dyno guru's

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Feb 13, 2007 | 06:17 PM

dawg

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From: Vermont

dyno guru's

I know humidity can affect dyno runs, but what about cold weather? Obviously the dyno is inside a shop. Is it better to trailer a bike to a dyno or ride it?

Feb 13, 2007 | 06:18 PM

Bryan TTM

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RE: dyno guru's

cold is good

Feb 13, 2007 | 06:44 PM

Biggzed

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RE: dyno guru's

Quote:

ORIGINAL: dawg

I know humidity can affect dyno runs, but what about cold weather? Obviously the dyno is inside a shop. Is it better to trailer a bike to a dyno or ride it?

Tough to say. Depends on the state of tune prior to the dyno sesssion and how far you have to ride to get to the tuner. If it is running extremely lean, you have a long way to go, you could do damage. Chances are it will be ok though.

Feb 13, 2007 | 07:10 PM

bountyhunter

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RE: dyno guru's

Why take the chance?

Feb 13, 2007 | 07:42 PM

dawg

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From: Vermont

RE: dyno guru's

Yeah, I can borrow a buds trailer so I'll probably just trailer it there. It makes sense. The map that Jaime provided seems to be good, no pops or anything, but I have no experience with PCIII up until now.

Feb 13, 2007 | 07:44 PM

geargrinder

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From: Omaha Nebraska

RE: dyno guru's

Quote:

ORIGINAL: dawg

I know humidity can affect dyno runs, but what about cold weather? Obviously the dyno is inside a shop. Is it better to trailer a bike to a dyno or ride it?

If you aredynoing for strictly HP/TQ numbers, if the dyno is properly operated, the operatorwill be using SAE correction which compensates for elevation, barometric pressure, humidity andtemperature. The dyno sheet will state "SAE" somewhere and using this correction factorassures thatthe numbers can be comparedfrom test to testno matter what theatmospheric conditions are. This is like zeroing a scale before measuring weight.Today the most widely used SAE correction factor is the SAE J1349that corrects to as ifit were 77 deg F, 29.235 barometric pressure and 0% humidity.

Ifthe less commonword"Standard" is stated on the dyno sheet with the numbers,the oldSAE J607correction was used thatprovidesapprox 4% higher numbers then the SAE J1349. It corrects as if the temp was 60 deg F, 29.92 baro pres and 0% humidity.

If the dyno is not properly operated, no atmospheric correction is used and anyof these condition changeswill cause a lower HP/TQ number -higher humidity, higher air temps or lower barometric pressure.Not using anyatmospheric correction factor makes itimpractical to compareHP/TQ numbers fromhour to hour, dyno session todyno session orfrom bike tobike such as this forum. However, many shops located near or below sea level in cool climates do not like to use SAE correction because it causes lower numbers.

If you are dyno tuning, it is best to tune on a day that is somewhere in between the atmospheric extremes that your engine will be mostlyoperated in. Even though many of today's factoryECMsare fairlycapable at compensating foratmospheric conditions for fuel and spark, once modified they become less capable with each mod.