Colossal Reactors Turbine Calculator

2.6: coils over the rod controllers set the steam flow

From Colossal Reactors 2.6 every coil block has a flow value as well as its efficiency. The coil cells right above a rod controller are averaged for flow (air counts 1.0), and flow multiplies the steam the blades take, so the RF too: crying obsidian there takes ×2.8 the steam from the same blades. Gold and netherite have none (×1.0); iron ×1.25, lapis ×1.1, redstone and steel ×1.5, stainless steel ×2. Coil layers past the first add up to +20% more, up to a number of layers set by the casing's height and footprint, and less below 64 blades. In the Turbine Builder that's the Rod-column coil. FTB Evolution 2 replaces the coil list with one that has no flow values, so every coil there is ×1.0 and only the extra coil layers add flow. Checked in game on the 2.6 dev build; the 2.6.0.0.0 release computes it the same way.

flow  = min(avg flow_coe, avg flow_max)
        over the cells above the rod controllers
      × (1 + 0.2 × (1 − 1/layers) × min(1, blades/64))
steam = blades × 150 mB × flow

Fill the whole coil layer

Since Colossal Reactors 2.4.2, coil efficiency is the average over every cell of the coil zone, and an empty cell counts as 30%. One gold block in a 25-cell layer gives 32.8%, not 100%. In game on 2.4.2: one gold block 17,711 RF/t, a full layer of gold 54,000. Any metal block beats an empty cell, so a mixed layer beats gaps, and a full layer of your best metal beats both. Up to 2.4.1 air was skipped and one block did the job of a full layer; the author called that a bug (config 001_legacyIgnoreAirInCoilAverage brings it back). FTB Evolution 2 has every cell counting from pack 1.6.0.

coilEff = Σ eff_coe / coil-zone cells   (air = 0.3)
2.4.1, or legacyIgnoreAirInCoilAverage:
coilEff = Σ eff_coe / coil blocks       (air skipped)

A rod controller on every rod

From Colossal Reactors 2.5 a turbine can have several rod controllers: all in the deck, all facing the same way, each right on top of a rod. If any rod has none, blade efficiency is multiplied by 0.95. The Turbine Builder puts one on every rod it places. Up to 2.4 a turbine had exactly one, in the middle of the deck.

bladeEff × 0.95   if a rod has no
                  rod controller above it

2.4: air counts as coil, so the deck must be solid

Up to 2.4 the controller finds the coil zone by counting layers down from the roof that hold a coil block, and its coil check says yes to air. The count only stops at a layer with no air at all. Leave a gap in the deck around the rod controller and the count runs down into the rotor, and the turbine won't form. From 2.5 it takes the deck from the layer the rod controllers sit in instead, and a gap in the deck no longer matters (checked in game).

2.4: inferCoilLayersFromStructure
       isCoilBlock(air) == true
2.5: coilLayersFromControllerDeck

Blades count, not shafts

Steam capacity is every blade below the deck, and rods can stand anywhere there. The Turbine Builder's Flow pattern (Efficient and Productive up to 2.5) makes one centre shaft, but a grid of rods on every other cell fills half the rotor with blades. On a 9×9 casing that's 140 blades instead of 60. Its HyperFlow pattern builds a rod grid: from 2.6 the same one as this page, full rings included (2.5 stopped each ring a cell short of the next rod: 100 blades).

steam/t = blades × 150 mB   (mod: 1000)
RF/t    = steam × 9 × coil × blade eff
          (mod: 4 RF per mB)

Climbing rings pay 3% a step

For each layer that has more blades on its busiest rod than the layer below, output goes up 3%, until the first layer with fewer; from then on every drop costs 3%. Equal layers do nothing. A single shaft climbing to 14 rings on a 32-wide casing gets +39%.

eff = 1 + 0.03 × steps up − 0.03 × steps down

Blade counts run into each other

A rod's blade count is the unbroken run of blades in each of its four directions. A blade points away from the rod it was put on, and from Colossal Reactors 2.5 a run only counts blades pointing away from the rod, or blades between it and another rod in the same row (both rods count those); another rod's blade sideways in the run ends it. Up to 2.4 every touching blade counted. The total on every rod must be a multiple of 4, or the turbine won't form. That's also why one blade on its own is not enough: they go on in rings of four.

count = Σ 4 sides (blades in a row from the rod)
count % 4 == 0  for every rod

The guides are out of date

The mod's own guide still says 7 RF per mB, and FTB Evolution 2's guide gives 48 mB per blade. Its line that empty coil space counts 30% is right since 2.4.2. The calculator uses what the code and the pack's config do.