Hi all,

Just going over the plans for the fuel system on the project. As I'm paying close attention to weight distribution I'm thinking about mounting my fuel pressure regulator in the back with the pump and filter. Usually FPR's are mounted close to the fuel rail, is there a reason for this and would mounting it in the rear of the car cause issues?

Thanks in advance,
Jay

A returnless system is the normal approach on most modern vehicles, with a fixed regulator installed either with the fuel pump or as part of the filter, sometimes combined with a pwm controlled pump to keep the power useage low.

If you're looking for every last bhp then this is not as efficient, as the fuel in the rail will be as hot as the engine at idle but cooler at wot, whereas with a circulated system the fuel temperature at the rail will be lower and more constant, giving you denser fuel at the point of delivery all the time.

You could run a circulated system with the regulator at the tank return, i've not seen it done but it should work similarly to any other circulated system, the only thing that might be an issue is if you get pressure resonance due to the longer circuit before the regulator. I have a feeling that it will still be less than a returnless system as a returnless system will experience a similar effect to water hammer due to the fuel in the system only moving when an injector is opened.

Some OE fuels systems have dampers in the fuel circuit tuned to defeat pressure resonance, there are aftermarket versions if this is an issue, but the only way to know is with an electronic fuel pressure sensor that has a decent data rate as the resonance is likely to be a figure related to the rpm ie 15 or 30hz at idle, and unlikely to be spotted on a mechanical gauge. It would likely show up when trying to tune the engine, with parts of the map being unstable with no visible reason.

The only other issue i can see is if you need a referenced pressure regulator, then you will need to run a reference map line to the rear to operate the regulator, depending on how much boost you are going to run, and how fine your injector control is; ie if you only have 1 bar boost, then you could get away with a continuous 4 bar rail pressure and counteract the relative fuel pressure that is delivered with your mapping, but go much higher than that and the relative pressure will change too much to accurately compensate in the mapping, and you would need a referenced regulator.
This does very much depend on your engine and ecu setup.

Dave

I think that the weight of the fuel pressure regulator is so low that moving it to a sub-optimal position is not very imaginative and that there are other things you could do achieve you required weight distribution.

Author:Subject: Fuel pressure regulator locationJ666AYP

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posted on 23/12/22 at 03:53 PM Fuel pressure regulator location

Hi all,

Just going over the plans for the fuel system on the project. As I'm paying close attention to weight distribution I'm thinking about mounting my fuel pressure regulator in the back with the pump and filter. Usually FPR's are mounted close to the fuel rail, is there a reason for this and would mounting it in the rear of the car cause issues?

Thanks in advance,
Jay
  

obfripper, thanks for that. Given me alot to think about, quite abit I didn't even contemplate.

Jay

Snapper, I get where you are coming from but at the same time moving 0.7kgs to a lighter area of the car and moving all of the fueling system into one area made sense to me. Well atleast in my mind it did

J

[Edited on 8/1/23 by J666AYP]