[mm340i]

I have a 2023 M340i with 15K miles, bone stock, 91 octane gas. My turbo seems really quiet. I can usually hear some intake noise during the first pull after warming up, but then it goes away for the rest of the drive, even if I let the car cool down. I don't have any check engine lights or messages, but I don't have a scanner to check beyond that.

Power feels okay, though the car seems more spirited on some days compared to others. The HP/torque bars will show about 386HP and 370 LbFt.

I recently put 2 gallons of E85 into the tank, and although power felt somewhat higher, the gauge numbers were the same, the turbo seemed quieter, and at low RPMs the engine felt a tad 'lumpy'.

I drove an M240i not too long ago, and the turbo sounds were way more prominent and consistent, though power seemed about the same.

Is it possible that I have a boost leak or something along those lines?

[Planoser]

HP/Torque "gauges" on the dash will never adjust unless you get a tune done.

what year was the 240 you drove? the 2020 years and prior were louder than the newer ones.

[weinerbarn]

The gauges aren't actually measuring anything. It's simply a representation of what's been programmed in as far as the range and current throttle input. The car doesn't have some sort of onboard dyno that measures HP/TRQ. Like Planoser mentioned, a tuner can change the sport gauge range and scaling so it's representative of what you might expect from the tune but it's still not a measurement.

[mm340i]

Thanks for the replies. So the higher octane with ethanol did seem to help power.
I still don't get why the turbo is so quiet.
I drove a 2022 or 2023 M240i, and the turbo sound was very prominent on each pull.

[Planoser]

is your air filter old/dirty/clogged?

[Planoser]

In all seriousness, these cars dont make alot of turbo sounds in stock form - they aren't supposed to. Maybe the other car you drove wasn't exactly stock?

[mm340i]

Originally Posted by Planoser

In all seriousness, these cars dont make alot of turbo sounds in stock form - they aren't supposed to. Maybe the other car you drove wasn't exactly stock?

The other car was a loaner from the dealership. I'm starting to think the 3 series has more sound insulation, but I'm still going to check my air filter just in case

[weinerbarn]

I think the intakes are the same between series so I expect the sound silencer in the intake tract won't differ but it's possible the exhaust is different and maybe has less resonators maybe. You can definitely hear more spool when resonators and secondary cats are removed on some models.

[mm340i]

I can't hear anything after the first pull, unless I go into manual and stay around 2K RPM and gradually build boost. Once I'm at ~8-10PSI I can hear a bit of intake sound coming from the turbo.

[totalone]

Originally Posted by weinerbarn

The gauges aren't actually measuring anything. It's simply a representation of what's been programmed in as far as the range and current throttle input. The car doesn't have some sort of onboard dyno that measures HP/TRQ. Like Planoser mentioned, a tuner can change the sport gauge range and scaling so it's representative of what you might expect from the tune but it's still not a measurement.

do you know if bootmod does that?

[weinerbarn]

Originally Posted by totalone

do you know if bootmod does that?

Bootmod3 is just the delivery mechanism for the tune. The person creating the tune would need to set the sport gauge range. But yes, usually even the OTS tunes included with Bootmod3 have the sport gauges changed. My X5M comp now reads up to 800HP/TRQ.