What size is fuel line ?

[Pentalab]

Just out of interest, what diam ( ID / OD) is the fuel line from tank to eng bay ? What is it made from, aluminum, steel, SS ? My understanding is the 11+ cars don't have a fuel filter...(only 05-10 4.6 engs).

If it's only 3/8" as I suspect (I could very well be wrong).... then increasing the diam of the fuel line to 1/2" would result in a 78% increase in cross sectional surface area.

If it's actually 1/2"...then increasing it to 5/8" would result in a 56.25% increase in cross sectional surface area.

If it's 3/8"...then increased to 5/8".... that would result in a whopping 2.77 X increase in cross sectional surface area.

The rational here is.... a bigger fuel line may well relieve some stress from a given fuel pump setup. I may well be out to lunch here, it may all be a just a moot point.

 

[07 Boss]

Here’s some fuel for thought. Haha, fuel. Anyways, now your pump needs to pump more fuel to maintain a certain pressure? No?

 

[MrAwesome987]

Here’s some fuel for thought. Haha, fuel. Anyways, now your pump needs to pump more fuel to maintain a certain pressure? No?

Guessing here, but wouldn't it be the same amount of fuel required once the line is pressurized? I think this would only apply to returnless style systems.

With a return style, I believe you are correct - you would need more fuel pump to maintain the same amount of pressure.

 

[MrBhp]

The pump will simply pump what it will pump. The larger line size will only decrease pressures loss due to friction. That's pressure loss on the other end, as in the first orifice it encounters at the engine. You may end up with more usable fuel, if the pump already has spare capacity. I wrote a very extensive article on this very thing concerning Dodge Cummins trucks. They had severe fuel starvation issues, even when stock. It was killing the injector pumps. Doesn't matter if it's a return system or not. You could actually end up with a lower pressure reading at your gauge, while having more fuel to use.

 

[RED09GT]

The stock line necks down to 3/16" where the line from the chassis goes to the line that runs to the fuel rail, is 5/16" to the fuel rail, and necks down to 3/16" where it enters the fuel rail.
I have a -8AN (1/2") line from the fuel hat to a fuel lab filter, then to the fuel rail. I used the Fragola -8AN fuel rail adapter, I do not recall the part number off hand.
I have 60 lb injectors and GT500 pumps and my fuel pump duty cycle tops out at 0.42 (84%) with pump gas and 18lbs of boost on a ported head/cammed 4.6 so that suggests that it moves significantly more fuel with the same pumps and injectors as the stock line would. I have not had it on the dyno to see what it actually makes for power, hopefully that changes in the next month or so.

JeremyH has some good posts about the S197 fuel system on this site.

 

[RED09GT]

Also, fuel pumps are the opposite of injectors. Injectors can flow more fuel with more pressure but pumps will pump less volume if they are required to deliver a higher pressure.
A larger fuel line will decrease the amount of work the fuel pump has to do to meet the demands of the engine.

 

[Pentalab]

I suspect in some applications, a bigger diam fuel line might just alleviate the requirement for multiple pumps, bigger pumps, single or dual baps, etc, etc.

Ok, so why doesn't the 11+ engs have a fuel filter ?? The 05-10 cars have the fuel filter tucked inside the rail... below driver's seat. Can it be tossed ? Like if the entire line was being replaced with a bigger line.

 

[MrBhp]

I can't see a larger line helping to such a large degree. The pump still has to supply the minimum pressure to the injectors. If you were to run just one giant pump big enough to supply large hp with both volume and pressure at wot, then the pump would probably heat the fuel quite a bit when cruising. I know some guys are in fact doing this, but they aren't dding their cars.
Larger lines don't necessarily lead to less load on the pump, in extensive testing we found the highest amperage draw was at just few psi. As back pressure (resistance) goes up, volume, as well as amperage draw goes down. This isn't a blanket statement for all pumps. Impeller and volute design affect this behavior. But for automotive fuel pumps, it pretty much holds true. Larger fuel line will help your pump to supply all it can, but it still won't pump more than it's capacity at a given pressure.

And do the new cars seriously not have a filter?

 

[Flusher]

The pump will simply pump what it will pump. The larger line size will only decrease pressures loss due to friction. That's pressure loss on the other end, as in the first orifice it encounters at the engine. You may end up with more usable fuel, if the pump already has spare capacity. I wrote a very extensive article on this very thing concerning Dodge Cummins trucks. They had severe fuel starvation issues, even when stock. It was killing the injector pumps. Doesn't matter if it's a return system or not. You could actually end up with a lower pressure reading at your gauge, while having more fuel to use.

Link to the article please.

Do have formulas for pressure and flow relative to tube/hose sise?

Thank you

 

[MrBhp]

Link to the article please.

Do have formulas for pressure and flow relative to tube/hose sise?

Thank you

Not off the top of my head. I never thought I'd forget all that info. I spent quite some time writing code with those formulas. The computer has ruined me. I'll try to dig up that article on the Cummins work. It was extensive and enlightening. The formulas are fairly simple. I'll see if I can link some online tools.

 

[RED09GT]

Here is some good reading material.
https://www.s197forum.com/threads/3v-fuel-systems-and-their-capacities.127062/
JeremyH chimes in at post #10

 

[MrBhp]

Here is some good reading material.
https://www.s197forum.com/threads/3v-fuel-systems-and-their-capacities.127062/
JeremyH chimes in at post #10

That's a nice thread. Answered a few of my questions. But I'm still wondering if there is an injector I can use that will support my turbo on 8lbs now, 18lbs later, on gas and e85.

 

[RED09GT]

ID 1300 or FIC 1440 would probably get it done.
I'm going to change out my 60 lb injectors at some point for something more modern.

 

[Juice]

Fuel line diameter is dependent on hp you are making. If you have monster injectors to feed your high hp engine, and the fuel pump(s) to support the hp, and you still cannot maintain fuel pressure under WOT, thats when you need to upsize.
If fuel pressure is good under WOT conditions, a larger fuel line will have zero impact. Your fuel pump wont have to work any harder.

 

[Juice]

Here’s some fuel for thought. Haha, fuel. Anyways, now your pump needs to pump more fuel to maintain a certain pressure? No?

No. Just takes a little more fuel to fill the larger line. Once at pressure, the same volume flows to the engine.

 

[JeremyH]

Stock line varies between hard steel and soft ptfe type line and sizes between 5/16 to 3/8 ID. Biggest restrictions in the system as a whole is the rail fitting ID which is significantly smaller than the line, followed by the pprv on the hat.

Yes 11+ cars have a fuel filter. The 05-14 S197 filter is the same between all engines in that year range, 3.7, 4.0, 4.6, 5.0, 5.4, and 5.8.

6an is a small upgrade mostly cosmetic and allows getting past the restrictive rail fitting and 8an is a significant upgrade in either electronic returnless for the 3v or mechanical returnless in the coyote.

Some real world data for ya, 3v with dual gt500 pump bap and e85 setup around 650rwhp. Was maxing fuel pumps 100% and limiting rpm. We deleted the pprv installed 8an line from hat to rail and a new high flow fuel filter. Duty cycle dropped from .50 to .37 allowed him to rev out with a max of 74% duty cycle.

https://www.s197forum.com/posts/1948614/

If your running double, triple or even more fuel volume through the stock line and filter then def this an upgrade to consider. Not to mention if you run ethanol your having to push around 25% more volume at the same power level as you would with gas.