It's about time for me to upgrade my full fuel system for high-power and E85 (EFR prep) but the more I read, I keep realizing that I'm missing key information due to NA vs NB fuel system differences. Just need to throw my current thoughts out there so I can get some feedback before I dump money on the wrong parts or cause fueling issues.

I'm gonna be replacing most of the fuel system in the near future, but currently, I am getting the car drivable using:

• NA chassis (return style system)
• NB (99') motor and fuel rail
• NA FPR on rail
• DW300 (hardwired)

I used this to get the first start with my old tune and AFRs were close after scaling for ID1000s so this setup seems to check out for now.

My main concern is regarding the lack of a fuel pressure damper when I convert over to an adjustable FPR setup since NBs came with a damper. The new system will have:

• Radium rail
• Feed/Return lines from the rear of rail. Front capped
• FuelLab FPR w/ gauge on return
• Ethanol sensor on return

I don't know how NAs handle fuel pressure damping but I'm assuming it's either handled in-tank, or it was an addition on NBs. Is there any need to add some sort of fuel damper to the system to prevent fuel pressure fluctuation?

 

I don’t believe a damper is considered ‘essential’. My 260whp car doesn’t have one.

Radium make a boost referenced damper which you can mount directly to the rail (perhaps in the location you’re planning to plug). They also make adaptors to attach a factory damper to their rail (potentially cheapest option).

My new set up (yet to be tuned), has the feed at the rear ended of the rail, the damper in the outward facing port, and the return at the far (front) end, which goes to the FPR and flex sensor mounted on the body rail.

 

I kept the chassis mounted damper and removed the rail mounted one for the return adapter. I've got a cheap shitty Chinese pressure sensor on my FPR that shows my base fuel pressure steady rising from 60 to 80 over the course of an hour drive, but I don't see any high frequency noise or anything from it. At some point I'll probably remove the 2nd damper, just to clean up the bay a bit.

I don't think they are as necessary when the FPR is closer to the injectors.

 

Exactly the info I was looking for

Im shooting to "do it once, do it right" so went ahead and added an adapter and OEM damper to the rail instead of a plug. I'll be shooting for 400whp on the kill tune, so will likely bump the base pressure up to 60. Read that some people run into idle surge issues without a damper so shouldn't run into that now.

Im assuming the chassis-mounted damper is also an NB thing? Haven't heard of that on NA's

 

I don’t picture how you are connecting feed and return to the same port on the rail. Nevertheless, I agree that you need a damper if the rail is dead-headed (no FPR on the outlet of the rail). NA’s had no dampers. They had the FPR on the opposite end from the feed.

 

Poor wording on my end. The radium rail has two ports at the rear. One on top, one on the end. I'll feed through one, return out the other going to the remote FPR, and will put a non vac-referenced damper on the third front port.

(Tangent thought) I personally dont see why having the feed and return on opposite ends would make a difference in the pressure each injector receives, but that's also an opinion based on zero empirical data.

 

I don't think it's too far out of line to try and keep the fuel flowing the same direction. I am sure it experiences similar effects to water hammer which is why the deadhead setups got dampers in the first place. If your feed is always flowing towards the return then the hammer is on the FPR itself which it should be able to react to.

If you feed and return from the same end you've got to reflect the hammer off the capped end of the rail, past all the injectors.

 

Ok, im starting to understand now. It didn't click till now that the damper was on NBs primarily due to the returnless system, so mine will just be mostly an overkill feature.

I BS'd physics in college, but I think I understand the point you're making about the hammer effect. Pressure pulses are being reflected in the rail when it's not straight through, thus adding pressure "noise" around the injectors? Man, I love what a great resource this forum is.