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With the creation of Ti-Automotive’s and other manufactures new high output in-tank fuel pumps, the need for better and beefier fuel pump wiring should be on your upgrade list. It’s no secret that if you provide these pumps with the highest voltage that your charging system will provide and wire capable of flowing the healthy current requirements, that these pumps can perform extremely well. But first, let’s cover a few facts.
For those not fluent in ohms law and for simplicity, we will think of electricity as water in a garden hose. Voltage will be your line pressure, current will be the amount of water flowing through the hose, and resistance will be the restriction as in the diameter of the hose itself. Most of these pumps can draw well over 20 amps at full load, and they are located at the rear of your vehicle, meaning that you will require at least 10-12’ of wire from the back of the alternator (where you will receive the highest output voltage or pressure) to the fuel pump. Most of the kits available use between a 14-12 awg single wire for a single pump setup and two 12-10awg wires for a twin pump setup. Now let’s leave fuses and relays aside for a minute. If you want the most out you your fuel pump as I mentioned you will need to give it what it wants (max charging voltage). For any given length of wire you use there becomes a limit of how much current you can flow through it while maintaining specific voltage or pressure behind it. The longer you make the wire the more of a voltage (pressure) drop you will see at the end. Would you be surprised to know that some of these kits available will have over one volt drop at the fuel pump!!!!!! That’s crazy!!! Ever wonder why your injectors never made it as far as you wanted!? This becomes a bigger deal if your charging system only ever hits around 14-14.3 V max. That means your fuel pump at WOT is only ever seeing around 13v when you need it the most!
Here are a few examples: Assuming we want to do better than most automotive applications we will use a 2% voltage drop which is acceptable instead of most automotive circuits which can be up to 5%. Let’s use a starting voltage of 13.8v and run a straight wire from the alternator to the pump with no fuse or relay for our calculations. Keep in mind that there is a voltage drop for every device (fuses, relays, connectors, crimps etc…) and every connection. This is unavoidable and means if we use 12’ of 14awg wire at 25amps, we can expect to see 13.04v at the pump. Next 12awg will see 13.32v, and finally 10awg will see 13.5v. To simplify, the smaller the garden hose the less pressure and water flow there will be at the end of a given length. This is unacceptable if you want your pump to work at its absolute best!
Now we add in our Fuses and relays which will account for between .04v to .06 depending on hardware. That puts our first scenario at 12.98v! Yikes! We have not even accounted for when electronics get hot their ability to maintain and do their job becomes harder and their life span will be decreased. I am not sure about you but the last thing I want on my race car is a relay failing.
By now some of you are thinking “have you ever looked at one of these pumps? The wire on the pump is only 14awg! “. The answer is YES is have! There are a few things to consider, the wire length is extremely short (under 5”), and the wires are being cooled by fuel even if they are not completely submerged. For example a one foot length of 14awg wire, providing you could keep it cool could flow 60amps at 13.8v with only a 2% drop! While this is an extreme use of a 14awg wire it illustrates what I’m talking about.
So, if you want the most out of your single or dual pump fuel system and are not interested in a “Boost a pump”, this might be the solution for you! Our kit will provide the maximum voltage and handle the current requirements of your single/twin pump setups. Our kit uses 6awg cable, a 50 amp circuit breaker, TE 150 amp high current relay and bulk head studs to bypass OEM connector. The only difference between the single pump and twin pump is a larger breaker and 4awg wire instead of 6awg.
A few things to note about the Honda S2000. The factory Sumitomo terminals in an OEM sending unit connector that pass current to the pump were never rated for 25 amps. Yes, I am aware that many people have done this with success but it still represents a weak link in our opinion and we wanted to make a bomb proof wiring setup for those who want it. Second is, as most of these cars are 15 +or- years old, the OEM grounds are showing their wear or have corrosion. They must be in top condition, mainly the ground that travels between the body and block. This is the path that electricity will flow back to your alternator when the vehicle is running with a fully charged battery. So, if that’s not up to snuff no fuel pump rewire will ever help you. Third is the OEM charging system will never output the voltage that will make your fuel pump really happy! The max you will most likely see is 14 to 14.3, if it even holds that until red line. For those of you who are wanting the most performance, our upgraded billet 6 phase 175 or 240 amp alternator with upgraded power and ground wires is the solution for you! It will maintain a solid 14.5-14.7v while running hot. Cold charging voltage will start out around 14.9-15v and will not tap out when you suck 50 amps off the mainline for your hungry twin pump system!
Honda S2000 Twin Pump Fuel pump wiring kit
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