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Front splitter
What does a front splitter do and how big should it be? · Standard part · basis: Design rules and figures from the cited sources; example geometry by Xem Studio
Also called: splitter, air splitter, front lip splitter, splitter overhang, splitter height, how does a splitter work, splitter downforce, track car splitter, rc touring car splitter, chin spoiler
Exact dimensions. True size, with no printing tolerance added.
- sizes
- 8 in table
Notes
- A splitter is a horizontal plate at the bottom of the front bumper: air stagnates on top while the underside, close to the ground, runs at low pressure, so it produces front downforce very drag-efficiently (HPA).
- Because it works in ground effect it is very ride-height sensitive; HPA suggests a ~70 mm static height and not below ~60 mm on club cars, and a rounded leading edge (at least 10 mm radius, 40 mm preferred).
- Overhang should match the rear wing so the car stays balanced: ~100 mm for a 200-300 hp single-element car up to 200-300 mm for 1000+ hp cars (HPA).
- Used on: Touring and time-attack cars (HPA).
- The file is a reference example built by Xem Studio from the numbers above (150 mm overhang (HPA 500-600 hp tier); width illustrative car width.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.
Front splitter size chart
| parameter | value or range | source |
|---|---|---|
| Overhang, 200-300 hp, single-element wing | up to ~100 mm | HPA splitter |
| Overhang, 500-600 hp, dual-element wing | 150-200 mm front, 100-150 mm side | HPA splitter |
| Overhang, 1000+ hp | 200-300 mm front, ~200 mm side | HPA splitter |
| Static height target | ~70 mm; avoid below 60 mm on club cars | HPA splitter |
| Leading-edge radius | >=10 mm, 40 mm preferred (bottom radius matters most) | HPA splitter |
| Splitter endplates | about 100-150 mm tall | HPA splitter |
| Downforce increment (Katz & Cain) | dCL about -0.10 with dCD < 0.02 | Cranfield / SAE 2018-01-0725 |
| Model splitter sizes tested (35% scale) | 6-41 mm | Cranfield / SAE 2018-01-0725 |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| High Performance Academy | Aerodynamic performance devices for club level cars: front splitters | web | Publisher's page; dimensions are facts |
| Cranfield University / SAE | On the Aerodynamics of an Enclosed-Wheel Racing Car (Soares et al., SAE 2018-01-0725) | web | Publisher's page; dimensions are facts |
Free files
★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json
| front-splitter-splitter | Front splitter 150 × 1800 mm with an up-turned lip at 0° (illustrative where noted) | STEP · STL |
https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.Plain text: sheet.txt · JSON: /api/geometry?object=front-splitter
Fits with
Questions
Why is the leading edge rounded?
The underside is the suction surface; HPA recommends at least a 10 mm radius (40 mm preferred) so flow stays attached.
Can a splitter be too low?
Yes. Low ride height under braking can separate the flow, lose front downforce and cause bouncing (HPA).