| Author |
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Vagelis46
| | Posted on Tuesday, January 09, 2007 - 05:25 am: | 
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The dyno-run below is from the UK Micron-factory website.
This question goes to Al, or someone else involved in the exhaust shootout at americansportbike.com ................
Are the plots, from the exhaust shootout given from americansportbike.com, showing power and torque at the WHEEL?
or are they calculated crank-shaft values?
I am asking this because the dyno run (shown below) for the XB12S at the Micron-factory website gives less power than the run for Micron from the americansportbike's exhaust shootout.
Can we assume that the difference is because the Micron-factory plot, uses the stockECM, stock-airfilter and stock-airbox ?
Because, americansportbike's dynoruns gives 5-8 Hp more than the Micron-factory dynoruns all through the rev range, both for the stock pipe and the Micron.
My experience with the open airbox says that it does give 5-8Hp throughout the range, but I want to verify it ......
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Jandj_davis
| | Posted on Tuesday, January 09, 2007 - 10:11 am: |
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Vagelis46 - If you read the shootout very carefully, you will see that the Dyno that was used was not optimized. The Dynojet software that was running was not configured for the specific drum weight of the dyno. This made the HP and TQ numbers appear slightly optimistic. Again, this is all outlined in the write-up if you look for it. |
Al_lighton
| | Posted on Tuesday, January 09, 2007 - 10:30 am: |
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What J&J said.
It is always dangerous to utilize absolute numbers from different dynos, different days, different bikes, different operators. You just want to rely on curve shapes.
We'd produced 101 RWHP reliably on a dynojet 250 at sea level with a Micron. This same dyno, same operator, same bike, routinely makes 89-91 RWHP with an XB12 in stock trim, depending on temperature. 89-91 RWHP is a "good" number for a stock XB12, so I consider the 101 RWHP to be a good number for a Micron with an open airbox, breathers routed out, K&N, and an optimized fuel map.
To normalize the shootout runs to a reasonable norm, you can take the XB12 stock peak values, divide them by 90-91 RWHP (the conditions were cold at the shootout, peak power would likely be on the higher side for a stock bike) to get a calibration factor, then multiply that times the values obtained on any other pipe, and that will get you much closer to the actual. But we never put THAT particular XB12 on the Vallejo dyno, so we don't know if THAT XB12 is a 90-91 RWHP stock bike. So this isn't perfect, but it is close.
Al |
Diablobrian
| | Posted on Tuesday, January 09, 2007 - 10:40 am: |
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different dynos give different numbers.
Even the same dyno on different successive runs will give different numbers as the
atmospheric conditions change.
The primary value of a dyno chart is in comparing the shape of the curves (lack of
"holes") and location of peak power within the rev range. That data point is not relative
to outside factors like temperature, the barometer etc.
Direct comparison of different dyno charts from different dynos to compare peak values
is primarily the realm of marketing types and bench racers.
Reading dyno charts is a skill many think they have, but few really understand.
You are now among those few
And yes due to a software upgrade issue the dyno in the shootout was slightly optimistic,
but it was not by a large margin and it did not affect the validity of the runs as far as
relative values. All runs were done on the same dyno with the same variation in output. |
Vagelis46
| | Posted on Tuesday, January 09, 2007 - 11:23 am: |
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Thanks for the info.
I would like to take this subject a bit further. Has any of you seen how close (or far away) the peak RWHP of the following bikes are, at the SAME DYNO :
1.XB12R with Micron + raceECM + KN + open airbox
2.Triumph 675
3.A Jap IL4 (2004 or up e.g. gsxr600)
4.Ducati 749
I am asking this, because I would like to have an idea of how close my XB12R is to these bikes(In theory), after I have done the above mods.
Unfortunately in Greece Dynos are not very common, and not many Buells around. So you guys in the US, have more data and can help me. |
Vagelis46
| | Posted on Tuesday, January 09, 2007 - 11:44 am: |
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Oh and by the way,
Diablobrian, I really hated the Diablo Corsas on my XB12R. In the begining I thought they were Great, but as soon as I got comfortable with them and started pushing, I started loosing the back end at full lean. Like almost highsided a few times. Especially inside the track.
So I switched to Dunlop 208RR, and what a BIG improvement......No more problems at full lean.
Give them a try, next time you change tires and who knows, you might change your name to 208RRbrian..... |
Diablobrian
| | Posted on Tuesday, January 09, 2007 - 03:04 pm: |
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The diablo in my handle is a different kind of diablo.
It refers to my Brother (Diablomichael) and myself as a racing and motorcycle customizing entity.
It has gotten put on a back burner as of late due to other commitments and problems with the race bike.
I do, as a coincidence, run Diablo Corsas on my bike, but that is kind of an offshoot of
having been a Metzler fan since my first ME 33/88 pair on my 86 gixxer years ago. They used to be
"the tire" back in the day. These days their sister company Pirelli is at the track, where I buy
my tires, and I feel very comfortable with the grip and feel of the Corsas.
That does not mean that they are the only tires for a Buell, but they do work very well!
I hope the 208RR is better than the previous generations of Dunlops. Earlier models were
causing nasty problems under braking in corners in particular. The bike would stand up
mid-corner and it caused many of the porr reviews Buell received in the press.
On the good side it looks like we will be back at the race track this season with the black
and orange Mid-America H-D/Buell XB12R (On Michelin race slicks) |
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Micron dyno Run + Exhaust shootout question