Warm-up time

I'm finally driving a modern truck and am surprised by a couple of things.

One is how fast the thing warms up. From our house, it's 1/3 mile on a dirt road until we hit pavement. Unless it's cold (below about 15F) the temp gauge has started to move and the heater is blowing warm air by the time we get to the paved road – total time is probably a minute or two.

It's a 2005 4 cyl Toyota truck, kept in a garage. Our 2003 (2004?) CR-V does the same thing (4 cyl also).

My question is – what's changed in newer engine setups? Do they recirculate the coolant in the head or around the exhaust manifold or something? It can't just be where they locate the temperature sender, nor can it be just hotter thermostats. I presume it's intentional to improve emissions, but how do they do it?

I noticed that too.....when I went from driving the Camaro daily(took a good 15 minutes to warm up in the winter) to the Jag that was one of the first things I noticed....It's actually one of the few good points about a modern car.

Better designs in coolent circulation would be my guess. I dreaded the amount of cubic feet in my (10 year old) toyota when we got it, but it actually warms the air a lot quicker than any of the rest of the cars we own. Interesting question.

Improved emissions is the reason for the quick warm up time. Driver comfort is only a peripheral benefit.
The quicker the engine gets to operating temp, the quicker it can go "closed loop" (fully computerized engine management). That's also the reason for heated O2 sensors.
Improved coolant circulation and internal design changes to optimize thermal efficiency all play a part in the equation.
The resulting increase in fuel economy over an older, colder, engine also helps the manufacturers meet CAFE standards.
Jeff

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...Improved coolant circulation and internal design changes to optimize thermal efficiency all play a part in the equation....

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So then it's probably thinner, more intricate, castings. Then there'd be less metal to absorb heat so coolant and air would absorb more. Makes sense.

I noticed Chevy changed where the heater hoses attach to the intake. This allows hot water from the motor to go through the heated and not the water from the radiator. I notice my 96 PU is defrosting quickly like you said.

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My question is – what's changed in newer engine setups? Do they recirculate the coolant in the head or around the exhaust manifold or something? It can't just be where they locate the temperature sender, nor can it be just hotter thermostats. I presume it's intentional to improve emissions, but how do they do it?

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I think it is a combination of things.
A lot of castings made of thinner material & a lot of aluminum with high thermal conductivity. Smaller water jackets, very efficient radiators that have small coolant volume but great cooling effeciency. A much smaller volume of coolant to heat up but which is circulated at a higher rate when the engine is hot. Note that the late cooling systems have noticeably less coolant capacity than the older ones. These things all contribute to faster warm up.

I'm amazed at how a modern radiator that may only hold only one or two quarts by itself can be so effecient at removing engine heat. A lot of improvements in the last few years.
D