So as some people already know i am going to be going turbo soon. I am using a GT2871 and planning for about 375 to 400whp. will be upgrading to 9.0:1 diamond pistons ARP headstuds and a MLS headgasket.

So i have everything already planned out except for what i will be doing with the fuel system. I have had a couple ideas and wanted to see what everyones opinion was.

1 Keep it stock and use 60# injectors
2 Convert it to a return style system
3 Convert to a return style system and use a 1:1 rising rate fuel regulator.


1 I dont really want to keep it stock as there is problems with cyl number 4 being starved for fuel. Also the need for extremely large injectors is needed when the manifold pressure comes close to the fuel pressure. If i was running 20PSI manifold pressure the effective fuel pressure would only be around 30PSI. This increases the need for large injectors and develops lots of problems for tuning when under vacuum.

2 this would be better than option one and reduce the risk of cyl 4 leaning out. But wouldnt i still have problems when the Manifold pressure reaches near the fuel pressure? And still have all the problems with overfueling under vacuum?

3 Converting to a return style would eliminate number 4 cylinder getting starved for fuel. Using the 1:1 rising rate regulator i would be able to use smaller injectors and still provide enough fuel under high boost conditions as for every PSI the manifold pressure increased so would the fuel Pressure. This would also make tuning a hell of a lot easier.

Whats everyones opinion on this? what option should i go with? Or is there something that i have missed??

 

1:1 return system would be the best for that setup. Ditching the returnless is always a great way to go.

 

agreed.

I had issues with my number 1 leaning out on my Probe, as soon as I swapped up to a 2:1 regulator, the issue was gone. However, it was a 1:1 from the factory, and had tiny injectors.

 

what about keeping it returnless and mounting the 1:1 regulator near the fuel tank would that work?? I dont think it would be as good as a return style system with it though. The only reason i was thinking to mount it near the tank is so that i dont have to run a return line. but i guess ill just have to run a vacuum line to the regualtor by the tank then so i guess i should just do it proper and run the return line.

Also do you think the stock fuel lines should be upgraded to bigger ones for more flow or are the stockers good enough? And if i convert to a return style with a 1:1 regulator whats a good psi to set the fuel pressure to?

 

While this is possible there is a couple of things that I would like to mention. If you look at the internals of the fuel rail there is a half pipe on the inside of the fuel rail at the fuel inlet that will prevent fuel from entering the fuel rail and going straight out the #1 injector. Is this a flaw in design for higer pressures? the problem with cylinder #4 is downstream from get fresh cold Engine Coolant. If the engine runs hot the cylinder #4 is the last to get cooled and it will naturally be the hottest of the four cylinders. It has been commonly seen in V-8's that #7 and 8 Cylinder will have engine failure.


I believe that everones post is good but the post #2 is likely the best answer.

 

if you convert this thing to returnless, and use the 1:1 regulator. what is the fuel pump going to do in the tank? freak? drop the tank, change the pump, throw what we know to the wind and have to recalculate the whole injector table.

or just set it up as a return style without a regulator, and see what happens?

 

well i was planning on upgrading the pump to a walbro 225 so i thought while im there i might as well upgrade to a returnless system. The whole idea of using the 1:1 regualtor is so that i can use samller injectors and still make the same amount of power and not have tuning issues under vac with such large injectors.

 

Option #3 with the new pump.

 

ya option 3 is what i was leaning towards. I understand that with the 1:1 regulator the fuel pressure will be a constant value ABOVE manifold pressure but my question is what fuel pressure should i run ABOVE the manifold press?

 

I would just run the injectors and the pump for that power level. cheap and easy.

 

Parts for return-style fuel system

1. Walbro GSS342 (although too big to fit on module inside the tank (black box))
2. Aeromotive 1:1 fuel regulator
3. Fuel pressure gauge
4. fittings
5. fuel lines

 

My advice is to stop considering doing something half assed. If you are going to do it do it right and complete the first time.
Does it cost more? Yes, but not as much as starting over should the half assed way fail.

 

SAY IT LOUD!!!LOL

 

Actually, I did it yesterday. Car runs nice. You can hear the pump inside the car. It's kind of a supercharger whine. I'm looking for a pump with the same length as the stock pump. I'll change it as soon as I found one. I called the auto parts where I bought the pump they said with the specifications of the walbro (255 LPH) there where no smaller than 4-3/4". If you can recommend one, please do. Thanks.

 

I wouldn't say you were doing it half-assed
As for a smaller size (physical) pump, I would search the net.

 

I know man. I called the auto parts to verify if they had a smaller one. They didn't have one. The cap of the "module" inside the tank was tied with straps (we make sure it was very tied). My mechanic (who really did the job) told me it will be okay, so the guy from the auto parts, who did the same thing. I still have to buy a gas filter, since we have to replace the stock. Car runs fine. The other step will be either turbo with a super 20G or twincharged. Although my mechanic recommend me going full turbo (he's a turbo guy ), has a toyota starlet @ 30 psi)

Sorry to thread jack OP, just giving my thoughts on my return-style fuel system installation.