fuel pressure riser (stillen)

im basically just looking for opinions/experience with one and if those fly well then a place to get one. gratzi

Please be more specific, do you mean a rising rate fuel pressure regulator, or an adjustable fuel pressure regulator?

well i guess i was thinking a manually adjustable one, but an electronic one where you could dial in for different rpms at WOT would be even better. im kinda new to fuel management and stuff, i only have experience with bolt ons so far.

so...to answer your question directly, i dont even really know the difference :-[

Rising rate fuel pressure regulator - A simple method of fuel correction in turbocharged systems. These are better than nothing, but far from good. They increase fuel pressure in your fuel system as a function of manifold pressure. Basically what they do is monitor your manifold pressure and as it increases the regulator increases fuel pressure. The idea sounds good, the higher the manifold pressure, the more air is entering the engine, therefor you need more fuel to keep the A/F proper. One problem with this idea is that increasing fuel pressure 2 times will not increase fuel delivery 2 times, but somewhat less. It becomes obvious that this type of fuel correction is only viable in low to medium-low boost applications (up to roughly 9 psi), too high boost will spike fuel pressure very high (fuel pressure in a rising rate system is limited by the maximum pressure delivered by the given fuel pump). So if you turn up the boost in a rising rate system past a certain point, it is not feasable to expect the fuel delivery to keep up with you. Also, these devices work on boost pressure, regardless of RPM, so it will add the same amount of fuel at 5 psi (3000RPM) as it will at 5 psi (6000RPM), obviously at twice the RPM the engine will require twice the amount of fuel. These devices have many shortfalls (high fuel pressure, incorrect fuel correction) but are far better than nothing.

Adjustable fuel pressure regulator - They do the same thing as a rising rate FPR, but without monitoring boost, they are manually adjustable. This will add a certain amount of fuel throughout all RPM's. These are passive devices that, once set, stay at that setting, and do not vary with manifold pressure. These simply add fuel, and are useful in some applications, but are still garbage in my opinion.

thanks for explaining those, useful info. so what would you recommend then? an electronic AFC?

Originally posted by neunan
thanks for explaining those, useful info. so what would you recommend then? an electronic AFC? Why would you need more fuel with just some basic bolt-ons??

well, for one i figure it cant hurt. and i also read that it would help even though im still NA. no?

Originally posted by neunan
well, for one i figure it cant hurt. and i also read that it would help even though im still NA. no? No, it won´t hurt if adjusted properly (dyno needed) but it also won´t do much with just the bolt-ons you have got on your car. If you would get a new cam or anything like that it would be another story though...