Parallel fuel rail mod-needed or not ?
 

I've been trying to source the parts or a kit to carry out the parallel fuel mod at a sensible price while my engine is out of the car. I haven't been able to get hold of any kits as most places are out of stock and buying modded rails then all the fittings comes to around £300 !

I know I could just cut the fuel rails and then join fuel hose straight onto that but i'm not too sure how secure they would be !

I want to get the engine back in the car asap now so is this mod really important or not ?

I'm going to be running an Andy F 20g,550cc's,around 3.5 bar fuel pressure,FMIC,Apexi Power FC amongst other things,should be around 380ish bhp. At this level how beneficial is the fuel rail mod ?

Simon, You can use your existing fuel rails just be sure to barb the ends where you make the joins to the rubber hose there is no problem doing it this way. I have set up many using this method where screw on fittings where not requested and also was originally on my own car running 4 bar for many many miles.

Thanks for that mate. Do you know what bore size hose I need to get and roughly what length ?

You need
12 X 6-14mm hose clips
2 X Metal tee peice 5/16"
4ft 8mm ID high pressure fuel injection hose.

Nice one mate :thumb:

Also,do you know where I can get a tool from to flare the pipe with at a reasonable price ?

The standard subaru fuel hose is actually 7.6mm IIRC and can be quite difficult and a little more expensive to get hold of. However you can use the 8mm as mentioned above.

If you want the 7.6mm I can dig out the supplier I used if you would like.
Mike

If the 8mm is fine then I will just use that mate,thanks anyway.

anyone have any good suppliers of the required parts.

Could you give me a quote on doing this mod :notworthy

Professional Motorsport Parts, Spares & Rally Equipment from Rally Design

parts:
2 x 8mm - 5/16" T-PIECE (LMA602) = £7.76
3 x 1m x 8mm - 5/16" ID HOSE (LMA367) = £24.90

got hose clips elswhere (use decent screw types)

Does it make a difference where the fuel pressure regulator is fitted ?

Mine was fitted on the turbo side of the engine-at the end of the flow as it returns to the tank.

I've read that some people prefer to fit the fpr on the fuel filter side so it then supplies the rails first.

Is there any real difference between the 2 locations ?

FPR is always at the end of the fuel piping keeping fuel pressure "upstream" on set pressure. offcourse mounting location could differ but would not prefer to mount a pressurised fuel component next to a component which gets to temperatures of over 900 degrees and spins at several 10K rpms
:p

It's not right next to the turbo !! It's mounted sorted of on the inner wing by the standard boost solenoid !

My fuel rail has had an adaptor fitted onto it where the OEM fpr used to be and now has some hose going to the fpr. I think it was fitted by Zen performance.

sounds ok to me.
mounting location depends on the available space and personal preference I guess
mine is on the right side firewall were fuel pipes enter the engine compartment

FPR is always after the filter and all of the injectors.
Basically, your feed comes out of the fuel filter, through the rails and your FPR sits in the return line between your rails and your tank. That way there is a constant pressure in your rails.

If you put it before the rails on the fuel filter side the only thing that will be at the correct pressure is the filter itself.

Here's a pic of mine, you'll notice that I have the return from each rail going to the reg (one to the left side of the FPR and the other to the right side). The return from the FPR comes out of the bottom and returns unused fuel to the tank.

http://www.scoob.co.uk/rebuild/fuelsetup.jpg

I hope thats of some use.

Daz

I would have said its not needed at that stage at all, I have it done myself but more for WHEN I go to a much larger turbo then a 20g. Prob a nice safety mod though.

Renno

My standard rails and regulator set up failed at 330bhp.

Basically the reg failed letting too much fuel back to the tank. This resulted in a slightly hot piston which picked up in the bore.

I'd say for a 20G its a must, not necessarily the parralel setup but definately swap the regulator.

Daz

What is the max setup run using the existing fuel rails (non-parallel)? I'm near 500 bhp with oe rails, 850 injectors, soon to be bosch pump and SX reg, dont seem to have any issues...

Oh yeah for sure the regulator 110% but I wouldent bother doing the parralel for a 20g.

Think id want them for 500 to be honest. But there are many like you without and running that power.

Now that looks good ;)

Thats how I wanted to do my rails but it's all getting abit too expensive now and I want to get the car back together !

horsepower is not the correct measure to deside whether you need uprated FPR or not! (parallel or not).
If you use an uprated fuel pump it will flow alot more fuel.
The standard FPR is less capable of handling this high flow combined with higher intake pressure.
actually the fpr has less to do the more power you use (less fuel needs to return to the tank)
therefore it is wise to uprate the fpr when you uprate the fuel pump.

Ive heard the Walbro over powering the standard reg before to but I know 50 suabrus with Walbros and no reg and it doesent seem to have happend, Inc my own which ran for over a year with 16g ecutek walbro etc etc with standard reg. Im sure it can happen and has happend but does seem to be rare ???????

true standard FPR is not that bad.
point was that need for aftermarket FPR has no direct link to horsepower but more to uprate fuel pumps and/ or need for adjustable fuel pressure.

Agree, for the year I ran without the reg I had it siting there and had every intention of putting it on but being lazy I suppose I dident until I went slightly larger turbo. Id always do it anyway for the bit of safety. Ive heard of a good few failures with the FSE reg but not one on the likes of Fuelab or SX. Maybe more a conisedence that its always the FSE ive heard about. I think someone described it as the devils regulator on here once :lol1:

Glad i've got the SX then ;)

Just been reading through this again. My SX regulator only has 1 entry and 1 exit so how do I fit this if i'm going parallel ?

You only need two ports on the reg.

Feed from filter >> Fuel rail >> Return on reg >> Reg outlet to tank >>

Thanks mate,I was worried it was going to cost me even more ££££ :thumb: