mrx

Hallo,

i have a short question about the repeatability of dyno runs.
for example: i have a car two times on the same dyno. maybe two times directly in a row or two or more runs
on different days.

for compensating the outer parameters like air temp, humidity, hight above sea level etc. we have the normal
SAE correction, but whats about parameters like Intake Air Temp, Oil Temp, Water Temp and the starting rpm of the dyno run?

how big could be the effect of these parameters on my resulting power output?

if my understanding of physics is right, Intake Air Temp, etc. could have a effect on the power output of the
car which is not corrected by any correction factor, so maybe its possible that one time the car produces
real 200 WHP with a lower IAT and another time only 190 WHP with a higher IAT...

what do you think? is this possible?

and if yes, what did tuners i.e. do to bring the IAT and ETC back to a known level (i.e. First run conditions)
especialy with IAT i noticed, can take very long to bring it down...

Best regards
Malte

flip1199

if i understand your question correctly most tuners let the car cool for a few mins between runs and also utilize a big *** fan blowing into the i/c. Were u more converned on your power at a certain temp or your tune? because if u have a good engine managment it will have iat correction to compensate for changes in temp.

mrx

no, i'am not interested in my IAT correction of my ems... its only about the power measured at the dyno.

what i was thinking of is that IAT Temp is not calculated into any correction factor of the dyno insted of ambient air temp which is not the same.
and also coolant temp and oil temp is not calculated into the measured power output.

and if i.e. IAT is not corrected by the dyno the same car, will produce two different HP on each run with different IATs - right?

and my question was about how big the difference in general could be if you not do all the dyno runs at exact the same conditions (IAT, ECT, OIL TEMP)

93H22ACX

4 months after i got tuned it still made the same power...and this was done with two different dynos at two different sites.... hope that answers your question.

mrx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93H22ACX &raquo;</TD></TR><TR><TD CLASS="quote">4 months after i got tuned it still made the same power...and this was done with two different dynos at two different sites.... hope that answers your question. </TD></TR></TABLE>

not realy... maybe you had only luck ;-) or did you have a datalog from iat and coolant temp?

where your dyno sheets 100% match?! when i made some runs i had a small difference between some runs... not much but noticable. its not about gain or loose 20 whp or so... more or less 2-3hp something in this region.

93H22ACX

the second time i dynoed at the different site... it made 2more whp lol.

mrx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93H22ACX &raquo;</TD></TR><TR><TD CLASS="quote">the second time i dynoed at the different site... it made 2more whp lol. </TD></TR></TABLE>

ah you see... so not 100% identical ;-) 2hp are 2hp :-) that was my concern... from what can that come... dyno tollerance or conditions like other iat etc.

hope a pro can make some technical answers to this questions...

cinq

I don't think anyone can have two runs that are exactly identical. Like signing your signature...they may look the same, but not identical.