With productivity (specifically, legendary productivity 3 modules), advanced pyrolysis is less efficient than basic pyrolysis even if all products are converted to petgas via coal liquefaction and cracking. For 1000 petgas, advanced wood pyrolysis needs 63.1 wood, while basic wood pyrolysis requires only 57.3 wood.

It seems strange that the "advanced" version becomes strictly inferior in the endgame (or even in the midgame, if using biochambers)...

Hm, that might be a bit of an issue. Will look into it. (Note: Deleted a long answer, since I need to think about things some more).

Okay, here are my results so far, on the 2.1 experimental branch: It does in fact seem that higher productivity works in favor of the basic pyrolysis chain, probably because part of the wood input on the advanced one is directly converted into petroleum gas, which receives no further bonuses at that point. I checked my old calculations (using this Factory Solver mod) and found that the advanced pyrolysis chain still normally yields ~25.6% more petroleum gas than the basic one (with significantly fewer machines, and less power consumption and pollution). With tier 3 productivity modules, all numbers change in favor of the basic chain and the difference drops to just ~6.3%. With legendary modules, it drops to negative ~7.5%. However, this all comes with other kinds of cost (more machines, ~28.3% more of the extremely costly modules, ~29.3% higher energy consumption, ~25% more pollution).

I would like to mention that this is an inherent issue with the productivity mechanic: By pulling materials out of thin air at every stage, a discrepancy develops between short and long production chains, and this can become especially noticeable in Space Age and with various other mods. It already exists between advanced oil processing and coal liquefaction, which requires more cracking; but because the first process consumes its own, infinite resource (crude oil, the extraction of which can receive very large speed bonuses), the lower productivity on that chain doesn't matter in practice, as far as I can see.

I am still pondering whether this is something that I want to address, and if so, how (I don't really want to make my mod more complicated). Perhaps I could simply improve the yields on the advanced recipe just enough that the difference becomes zero at max productivity (with Space Age only), even if it doesn't exactly "solve" the underlying problem of different scaling. Maybe I could create a late-game technology that improves productivity on just this one recipe by a bit, although that will mess with ratios downstream, so I am not keen on doing that. Honestly, all the ratios just seem really nice, except when productivity enters the picture...

(It doesn't seem relevant to balance for biochambers, since they are complicated to use, are best used on Gleba and offer their own recipes for various oil products.)

Anyway, do you have any ideas on the matter?

For me, it only came up quite late in the game when running FactoryPlanner calculations for the best way to make rocket fuel in orbit on a platform (growing wood and pyrolysis vs coal synthesis from asteroids), and I was surprised that the "advanced" process came worse off.

In vanilla spage, advanced oil processing is a lot better than the basic variant, and the difference compounds with productivity. You get 45 petgas for 100 oil in basic, while advanced oil processing directly returns 55, in addition to the other product that make the total w/o prod come to 97.5. With legendary Prod3, the totals are 90 vs 291 (or 416 with biochamber cracking, which you can use with biter egg nutrients).

Your advanced pyrolysis is a lot less "advanced" in comparison: you get a lot less coal out, and the difference is compensated by crude oil (good, since it's an "early" ingredient, and makes the processing more interesting) and petgas (last end product of the chain - strong contrast to adv. oil processing/coal liquefaction).
With coal liquefaction, the "advanced" version (or rather the normal one, compared to "simple coal liquefaction") provides more heavy oil than the simple one, in addition to the other output types.

I think the idea to keep the energy content consistent between the recipes is one point you could change, since such a parity doesn't seem to be typical for similar recipe pairs.
Another would be to increase the proportion of crude oil compared to petgas, though I don't know how much you'd need to change it to still be positive at legendary prod3.
My last idea would be to simply change the naming - if instead of basic/advanced tiers, you simply have two different recipe flavors, there's no expectation for one to be generally superior in the first place, and there would be no reason to change the current balancing....

Thank you for your reply! I appreciate your thoughts on the matter.

I wanted my mod to only contain recipes that remain useful, but for different purposes, and energy parity seems important for that. The advanced recipe is normally best for oil production, but when energy is abundant and investment cost no longer matters because the factory must grow (the factory must grow), productivity may eventually turn things on their head by favoring chains that are overall longer. And it's not fun to have to balance for that.

Interestingly enough, when productivity rises, the basis for coal liquefaction in an advanced chain producing plastic eventually disappears and a few furnaces performing basic pyrolysis have to be included instead to provide enough coal. But at roughly the same point, advanced oil processing must be abandoned in favor of coal liquefaction instead, if higher yields are to be gained. I don't like how processes may disappear from the chain, so I would like to see if I can fix that.

Maybe I could somehow increase the complexity of the advanced chain to fix the scaling issue, but I don't want to change the mod that much. I could shift the recipe product ratios away from petroleum gas, but I like them as they are, so we'll have to see. Maybe I could do something terrible and heretical and limit max. productivity on the basic pyrolysis recipe, so that it may improve but never surpass its complement. How do you feel about villainous deeds? Cold blood? Just 10% off the top...

As for naming, you make a good point about the game's use of terms. In my mod, "advanced" is largely meant to indicate a later-game, more refined process that distills a material into multiple products instead of just one, but I can see how it may lead to misunderstanding, when the yields aren't immediately greater and can fall behind later down the line. Perhaps it's better to change their names to "Wood carbonization" and "Wood distillation", but I'll have to think about that.

I'll continue my investigation, but as always, suggestions are welcome. Thanks again for the input.

Just uploaded v1.4.4 to the portal. Long story short, productivity seems impossible to balance for, but to mitigate the problem, I very slightly increased yields on the advanced recipe and also made it work in the biochamber from now on. Assuming the use of an electric boiler for steam, the advanced chain should normally produce ~24.8% more petroleum gas than the basic one, and this increases to a whole ~40.8% with the biochamber. With max productivity, the normal difference falls to minus ~8.6%, but with biochambers, it only falls to ~12.4%. Just some really rough balancing to keep the gap from endlessly widening.

By the way, it makes sense to also compare the footprints. I have found that space savings from the advanced chain allows for more greenhouses to be built, which may actually reduce the difference in yield between factories of the same size – with max productivity and chemical plants – to roughly 0%! So things are not quite as bad as they seem. And the advanced chain is still much cheaper.

I also changed the names as you suggested! I might make more adjustments, but balancing things just seems really difficult. If you happen to have the time, do let me know what you think of the changes so far.

Upcoming balance change! It should be better.

Uploaded v1.4.6! I somewhat gave up on the energy parity and increased the proportion of coal outputted by the advanced... well, the distillation recipe a bit, to close the gap. There are some downsides, though: More coal liquefaction is going to be needed for the production of petroleum gas, the biochamber confers perhaps too large of an advantage to the distillation chain (particularly to solid fuel), and the recipe doesn't reflect real life wood distillation quite as well with its new ratios. More info in the changelog.

Just uploaded v1.5.0 with much better balancing for the endgame! If you want to know about the details, read the changelog (or even the end note in prototypes/recipe.lua within the mod folder). I hope that the changes are to your liking!