How much horsepower will a pod filter add?
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.
Where each one wins
| RPM | pod filter | stock foam filter | diff |
|---|---|---|---|
| 1500 | 2.42 | 2.35 | -0.07 |
| 2000 | 3.33 | 3.23 | -0.10 |
| 2500 | 4.28 | 4.15 | -0.13 |
| 3000 | 5.27 | 5.11 | -0.16 |
| 3500 | 6.33 | 6.14 | -0.19 |
| 4000 | 7.44 | 7.22 | -0.22 |
| 4500 | 8.60 | 8.35 | -0.25 |
| 5000 | 9.81 | 9.52 | -0.29 |
| 5500 | 10.26 | 9.96 | -0.30 |
Horsepower at each rpm. Everything except the part named is identical between the two runs.
The stock foam filter and airbox against an angled pod, with everything else identical and the jet allowed to follow.
It is a real gain and a small one. That is worth saying plainly, because the filter is often the first thing bought and the least it can do on its own.
Watch the main jet figure change with it. More air needs more fuel, and a filter fitted without re-jetting can cost you more than it gives.
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 | Stock cam — Hemi & Non-Hemi factory grind |
| Valve springs | 18 lb Hemi specific (OMB/GPS) |
| Retainers | Stock retainers — OEM (ARC DJ-1040) |
| Valves | Stock valves — OEM |
| 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 | Stock coil — factory (no rev limiter) |
| Carburetor | 22mm clone carb — GPS / OMB Stage kit carb |
| Air filter | Pod / cone filter — GPS / OMB angled filter kit |
| Exhaust | GPS header + screw-on muffler kit |
| Fuel | Pump 87 octane |
The other one
| 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 | Stock cam — Hemi & Non-Hemi factory grind |
| Valve springs | 18 lb Hemi specific (OMB/GPS) |
| Retainers | Stock retainers — OEM (ARC DJ-1040) |
| Valves | Stock valves — OEM |
| 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 | Stock coil — factory (no rev limiter) |
| Carburetor | 22mm clone carb — GPS / OMB Stage kit carb |
| Air filter | Stock foam filter — factory |
| Exhaust | GPS header + screw-on muffler kit |
| Fuel | Pump 87 octane |