Thread: Rising rate AFPR

I'm shopping around for an afpr and found some rising rate regulators. If I understand correctly, these raise the the pressure from base as turbo pressure increases? Similar to a stock reg using vac to increase? Or am I way off course here?

I know your ecu has to be tuned for for higher pressures to really benefit from higher pressure. But if these rising rate's increase what your tuned for based on boost, wouldn't that throw the mixture off? Or can this be adjusted with a safc or something?

an ecu is tuned for higher base pressure (idle) usually in my experiance , all the fuel pressure regulator does is adds 1 psi of fuel pressure to 1 psi of boost with gives you more fuel that you need under boost but lets you mantain lower fuel pressure for just normal driving

from what i read you are looking to raise the fuel pressure then correct the mixture by using a safc like say your map is tuned for 3 bar you want to go to 4bar then correct the offset with a safc and personally i dont recomend that get a 4bar map i thats what ur lookingto do

I'm still learning the more technical aspects of ecu tuning, so bear with me.

When the fuel psi rises from one of these regulators, it also increases the injector flow rate toò, right? So, say I'm tuned for 4 bar. I would have base psi at 4, then as boost builds the psi would raise beyond 4bar? And the ecu won't freak out when it senses this? Or do you set the reg to raise TO 4bar?

Also, what is your opinion on these regulators? Any real benefit over a standard afpr?

So there are a few different rising rate fuel pressure regulator. There is factory(the fuel pressure will increase with boost) which has a static base, aftermarket that have adjustable base pressure settings that increase pressure as they see more boost (usually 1psi fuel pressure per 1psi boost pressure), and then there are FMU (fuel management units) which is a mis-nomer IMO. They have different ratios of fuel pressure to boost pressure. Example: 3 BAR base pressure, and for every PSI of boost it see's it will increase fuel pressure 6psi.

I would use a factory unit and proper engine management.

Raise pressure, yes. Correct it with a safc, no. I want to do it right. I'm currently running your average de+t modeled after a stock det. All DE except the 370 injectors and safc2 to comp for higher boost.

I've enjoyed my tiny turbo, and am planning out my next phase....installing my T4. So I'm trying to learn the finer aspects of maps and tuning, and the parts that I'll need to move beyond the 300hp mark. As well as how to properly use them.

I was really hoping to get a Calum rt for my 4bar endeavor, but right now, trying to get one of those is like chasing after a unicorn. So maybe a Nistune.

So any info I can get besides what I search for, is greatly appreciated!

Thanks for the clarification. I'm wanting a calum rt or nistune for management, but wouldn't I still need to raise the pressure with an afpr if I plan to use 550 or 740cc injectors? Or can you still run 3bar if your ecu is tuned for for the larger injectors, and not have any issues with fuel starvation?

My buddy has the fuel pressure setup you are talking about on his 1000whp cobra. Costs him about $800 (not worth it) It runs together with his engine management and ups the fuel pressure electronically as the boost raises to give you that little extra fuel pressure and to ensure you don't run lean. However I don't see how you would need this on our cars. Just go with a normal adjustable and set it and forget it.

That's what I originally planned, but was curious if the rising rate's were worth it. Didn't know if there would be any real added gain.

i agree with sneaky get a nismo afpr and set it and forget it.

the raising rate fpr are more of a bandaid for say hondas where their engines arent turboed from the factory some use it straight up with a high flow fuel pump and use the 12 to 1 or 1 to 1 discs in them to acheive 1psi of fuel to 1 psi of boo however with our cars using a proper fuel map and a afpr like the nismo and a set of good injectors you really dont need raising rate regulators they will more or less act as a piggyback unneeded if you ask me