The Aprilia RS 660 Makes 95hp on the Akrapovic Dyno

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Ever since 2018 when A&R first caught wind of the Aprilia RS 660, we knew this twin-cylinder sport bike was going to be a class killer.

Up until its introduction, the middleweight twins segment has been full of either outdated legacy machines, or bikes that serve a price point above all else.

There is nothing wrong with that per se, but it left the door open for a brand like Aprilia to come in and mix things up with a cutting edge motorcycle.

That is where we are today with the Aprilia RS 660, with its high-power, high-revving parallel-twin engine, its advanced electronics, and its track-tuned chassis.

Compared to the rest of the class entries, the Aprilia isn’t cheap, but at $11,300 MSRP, it still packs plenty of value for what it offers. And on the racing side of the equation, it promises to be an absolute beast.

That promise is the big caveat though, because we don’t actually know exactly what to expect from the Aprilia RS 660. So far, it’s only been a handful of journalists who have had the chance to ride the RS 660, with even fewer doing so at the track.

Riding a bike in pre-production form too, we have seen some gremlins emerge from the Italian bike – and it remains to be seen if those will be ironed out before the final production version hits dealership floors.

So, we sit and we wait. We pass time until we can see if expectations, inklings, and potentials are met in reality with real world tests and comparisons. We can infer some performance attributes, however, while we pass the time.

Take today’s news from Akrapovic, which has released two exhaust systems for the Aprila RS 660 (one race exhaust, and one street-legal system).

On the Akrapovic dyno, the Aprilia RS 660 makes just a hair over 95hp in stock trim (and 97.4hp with just the addition of a free-flowing pipe). That’s not too shabby, on the face of it – a strong understatement, if there ever was one. See Akrapovic’s results in the table below:

Before we go further, here is where we have to make the obligatory statement about how dyno numbers should be a used for relative comparisons, rather than for their absolute values.

That is to say, the same bike can read vastly different horsepower figures on different dynos…and can even show a fair bit of variability on the same dyno on the same day. It is an imperfect tool that is prone to misinterpretation (and manipulation).

Actually, this caveat can no better be shown that with Akrapovic’s own dyno results, as the Slovenian company is known quite well for its optimistic readings.

Take for instance Akrapovic’s reading for the Yamaha MT-07, another middleweight-twin contender. The Slovenians show the Yamaha at just barely under 70hp on their dyno, while quoted power from Yamaha is 72.4hp (54 kW).

A 2.5hp discrepancy seems good, that is until you realize that one is taken from the wheel, while the other comes from the crank.

At 95hp, this Aprilia RS 660 reads just short of Aprilia’s claimed horsepower figure, which is taken also from the crank. It actually reads higher than that, because Aprilia quotes its power figures in metric horsepower, which is slightly higher than proper mechanical horsepower.

As such, if Akrapovic is to be believed, the RS 660 they dyno’d is just 3.4hp short at the wheel what Aprilia claims at the crank, which is a bit of a mechanical impossibility, unless Aprilia has been sand-bagging power figures.

Apologies for the click-bait headline (I’m going somewhere with this though, I promise), but the chances of other dynamometers in the real world showing a 95hp reading on the Aprilia RS 660 is fairly low.

That is not to say that the Aprilia RS 660 is any less potent than it was hyped, however.

Not too long ago, I was talking to a colleague about what our butt dyno’s were telling us while riding the Aprilia RS 660, and we agreed on a number closer to 85hp at the rear wheel, which seems reasonable if Aprilia’s 100hp crank figure is to be believed.

Contrast that to another conversation I had with a different colleague who was able to spend a little time with the Aprilia RS 660 while other similar bikes were on the track with him, and his opinion was clear that the Italian twin was going to be a formidable opponent, even just in stock trim.

If we come back to my words of warning about how to compare and interpret dyno figures, I will leave you with a little food for thought.

While the Aprilia RS 660 surely doesn’t make 95hp at the rear wheel on what we’ll call “typical” dynamometers, if we compare Akrapovic’s arguably optimistic readings against each other, they do paint an interesting portrait of the Italian sport bike.

With both in stock trim, and read with the same optimistic bias, the Aprilia RS 660 makes 36% more power than Yamaha MT-07 when the bikes were both in the Akrapovic lab. 

I was about to type that this comparison is a more realistic reading of Akrapovic’s numbers, yet it is fairly astounding in its own right, even if you give up some margin for error for a handful of variables that can sway the calibration.

We will reserve final judgment for when there is more third-party data, but the hype about the Aprilia RS 660 being a class killer is very, very real.

Aprilia promised us a bike that made close to 20hp more than its competition, and so far the augurs point to that actuality coming true.

Source: Akrapovic