Split fuel rail mod

[Guest loren]

 Koom']

[quote name='wildturkey said:

i'm looking at the split setup too on my 89 rs leggy........I've been told I can run 2 right hand rails with the factory fpr's (1 on each side i guess). Is this just as good a setup as splitting them and running a single aftermarket fpr?

/quote]

you don't need an aftermarket FPR at all unless you want to change the fuel pressure.

The first time I did this I jut used one stock FPR.

TBH I would be worried about using two different stock FPRs... what guaruntee have you got that

they are set the same? although I guess you could just put a pressure gauge on each one... but

still, it's more complex than required.

Prodrive used to use this setup on the Group A cars. There's also alot of people around running two factory regs without issues. If one of the regulators was relieving at a lower pressure than the other, then that would be the pressure throughout both fuel rails (to a certain degree, I'm not gonna get entirely into the fluid dynamics here) and the second regulator just wouldn't relieve.

If you fitted a fuelpump that could supply a big enough flow rate that one regulator couldn't cope, then you could possibly create a situation where one rail "could" be at a significantly lower pressure than the other but the chances of doing that through factory fuel lines is rather slim.

I stand corrected.

[Guest loren]

 ReubenH']

[quote name='loren said:

TBH I would be worried about using two different stock FPRs... what guaruntee have you got that

they are set the same? although I guess you could just put a pressure gauge on each one... but

still, it's more complex than required.

/quote]

More complex than required? it's easy as pie and works a treat. And they have stickers on them with a part number, kinda helps in matching them up.

I think koom covered it, but thanks for trying :

[dubbedup]

what are the benifit of doing this mod?

[Guest loren]

The fuel travels clockwise, same as in the northern hemisphere as it's supposed to.

You get more power and better fuel economy when the fuel travels in the right direction.

[dubbedup]

thnx

[subieboy]

 loren said:

The fuel travels clockwise, same as in the northern hemisphere as it's supposed to.

You get more power and better fuel economy when the fuel travels in the right direction.

Gold

[Guest boostcut]

 loren said:

The fuel travels clockwise, same as in the northern hemisphere as it's supposed to.

You get more power and better fuel economy when the fuel travels in the right direction.

are you for real????? hahahahahahahahahah

[Guest keltik]

Of course he is. Everyone knows the coreolis effect changes the polarisation of the fuel molecules so they dont burn as well going against the earths rotation

[Guest loren]

 keltik said:

Of course he is. Everyone knows the coreolis effect changes the polarisation of the fuel molecules so they dont burn as well going against the earths rotation

What he said... I didn't want to confuse anyone so left the technical details alone.

[Guest boostcut]

even if this was true i still think that no one could actually prove it to work on this forum.... it sounds completely stupid

[ReubenH]

Rofl. This place is starting to sound like bloody legacyGT.com

[Optical]

 Koom said:

Prodrive used to use this setup on the Group A cars. There's also alot of people around running two factory regs without issues. If one of the regulators was relieving at a lower pressure than the other, then that would be the pressure throughout both fuel rails (to a certain degree, I'm not gonna get entirely into the fluid dynamics here) and the second regulator just wouldn't relieve.

hmm, yeah you're right, the rails wouldnt even act in parallel as intended either. The reg with the higher pressure would never open (as the first relieves all the pressure) leaving one fuel rail as a dead end...

find two identical regs and there should be no issues running two

[Guest loren]

 boostcut said:

even if this was true i still think that no one could actually prove it to work on this forum.... it sounds completely stupid

umm, no need to prove it, use the power of teh interweb... plenty of proof already out there.

[Koom]

 Optical']

[quote name='Koom said:

Prodrive used to use this setup on the Group A cars. There's also alot of people around running two factory regs without issues. If one of the regulators was relieving at a lower pressure than the other, then that would be the pressure throughout both fuel rails (to a certain degree, I'm not gonna get entirely into the fluid dynamics here) and the second regulator just wouldn't relieve.

/quote]

hmm, yeah you're right, the rails wouldnt even act in parallel as intended either. The reg with the higher pressure would never open (as the first relieves all the pressure) leaving one fuel rail as a dead end...

find two identical regs and there should be no issues running two

Fuel will still be flowing down the "dead leg" as there will be two openings i.e. injectors.

I've always had a wee bit of apprehension about this setup (parallel) but it wouldn't really change much if it was a series setup with bigger fuel lines. Cause say for example that you had a parallel setup that tee'd back together into a single regulator, what guarantee is there that as the injectors start flowing more and more fuel that one leg won't take the majority of the flow (due to some sort of internal flow restriction due to the tee-piece or something) and still leave one leg to starve?

As long as the fuel pump can supply enough flow to feed the demands of all four injectors and still have excess flow (at that pressure) that needs to be relieved then the system "should" work.

[Guest]

Sweet never knew that .....................

But do I need to change the fuel flow direction for when I drive back home on a trip ?

If is all good if I drive up and down the island, but what if i drive from Hastings to New Plymouth?

If I laugh anymore my testies will hurt ;D

[Guest boostcut]

when i set up my fuel system, i got some half inch fuel hose and 2 tees and 2 90 bends. i fed in the front and ran in series out the back. works perfectly, im just going on the bigger is better theory. i also use a standard FPR and i made an adaptor to run a 3/8 inch line up to the return. i havnt had the car det or lean out yet. and it gets raped

[Guest]

Hey people,

I'm getting on to doing this mod, and have my intake manifold off, was going to pull my fuel rails off and the stock fuel lines that run to these so i can get started, but along the way i discovered that attached to my stock fuel lines under the intake manifold is another fuel (??) line that goes from the throttle body to a black cylinder-shaped plastic thing that's quite big that sits infront of my ABS set up, then i think circulates back to where the fuel feed (where the fuel line connects to after it goes thru the fuel filter) and return lines go? What does this actually do? and can i remove it or what? This is on a '91 facelift legacy.

Sorry if this is hard to understand.

[driftrex]

 tedebare said:

Hey people,

I'm getting on to doing this mod, and have my intake manifold off, was going to pull my fuel rails off and the stock fuel lines that run to these so i can get started, but along the way i discovered that attached to my stock fuel lines under the intake manifold is another fuel (??) line that goes from the throttle body to a black cylinder-shaped plastic thing that's quite big that sits infront of my ABS set up, then i think circulates back to where the fuel feed (where the fuel line connects to after it goes thru the fuel filter) and return lines go? What does this actually do? and can i remove it or what? This is on a '91 facelift legacy.

Sorry if this is hard to understand.

yip you can rip all that shit out along with the metal lines that go under manifold.

[Guest keltik]

Charcoal canister, its there for emissions purposes. Up to you what you do with it, im pretty certain its not essential.

[wrx_lou]

 loren said:

The fuel travels clockwise, same as in the northern hemisphere as it's supposed to.

You get more power and better fuel economy when the fuel travels in the right direction.

Gold indeed.

[driftrex]

charcoal canister is only required in japan for emission laws, which we dont have. mine is long gone.

[Guest]

Okay, so it's completely safe to remove the charcoal canister, and no fuel is going to leak out of where the line comes out of the throttle body and goes to it, or from the other line in the circuit of that setup?

[driftrex]

 tedebare said:

Okay, so it's completely safe to remove the charcoal canister, and no fuel is going to leak out of where the line comes out of the throttle body and goes to it, or from the other line in the circuit of that setup?

any vacum lines that go to it will need to be blocked and the main vent hose that goes to it from your fuel tank and under your manifold will just need to be poked into your chassis rail as not to smell fumes all the time.

sorry i cant tell you exactly which hose you do what with as mine is totally gone and cant refer back to it.

[Guest keltik]

Just poke that line somewhere, who cares where - its only spewing petrol fumes into an area near HT coil packs and hot exhausts.

[driftrex]

 keltik said:

Just poke that line somewhere, who cares where - its only spewing petrol fumes into an area near HT coil packs and hot exhausts.

haha yea tru. could make it vent out the back of the car just as easy tho, hmm maybe i'll do that.