At both the unveiling and riding introduction of Triumph’s new Street Twin, the manufacturer noted that the new 900cc engine made more torque – and at lower rpm – than the previous 865cc mill. At the riding introduction, Triumph expanded its claim to include the Street Twin producing less peak horsepower than the previous, smaller engine. So, imagine our surprise when we actually get our sweaty mitts on a production model Street Twin and dash it over to our local dyno shop – and learn that the new engine makes both more torque and horsepower than the most recent dyno run we have of the old 865cc engine.
Well, isn’t that quite the pickle we’ve gotten ourselves into. What was supposed to be a quick, “Hey, look at the numbers the new Bonneville Hi-Torque 900 engine puts out,” turned into a bit of a mystery. Well, after a cup of coffee, it turned out to not really be much of a mystery after all.
We’d chosen to compare the Street Twin’s numbers to the 2015 Bonneville Scrambler (from the Scrambler Slam: Ducati Vs Triumph shootout) because both the new 900cc engine and the old 865cc Scrambler version had 270° crankshaft. We made this choice because, we wanted an apples-to-apples comparison and because typically, 270° Twins tend to make slightly less power than 360° Twins. So, we didn’t want to be accused of setting the Street Twin up for failure.
However, once we took a glance at the shape of the dyno graph put out by the 2013 Thruxton, we knew that Triumph had been referencing its 360° crank-powered engines in the Street Twin graphs in their press kit. So, we ended up learning that the performance figures in the press kit were pretty dang honest – weighing in at less than the expected 10% difference between crank torque and horsepower (as typically published by the manufacturers) and rear-wheel power/torque that publications use. Where the truth may have been stretched a bit was in the claim of an 18% increase of peak torque for the Street Twin. The current 57.8 lb-ft of the 900 versus the 53.2 lb-ft of the 865 Thruxton yields about a 9% bump. (The usual caveats of these figures being from different dynos on different days do apply.)
Regardless of how we want to split hairs, the Street Twin maintains a torque advantage over the Thruxton below 5,000 rpm – right where most urban scoots spend their time. A quick, unofficial butt-dyno test ride confirms that the Street Twin does feel quicker around town than the previous generation Bonnies. More of that impression awaits in an upcoming shootout with a gathering of other urban-focused Twins in the near future.