Why does my car sound "throatier" when cold

[daepp]

In the first 5-10 minutes after start up, the exhaust note on my 911 sounds much deeper - throatier, if you will, and regardless of hand throttle position. The car always sounds great since the rebuild/incr. in C/R, but I sure wish it sounded all the time like it does when it's cold. Some thermodynamic issue?

BTW - I love the sound of the stock exhaust.

[defcon65]

I have noticed that, too. In cold weather it sounds more like a race car, especially above 5500 RPM.

Regards,

[madmmac]

The motor is tighter when it is cold.

[daepp]

So where do you think is loosens up - rings? exhaust connections?

[SCHNELE]

The air is cooler and more dense resulting in more efficient combustion. IMHO

[911teo]

Originally posted by SCHNELE
The air is more cooler and more dense resulting in more efficient combustion. IMHO

Bingo! and it will affect more Turbo and supercharged engines.

[Zef]

Closer tolerances in engine when cold...!

[carsngolf]

It's definitely air density. More oxygen molecules per cu. ft. Same effect as turbocharging. It's also why you need smaller jets in the carbs when you go to high altitude.

[Jack Olsen]

The temperature of the air also has an effect on the way sound travels (more slowly), which could factor in. I wonder if temperature changes the ratio between how (or how quickly) the lower and higher frequencies travel?

I also wonder if the engine and chassis might also vibrate differently based on their own temperature? Does an ice-cold tuba play any differently than a warm one? I don't know. If memory serves from my pre-Southern-California days, a basketball bouncing off of outdoor asphalt has a different sound to in the winter than it does in the summer.

Do the components of our ears work differently when it's cold?

[petrolblue83911]

Why would the air temp change as you warm up the car?, the in-coming air is from outside right? -am I missing something?