Dyno Tuning

TLRam1 · November 18, 2009, 04:56:52 PM

Good information BA!!

Do you have the rough ambient temps, humidity when these were ran?

I have many options to choose from on mine, thinking about what direction I need to go.

Greg Cothern · November 18, 2009, 05:06:11 PM

I for one am very interested in the HP #'s etc between the two runs and trying to keep the info as even as possible in its comparision.

BA · November 18, 2009, 05:36:06 PM

Baseline testing showed peak HP of 78.43, torque of 47.4, at 82*F, 29.68in-hg, and 10% humidity
Final jet change showed peak HP of 78.82, torque of 46.4, at 78*F, 29.64in-hg, and 23% humidity with the large gain in the mid-range.

Ambient conditions can make a big difference in the top HP numbers. Accurate comparison should have been done on the same day under similar conditions. At first when I initially went to the 108 jets at 2-3/4 turns on the screws I got 79.29 hp and 47.5 ft-lbs of torque, but it was 72*F, 29.37in-hg, with 15% humidity. When I rode the bike on Saturday it was close to 60* and it ran great (cool dry air will increase both torque and HP). In the dyno shoot-out in October I pulled peak HP of 80.19 with 47.68 torque with my 105 main jets and 2-3/4 turns on the screws, but it was very cool since I was the first across the dyno that morning (actual conditions unknown).

TLRam1 · November 18, 2009, 08:58:39 PM

I also think the low humidity helps you out also, in DFW area I think we're around 50-60 %, give or take, around 500-600 ft above sea level.

I would still like to run mine side-by-side for a comparison, I think my 01 pulls stronger than my 97 or 94 before that.

L J VFR · November 19, 2009, 08:08:47 AM

I think my 01 pulls stronger than my 97 or 94 before that.

Terry, it's just the year model, the 01 was the fastest year you know.....

TLRam1 · November 19, 2009, 08:39:17 AM

Quote from: L J MAGNA on November 19, 2009, 08:08:47 AM
I think my 01 pulls stronger than my 97 or 94 before that.

Terry, it's just the year model, the 01 was the fastest year you know.....

Works for me.

BA · November 19, 2009, 10:57:56 AM

High humidity displaces the amount of oxygen in the air available for combustion, just like low pressure and high temperature does.

lragan · November 19, 2009, 11:26:35 AM

Quote from: BA on November 19, 2009, 10:57:56 AM
High humidity displaces the amount of oxygen in the air available for combustion, just like low pressure and high temperature dies.

This makes perfect sense, BA. Folks think of humid air as "heavy" but it is not -- ask any light airplane pilot. Water has a molecular weight of 18, and oxygen in the air has a weight of 32. Air is mostly Nitrogen, which has a weight of 74, if memory serves me right here. So water vapor not only reduces the available oxygen slightly, it lowers the mass of air through the engine as well -- as you say, just like riding at high altitude or in hot temperature. The pilot's nightmare is "high, hot, and humid". Caused more than one crash due to inadequate power and lift.