IT Affects on results

[CR4ZYGT422]

Hey guys just wondering how much affect the IT temp on a dyno run affects the end result. You see a lot of dyno sheets with differing IT temps. What is the required or middle ground for it temp and how does a lower then standard reading affect the final outcome.
Thanks Leroy

[ratter]

The mainline does not use air intake temps for it's calculations, it has a weather station attached and uses the information from this weather station in accordance to which correction factor standard is being used (visible on print out) to make it's adjustments

[CR4ZYGT422]

Yeh thats the point I'm trying to make or ask. If I have one dyno sheet showing me 315rwkw with an it of 17 and another with 302rwkw with an it of 46 how do these compare. Or are you saying this does not make any difference to outcome?

[ratter]

ambient air temps will mean the car may make different power due to the settings in the ecu but the intake temp reading will not alter the reading the dyno gives you, basically the dyno will report what it see's and the intake air temps do not alter this reading

[awddynotodd]

First of all, we do not report Intake Temp on our Dyno Reports, so the graphs you speak of will not be from a Mainline Dyno.
As Mick (Ratter) has mentioned, a Mainline uses Ambient Temp, Humidity and Baro Pressure for Power Correction, we do not use Intake Air Temp, as it can introduce cheating or mistakes.

By using the OBD Data Logging on Mainline Dyno, the operator can actually see what the IAT is the ECU sees, so things like Intercooler (or lack of) efficiency can be checked.

As already mentioned, the Dyno Software can only correct for so much, we can't predict what Ignition Timing a given car has due to the Intake Air Temp. That's why it is so valuable to have data such as the OBDII data in the dyno software.

While Atmospheric Correction Standards are designed to level out the testing due to differing weather conditions, things like intakes/intercoolers and the tune in the ECU can vary the results.

To answer your question directly, the result you quoted of 315RWKW with an IT of 17, and another of 302RWKW with an IT of 46, without any power correction, the test with the lower IT would naturally give a better result, the difference with no correction could be as high as 10%, as the difference between 17deg and 46deg IAT will change the Manifold Air Density by 10%, so the power will also be effected by 10%, so there is obviously some correction being applied on the 2 results you quoted, and has brought the results to within 5% of each other.
Bear in mind, an actual IAT of 17 deg would probably allow the ECU to set the full amount of Ignition Timing the tuner/OEM has set, whereas an IAT of 46 you would expect a serious amount of Spark Retard being applied, and hence lower power figures.