ModelSamplingSD3_motorway_edition

ModelSamplingSD3_motorway_edition is the Motorway-pack version of ComfyUI's ModelSamplingSD3: it applies a single timestep-shift value to a model, reading the model from the MOTORWAY 🚌💨 bus by key instead of over a wire.

The native node is the older, simpler member of the flow-matching shift family. Where ModelSamplingAuraFlow and ModelSamplingFlux give you a shift curve, SD3's just takes one shift number (default 3.0). It exists because SD3 - and the flow-matching models that followed it - concentrate their meaningful denoising in the high-timestep range, so the default uniform spacing wastes steps. Raising the shift concentrates steps where the model actually paints. In practice, most newer workflows have moved to ModelSamplingAuraFlow for finer control, which is exactly why the KB's own verdict on SD3 calls the model the most spectacular failure in the open-source image-gen space - but the shift node named after it still ships and still works on the models that want a plain shift.

What the motorway edition changes

Generated by clone_nodes_in_the_dangerzone/nodes.py, so the interface is: MOTORWAY 🚌💨 in (required), the shift widget (0–100, step 0.01), and two key strings:

• INPUT_model_key (default model) - bus key holding the model to shift.
• OUTPUT_MODEL_key (default MODEL) - bus key the shifted model is written to.

It pulls the model off the bus, applies the shift, writes it back under MODEL, and outputs only the cloned bus. Pull MODEL out with a Motorway 0x1 to feed the sampler. Same behavior as the native node, just bus-native.

Installing

cd ComfyUI/custom_nodes
git clone https://github.com/agilly1989/ComfyUI_agilly1989_motorway

or ComfyUI Manager → "ComfyUI_agilly1989_motorway", then restart. No pip deps, no model downloads.

The fragility you should know about

The whole _motorway_edition family is the pack's riskiest corner, and this one's no exception. The clones are auto-generated at import time over every node ComfyUI has registered - a 2025 report shows an unrelated RandomModelClipVae class missing a CATEGORY attribute crashing the entire Motorway import. The folder is literally named clone_nodes_in_the_dangerzone, and the README admits most-but-not-all clones work.

The 1.1.7 hotfix then disabled the clone loader outright, so on current versions this node likely isn't registered - if it's missing from your menu, that's expected. If you're not committed to a Motorway graph, use the native ModelSamplingSD3 (or ModelSamplingAuraFlow, honestly) and skip the bus-shaped risk.