Fuel pressure regulator question

[AZtrophy]

If you were to run -10an lines for the feed and -8an for the return, would using a FPR with -6an ports all the way around be... less than desirable?

One of the kits is setup this way and I would've thought it best to try and match the actual line size. I believe that reducing the size at the regulator will increase the pressure but reduce volume, right? Not sure if this is a factor so I wanted to consult the experts.

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[AZtrophy]

I've seen a few articles talking about losses due to line length and how a larger diameter line will have a lower loss.

What I'm asking about here though is whether the restrictions at the FPR will have a negative impact on the system? My guess is that it will.

In the case of a Y-block you would have essentially doubled the volume which allows you to go from say -8an to -6an x2. With the FPR, it's -6an at a single point so I can't see how the FPR is appropriate for the system.

Hoping you guys can set me straight.

 

[beefcake]

if your feeding the regulator first, no point in doing any more than 6 / 6.

if your going to the rails first, the 10 would be ok, but still alot of line, and then a 6 return would be plenty

 

[AZtrophy]

Thanks for the reply, Terry!

AFAIK, there are no install docs for the Sai Li Triple Pump Return system (I think it's new whereas before he only had the modified GT500 option). I have emailed the company to be sure though.

That said, I was using Lethal's return diagram as a basis and they are doing a single -10an feed to y-block > -8an to rails > -8an to FPR > -8an return. I then hacked up a pic from Aeromotive to sort of illustrate this in one shot (see below).

I assume that the FPR in this illustration would subsequently support the three -8an supply/return lines (ie. have two -8an inputs and one -8an output). The FPR supplied by Sai Li is -6an x3. At the very least, it seems like an oversight to sell a kit with -8an return only to bottleneck it at the regulator.

 

[AZtrophy]

Some updates below (though I'm no more certain of anything than before...). Also, I want to point out that I'm not trying to talk smack about anyone here. I wouldn't have bought Sai's kit if I thought it wasn't going to be a solid choice.

Sai indicated that there are instructions that can be emailed but I haven't seen them just yet. He also mentioned that this system has been run on 1800whp vehicles with no issue which is very encouraging. "It will not be a restriction as we are placing it after the rails."

Aeromotive unfortunately contrasted this by saying that the 13129 model that comes with the kit is not their recommendation (based on the triple Walbro 465 pump config) and instead suggested either of the following regulators: 13110 (4-port) or 13134 (2-port). As a note, the 13134 is only ~$60 more than the 13129. The description for the kit FPR (13129) also indicates that it supports up to 1000hp (not whp).

If at the end of the day the consensus is that -6an is sufficient, then the kit could have been even more affordable by running return lines and fittings of that size instead of -8an, no? Certainly not enough to make or break your wallet but if $60 more for a regulator was outside of the scope then I can't make sense of this decision.

Thoughts/inputs anyone?

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