If you're digging through forums looking for s&s 585 cam dyno numbers, you probably already know this isn't exactly a "lazy" cam choice for a Twin Cam. It's one of those grinds that sits right on the edge of being a monster, but it requires a bit of a recipe to get it right. You can't just throw these into a stock motor and expect it to scream; you have to understand where that power lives and how to extract it.
When we talk about dyno results for the 585, the conversation usually shifts toward the mid-to-high RPM range. This isn't your typical "stump-puller" cam that hits hard at off-idle speeds. Instead, it's designed for the rider who likes to downshift, twist the wick, and feel the bike pull harder the faster the engine spins.
What the Numbers Usually Look Like
Let's get into the actual math. If you're running a 103-inch Twin Cam—which is arguably the most common platform for this swap—your s&s 585 cam dyno numbers are going to vary wildly based on your compression.
In a relatively stock 103 with just a good 2-into-1 exhaust and a high-flow intake, you might see numbers landing around 95 to 102 horsepower and roughly 100 to 108 lb-ft of torque. Now, that sounds decent, but the "shape" of the dyno graph is what matters. With a stock compression ratio (around 9.7:1), the torque curve might look a little soft until you hit about 3,000 RPM.
However, once you bump that compression up to about 10.5:1, the 585 really starts to sing. With a bit of headwork and increased compression, it's not uncommon to see these cams pushing 110+ horsepower and torque numbers that stay well into the triple digits across the entire upper half of the tachometer.
Why Compression is King for the 585
One thing you'll notice when comparing different s&s 585 cam dyno numbers is that the bikes with higher static compression always have much prettier graphs. Because the 585 has a relatively late intake closing point, it bleeds off some cylinder pressure at low speeds. If your compression is too low, the bike can feel a bit "soggy" when you're pulling away from a stoplight.
It's almost like the cam is waiting for the engine to catch up to it. If you're building a 106 or 107 big bore kit, the 585 becomes a much more versatile beast. The added displacement helps fill in that bottom-end void, while the cam's lift allows the heads to breathe at 5,500 RPM. If you see a dyno sheet where the torque line stays flat as a table from 3,500 to 5,500 RPM, you're looking at a well-tuned 585 setup.
Comparing the 585 to Other S&S Grinds
It helps to look at the 585 in context with its siblings. A lot of guys debate between the 583, the 585, and the 570.
The 583 vs. The 585
The 583 is the "Easy Start" king of low-end grunt. On a dyno, the 583 will show a huge spike in torque right at 2,000 RPM, but it falls off a cliff after 4,500 RPM. If you compare those s&s 585 cam dyno numbers to a 583, the 585 will look "weaker" on paper at the start, but it will absolutely sail past the 583 once you get moving.
The 570 vs. The 585
The 570 is often called the "best all-around" cam, but the 585 is for the guy who wants just a little bit more. The 585 has more lift and longer duration, meaning it can move more air. If you have ported heads, the 570 might start to choke out where the 585 is just getting started.
The Role of the Exhaust System
You can't talk about s&s 585 cam dyno numbers without talking about pipes. This cam is sensitive to backpressure. If you run a set of "drag pipes" or certain true duals with no crossover, you're likely going to see a nasty dip in the torque curve right in the mid-range—exactly where you want to be riding.
Most tuners will tell you that a high-quality 2-into-1 system, like a Bassani Road Rage or a D&D Fat Cat, is practically mandatory to get the most out of this cam. The scavenging effect of a good 2-into-1 helps pull those exhaust gases out and gets the intake charge moving sooner, which helps mitigate that slightly soft bottom end we talked about. On the dyno, a swap from mediocre duals to a proper 2-into-1 can easily add 5-8 lb-ft of torque in the mid-range with the 585.
Riding Characteristics: Beyond the Graph
Numbers are great for bragging rights at the local bike night, but how does it actually feel? The 585 has a very distinct "hit." It's not a violent snap off the line, but rather a progressive surge of power.
When you're cruising at 70 mph in fifth gear and you need to pass a semi-truck, you don't even necessarily need to downshift. But if you do drop it into fourth and pin it, the 585 responds with a mechanical urgency that's really addictive. It makes the bike feel much lighter than a 800-pound touring machine has any right to feel.
Is it too much for a heavy bagger?
This is a common question. If you ride a heavy Ultra Classic and you frequently carry a passenger and luggage, you might find the s&s 585 cam dyno numbers a bit misleading for your needs. If most of your riding happens between 2,000 and 3,000 RPM, you might actually be happier with a cam that peaks earlier.
However, if you ride solo, or if you're the type of rider who isn't afraid to let the motor rev, the 585 is a blast in a bagger. It turns a touring bike into a "hot rod bagger."
Tuning for the Best Results
Getting those peak s&s 585 cam dyno numbers isn't just about the parts; it's about the person behind the laptop. Because of the 585's profile, the timing map needs to be spot on. A generic "canned" map from a handheld tuner will get the bike running, but it won't give you that crisp throttle response this cam is capable of.
A professional dyno tune will focus on smoothing out the transition as the cam "comes on the pipe." A good tuner can work wonders with the ignition timing to help the bike feel more responsive at lower RPMs, effectively masking some of the cam's natural tendencies to favor the high end.
Summary of Expected Gains
If you're looking for a quick reference, here is what a "healthy" build usually produces:
- 103ci Engine (Stock Heads, 9.7:1 Compression): 98 HP / 104 TQ. Power starts at 3,200 RPM.
- 103ci Engine (Ported Heads, 10.5:1 Compression): 112 HP / 110 TQ. Power starts at 2,800 RPM.
- 110ci Engine (CVO heads, 10.2:1 Compression): 115 HP / 118 TQ. Very broad powerband.
At the end of the day, the s&s 585 cam dyno numbers show that this is a "performance" cam in the truest sense. It rewards the rider who wants to go fast and isn't afraid of a little mechanical noise (they are a bit "clicky" due to the high lift). If you've got the budget for a good exhaust and maybe a bit of headwork down the road, the 585 is a choice you aren't going to regret when the light turns green and you've got an open stretch of pavement in front of you.