How to make 550 hp from a 408 Cleveland stroker
within 1% of peak across that whole range
Engine dyno, as configured — flywheel horsepower. Standard test config: stock manifolds through 18" of pipe, air cleaner lid flipped, no accessories driven. Factory SAE net ratings are measured as‑installed and read 15–25% lower. Rev ceiling for this combination: 6600 rpm.
A 408 is a 351C block with a 4.00" stroke crank, and it changes what the engine is good at. Competition Engines dynoed one in November 2024 with the SuperFlow sheet on screen: 588.5 hp at 6,700 and 536.4 lb-ft at 4,800, on pump gas, on a solid flat tappet, with iron 4V heads that had been "tongued" — port fillers epoxied into the intake runners to shrink the 4V port down to the size the engine can actually use, flowing about 350 cfm at .650". Scott Cook intake, a Pro Systems 780, Tri-Y headers.
Two things in that sheet matter for this page. The torque: 536 lb-ft is a number a 351 cannot make at any rpm, and the 408 made it at 4,800 with a cam that was still pulling at 6,900. That is what the stroke buys — the same peak-horsepower cam now has an extra 80 lb-ft under it. And the heads: the builder shrank the 4V port rather than opening it up, because the big port is a high-rpm race-engine port and a 408 street engine does not live there. The CHI 3V and Trick Flow 225 options on this page are the bolt-on way to get a right-sized port without the epoxy.
The build below is the pump-gas hydraulic-roller version of that engine, which is why it lands at 550 rather than 588. Give it the solid cam and the race port and the calculator will follow the Competition Engines number.
A 408 is the answer to almost every "can a 351 make X" question. Four inches of stroke, modern heads with the bowls blended, and a cam that would be peaky in 351 cubes suddenly pulls from down low.
Displacement is the cheapest torque there is. Compare this curve against the 500 hp non-stroker page — similar peak, completely different engine to drive.
The rods and the crank are where the money goes and where it should. At this output the bottom end is doing real work.
The build
| Block | Ford Performance BOSS 351 — 9.2" deck (~$2,650) |
|---|---|
| Crank | Eagle forged 4340 — 4.00" stroke / 408 ci (~$900) |
| Rods | H-beam 4340 forged (Eagle/Scat/Molnar) — builders' guide ~900 HP |
| Pistons | Auto Tec 1000520 forged 4032 flat 2V — 408 · 1.185" CH · −3cc · ~$718 |
| Head gasket | OEM compressed (.040") — neutral |
| Cylinder heads | CHI 3V 225cc — the modern Cleveland head |
| Porting | Bowl blend / pocket port |
| Camshaft | Howards 240/246 — hyd flat (CL231721-10 · .640"/.649") |
| Valve springs | PAC-1243 dual |
| Rocker arms | Full roller 1.73 — needle bearing |
| Intake manifold | Edelbrock RPM Air-Gap |
| Carburetor | Holley 850 cfm — strip |
| Exhaust | Long tube 1-3/4" — hot street |
| Ignition | MSD Pro Billet distributor + 6AL box — ~8,000 rpm |
| Fuel | Sunoco 260 GT Plus 104 — unleaded, 13% ethanol |
| Air cleaner | Stock air cleaner, LID FLIPPED — DYNO STANDARD |
The Competition Engines 408 that anchors this page was tuned on a SuperFlow before the pulls in the video; their builder said he had not touched a jet, which tells you the carb was built for the engine. That is the tune this page assumes, and it is worth 23 hp here. Source: Competition Engines 408 Cleveland dyno (SuperFlow WinDyn, STP/STD, sheet dated 11/20/2024).
Change these numbers yourself