Adjustable fuel pressure regulator on vvt NB2 (afpr)
 

Was hoping to find some direction to install an adjustable fuel pressure regulator on a vvt NB2. Engine is built etc.. For my fuel there is Currently stock fuel lines with a dw200, and 660cc injectors installed. On the dyno we are running out of fuel at the top end at only 300hp. We would like to do two things, one is install a guage for fuel pressure and two, install an afpr for fine tuning

​​​​​​ most of the threads that are searchable on this site the results are from flamming kids on a totally stock 1.6s. Lol. So Information is difficult to find with so many wrong questions originally posted, and any good information is not application specific enough with all the model year changes. with the fact in mind that my motor is no where near stock, whats going to be the best way to install an afpr and guage on these cars? Particularly a nb2?. thanks in advanced.

Easiest way is getting a spare fuel feed line from a parts NB, then getting a FPR adapter flange for the fuel rail. From there it's just hooking up fuel lines. Doorman makes the quick connect to hose barb adapters, or get the full kit to do it in nylon.

Some people use the evap line as a return, I wouldn't with an oversized fuel pump running full tilt 24/7. PWMing the pump might make it possible.


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What's the benefit of switching to a return style fuel system?

For the OP, he wants more Fuel Pressure. You cannot get more pressure at the rail if you are already shunting the pressure at the tank.

At least I assume he wants more pressure as that is the only reason to use an AFPR. Drive more fuel through the undersized injectors.

I understand needing to add the AFPR, mainly dead heading aftermarket pumps. I've been searching through the site and I haven't been able to figure out why some choose to go with a return style with a AFPR and others are sticking with the non-return style by replacing the FPR with a AFPR at the fuel tank.

It seems that the general idea is that tuning is easier with a return style and that sticking with the non-return style is cheaper. Is that about it?

I am all for spending money where needed and saving money when possible. Is there any downside to going with basic fuel hoses compared to ptfe AN lines? Cost difference is pretty huge.

I personally did not see perceptible changes going from Returnless to Return. I suspect there could be some. I am running 15psi tops, so I don't get any extra fuel up top. I did not notice improvements in idle, lowering of idle pulse width (that was surprising to me) and NO improvement in hot restart issues.

I am using stock FPR in both cases. Stock 60 psi in tank, 43 psi referenced at the rail, full size return line.

My VE table is flatter, but I don't see that necessarily as an improvement.

That has been my experience.

DNM

i'm mostly worried about the stock in tank fpr not allowing enough pressure for the power output. would simply enlarging the fuel pump and injectors on a completely otherwise stock nb returnless system get desired results? i wasnt looking to go return style.

I run a returnless boost referenced fuelab regulator for 90 psi rail pressure with 30 psi manifold pressure. I run it between the return line and the tank with one additional piece of pa12 line, it's somewhere in my build thread. Works well, has for a long time now. I do run a dw300, so not sure if your pump will keep up.

@deezums can you recall what you size tap you used for that return line in tank? The hole where the original regualtor went into? I've seen some people just leave that hole the way it is but others do what you did.