Mods: Krastorio 2 1.0.7
Mods: FNEI 0.3.4
Mods: Krastorio 2_extended_endgame

Advanced Chemical Plant + 4 Productive Module 4

16 Beacon + 2 Speed Module 4
15 Singularity Beacon + 2 Speed Module 4

= Crafting Speed 157.2

Build "Plastic Bar"

Input - Coal - 1 Superior Loader
Input - Petrolium Gas - 1 Steel Pump + 1 Steel Undeground Pipe

Must Coal 90 item/sec + Petrolium Gas 1800/sec + 40% = Plastic Bar 252/sec

Result:

Input - Coal = 60 item/sec
Input - Petrolium Gas = 1200/sec
Output = Plastic Bar = 246/sec ( this is bug, becouse must be Coal - 60 + Gas 1200 +40% = Plastic Bar 168/sec)

Liquid is not wasted faster 1200/sec, but result broken

Interesting. I see the same thing without any other mods too. I would've expected it to be limited to 60 ticks/s, i.e. 168 plastic/sec.

With 17 Singularity Beacons the output rises even further.

Of course it should be outputting 157.2 * 2 * 1.4 = 440 plastics/sec. So it's still limited by the 60 ticks/s somehow but the game seems to exceed this but only in the output, not the input. Weird. Free plastics!

This is a well know game limitation discusses until exhaustion:
https://forums.factorio.com/viewtopic.php?t=50773
https://www.reddit.com/r/factorio/comments/4ru58a/speed_modules_cap_through_beacons/

No machine in Factorio can produce more than 60 recipe per second, excess are waisted or not consumed. This is a choosen (by developers) game limitation, some mod workout it with expensive recipes, look on the portal.

Sure, the speed limitation is well known, but I never knew that it can also cause a productivity glitch because the productivity ticks still progress at the full buffed speed, and not the limited 60/s. (Until they themselves tick at 60/s I guess.) So you get free output, or as much as 100% productivity bonus.

Anyway, the speed limitation is not a problem in the base game because it can't be reached, but in Krastorio2 with the singularity beacons and high speed chem plant etc. you can easily reach it for some of the recipes.

I think there was a Krastorio2 addon mod which changed the relevant recipes (plastics, gear wheels etc.) to batch production so the speed limit can't be reached.

Yes the productivity glitch come out from the fact that the calculations of produced products is not completed, and the results are "randoms".

Most of mod reach that limit, because is an exponential property, the base game is near to this limit, many mod try to find a way to fix it, the Schallfake solution is one of the most used by modders:
https://mods.factorio.com/mod/SchallRecipeScaling
Unfortunatelly, Factorio dev don't have leave many tools to modders to solve this problem, still an open and modders probably will never handle seriously, neither Factorio dev.

If u are asking us to implement the Schallfake solution or nerf the K2 items the answer is no.

I mean you did the same thing to iron and copper plates and also with the other high-volume recipes, so why not plastics and gear wheels too?

Because players don't "smelt" material with "hands", instead almost all other recipes are handcrafted. We find "not vanilla" have two kind of recipes, is something for expert players, and because we tried to make the mod more "vanilla style" as possible to make players re-enjoy the first Factorio experience another time, and exist mods that introduce this walkaround (like an option), we don't implement it.

Alright, that makes sense, thanks for the explanation.