Andrews TW21 vs TW26A
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: 5000 rpm, limited by cam.
Where each one wins
| RPM | TW21 | TW26A | diff |
|---|---|---|---|
| 2000 | 96 | 99 | +3 |
| 2500 | 102 | 106 | +3 |
| 3000 | 107 | 111 | +4 |
| 3500 | 110 | 114 | +5 |
| 4000 | 104 | 110 | +6 |
| 4500 | 97 | 103 | +6 |
| 5000 | 89 | 95 | +6 |
Torque, lb-ft, at the rear wheel. Everything except the part named is identical between the two runs.
Both of these are chosen for the same reason — a mild, bolt-in cam for a stock-compression Twin Cam that keeps the bike pleasant below 3,000 rpm.
They do not behave the same. The shorter grind signs off earlier and its rev ceiling comes down with it; the longer one keeps breathing further up and takes the peak with it. The delta table shows exactly which rpm you are trading away to get that.
Pick by where you ride, not by the bigger peak number. On a heavy touring bike ridden in top gear, the earlier grind can be the better cam even though it loses the headline.
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 | Andrews TW21 · 220/228 dur · 0.498" 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 | Andrews TW26A · 226/230 dur · 0.490" 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) |