# Cosworth YB engine

- Source: https://racingcarnetwork.com/wiki/cosworth-yb/
- Publisher: Racing Car Network (racingcarnetwork.com), the race car marketplace
- Type: engine · Brand: Cosworth
- Discipline: parts
- Era: 1980s
- Last updated: 2026-07-06
- For sale on RCN: https://racingcarnetwork.com/for-sale/cosworth-yb/ (8 live listings right now)

The Cosworth YB is the turbo four that terrorised the late 80s: the Sierra and Escort Cosworth's 2-litre — 500+ hp in RS500 touring-car trim, Group A rally legend — and still the beating heart of a huge fast-Ford competition scene.

## Specifications

| Spec | Value |
|---|---|
| Type | 2.0 L turbocharged 16v inline-4 |
| Power | 204 hp road / 300–550+ hp competition |
| Variants | YBB, YBD (RS500), YBT/YBP (4x4 rally) |
| Application | Sierra/RS500 touring, Escort Cosworth rally |
| Block | 200/205 casting hierarchy (build lore) |
| Servicing | UK/EU YB specialist network |
| Years | 1986–present (competition use ongoing) |
| Class | Group A touring/rally, historic fast-Ford |

## History

Cosworth's YB (1986) turned Ford's humble Pinto block architecture into a weapon: 16-valve head, Garrett turbocharging and enough development headroom that the RS500 evolution's race engines exceeded 500 hp in period touring-car trim — the powerplant behind the Sierra RS500's era of circuit domination and, in YBT/YBP forms, the Sierra and Escort Cosworth 4x4 rally programmes into the mid-90s WRC.

Its competition record spans both disciplines completely: touring-car championships across Europe, Australia and Asia in the RS500 years; Group A and early World Rally Car-era results with the Escort Cosworth; then decades of national rallying, rallycross and drag-strip careers as the fast-Ford scene made the YB its default answer to every power question.

That scene sustains the engine today: specialist builders across the UK and Europe hold the knowledge (block selection — the 200 and 205 castings lore — head work, turbo matching), parts remain manufacturable, and YB-powered Escorts and Sierras anchor historic rally grids. Values track the fast-Ford boom: documented big-power builds now price like the serious motorsport hardware they always were.

## Palmarès

Touring-car titles worldwide in the Sierra RS500 era (European, national and Bathurst-legend campaigns); Group A and WRC-era rally results with the Sierra and Escort Cosworth 4x4; thirty subsequent years of national rally, rallycross and sprint careers — the fast-Ford record entire.

## What to check before you buy

Block and paper first: casting identity (the 200/205-block hierarchy matters for big-power builds), bore history and whether the bottom end matches the claimed spec — YB folklore is thick and invoices cut through it. Verify head and turbo spec against the stated power, fuelling/management provenance, and hours since the last build by a named YB specialist (the community knows every reputable one). Rally-spec YBT/YBP units with homologation-correct details carry historic-eligibility value beyond raw power. The market is mature and liquid; the premium for documentation is the cheapest insurance in it.

## Did you know

- RS500 race YBs made over 500 hp in period — from two litres, in the 1980s, reliably enough to win championships on Sunday and drive home folklore forever.
- Cosworth block castings have their own collector market: the '205' block's reputation means bare blocks trade like relics among fast-Ford builders.
- The YB's architecture traces to Ford's Pinto — the school-run four-cylinder that Cosworth's head turned into a touring-car tyrant.

## Related entries

- Millington Diamond engine — https://racingcarnetwork.com/wiki/millington-diamond-engine/
- Ford Escort Mk2 RS1800 — https://racingcarnetwork.com/wiki/ford-escort-mk2-rs1800/
- Quaife QBE69G (69G) gearbox — https://racingcarnetwork.com/wiki/quaife-qbe69g-gearbox/
- Subaru Impreza WRX STI (clubman rally) — https://racingcarnetwork.com/wiki/subaru-impreza-wrx-sti-rally/