SRT-Tom

The March 2012 issue of Road & Track had an informative explanation of direct fuel injection. Here it is:

"Fuel injection covers a broad range of methods of squirting fuel into an engine, and direct fuel injection is just one of those methods. Thus, an engine can be both fuel injected and direct fuel injected, but not all fuel-injected engines use direct injection.

What direct signifies is a system that sprays fuel directly into an engine's combustion chamber. This is significantly different than multiport fuel injection found on the overwhelming majority of automobile engines in the last 20 years.

Multiport fuel injection places a fuel injector just upstream from the intake valve. This allows a relatively low fuel pressure- say 30 to 60 psi- that in turn allows relatively simple and thus inexpensive pumps and injectors.

Direct fuel injection must overcome the high pressures inside the combustion chamber and thus operates at approximately 2,500 psi. This requires more expensive pumps and injectors, higher-strength plumbing and sound deadening, so direct fuel injection is considerably more expensive, typically costing several hundred dollars more per engine than multiport injection. What you get for the extra money is a finer spray of smaller fuel droplets and increased cylinder cooling, both of which yield greater engine efficiency.

We're in the middle of the switch to direct fuel injection, so you'll find thenewest engines use it and not necessarily the most powerful, expensive, or sportiest powerplants."