[Steve @ BMS/Fuel-It!]

We have a build thread going here but for those just looking for baseline #'s we put the 2020 M2 Competition on the dyno and were pleasantly surprised to see it hit 431whp on 91 octane despite the really high outside temps of 118 degrees!
BMW is clearly sandbagging when they spec the car at 405bhp but we'll take it!
Putting the JB4 on map 1 got us 470whp with an otherwise completely stock car.

[dRDiesel]

[TimboBlackkers]

The dyno corrects for ambient temperature right?

Everyone seems to mention ambient temp in their dyno runs if it's a hot day.

The other thing is that the BMW DME will correct for high temperatures by adding boost, so that the car feels consistent in all weather.

Doesn't this mean high ambient temperatures are an advantage? As the DME has compensated for the low density air, then the dyno applies a correction factor to standardise the results.

Let me know if I'm completely wrong here.

[luchocamp]

Originally Posted by TimboBlackkers

The dyno corrects for ambient temperature right?

Everyone seems to mention ambient temp in their dyno runs if it's a hot day.

The other thing is that the BMW DME will correct for high temperatures by adding boost, so that the car feels consistent in all weather.

Doesn't this mean high ambient temperatures are an advantage? As the DME has compensated for the low density air, then the dyno applies a correction factor to standardise the results.

Let me know if I'm completely wrong here.

If you take same car and same dyno on 60F and 100F it will make more hp and torque at 60F because better ambient temp.
Dynos alone do not tell anything... needs to have base dyno for correct ambient, altitude, DA and them start compare after you install different parts.
Dyno is just a tool, same as Dragy or VBox. ( and every dyno even same brand reads different because operator settings )
But Dyno only measure in one gear, so if you want to race against another car and win because you have more hp/tq than other car you must race in 5th gear starting from 2500rpm same as dyno

[TimboBlackkers]

Originally Posted by luchocamp

If you take same car and same dyno on 60F and 100F it will make more hp and torque at 60F because better ambient temp.

This is false, the dyno will report the same HP/TQ regardless of the weather..

All Dynos have a weather station and apply a WCF or weather based correction factor to the HP/TQ numbers. This is based on a SAE or DIN standard (depending where in the world you are).

My argument is that the BMW DME is ALSO correcting for the weather by increasing or reducing boost, in order for the car to feel consistent regardless of the weather. Hence hot weather will lead to a DME boost up (more boost required to hit the desired load target in hot weather) as well as a dyno correction that will produce high HP/TQ numbers.

Does anyone remember old school turbo cars that were noticeably faster in cold weather and slower in hot weather?