# Front splitter

> What does a front splitter do and how big should it be?

- Category: Car design › Car aero
- Kind: Standard part
- Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
- Page: https://xemstudio.com/objects/front-splitter/ · JSON: https://xemstudio.com/api/geometry?object=front-splitter · Plain text: https://xemstudio.com/objects/front-splitter/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files Xem Studio Design License (free to use and sell from, not to redistribute as files: https://xemstudio.com/license/)
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no printing tolerance added.

## 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.

## Sizes

| 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

- High Performance Academy: [Aerodynamic performance devices for club level cars: front splitters](https://www.hpacademy.com/courses/aerodynamics-fundamentals/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)](https://dspace.lib.cranfield.ac.uk/server/api/core/bitstreams/9b476386-44d0-4c0f-a49e-c3372274d351/content) — web — Publisher's page; dimensions are facts

## Free STEP/STL (1 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/front-splitter/index.json · license: https://xemstudio.com/files/hardware/front-splitter/LICENSE.md

- front-splitter-splitter: [STEP](https://xemstudio.com/files/hardware/front-splitter/front-splitter-splitter.step) · [STL](https://xemstudio.com/files/hardware/front-splitter/front-splitter-splitter.stl) — Front splitter 150 × 1800 mm with an up-turned lip at 0° (illustrative where noted)

## 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).

## Fits with

- [Single-element rear wing (race car)](https://xemstudio.com/objects/rear-wing-single-element/)
- [Dual-element (two-element) rear wing](https://xemstudio.com/objects/rear-wing-dual-element/)
- [Swan-neck rear wing mount](https://xemstudio.com/objects/swan-neck-wing-mount/)
- [Gurney flap / wickerbill](https://xemstudio.com/objects/gurney-flap-wickerbill/)
- [Wing endplates / side dams](https://xemstudio.com/objects/wing-endplates/)
- [Splitter tunnels (front diffuser)](https://xemstudio.com/objects/splitter-tunnels-front-diffuser/)