How much horsepower does a Rotax 670 have

The Rotax 670 is a twin-cylinder, two-stroke engine you'd find in snowmobiles and light off-road vehicles. In standard factory trim, it cranks out about 85 to 95 horsepower. But honestly? The exact number depends on what it's bolted into, how it's tuned, and if anyone's messed with it. This article breaks down horsepower for stock and tweaked versions, where you'll see it, and answers some common questions people actually ask.

What is the stock horsepower of a Rotax 670?

Stock, you're looking at roughly 85 to 95 ponies. It's a liquid-cooled, 670cc twin with rotary valve induction — old school stuff. Most factory tunes, like in Ski-Doo sleds, hit around 90 hp at the crank, peaking somewhere between 7,000 and 7,500 RPM. The torque curve is fat and flat, which makes it a solid workhorse for trail riding or hauling stuff around. Not a screamer, but dependable.

How does horsepower vary by application?

They slapped this engine in a bunch of different toys, and each one got its own flavor of tuning:

• Ski-Doo Snowmobiles (MX Z, Summit, etc.): 88-92 hp. Geared for mid-range grunt and not blowing up.
• Bombardier ATVs (like the DS 650): About 85 hp. They choked it down with a different exhaust and carb setup so it'd chug along at lower RPMs better.
• Light aircraft or experimental stuff: 90-95 hp if you throw on an aftermarket pipe and mess with the ignition.
• Racing or built versions: You can squeeze up to 120 hp, but that takes porting, high-compression heads, and tuned pipes. It gets expensive fast.

How does the Rotax 670 compare to similar engines?

Just to give you a feel for where it sits, here's how it stacks up against other two-strokes from back in the day:

It's right in the middle of the pack — not gutless, not a monster. That balance of power and weight made it a favorite for recreational stuff.

What factors affect the horsepower of a Rotax 670?

Lots of things can bump or kill the power on these things:

• Exhaust system: Stock pipes are restrictive. Aftermarket tuned pipes? You could pick up 5-15 hp.
• Carburetion and intake: Bigger carbs or reed valves let it breathe and drink better.
• Ignition timing: Messing with timing can move the powerband around.
• Compression ratio: Mill the head or use domed pistons to raise it — more power, but you'll need high-octane fuel.
• Porting: Cylinder work can really wake it up up top, but you'll probably lose some low-end grunt.
• Altitude and air density: Higher up, the air's thinner — power drops off. Simple as that.

Is the Rotax 670 a reliable engine?

Yeah, actually, they're pretty tough if you don't neglect them. The crank is beefy, and the cooling system works well enough. Common headaches are carb tuning being finicky and piston rings wearing out after a lot of miles. Keep up with maintenance — check rotary valve timing, use decent two-stroke oil — and they'll go a long time. I've heard of people getting 5,000 to 8,000 miles out of them in snowmobiles before needing a top-end rebuild.

What is the torque output of the Rotax 670?

Torque is around 70-75 lb-ft, peaking at 6,000-6,500 RPM. The curve is nice and flat, so it pulls hard for climbing or acceleration. If you mod it, you might see over 80 lb-ft, but that usually pushes the powerband higher — less grunt down low.

Frequently asked questions about Rotax 670 horsepower