I just brought home a 2021 M6 Grand Touring with the 2.5L turbo. Something smelled very hot under the hood. It was the turbo. My laser temp read over 400 degrees F surface temp. I never had this with my '18 - same model.
How concerned should I be?

 

Simple answer, if temperature'sour are concern have MAZDA service inspect it. You are not really giving enough to go on. So, the answer could be both yes and also NO. A Turbocharger during normal (if their is such a thing) _ driving is not producing boost or high boost levels so the temperature would be very low or equal to the other parts similar in material (aluminum) on and around the exhaust system.
I might also add check your information on your measuring device to see if it can measure reflective material. Some have an adjustable emissivity setting, which can be set to measure the temperature of reflective and non-reflective surfaces.

 

400`F ( 200`C ) doesn't sound outrageous for a turbo charger. https://www.google.com/search?q=aver...client=gws-wiz

The smell you found is rust proofing burning off the exhaust. It will linger, but reduce noticeably over the next 500 - 1000 miles.

 

Thanks.
After some interweb research I've kinda come to that opinion. The smell was a little disconcerting never having experienced it on the '18.
I may yet have the service guys look it over if the smell doesn't dissipate after a couple hundred miles.

 

I bought a jeep pentastar v6 performance upgrades and my turbine performance has improved. Ordered here https://boostyourengine.com/3-6-pent...ance-upgrades/. I would advise you to clean the turbocharger, if nothing changes then you can take some upgrades to the tube, thank you