After a car heats to normal operating internal temp what is its external temp measured againist the block?
Hot! Different parts of the block will have different temperatures. However, away from the exhaust manifolds, the temperature would be close to the cooling system temperature, which is about 200+F if the system is under pressure. So don’t touch the engine with your bare hands.
The areas neear the exhaust system are considerably hotter.
Surface temp will vary considerably depending on where you aim the infrared pyrometer…or touch the engine with the thermocouple. Areas by the exhaust ports will be extremely hot, areas by the lower part of the water jacket will be far cooler. Just the cat converter can get up to 800F, and the manifold area through which the hot gasses pass that heat the converter up is even hotter.
Much also depends on climate. Heat from the engine is dissipated by the cooling system, by radiation, and by the air passing through the engine compartment. A big old V8 just off the highway in the summer in Dallas on a 110F day is going to be much hotter on its surfaces than a engine coming off the city streets in North Dakota in winter at -20F.
In short, there is no standard temperature on the engine’s outside surfaces. Its thermostat is designed to keep its internals operating at at least a certain minimum temperature and its cooling system is designed to dissipate excess internal heat beyond a set temperature, but the externals are simply designed to withstand whatever heat is there.
What is the temp near the exhaust manifolds? How hot can it get?
Engine Temperatures get hot enough you can cook food in the engine compartment while you drive. There’s actually a cookbook on the subject called “Manifold Destiny”
http://www.howtodothings.com/automotive/how-to-cook-food-on-your-car-engine
I don’t know why you want it, but there are thermometers with probes which can be held against the exhaust manifold to record the temperature, since exhaust manifold temperatures vary a great deal. If you are putting in headers, you need alot of clearance to avoid fires.
If you should spill oil on the exhaust manifold while driving due to a leak, the OIL WILL IGNITE and you will have an expensive underhood fire. If gasloine leaks on the exhaust manifold you will have a serious fire and you best abandon the car.
As Doc is suggesting, you’ll need to measure yours. There are no specifications on this, and different engine sizes and configurations will have different temperatures at the manifold.
Your most affordable way to measure this is probably a temperature measuring meter that comes with a thermocouple rated for high temperatures. Radio Shack probably sells these. It’s been years since I looked for one, so my memory is gone on the type of bimetallic probe to get. You’ll need to seek the ranges on the package.
For those who have served in the military, the muffler/exhaust of a heavy armored car or tank will heat a number of rations very quickly. Soldiers do this routinely.
Is this some kind of punk’d or candid camera question? Where are the cameras?
Since most of the metals in that make up your engine block and components have melting temps of 1,800 to 2,200 degrees F. and your engine coolant can, under pressure, be around 230 to 290 F., lets assume the engine gets really hot, but not so hot that the metal melts.