what have engine manufactures done to the base engine to meet emissions standards?

Answer 1

The base engine is pretty much the same. Manufacturers on the other hand have added catalytic converters to clean up the exhaust, EGR systems to reduce the amount of NOx emissions, added computer controls to tightly regulate the amount of fuel being injected to the engine for the amount of air. Some manufacturers have gone to the hybrid system that reduces the amount of pollution by not letting the engine run constantly. Other manufacturers have made their vehicles able to run on E85 which is mostly grain alcohol which is cleaner for the environment as well as reduces how much oil we need to import from the middle east.

Refineries have also done work by cleaning the amount of impurities going into the gas.

Answer 2

Well a number of things but none that seem much different. For one the engines of today, still look and fire much the same as engines from the 40's. However the way the engine is put together has changed some. New and lighter materials are used, tighter tolerances and better designed heads and blocks improve the the way fuel is burned. Fuel injection helps also. The latest thing is direct injection. This gives a better burn which means less emission coming out. Its things like that car makers are doing to meet the standards.

Answer 3

The shape of the combustion chambers, the diameter of the pistons, the compression ratio, use of fuel injection, EGR, three-way catalyst, the ignition timing, the size of the valves, the PCV system, etc etc.

For example, do you remember the Dodge 426 cubic-inch Hemi? Very powerful V8 made in the 1960s. They cant make it anymore because of the newer emission standards.

When Dodge brought back the Hemi a few years ago, they had to make it smaller. The old hemi used 4.2" pistons and big piston domes. The pistons were so big, all the gas wouldnt burn in the cylinder. This caused too much hydrocarbon emissions. So Dodge had to make the pistons smaller to meet emissions. Thats one reason the new Hemi engines are only 352 cubic inches.

Answer 4

its not the engine so much as the exhaust sytem that has much of anything to do with emissions, oxygen sensors, o2 sensors, cat converters etc