.
Get it here:
https://www.mediafire.com/file/l0nxj78pihbjkgn/%25210_WxTech_tougher_P-40_engines.7z/fileFrom the included readme file:
This mod is an expedient to overcome the long-standing 'glass jaw' of the P-40 series, whereby the engine was too easy to knock out even with the smallest calibre gunfire.
This mod builds upon the stock meshes (up to BAT 4), and should work with all game versions. Obviously, the intended user is the off-line player.
If you have any P-40 mod which has improved the nose modeling, but retains the same hit box structure, you can simply copy these hit box data to your preferred Engine1 meshes. Unless, of course, the plane class has had the damage calculations improved upon, in which case this mod is surpassed, superfluous and superseded.

At least for those planes so improved upon.
The planes now altered:
----------------------
Hawk81A-2
P-40B
P-40C
Tomahawk IIa
Tomahawk IIb
P-40E
P-40E-M-105
P-40F
P-40K
P-40L
P-40M
P-40N
The foregoing are all stock in BAT 4.0. Planes not altered are any mod planes having their own assigned slots (don't use the stock plane folders.) It would be easy enough to copy over the whole [CoCommon] section from a plane of the same or similar model.
Here I've merely reduced the sizes of the various hit boxes within the Engine1 meshes. These hit boxes are for:
Case
Cylinders
Prop Governor
Oil cooler
Supercharger
The most critical here are the first two (case and cylinders), which I've given the most pronounced reduction; their volume has been reduced to about 1/4. This reduces the chance of a hit, resulting in roughly double the number of rounds required on average to kill the engine. A lucky or well-aimed burst will still knock out the engine (the prop stops) as easily as before. But in general the chances have been about halved. Which makes the P-40 effectively a tougher bird now.
I did try to edit the hitBone method (for damage calculations) in the P-40 plane class, which would have been the more elegant solution. But for some strange reason my BAT 4.0 Red Core game just refuses to 'see' so many of the plane classes I try to alter, insisting on reading from the SFS archives. Until that hurdle is overcome, this expedient will serve well enough. I sure do enjoy the generally greater volume of fire I have to lob their way. And the better survivability when strapped into one.
Another thing fixed along the way is the air intake 'hump' along the upper surface of the forward cowling for those planes from the E onward which have them. (The K and L do not.) I've somewhat flattened them along with reducing the height, so that they do not protrude so unrealistically as a sharp ridge.
As always, this work is offered for the use by any and all, for any purpose, without restriction.
WxTech
May 24, 2021