How to build a 15 hp Predator 212
Engine output on a stand — there is no drivetrain and no chassis in these numbers, which is the same basis Harbor Freight rates the engine on. Simulated at 800 ft and 75°F; thinner air makes less power and wants less fuel, so both the horsepower and the jet move with them. Governor removed. Compression 9.06:1.
The top of the naturally aspirated ladder on stock displacement. A TSB cam, 40 lb springs, billet everything and a rev range that would have been unthinkable on this engine as delivered.
Be clear about what this is. It is a race engine now — it wants maintenance, it wants a clutch that can live at these rpm, and the margin for a mistake in assembly or jetting has gone.
The 400 TSB is Hemi and Ghost only. If you have a non-Hemi head this is not your build, and the calculator will tell you so if you try it.
The build
| Engine | Predator 212 Hemi (Gen 2) — 27/25mm valves · 5.5mm stems |
|---|---|
| Governor | Governor removed (full rev range) |
| Piston | Stock flat top — Hemi OEM (ARC DJ-1285PH · .550" CH) |
| Head | Stock Hemi head — as-cast factory |
| Head gasket | Stock HEMI — fiber .045" (ARC DJ-1310TP) |
| Camshaft | DynoCams 400 TSB — .3997" · 267.1/272.4 @.050 · ⚠ HEMI / Ghost / 196 clone only, not Non-Hemi |
| Valve springs | 40 lb dual springs race head |
| Retainers | Billet w/ keepers, 36 lb — ARC DJ-1046 ($11.00) |
| Valves | Stainless kit, Hemi 27/25mm — GPS KDVALKIT27-25 · ARC DJ-SSVALVE HKT |
| Rocker arms | Stock rocker arm — 1:1 ratio |
| Connecting rod | ARC 6256 Billet — Hemi (+.020" raises CR) |
| Flywheel | ARC 6696 Billet — Hemi Speedway (32° BTDC) |
| Ignition coil | ARC rev limiter coil — 9,000 rpm |
| Carburetor | Nibbi PWK24 — 24mm flat slide |
| Air filter | Pod / cone filter — GPS / OMB angled filter kit |
| Exhaust | DynoCams race exhaust pipe |
| Fuel | Pump 87 octane |