Looking to upgrade my fuel system, currently 100% stock. I eventually want to use an Aeromotive A1000, it uses -10an lines. Can I run the -10an now and use like a 110gph holley mechanical until i put in the electric pump?
Been there...done that!
We were struggling with methanol fuel delivery issues using Holley pumps, we could static flow enough fuel for our needs but in operation (drag) we were leaning out. I think it was caused by the weight of fuel in the lines and under racing conditions it would cause the pumps' internal regulator valves (not the pressure reg up front) to open. We would loose volume big-time.
That was down to pump design, with the pumps reg valve being inline with the outlet....we ditched the pumps and went to a different style and the issue was solved.
IMHO your pump should handle the 10an line now and the A1000 "should" be able to push that volume unless you have a pretty quick ride.
As with most things on a muscle car - bigger is better. Bigger cam, bigger cubes, bigger carb, bigger NOS shot, bigger explosion
That said, most cars can get by just fine with a 3/8" fuel line. Use hard line and keep the rubber links to a minimum. hard line will have less surface tension and will flow better that the same length in rubber. I like -6 stainless for the ease of install and durability but it costs a bunch.
<font size=-1>[ This Message was edited by: pbrown on 10/8/06 10:30am ]</font>
A -10 line is 5/8 inch. if you weigh a column of fuel that is 15 feel high and 5/8" diameter compared to a column of fuel 15 feet high and 5/16 inch in diameter it weighs 3 times as much. (you have 3 times the fuel)
I have NEVER seen a need for a gas line (not Nitro-methane but Gasoline) larger than 3/8 inch. Alcohol tops out at 1/2 inch.
in operation all the acceleration that you have is pushing the fuel back to the tank. The more weight in fuel the more that acceleration affects it. Drag racers solve this problem by mounting a non-regulated pump at the tank pushing 9-12 psi to a regulator beside the carb so that the acceleration doesn't affect the pressure of fuel to the carb. if you want performance then throw the regulated pump away (or sell it to a street jockey) and use a racing electric pump that is mounted below fuel level at the tank and use an appropriately sized (3/
fuel line. Leave the 5/8 inch line to the guys who need that much fuel.
yup, most guys are overkill on the fuel system. i run a 600hp 408 stroker, on alcohol. mallory 140 pump, -8 to the aeromotive regulator, -6 to the carb. i lose 2 lbs going down the track. have swapped in a 250 with no et improvement.
Bigger isn't always better or needed. My Falcon runs 11's in the 1/4 using the stock 5/16 line and tank pick-up with a 100GPH self regulating Carter pump. The Holley Blue pump dead headed thru 3/8"(-6)line on my Morris has no fuel issues running 1.45 60 foots and 6.80's in the 1/8.Not sure where this myth of running sewer sized fuel lines came from.
I think the key is:
If you are upgrading to a larger fuel line, do you have a pump that will support it and do you have the demand for it?
In my case I upgraded to 3/8 with a return system for obvious reasons, one of which was to replace the 40 year old 5/16 hard line.
My Mallory 140 supports it and with a 408, nitrous, and a 750 DP the demand can be created.
There is somethings you are all overlooking and one is line friction. The smaller the line, the longer it is and higher the pressure....the more frictional loses you have.
The actual size of a 6an lines is .34 , 8an is .44 and 10an is .56".
If you want to size your lines properly go to the Areoquip site, download their catalogue and near the rear is a line sizing diagram.....both for suction and supply...
Greg ....on a 1G launch you would double your numbers...on a 2G launch you would treble them??
<font size=-1>[ This Message was edited by: cmf60 on 10/9/06 7:39am ]</font>
The metal lines are dimensioned on the external diameter so the inside diameter would be smaller. In a seamless tube (metal line) the line friction at 12 psi is meaningless at the flow rates that gasoline engines and their fuel pump can use. If it was 2000 psi hydraulic line flowing 5 gallons per minute and 20 feet long the resistance would make a big difference. For most street aplications you can use 5/16" line and if you want a margin of overkill a .375" line is more than enough for any gasoline engine.
BTW: the vertical gravity is null when calculating the load on a pump with regards to a column of fuel being pushed back into the pump due to acceleration.(unless you are accelerating in a vertical direction.) Because of that a "1 G launch would only place 1 force of gravity on the fuel in the line. The weight of the entire fuel column would press against the valve of the pump and the PSI on that valve would have to be calculated by dividing the weight of the fuel column by the area of the valve. If you had 1 pount of weight in fuel and a valve that was .333 inches in area then you would have 3 psi at the pump (valve).
If you had a 2 G launch then the pressure with the same line and valve would be 6 psi at the valve.
Electric pumps come with instructions for optimum line sizes for matching the flow of the pump with the line size that you will be using. If you are using a forward mounted pump then you are working with suction and the column of fuel pulling a vacuum on the pump. If the fuel gets hot you also run the possibility of vapor lock where the fuel boils in the line before it gets to the pump and the pump loses its prime - which stops the fuel flow completely and immediately.
<font size=-1>[ This Message was edited by: PaulS1950 on 10/9/06 12:21pm ]</font>
fuel line size dictates how large of a reciever you have on your fuel line. Consider your fuel line as a tank to your carb bowl, or to your fuel rail. The more fuel in the tank(line) the more fuel readily available. Your pump is going to deliver roughly the same amount of fuel with either line, it is a flowrate thing. flowrate = velocity x area.
Now follow me we already know the flowrate it is rated on your pump for example 100gph. We already know the area, we get it from the diameter of the line. So the only thing that changes is velocity.
This is why there is some advantages to running bigger line, but not to big. bigger lines hold more fuel so the fuel doesn't have to move to fast in the line. The faster something flows the more turbulent the flow, and then you get air in your fuel etc, bigger lines will reduce this.
All the flow stops when your needle and seat shut the flow off. Your engine starts and stops the flow throught the line many times a minute. There is more turbulence caused by the fuel turning on and off than any that might be generated in a line by the fuels flow.
Since the fuel is always under pressure in the line and no more fuel can flow through any line than the ammount that will flow through the needle and seat. How big a line do you need to flow enough fuel to get through two needle and seats? The holes in the seats are less than 1/8 inch each. (unless you get the ones that are made for alcohol and they are bigger) but none of them is larger than half the volume that can flow through the 3/8 inch line.
This will come from left field, but, have you checked the voltage at the pump, under way at WOT?
Another post on here a while back was trying to trace a mystery leanout and they learned there was something kitty-wompus in the electrical system that put out 13.6 V at idle, but less than 10 under way at full chat, with a proportionate drop in pump output and a dangerously leaned out engine on the top end.
Don't recall all the particulars, but one of them was to add a switch to shut the electric fan off, and then doubled up on the gage of the ground cable, which added a significant amount of power all by itself (in addition to 'breaking the dam' for the electrical system.)
Dunno if this helps, but worth looking into if an electric pump isn't putting out,