Fuel Rails?

[Cyprus106]

So I'm trying to get an article knocked out, but I need a little more fuel rail info. I need some advanced overview of fuel rails, not the basic, fuel goes into and distributes... I mean like why there's sometimes two lines, one on either side, and why sometimes there's only one... (distribution)... that kind of thing. Rail knock, potential problems with bigger injectors, more flow, etc... I want to be able to toss a lot of info on the rail, but I can't find much. What I know is not exactly basic, but not deadset either. All I know is what I was taught, and I want to be dead sure it's right before I toss out a write-up including that info... Anybody wanna throw in their rail info? Maybe a link or two?

[SaabJohan]

Well there isn't really that much to say about fuel rails, fuel goes into it on one side, the pressure regulator sits (usually) on the opposite side and regulates the fuel pressure by controling the outflow back to the tank. The regulator controls the fuel pressure so that the pressure difference over the fuel injectors are constant independently on plenum pressure.

The rail should not have a too small volume as that can cause pressure fluctations which affects the performance on the injectors. The fuel rail must hold up to the pressure and must be resistant to the fuel (there are some special demands when using for example methanol). With a gasoline engine the fuel pressure is in general low, the highest pressures, direct injection engines excluded, are probably seen in F1 which pressures are likely to come closer to 100 bar which will be the limit from next year.

A few engines have been fitted with a returnless system, putting an electronic fuel regulator in the pump which sits in the tank.

There isn't really that much to say about fuel rails, it's more about the fuel injectors, fuel pumps and so on.