3/ 8 vs 1/2 vs 5/8 inch fuel line

[Mad_Trbo]

Can anyone point me to projected flow rates for the different size tubes listed above?

I am looking to make some changes to my fuel system and want to make sure I only do it one time.

Again looking for max flow rates in gph or lph. It would be great if I could get this information at a certain pressure rate.

Thanks!

 

[Mad_Trbo]

Magnafuel Fuel Pumps

How does the board feel about the magnafuel fuel pumps for street duty??

Seems they are claiming no step down is required for situations such as idle or prolonged driving.

I would love to hear anyones experiences.

 

[bison]

Can anyone point me to projected flow rates for the different size tubes listed above?

I am looking to make some changes to my fuel system and want to make sure I only do it one time.

Again looking for max flow rates in gph or lph. It would be great if I could get this information at a certain pressure rate.

Thanks!

A -8 feed and a -6 return will take you a long way. Dual feeding aftermarket rails with a pair of -6's off a block which is fed by the -8 is typical. The factory fuel rail does not work well when dual fed and is not worth the time to try since aftermarket rails are readily available.

 

[turbofabricator]

The stock fuel lines are good to about 125 mph. To put this into perspective, the stock fuel lines are crimped down to a .257" at each fitting. That's roughly a 1/4" fuel line. Most guys go with a -8AN to the fuel rail which is more than enough to feed 1000+ hp at 60psi fuel pressure. The pump feed size is more critical than the pump to rail size, in that it is a suction line, and most EFI pumps are not good sucker pumps. Mounting the pump behind the tank or better yet in the tank is the best way to plumb it. The pump should be at the lowest point in the system, in that it is lower than the tank, and behind it, so gravity and G-forces are in your favor.
A -6AN line from pump to rail will supply enough fuel for over 800 hp. at 65 psi. Most Sprint cars run a -6AN feed line to their injector valve, and they run methanol which requires twice as much volume and it has a higher specific gravity. They make over 650 HP with one -6AN feed line and they run around 60psi fuel pressure.

The problem with running a huge supply line is that the pump has to push that entire column of fuel under 1+ G at launch. The pump has to work harder to push the weight of the fuel column to the fuel rail.

So, to answer your question, you need to have enough cross section to feed the power out-put of your engine. A -8 is typical but usually WAY over kill. Again, consider that the stock line size is necked down to a 1/4" in 4 places, and it will feed over 600 hp.

Good reading here. pg 76

 

[Mad_Trbo]

This the kind of technical information I like to receive.

Thanks I'll read through over the next couple of days!

 

[Hot Air]

I went with -10 feed and -8 return. I know, that is BIG for a 109 block but I didn't want to do it twice. Besides, if Champion's iron stage block is not priced out of sight, there might be a stage motor in my future. Now that we are thinking about E85, I'm glad I have some extra line capacity!
Conrad

ps to Tom (Champion)...keep price less than $2,000 and you will sell a bunch of these Stage blocks! Otherwise, the LS1 swap will take off.

 

[Blown&Injected]

The stock fuel lines are good to about 125 mph. To put this into perspective, the stock fuel lines are crimped down to a .257" at each fitting. That's roughly a 1/4" fuel line. Most guys go with a -8AN to the fuel rail which is more than enough to feed 1000+ hp at 60psi fuel pressure. The pump feed size is more critical than the pump to rail size, in that it is a suction line, and most EFI pumps are not good sucker pumps. Mounting the pump behind the tank or better yet in the tank is the best way to plumb it. The pump should be at the lowest point in the system, in that it is lower than the tank, and behind it, so gravity and G-forces are in your favor.
A -6AN line from pump to rail will supply enough fuel for over 800 hp. at 65 psi. Most Sprint cars run a -6AN feed line to their injector valve, and they run methanol which requires twice as much volume and it has a higher specific gravity. They make over 650 HP with one -6AN feed line and they run around 60psi fuel pressure.

The problem with running a huge supply line is that the pump has to push that entire column of fuel under 1+ G at launch. The pump has to work harder to push the weight of the fuel column to the fuel rail.

So, to answer your question, you need to have enough cross section to feed the power out-put of your engine. A -8 is typical but usually WAY over kill. Again, consider that the stock line size is necked down to a 1/4" in 4 places, and it will feed over 600 hp.

Good reading here. pg 76

Nice.

I often get the roll eyes when I claim -8 is more than enough and -10 way over kill.

I was surprised to see how small the fittings are in our stock system and I know there are plenty of fast cars with the stock fuel lines.

 

[Chuck Leeper]

Huh??

There was once, a "turbo goorew", that claimed 1000HP with stock fuel lines!!
NE 1 recall that "discussion"??
Here's what the folks @ WELDON say, in thier catalog.
-6
suction 51 GPH
pressure 194 GPH
-8
suction 89 GPH
pressure 336 GPH
-10
suction 137 GPH
pressure 515 GPH

They make no reference as to the PSI at which these values are determined..
I'm betting they are "free flow".

 

[Hot Air]

Folks,
You need to calculate the pressure drop of the feed line, return line, and fuel pressure regulator and look to see if YOUR fuel pump can handle it. Of course, the fuel requirements are based on the boost, FI capacity, HP, etc). Don't just look at the lines or the FPR or the fuel flow or the pump. You have to look at ALL of it since it is a "system". This ain't simple so be VERY careful. Your head gaskets and pistons will thank you if you get it right.
Conrad

 

[NCTURBOS]

I've never seen the need for the larger lines, even with cars in the 140mph range.


K.

 

[lazaris]

I've gone the times in my signature consistantly with completely stock fuel lines and a double pumper. Never had an issue. I've just stepped up to a Maganfuel fuel pump and bigger lines to go faster. My double pumper is now for sale. :biggrin:

 

[Turbo1dr]

The factory fuel rail does not work well when dual fed and is not worth the time to try since aftermarket rails are readily available.

The factory fuel rail is actually BIGGER internally than the aftermarket fuel rail I got with my GN1 intake. So it would seem to me that would hamper flow in a high HP car. I had a picture once comparing the two.

EDIT: Found it.