A little more on the New ford trickeling out
Another article on the new Ford Gasser, still no official HP/torque specs though. article Ford is being rather miserly with the story on this one.
Forum Discussion
parker.rowe wrote:ShinerBock wrote:
Direct injection is dirtier than port injection in regards to PM (particulate matter). In some cases, gasoline direct injected engines spew more PM than diesels, but much finer particulates than cannot be seen. This is why gasoline direct injection engines have soot on the pipes like old diesels used to before DPF's.
Benefits of direct injection....
You don't have to wait until the intake port opens to inject fuel into the cylinder. Therefor you can control injection timing and even have multiple injection events per stroke. You can wait until at the end of the compression stroke to inject the fuel so it doesn't pre-detonate. With a port injected engines, you have to inject the fuel into the cylinder on the intake stroke while the intake valve is open and run the risk of that fuel pre-detonating on the compression stroke before the spark plug ignites.
Because of this, direct injected engines can run at higher compression ratios then port injected engines making them more efficient. You can also inject a small amount of fuel on the exhaust stroke to cool the cylinder. This all helps reduce the chance of knock and allows you to advance timing for more power.
That's pretty much it.
I've seen lots of info about issues with relatively low mileage carbon buildup on the intake valves with strictly direct injected engines, because the injector is no longer spraying fuel in the port and keeping things clean (they are usually pointed right at the back of the intake valve).
I believe some manufactures are using, or adding port injectors back to direct injection engines as well.
Carbon build is mainly an issue with DI engines with external cylinder EGR's that inject exhaust gas back into the intake. While DI engines with in-cylinder EGR, like Ford's truck Ecoboost engines and GM's Ecotec truck engines, still have some carbon build up on the valves, it is is not enough to cause in major concern or significantly effect performance and efficiency.
