351 Windsor
Ford's 5.8-liter small-block V8, the big brother of the 289/302 Windsor family with more displacement, more torque, and more "why is my gas gauge moving so fast?" The power upgrade for Mustangs that need serious grunt.
What '351 Windsor' Actually Means
The 351 Windsor (351W) is Ford's largest displacement Windsor-family engine, producing 351 cubic inches (5.8 liters) through a larger bore and stroke than the 302.
Key specs:
- Displacement: 351 cubic inches (5.8L)
- Bore × Stroke: 4.00" × 3.50"
- Years in Mustangs: 1969–1973 (factory), swapped into many others
- Typical output: 250–290 hp factory, 350–450+ hp with modifications
- Also called: "351W," "5.8L," "Windsor 351"
Why it matters:
The 351W shares the Windsor block family architecture with the 289 and 302, but with a taller deck height (block is physically taller). This means:
- Same bolt pattern for bellhousing (fits Mustang transmissions)
- Same motor mount locations (with adapter plates)
- Different heads (larger ports, more flow potential)
- Stronger block (thicker walls, more main webbing)
351W vs 351C (Cleveland):
Ford made TWO different 351 engines—Windsor and Cleveland. They share nothing except displacement. The 351 Windsor has:
- Smaller valves but better low-end torque
- Taller, narrower engine (fits better in tight spaces)
- Windsor family parts compatibility
- More forgiving for street use
The 351 Cleveland has huge ports and valves for top-end power but gives up low-end torque. For Mustang street use, the Windsor is usually the better choice.
I drove a friend's 1970 Mach 1 with the factory 351W. Coming from my 289, the difference was immediate and wonderful. Where my 289 needed revs to make power, his 351W just pulled from any RPM. Also: his car got 12 MPG. Mine gets 18. There's no free lunch with displacement.
Why It Matters for Your Mustang
The 351W is the "serious power" upgrade for Mustangs:
For 1969–1973 Mustangs:
- Factory engine option (check your data plate)
- If you have one, rebuilding maintains originality
- If you don't, swapping one in is well-documented
For 1965–1968 Mustangs:
- Popular engine swap for more power
- Requires minor modifications (see below)
- Huge torque increase over 289/302
- Changes the car's character significantly
Power comparison (approximate):
- 289: 200–225 hp, 280–305 lb-ft torque
- 302: 210–250 hp, 295–320 lb-ft torque
- 351W: 250–330 hp, 380–450 lb-ft torque
That torque difference is what you feel on the street. The 351W pulls harder from low RPM, making it perfect for LA traffic and freeway merges.
351W vs Other Engines:
| **Engine** | **Power** | **Torque** | **Swap Difficulty** | **Fuel Economy** |
|---|---|---|---|---|
| 289 | 200–225 hp | 280–305 lb-ft | Factory (baseline) | 16–20 mpg |
| 302 | 210–250 hp | 295–320 lb-ft | Easy (same mounts) | 15–18 mpg |
| 351W | 250–330 hp | 380–450 lb-ft | Moderate (needs mounts/headers) | 12–15 mpg |
| 351C | 260–330 hp | 380–450 lb-ft | Difficult (different everything) | 11–14 mpg |
The 351W is the "goldilocks" big block—more power than you need, but not so much that the chassis can't handle it.
Cost Impact
| Repair Type | Typical Cost (LA) | Labor Hours |
|---|---|---|
| Basic 351W rebuild | $4,500–$7,500 | 35–60 hours + machine shop |
| Performance rebuild | $7,500–$13,000 | 50–75 hours + machine shop |
| Crate 351W (350–380 hp) | $5,500–$8,500 | Engine only, ready to install |
| Crate 351W (400–450 hp) | $8,500–$14,000 | Performance build, dyno tested |
| Swap labor (289/302 to 351W) | $2,000–$4,500 | 20–40 hours (includes mounts, headers, etc.) |
*LA labor rates: $110–$165/hour. Machine shop costs (rebuild): Bore & hone ($250–$450), Crank grinding ($200–$400), Valve job ($250–$500 per head, larger heads), Balancing ($250–$450), Hot tank ($120–$250). Parts cost more too: Pistons ($400–$800 vs $250–$500 for 302), Heads ($800–$2,000 rebuilt vs $500–$1,200 for 302), Intake ($300–$800 vs $200–$500 for 302). The 351W costs about 25–40% more to build than a 302, but delivers 40–50% more torque.
Ask me how I know these numbers.
Common Issues
Overheating
Larger engine = more heat, stock radiators struggle
Oil Consumption
High-mileage engines burn oil through worn rings/guides
Fuel Consumption
Expect 12–15 mpg in mixed driving
Timing Chain Wear
Stock chains stretch over time
Header Fitment
Tight fit in early Mustang engine bays
See This in Action
- Mustang Engine Swap Cost Guide
Detailed 351W swap costs, timelines, and what shops need from you
Want to Learn More?
Download the Mustang Restoration Starter Kit (LA Edition) for:
- Complete terminology reference guide
- Cost estimation worksheets
- Pre-purchase inspection checklist
- Shop interview questions
- Project timeline planning tools
No upsells. No bait-and-switch. Just the information Dorian wishes he'd had before he bought his first project car.