Fuel Rails

[04 Mach1]

So what's the HP limit with stock fox body fuel rails.

[qkjuicedpony]

We made 700rwhp with stock fuel rails...but we did have aftermarket braided supply and return lines

[04 Mach1]

We made 700rwhp with stock fuel rails...but we did have aftermarket braided supply and return lines

Was this a stick car??? How much spray?????

I think I might be maxing them out. C4 car with a vortech and 50lbs injectors. Car pulls hard to about 6400 then starts cutting out (acts like a rev limiter)wideband shows lean. I have a 255 forced induction with a 310 external and a KB boost-a-pump -6an feed and a -4an return. I have taken back to the tuner had the chip reflashed rev moved to 10,000rpms. Last week swap out valve springs thinking valve float. Fuel preasure holds steady. Any Ideas??????????

[EHardy1971]

:hmm:So you're still having the same problem?

[qkjuicedpony]

This car was a Glide with two kits.One on 150 one on 100. with 42# Injectors.


You really need a -8 feed and a -6 return on your car

[qkjuicedpony]

I had a car do the same thing once.

It had 2 BAD Injectors.



Did you buy those injectors new?

Have you had them checked or flowed lately

[coupe]

I was thinking bigger feed too. Pressure is only part of the story....flow is the other.

[04 Mach1]

This is the second set of new injectors in the last year. Was thinking I'm running out of volumn. I have heard of several 650hp + but they were on spary with either a seprate fuel system or tapped into the fuel line meaning the fuel rail did not what supply "all the power" I"m sure both of those kits had their own fuel supply. Is there anywhere near that flow test them? That would make sense having a bad injector.

[qkjuicedpony]

1TONY1 on SCF does them.He is in Ringgold Ga and has a pretty quick turn around time.

[qkjuicedpony]

I was thinking bigger feed too. Pressure is only part of the story....flow is the other.


Correct.


Not only that but you have a tiny return with that -4.

If it was me I would swap it to a -10 feed and a -6 return.

[Italian LX]

Lee's Cobra made 538rwhp with all of the stock fuel lines and rails, 255lph pump, and 42# injectors (maxed out). Although it was a 5-speed car, it also was blown which means it was actually supporting a lot more horsepower considering the drag from the blower.

However, that may be near the limit of the rails, and you could be pushing enough past that to see some issues. :shrug:

[04 Mach1]

Last time at the Dyno it put down 548rwhp.

Do you really think -10 is needed?? I just think that a -6 inlet to the fuel pump to a -10 is a big jump.

[qkjuicedpony]

Surely you plan on more power later down the road.


If you are going to upgrade why not do it one last time.

[coupe]

Brian's right. -10 won't hurt, so might as well do it. -8 is plenty though (if you happen to already have a roll of it or something like that)

[Italian LX]

Last time at the Dyno it put down 548rwhp.
Yeah, but that was going through an automatic which means your actual power numbers at the flywheel were a bit more than Lee's. . . .however, I'm still not sure if it would've been enough to tax the limits of the stock fuel rails.

What RPM did you make your dyno pulls to? Can you post the graph or send me the Dyno file?

[QWKSNKE]

Lee's Cobra made 538rwhp with all of the stock fuel lines and rails, 255lph pump, and 42# injectors (maxed out). Although it was a 5-speed car, it also was blown which means it was actually supporting a lot more horsepower considering the drag from the blower.

However, that may be near the limit of the rails, and you could be pushing enough past that to see some issues. :shrug:

yeah, swapping to 60's helped out my fuel issues.

Marc's car has gremlins in it anyhow. I bet if he took that motor out and put it in another car it wouldn't have ANY issues based off the issues he has had with it in the GT vs when he threw the whole drivetrain in the vert and no tune.

But yeah his car putting that kind of power down through a C-4 means he is making way more than I did with the procharger at the flywheel. Also, he turns his motor a lot higher rpm than I ever did mine.

[coupe]

The fluid coupling in the automatic trans does eat up some horsepower, but a C4 can be quite efficient with a good converter in front of it... much more so than an AOD or a TH400. Probably no more than 5% difference from a stickshift.