Why does that other bike make more power than mine?

[xb9fog]

Max numbers are dependent on what that particular complete engine package is ultimately capable of producing, and limited by whatever is the lowest limiting factor - this limiting factor could be exhaust or intake flow limits, combustion pressure, valve timing, lift, duration, tuning, etc.; a multitude of things. No matter how much tuning improvement you do, if something else is the limiting factor you will reach a point and gain no more. Max numbers are not 100% dependent only on the ecm calibration. That's why I NEVER have or will guarantee output numbers - there's too many variables involved. I post dyno graph examples of what I personally experienced on this website, with my bike and a couple of others; it's not meant as a guarantee but as an example. I can tell you the bikes I've used to develop ohiosportbike.com calibrations where broken in with a method that maximizes ring seal.

Here's a very good article from Axtell on ring seal, I remember reading it years ago and finally found it again.
http://www.axtellsales.com/RonsDocs/Ring%20Seal.pdf

I feel that combustion pressure is typically the biggest factor (variable) in explaining why 'identical' engines vary in power output.

[kicka666]

As Dave said there are a number of factors that will affect power outcomes, another big factor would be the dyno readouts will vary greatly from each other. I had my bike dynoed on a Dynojet dyno & on another Dynojet dyno & there was 10BHP difference between each. It all depends how they have been calibrated. My 2 cents.

[Mike]

Plus as Dave hints at...the bike itself.

Everything has tolerances.
The engine and trans. have tons of mating parts that were designed and manufactured to specific plus and minus tolerances.
On average...things will work out as an average. That is, you end up with an engine/trans. that have a nominal average of most all of the tolerances and thus power.
Some will luck out with a set of tols. that will produce a little more power...and some will end up on the short side and end up with just as reliable engine...but slightly down on max. atainable power.

Just a fact of designing, manufacturing, machining, assembling.

Then to a lesser extent, the bikes chassis itself.

Mike