What a Twin Cam Actually Makes: The Dyno Sheets from 88 to 117

Harley never published a horsepower number for the Twin Cam, only torque, and the forum numbers that filled the gap are mostly crank-horsepower guesses on rear-wheel bikes. Every number below came off a chassis dyno with the sheet on screen. They are rear-wheel — after the primary, clutch, gearbox, and belt — which is how every published Harley number is taken and how this site's simulator reports. Two cautions: Dynojet sheets read either SAE or STD (STD is a few percent higher on the same pull), and these are different bikes on different days. Each one is labeled.

Stock Twin Cam 88: 56 hp

2002 Electra Glide Ultra, TC88, all stock. Dynojet, correction not stated. 56.31 hp / 71.51 lb-ft. (Cycle Solutions.)

A bagger-weight 88 at the tire. The simulator's stock 88 reads 57.0 / 69.8 — within a horsepower. This is the floor of the ladder, and it is the reason a Stage 1 on an 88 feels like a bigger change than it is: there is not much there to start with.

Stock Twin Cam 103: 71 hp

2014 Softail Deluxe, 103, stock. Dynojet. 70.9 hp, peaking around 5,250 against a 5,500 limiter. (Cycle World.)

Fifteen more horsepower than the 88 from fifteen more cubic inches and a decade of factory development. The simulator's stock 103 lands within a horsepower of this, and it is the baseline the whole 103 ladder is built from. The stock 103 page runs it.

103 Stage 1: 74.6 hp / 92.6 lb-ft

103, Screamin' Eagle Ventilator Elite air cleaner, Vance & Hines Big Radius 2-into-1, tune. Dynojet, SAE. 74.55 hp / 92.60 lb-ft, best of five. (Kane's Harley-Davidson.)

Fuel Moto's published 103 Stage 1 baseline — the one this site's cam table is checked against — is 79.69 hp on their dyno with their pipe and map. The two sheets bracket what Stage 1 on a 103 actually is: mid-70s to about 80 at the tire, depending on the pipe and whether the map was custom. The Stage 1 and Stage 2 guide covers where each horsepower comes from.

103 Stage 2, same bike: 78.3 hp / 100.7 lb-ft

Same Softail, S&S 583 cams and a Heavy Breather added to the Stage 1 above. Dynojet, SAE. 78.29 hp / 100.67 lb-ft, best of five. Same shop, same pipe.

+3.7 hp and +8 lb-ft for a bolt-in torque cam. Read that carefully before you buy a cam by its horsepower number: the 583 is a torque grind, it runs on stock springs, and eight lb-ft in the midrange is what you feel on a Softail. The cam guide explains why a bigger cam is not automatically a better one here.

117 Screamin' Eagle Stage IV: 111 hp / 118 lb-ft

2017 Dyna Low Rider S, SE Stage IV 117 kit (CNC heads, cam, pistons, intake), SE Race Tuner, aftermarket 2-into-1. Dynojet 250i, SAE, January 2019. 111.28 hp @ 5,490 / 117.93 lb-ft @ 4,180. (Laidlaw's Harley-Davidson.)

The top of the factory catalog on a bike. This is a heads-and-pistons kit, not a bolt-on; it is the number the big-bore ladder ends at, and it is SAE, so a STD sheet of the same bike would read a few percent higher.

Reading the ladder

• 56 stock 88. 65–71 stock 96 and 103.
• 75–80 is a 103 at Stage 1 — pipe, air cleaner, and a map. Anyone can get here.
• 78 hp and 100 lb-ft is the same bike with a bolt-in torque cam. The torque is the point.
• 90–105 is a 103 with a real cam, springs, and compression, or a 107 big bore — the middle of the ladder, where this site's cam pages live and where the anchor set is thinnest.
• 111 (SAE) is a 117 Stage IV with heads.

Build your bike in the calculator as it sits and step it through this ladder. The gaps in the set — a 96, a cam-only swap on a stock 103, anything between Stage 2 and Stage IV — are real gaps, and a sheet from your own bike with the parts list is how they get filled. That is what the contact page is for.

Sources: Cycle Solutions — 2002 FLH Ultra Twin Cam 88, stock (hiXksPbD_MY, Dynojet, correction not stated). Cycle World — 2014 Softail Deluxe 103, stock (Dynojet). Kane's Harley-Davidson — 103 Stage 1 → Stage 2 (Tf8IG7IUbTE, Dynojet, SAE). Fuel Moto — 103 cam shootout, Stage 1 baseline. Laidlaw's Harley-Davidson — 117 SE Stage IV (xDBV0QvQ5Ys, Dynojet 250i, SAE).

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