I found this intersting because my car has always ran at 190 and I really though nothing of it.

http://www.cranecams.com/?show=newsLetters&no=146

 

One thing the article doesn't mention. Manufacturers are running the engines hot to bring down emission levels. A very hot engine burns the fuel more efficiently and the tailpipe emissions become lower because of it. That's why a hot engine gets better fuel mileage. A hot engine also helps remove any contaminants in the oil. My alcohol engine barely gets above 180*. The oil turns milky from condensation and alcohol saturation. By leaning out the carbs at the end of the day to get the engine over 200*, it will help burn off or evaporate the excess moisture in the oil.

All the new diesel engines are also built to run hot. The fan stat on a heavy truck doesn't turn the rad fan on until 205*. I get many drivers say that their engines are running too hot. I ask if the computer has ever shut the truck off and/or given a high temp warning. When they say no, I just say that it's running like it's supposed to. They don't get a high temp warning light until 230*. Diesels only run a 10 psi rad cap.

Modern cooling system are also working a lot harder than before. The cooling system needs to remove the heat generated by the engine. If you have an automatic transmission, the factory has a tranny cooler built into the rad. They're also started to put an engine oil cooler in the rad. That's a lot of extra heat that the cooling system needs to remove. Increase the hp of the engine and you can easily surpass the cooling system efficiency.

 

"If your engine will only run its best at the drag strip with the engine at 165°F, you probably have too cold of a spark plug heat range and you are probably jetted way too rich!"


So they are saying your car should run the fastest at operating temperature? My L98, along with my friends LT1, L67, and 97 cobra all run faster at cooler than operating temperature. So we all have too cold of plugs and are running rich

 

I run NGK-7 plugs which is considered a hot plug. 8, 9, 10 are colder. Because I'm dumping alcohol into my engine, the cylinder temperatures are cold and a hotter plug is needed.

Plug temperature needs to be hot enough to burn off the deposits but cold enough to prevent burning the end of the plug off. I believe plug temperature needs to be around 1200*