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Old 06-10-19, 09:39 AM   #1
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Default SV650X on a dyno

https://www.youtube.com/watch?v=jTm6URsJwKQ


...makes more power in 5th gear than 6th gear.
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Old 06-10-19, 09:59 AM   #2
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Default Re: SV650X on a dyno

That's really interesting, but what got me is the significant difference between 4th and 5th gears. I wonder why
Suzuki mapped the ECU for more power in 5th than 4th? Emissions and noise testing? 3.5bhp difference at 8,000rpm is quite a lot.

The differences between 5th and 6th are 0.5bhp max, which probably falls into the area of experimental error - the dyno guy points out that the shape of the 5th & 6th gear curves are very similar.

The baseline run with the bike as standard matches the results of pretty much every other dyno test I've seen on the Gen 3 bikes: around 71bhp and early 40s ft-lb of torque.
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Old 06-10-19, 10:41 AM   #3
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Default Re: SV650X on a dyno

You need to understand the fundamental principles and experimental error factors involved in testing. Inertia dynos without controlled conditions aren't particularly accurate/reliable/repeatable.
In order to determine engine power for certification/homologation purposes it must be done at steady state for a minimum period of time with all the environmental parameters held essentially constant. That means absorption dynamometers with temperature control for a start. These are expensive/complex, hence the use of inertia dynos by most "shops".
Running in different gears operates the dyno over different speed ranges for a start, never mind any effects within the power unit. Taking results from the dyno using different "road" speeds isn't going to give necessarily particularly comparable results.
How repeatable/accurate is the dyno anyway? It relies on measuring the acceleration of the rollers and calculating the input power based on the inertia and instantaneous speed. The bike is accelerating the wheel as well as the dyno, if the dyno calcs don't take the wheel into account the effect of being in different gears will change the result. The rolling resistance will also change with speed for both the dyno rollers themselves and the tyre/roller contact.
Lots of factors.
Inertia dynos are useful for assessment but +/-3% uncertainty is probably fairly good going, +/-5% wouldn't be unusual.
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Old 06-10-19, 10:41 AM   #4
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Default Re: SV650X on a dyno

In part 4, they fit a 180 section rear tyre which "transforms" the handling. The new SV uses a 5 inch rim which means the standard 160 section tyre doesn't fit that well.

https://www.youtube.com/watch?v=hcYyJVASJVA

In part 5 (not yet posted) the bike will have a new exhaust, power commander and quick shifter and will be back on the dyno.
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Old 06-10-19, 10:56 AM   #5
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Default Re: SV650X on a dyno

Quote:
Originally Posted by embee View Post
You need to understand the fundamental principles and experimental error factors involved in testing. Inertia dynos without controlled conditions aren't particularly accurate/reliable/repeatable.
Completely agree, but it's interesting that there's such a difference between the 4th & 5th gear runs, but only minimal differences between the 5th & 6th gear runs. As the runs were done back-to-back, I'm not sure the differences can be all be explained by the margins for error.
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