1999 HP numbers vs newer.

[Kat99]

Hello, new to the forum.

When i was doing research it seems the 98-99 katana has higher HP numbers listed even though they bike looks identical up until 2005.

Does anyone know why the difference in HP numbers??ive seen a difference of 6hp from 99 to 2000+ models.

Any help would be appreciated.

[caligonetx]

Suzuki took the hayabusa on its debute and ran 13 of them in a row at a drag strip/track and street. Among them all there was a 10hp difference.

Manufactored vehicles are set to standards and not adjusted to the bike, so there will always be tolerances.

Per HP/dyno numbers it matters if you use a standard or brake dyno, the ambient temperature conditions as well as chain tightness or even air pressure. If the software isnt calibrated properly that's another issue. Dyno-to-dyno will always be off, guaranteed.

This is why if you were really concerned w upgrades, you need to use the same dyno/tech before and after. Again, very little aftermarket components will make a substantial difference to torque unless you do internals or air/density mods.

Three weeks ago I ran my '00 kat 600 on a dyno at Tejas Motorsports; 1kmls on the chain, 2k on the tires and 17.5k on the bike. It's peak was 67hp

[The CyberPoet]

When i was doing research it seems the 98-99 katana has higher HP numbers listed even though they bike looks identical up until 2005.

Whose numbers are you looking at (which sources?)? Are you comparing new-vs-new in some magazine, Suzuki's own published claims, or new-vs-used/used-vs-used using general dyno outputs posted here and elsewhere?

The basis for the numbers did not change at all -- all the 98-06 bikes retained the same carbs (with the same jetting, resulting in the same fueling), the same displacement, same compression ratios and cams, same timing, same gearing, same sprocket ratios and same wheels. There was an exhaust change in the late models, but the actual constriction point (the header-to-midpipe connection) remained the same... Thus, from a technical perspective, any changes in output must be able to be tracked down to something that wasn't consistent across all the years...

So what did change?

Well, as caligonetx noted, there's simple differences in actual production units, where minor differences in clearances and sizes (tenths-of-thousands of an inch differences) across various parts happen to add up differently between different units and result in different outputs. And as he also noted, dynometer outputs are not consistent between different dyno's (even same model/brand in different locations). But even that's probably not the basis for your conclusions...

Aside from that, what else changed?

- The oil standards changed. In 1998, most bikes came from the factory with SF-spec motor oil. That later became SF/SG, then SH, and now the latest bike standard is a special variant of SL that is JASO-MA rated. The differences in the oils themselves may contribute to differences in blow-by at the rings, as well as pumping losses (how much of it's power the engine has to use to move the oil around instead of sending that same power out the transmission to the rear wheel). These changes would still be fairly minor in terms of new-vs-new comparisons (although they may make a big difference in new-vs-used & used-vs-used).

- The fuel standards changed several times. This is probably the basic cause for the differences you're seeing.
In 1998, most areas sold plain, old-fashioned gasoline, with very few areas having boutique fuel-blends mandated by the EPA, especially outside of the winter months. By '01, many areas had MTBE or TANE additives in their fuels to help control pollution, which decreased power on stock bikes by changing the stoichiometric ratio (ideal fuel-air ratio) without Suzuki changing the carbs jetting changing to compensate. By '03 - '04, the number of areas with some form of EPA-mandated additives was very wide-spread, and some areas had started switching out MTBE and TANE for ethanol instead (almost universally ethanol by '09), because although MTBE and TANE are far better for your bike, ethanol is far better for your water-table when spilled and at least in theory, better for the economy as a whole. Ethanol, unfortunately, shoves the stoichiometric ratio off even more, meaning the still-stock-jetting (still unchanged since the days of pure gasoline) will cause the bikes to produce less power.

Thus, even if you had a 1998 Katana still new-in-box, it would produce less power with current fuels than it would have in 1998.

Hope that answers you question.

Cheers
=-= The CyberPoet