# Cosworth DFX, DFR, DFZ and DFL (1976–1991)

- Source: https://racingcarnetwork.com/wiki/cosworth-dfx-dfr/
- Publisher: Racing Car Network (racingcarnetwork.com), the race car marketplace
- Type: part · Brand: Cosworth
- Discipline: parts, historic-racing
- Series: indycar, f1-historic, group-c
- Era: 1980s
- Last updated: 2026-11-06

The DFX, DFL, DFZ and DFR are the main offspring of the Cosworth DFV V8. The turbocharged DFX ruled Indy car racing for a decade, the DFL served Group C, and the 3.5-litre DFZ and DFR closed the line in Formula 1. Owners of period Indy, Group C and late-1980s F1 cars need them to run correctly.

## Specifications

| Spec | Value |
|---|---|
| Type | 90° V8, four valves per cylinder; DFX turbocharged, DFL, DFZ and DFR naturally aspirated [0][1][3] |
| Capacity | DFX 2,643 cc; DFL 3,298 cc or 3,955 cc; DFZ and DFR 3,491–3,494 cc [0][1][3] |
| Bore Stroke | DFX 85.67 x 57.3 mm; DFL 90 x 64.8 mm (3.3) or 90 x 77.7 mm (3.9); DFZ and DFR 90 x 68.6–68.65 mm [0][1][3] |
| Power | DFX about 850 bhp at 25 psi (Cosworth figure, 1978); DFL 490–540 bhp; DFZ 560–590 bhp; DFR 594–630 bhp [1][2][3] |
| Redline | DFX 9,500 rpm in normal use; DFL 9,250–9,500 rpm; DFZ 10,500 rpm; DFR 10,750–11,000 rpm at peak power [1][2][3] |
| Management | DFX: Hilborn mechanical injection on methanol, AiResearch T06 turbo used on the 1978 dyno [1] |
| Lubrication | DFX: oil pressure up to about 110 psi, roughly 20 psi above older DFVs; turbo uses about half a gallon of oil per minute [1] |
| Weight | DFZ 145 kg and DFR 140 kg per Taulbut; Wikipedia lists 155 kg dry for both [3][0] |
| Applications | DFX: Parnelli, Penske, McLaren, Lola, March Indy cars; DFL: Ford C100, Rondeau, Spice, Tiga, Ecosse; DFZ: Tyrrell, AGS, March, Lola; DFR: Benetton B188, later customers [0][2][19] |
| Years | DFX 1976–1987; DFL early 1980s to 1990 in C2; DFZ 1987–1988; DFR 1988–1991 in F1 [0][2][5] |

## History

The DFX started outside Cosworth. In the winter of 1974–75 Parnelli Jones decided to turbocharge a DFV for Indy racing, and his VPJ shop destroked it to 2.65 litres [5]. Al Unser gave it a first win at the Pocono 500 in June 1976 [5]. Cosworth then hired VPJ engine staff and opened a rebuild shop in Torrance, California [5][1].

By 1978 Cosworth quoted about 850 bhp at 9,500 rpm on 25 psi of boost [1]. A new engine cost about £14,600 ex works that year [1]. The DFX won ten straight Indianapolis 500s from 1978 to 1987 [6]. It was beaten in 1987 by the Ilmor V8 and gave way to the short-stroke DFS from 1989 [2][7].

The DFL took the DFV into sports cars. Cosworth widened the bore to 90 mm and built a 3.3-litre version and a long-stroke 3.9-litre version [4][2]. The 3.9 suffered from vibration that Cosworth never cured, and it was out of front-line use by 1985 [0]. The 3.3 found a home in the smaller C2 class, where lower tuning made it last [0].

In F1, the 1987 rules allowed 3.5-litre unblown engines next to turbos [0]. Cosworth answered with the DFZ, a stopgap that won the Jim Clark Cup for Jonathan Palmer and Tyrrell [2][3]. The DFR followed for Benetton in 1988 with about 80% new parts and a crank lowered by one inch [3]. A planned Yamaha five-valve head missed its power target, so the DFR ran with four valves [3]. It never won a Grand Prix, and its last F1 race was the 1991 Australian GP [0].

## Palmarès

The DFX won its first race at Pocono in 1976 and then ten consecutive Indianapolis 500s from 1978 to 1987 [5][6]. It took every CART title from 1979 to 1987 and USAC titles from 1977 to 1979 [0]. It won 81 Indy car races in a row from 1981 to 1986 [0]. Rahal's 1989 Meadowlands win in a DFS was the 153rd and last for the family [7]. The DFL gave Rondeau second in the 1982 world sportscar points and earned five Le Mans class wins from 1985 to 1990 [0]. The DFZ won the 1987 Jim Clark Cup and Colin Chapman Trophy with Tyrrell [3]. The DFR never won a Grand Prix, but Benetton took third in the 1988 constructors' table [0].

## What to check before you buy

Measure the stroke and confirm the capacity: Bore and stroke separate the family: 57.3 mm DFX, 64.8 or 77.7 mm DFL, 68.6 mm DFZ and DFR. Ask for the engine number and the last rebuild and dyno sheets: The family shares many castings, so paperwork and parts numbers prove which derivative you are buying. List exactly what comes with the engine: RCN DFX adverts include turbo and headers, a DFR advert has a harness but no ECU, and a DFS sold without turbo. Ask what rev limit the engine has run to: On DFV-family engines life drops sharply from 10,000 to 11,000 rpm, so rpm history sets the next rebuild date. On a DFR, do not assume DFZ parts fit: About 80% of DFR parts differ from the DFZ, including a lower crank position. On a DFX, ask for leak-down figures and piston inspection notes: Blow-by, exhaust valve heat and piston rocking were known DFX weak points in period. Confirm the target series accepts the engine before paying: Masters Racing Legends takes 3.0-litre F1 cars to 1985 only, and Group C Racing needs an FIA HTP or organiser passport. Ask who rebuilt it last: Known names include Langford & Peck for DFRs since 1989, Geoff Richardson and Race Engine Service of Midland, Texas.

## Did you know

- Taulbut suggests the DFR name may mean 'Re-Born', since the DFZ looked like the last of the line [3].
- Cosworth planned a turbo DFL with twin Lanchester balancer shafts and a projected 700 bhp, but it was cancelled [2].
- The Henry Ford museum holds a DFX donated by Cosworth, Ronald W. Dawes and Bobby Unser [6].

## Frequently asked questions

**How do I tell a DFR from a DFZ?** Capacity will not help, because both are 90 x 68.6 mm and about 3.5 litres. Taulbut records that about 80% of DFR parts differ, and the crankcase was redesigned to sit the crank one inch lower. Ask for parts numbers, the engine number and build records, and compare the crankcase with a known DFZ.

**Is a DFX just a turbo DFV?** It began that way, but it differs inside. The stroke drops to 57.3 mm for 2,643 cc, and it runs methanol through mechanical injection. Cosworth used thicker liners, forged RR58 pistons, a crank with four counterweights and H-section rods. Treat it as its own engine when sourcing parts.

**Can I race a DFR-engined F1 car in Masters Racing Legends?** Not on current published dates. The series covers F1 cars built from 1966 to 1985, with 3.0-litre engines, plus 1977 to 1985 turbo cars from 2026. DFR cars date from 1988. Check event invitations and festivals instead, and ask the organiser before you buy.

**Why does the DFL 3.9 have a bad name?** Its long 77.7 mm stroke brought vibration that period sources describe as incurable. It left front-line racing by 1985. The shorter 3.3-litre DFL proved more usable in C2, where it was tuned for less power. A buyer should ask which version is fitted and how many hours it has run.

**What does a DFX or DFR cost to run?** No published current rebuild price exists for either. In 1978 a DFX was rebuilt every 600 miles. A DFV-family engine at 10,000 rpm lasts about 1,000 miles, and a full DFV refresh was quoted at £12,000 to £15,000 in 2016. Get a written quote from the rebuilder before buying.

## Sources

- Cosworth DFV — https://en.wikipedia.org/wiki/Cosworth_DFV
- The Cosworth Turbo — https://www.motorsportmagazine.com/archive/page/february-1978/28
- Cosworth DFV – Horses for courses (Graham Robson) — https://www.motorsportmagazine.com/archive/article/july-2007/44/cosworth-dfv-horses-courses
- Note 95: Best 3.5L NA engines in 1987 and 1988 — https://www.grandprixengines.co.uk/Note_95.pdf
- Note 88: The Cosworth DFY and F3000 engines — https://www.grandprixengines.co.uk/Note_88.pdf
- The Way It Is No. 533: Indy car racing's Cosworth revolution — https://gordonkirby.com/categories/columns/theway/2016/the_way_it_is_no533.html
- Cosworth DFX V-8 Engine, 1975-1985 — https://www.thehenryford.org/collections/explore/artifact/363646
- Ford Cosworth DFS Indy V8 engine — https://silodrome.com/ford-cosworth-dfs-indy-v8-engine/
- Blown Cosworth DFR F1 engine — https://silodrome.com/blown-cosworth-dfr-f1-engine
- How to be an ace engineer: engine builder Richard Langford — https://www.autosport.com/f1/news/how-to-be-an-ace-engineer-engine-builder-richard-langford/10371553/
- Me an' my DFV — https://primotipo.com/2016/05/12/me-an-my-dfv/
- 1988 EuroBrun Cosworth DFZ F1, ER188-003 (Classic Sale at Silverstone) — https://iconicauctioneers.auctioneersvault.com/catalogues/the-classic-sale-at-silverstone-2022/147/
- Masters Racing Legends — https://www.mastershistoricracing.com/en/race-serie/masters-racing-legends
- Group C Racing Regulations 2018 — https://basethree.s3.eu-west-1.amazonaws.com/1538485403566?pdf
- COSWORTH DFX V8 Engine — https://racingcarnetwork.com/race-car/cosworth-dfx-v8-engine/
- Ford-Cosworth DFX Indy V8 Engine — https://racingcarnetwork.com/race-car/ford-cosworth-dfx-indy-v8-engine/
- Ford DFR Cosworth Formula 1 — https://racingcarnetwork.com/race-car/ford-dfr-cosworth-formula-1/
- Cosworth Ford DFR Formula 1 engine - $85,000 USD — https://www.indycompetition.com/racing-engines-parts/cosworth-ford-dfr-formula-1-engine-%2485%2C000-usd
- Cosworth Ford 3.3 liter DFL engine - $45,000 — https://www.indycompetition.com/racing-engines-parts/cosworth-ford-3.3-liter-dfl-engine-%2445%2C000
- Ecosse efficient racer — https://www.motorsportmagazine.com/archive/article/april-2004/70/ecosse-efficient-racer

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