Dyno correction factor

[Ragman]

Can anyone explain to me the difference the 'correction factor' has on the dyno sheet read out.
EG, have two different sheets here, one with a c/f of 1.37 SAE and one with .78 SAE
Supposing both sheets read 84 KW, are they in fact the same ??

[tweak'e]

i don't know what the factor means at all. i know they correct the fiqures for things like air temp, himidity etc outside variables. would love to know exactly what is corrected.

there is also operator correction factor. ie tweak it a bit to make the fiqures look good.

dyno's can lie.

[jet-6]

Its real easy to cheat a dyno, just lay the intake temp sensor on your exhaust manifold and watch the power tripple

[Mulisha]

Its real easy to cheat a dyno, just lay the intake temp sensor on your exhaust manifold and watch the power tripple

Yeah i have heard of that!

I once saw something like 750rwhp supra posted somewere on a site and it's intake temp was 290 degrees or some silly shit and he was getting flammed from every angle..

Rick.

[PGS 4WD]

There are different standards for correction, these are the SAE standards, they are tolerances if you like. The dyno I use has the option to select any of the current standards, SAE- J1349, JIS-D1001, ISO- 1585, DIN-70020 and EEC-80/1269.
Speaking generally as I don't have specific data on hand but the atmospheric calculations are based on how the air density is effected by humidity, barometric pressure and temperature, as these vary so does the quantity of air (oxygen/nitrogen and other components) that enters the engine. For example correction of 1.00 may be 50% humidity at baro pressure 1000 at air temp 15 degrees celcius. If the air temp is higher and the barometric pressure lower for example the correction factor may be 1.02, most accurate dynos will accept a maximum variation of +/- 4 to 6% from 1.00. The software should make it so that atmospheric variation from day to day is calculated out and the result shown is the same.
Unfortunatly not all dynos are the same, I previously worked with a dyno dynamics dyno where the front and rear rollers were not connected, as a powerful car climbs off the back roller it no longer consumes power driving the roller and the resultant power shown on the graph is higher, some people dont tie the vehicles on these dynos very tight to show higher figures.
Some dynos have user defineable correction factors and editing software, falsely raising the air temp or weighting the load cell are some ways that people trick dynos. Entering unusually high humidity or low baro pressure also. Check the correction on any of your dyno printouts if you actually want the truth, but with some operators there is no guarantee you are getting the result that is shown.

Joel

[Ragman]

Thanks guy's, thats answered all my questions.

[Dzltec]

Ragman,

heres a link that might explain it better than I can. http://www.ls1.com.au/forum/showthread.php?t=58222

This is also the dyno we use. We also have an air temp sensor on ours as well as an inbuilt weather station. You can put the air temp sensor anywhere and it will not effect the output of the dyno, its there to measure temperature only.


Hope this helps.

Andy