4.6L Stroker Build Overview
AMC 258 crankshaft (3.895" stroke) in a 4.0L block with .030 over pistons. Yields ~4.6L (281ci) and ~245-275 hp / 290-320 lb-ft with cam and head work.
The 4.6 stroker is the canonical XJ engine build. You start with a healthy 4.0L block (87+ for the better main webs), bore .030 over to 3.905", and install a 3.895" stroke AMC 258 crankshaft. Connecting rods are either reconditioned 258 rods (cheap, adequate) or 4340 forged rods (Eagle, Scat — for higher RPM or boost). Pistons are Hesco, KB, or Diamond hypereutectic/forged with the wrist pin moved up to compensate for the longer stroke.
Typical recipe (Hesco / Dino Savva / 'standard 4.6'):
- 4.0L block, decked to zero deck for tight quench
- AMC 258 crank, polished, balanced
- 258 rods, ARP bolts, reconditioned
- Hesco or KB pistons +.030, dished or flat-top depending on target CR (9.0-9.5:1 pump gas)
- Ported 7120 or 0630 head (99+ casting preferred for the larger ports), or aftermarket head (Hesco Stage 2)
- Comp Cams 68-232-4 (the canonical 'XJ 232' grind) or Hesco H-274
- 99+ tube intake, 62mm TB, Borla long-tube, 2.5" or 3" cat-back
- 24 lb/hr injectors (Mopar 5.9 yellows), Walbro 255 LPH pump
- Custom tune via HPTuners or stock PCM with injector slope adjustment
Dyno results vary widely — a clean 4.6 with the above will typically make 245-265 whp and 290-310 lb-ft on a Mustang dyno. Builders chasing the high end with bigger cam and head work see 280+ whp.
Cost: $4000-7000 in parts and machine work for a DIY build, $7000-10000 turnkey from a builder like Hesco or Golen.
Reliability: a properly built stroker outlasts the stock motor. Hesco short blocks have 200k+ examples on the road. Do not skip balancing — the 258 crank in a 4.0 block must be balanced as an assembly.
Why it works
- transformative torque
- reliable when built right
- factory-look install
Trade-offs
- expensive
- long downtime
- tuning required
Tools required
- engine hoist
- stand
- torque wrench
- machine shop access
- ring compressor
- harmonic balancer puller
Parts
| Part | Vendor | Est. price |
|---|---|---|
| Hesco short block 4.6 | Hesco | ~$4200 |
| Comp Cams 68-232-4 cam/lifter kit | Comp Cams | ~$360 |
| Mopar 24 lb/hr injectors | Mopar | ~$240 |
| Walbro 255 fuel pump | Walbro | ~$110 |
Sources
Related
- 4.7L Stroker Build Overview
- Cam Upgrade (Comp Cams 68-232-4 / Hesco H-274)
- All Jeep Cherokee XJ guides & tools
- Browse the full DIY database
Written and maintained by an AZ wheeler and driveway wrencher. How we source guides. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.