Red Shift 557TC vs Feuling 574 Reaper
within 1% of peak across that whole range
Simulated rear‑wheel horsepower and torque — measured after the primary drive, clutch and transmission, the same way a chassis dyno reads a bike. These are not flywheel numbers, and they are not directly comparable to a manufacturer’s crank rating. Rev ceiling for this combination: 5800 rpm, limited by cam.
Where each one wins
| RPM | Red Shift 557 | Feuling 574 Reaper | diff |
|---|---|---|---|
| 2000 | 99 | 88 | -11 |
| 2500 | 108 | 97 | -11 |
| 3000 | 113 | 103 | -11 |
| 3500 | 115 | 105 | -10 |
| 4000 | 114 | 104 | -10 |
| 4500 | 109 | 101 | -8 |
| 5000 | 102 | 95 | -7 |
| 5500 | 93 | 87 | -6 |
| 6000 | 42 | 79 | +37 |
Torque, lb-ft, at the rear wheel. Everything except the part named is identical between the two runs.
Two high-lift grinds aimed at the same buyer, on the same Stage 1 103, with everything else held identical.
More lift is not automatically more power on a Twin Cam. These heads run out of flow before the valve runs out of travel, so past a point the extra lift is buying less than the spec sheet suggests — which is why the two curves are closer than their numbers imply.
Both grinds want a spring kit rated well past stock lift. Check the spring line in the parts list before you order the cam, not after.
The build
| Engine | TC103 (2010 CVO / 2012+) 3.875 × 4.375 |
|---|---|
| Crank / balancer | A motor — non-balanced (Dyna / Touring / CVO) |
| Pistons | OEM cast piston (stock dome) |
| Head gasket | STOCK OEM MLS (.030" compressed) |
| Cylinder heads | STOCK 2006+ (-06 casting) · 1.805/1.575 |
| Porting | As-cast / factory (no additional work) |
| Camshaft | Red Shift 557TC · 242/242 dur · 0.557" lift |
| Valve springs | Stock springs (as fitted to the heads) |
| Rocker arms | Stock rocker arms — 1.625:1 |
| Pushrods | Stock pushrods |
| Lifters | Stock hydraulic lifters |
| Induction | Stock 50mm Delphi EFI (2008+) |
| Exhaust | 2-into-1 stepped (D&D FatCat / E-Series) |
| Air cleaner | Screamin' Eagle / Stage I high-flow |
| Tune | Dyno-tuned (matched to build) |
| Power adder | None (naturally aspirated) |
The other one
| Engine | TC103 (2010 CVO / 2012+) 3.875 × 4.375 |
|---|---|
| Crank / balancer | A motor — non-balanced (Dyna / Touring / CVO) |
| Pistons | OEM cast piston (stock dome) |
| Head gasket | STOCK OEM MLS (.030" compressed) |
| Cylinder heads | STOCK 2006+ (-06 casting) · 1.805/1.575 |
| Porting | As-cast / factory (no additional work) |
| Camshaft | Feuling 574 Reaper · 250/254 dur · 0.574" lift |
| Valve springs | Feuling Endurance beehive — .650" max lift — 1100 ('99-'04, 5/16" stem) / 1105 ('05-'17, 7mm stem) |
| Rocker arms | Stock rocker arms — 1.625:1 |
| Pushrods | Stock pushrods |
| Lifters | Stock hydraulic lifters |
| Induction | Stock 50mm Delphi EFI (2008+) |
| Exhaust | 2-into-1 stepped (D&D FatCat / E-Series) |
| Air cleaner | Screamin' Eagle / Stage I high-flow |
| Tune | Dyno-tuned (matched to build) |
| Power adder | None (naturally aspirated) |