Curious, why does the throttle body include an internal circuit for engine coolant?

If you look at the TB, you'll see a coolant input and output line, and I can only assume circulating coolant through the TB is either to keep the TB cool in warm weather, or warm in cold weather.... or both, and just keep the TB temp consistent in all weather?

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My guess is it keeps the throttle body temperature down. Since it's made of aluminum and because it is closely located to the engine,I'm sure it gets hot and by reducing the temperature of the throttle body,it also keeps the inlet air temperature cooler and more steady. Cooler,denser air helps produce more power.

 

To prevent throttle body icing, I presume.

The oldie XK 6 cylinder engines with FI had coolant heated TBs as well....but not the old V12s. Anyhow, I think there are other cars that have heated TBs but apparently not all designs are prone to icing

Cheers
DD

 

It's to prevent icing. I had that in an E Type, it was raining and about +1C. Sitting at a light the car started idling slower and slower until I blipped the throttle and then it was fine again. Took noticeably more effort than usual to break the ice and move the throttle.

These days it's also about emissions, as the air cools quite a bit across a throttle plate at small openings and a heated throttle body heats the air so it can vapourize the fuel better.

 

Other way around! Due to the amount of air being drawn into the engine, the intake is the coldest part. On V12's that's why the ignition module is mounted to the intake manifold, the air helps cool the module.

I measured the temperature of various parts of my V12 after a long drive and the intake runners were 40-50C cooler than water (and block) temperature.

 

6 cylinder cars drew their air from in front of the radiator, V12's from behind. At idle the V12 air intake is about 70C and it falls fairly quickly once the car is moving.

It's a great low tech system. It gives warm air for better mixing and economy at idle and low speed, and cooler air at higher speed for more power, yet there is greater turbulence in the cylinder to still give good mixing.