Dyno talk - are the numbers real?

[jules_1972]

Have a read.

True Rear Wheel Horsepower


Thoughts?

[Drasius]

Dyno numbers mean nothing by themselves, only the shape of the curve matters. When you have done mods they are a useful tool to compare before and after, but everyone can argue till the cows come home about who's dyno is the most accurate and we will never reach agreement. Does it really matter what number is on a bit of paper other than for silly cock waving contests? The track or the strip is where it's really measured anyway.

[g0zer]

get a gps with snail trail function

weigh you and your bike

rap out 1st gear, 2nd gear 3rd gear and so on. you will get a series of acceleration curves at various velocities (which correspond to rpm for a given gear).

from this data you can extract the drag coefficient.

you can also extract the change in kinetic energy per unit time for a given rpm range and power = work/time

[jaywright]

i agree with diasius! stuff the paper, hit the tarmac if ya cant ride and put that hp to work then it means nothing. in saying that does anyone know who a good tuner is. just bought power commander and want to get it tuned properly.

[Ferris]

Dyno numbers mean nothing by themselves, only the shape of the curve matters. When you have done mods they are a useful tool to compare before and after, but everyone can argue till the cows come home about who's dyno is the most accurate and we will never reach agreement. Does it really matter what number is on a bit of paper other than for silly cock waving contests? The track or the strip is where it's really measured anyway.

+1.

A single curve alone is semi meaningless, but worthwhile to use as a comparison tool to later curves after modification of either the fuelling, air or mechanicals.

While you may be able to get repeatable figures with one dyno, there's absolutely no guarantee that you'll get the same figures on a different dyno down the road, at the same altitude and ambient air temp.

[Paraletic]

yes and sortof.
they actually are a very simple machine, theres not much to go wrong.

chassis dyno's are suseptible to innacuraceys

engine dyno's are garry sweet (pretty spot on)

anyway a dyno does not measure horespower they only measure tourque.

hp is calculated.

HP = tourque x rpm / 5252 (if i remember correctly)