8 gauge wire for fuel pump re wire kit!

[spitefire1]

im looking to rplace the 10 gauge wire that goes to the relay to the battery with 8 fuse wire. will this hurt anythig or be better. im thnking it will be better for a 8 gauge instead of a 10 gauge.

 

[TSITurbo95]

Yes it will help, as it will provide more and steady voltage to the fuel pump. I have 6Gauge wire feeding my fuel pump, yes it is overkill, but it has plenty of breathing room.

 

[slowgsr]

its always a good idea, your battling voltage drop basically.. when you want a good 14.5 volts etc at your pump(s).. the larger size wire you use the lower the voltage drop will be at a given current and conductor length.

20ft lenght of run, using 10awg wire, drawing 30amps will give you about 8.7% voltage drop from 14.5v (source) to load..

For Engineering Information:

30 Amps Rated ampacity of selected conductor
1.1417 Ohms Resistance (Ohms per 1000 feet)
0.05 Ohms Reactance (Ohms per 1000 feet)
1.45 volts maximum allowable voltage drop at 10%
1.26 Actual voltage drop loss at 8.68% for the circuit
0.9 power factor

if you used a 8awg wire and the lenght/load stayed the same.. you would get 5.71% drop.


For Engineering Information:

60 Amps Rated ampacity of selected conductor
0.7421 Ohms Resistance (Ohms per 1000 feet)
0.052 Ohms Reactance (Ohms per 1000 feet)
1.16 volts maximum allowable voltage drop at 8%
0.83 Actual voltage drop loss at 5.71% for the circuit
0.9 power factor


Im an electrican, I just used an online calculator to figure this out rather then grabbing my codebook and looking up the equation, Its not often I have to do too many engineering calculations to design electrical systems, but sometimes I do. Anyways, heres the source Voltage Drop Calculator

I used overhead for one of the factors, since the wires are run in free air basically since its just single conductors.

If I did the calcuations myself, using CEC spec's for wire and resistance it may be slightly different, since there will be less variables (like a power factor) and a more basic 'answer'.

Actual current draw of your pump probably isn't 30amps, if its only 15-20amps then these drop numbers would go down (less voltage drop), but heck.. guys with external pumps running 60psi of base pressure and 40lbs of boost with a 1:1 regulator their pumps will work much harder during full power wich is where you will experience the most current draw and voltage drop when the pump is 'pumping' the hardest.

If you can't maintain a 'close to target' voltage at the dump due to voltage drop, it will severly limit the capabilities of your pump. However, using a 10awg wire on a single walbro in any circumstance will not limit you due to voltage drop issues.

So switch if you like, personally I use a 8awg for DUAL walbro's, it also served as the power source for my meth pump in the trunk.