Help design a fuel system
 

All right I'm not going to experiment with this so, I need some guidance. You guys have traveled this road and why reinvent the wheel. So here is what I got One low mile 93 Mark VIII engine, this will remain stock for the most part, summit fuel cell, and not much else. I'm starting with nothing, want after market fuel rails, need external fuel pump, filter and regulator. Will run return style system, this does not need to be rated for over 400hp since I have no plans to ever take the motor there, the car will only weigh about 2400lbs, so I don't need to. What would you all use for lines, pumps, fittings, filters, and regulators. Any hints for laying it all out are helpful as well. All right guys lets get those ideas coming. Oh here is where I'm at with the chassis I have to start thinking about laying in the ground work for the fuel system soon.

http://www.clubcobra.com/photopost/d...197_Small_.JPG

There's lots more pics in the link at the bottom.

Patrick

Need to know what motor and fuel induction you are wanting to run
 

fasterpatrick Pat what motor are you running? Who's system are you looking at? Does your system need a return line? Fuel line size min of 3/8" and return 5/16". Are you going to race? I have seperate fuel pumps and lines going to my motor with one way valves. Backup pump if the other ones fails while racing. I run 255 Walbro pumps in the tank. I like internal pumps better that external ones. 95% of all cars today run internals. Only down side is the pumps use the fuel to keep them cool. I have not had any vapor lock with my system.(2) 1/2" lines up to the motor and (1) 3/8" return to the tank. Separate relays for each tank on switches. 10 years no problems yet. Volume IMO is more important than pressure. Both are needed. A lean out condition happening on the track will burn up a motor in a heartbeat. Ask MOE.:eek:%/:o;):LOL::LOL: If you want to talk about this, send me a private e-mail with info to reach you at. Rick Lake Ps Aluminum gas line is easy to run and works OK IF you clamp it about every 12"'s to stop vibration. In NJ it is not allowed on street cars. Also some of the stainless steel brake lines are not DOT approved for the street either. You know our inspectors don't miss a thing.:( Rick

Fuel system mods
 

Fasterpatrick - I have a Unique 289FIA with a 351W and Accel EFI to a stack injection system, ~350 HP, 24 lb. injectors, and 45 lbs. fuel pressure. I ran 3/8" hard line to and returning from the engine. The only problem I have and will be correcting this weekend is when the tank gets below half full. The fuel tank has the pick up on the lower left front corner, so when a left turn is made and the fuel sloshes (?) away from the pick up, the engine quits momentarily. This happens at higher fuel loads when tracking the car as higher speeds in the turns occurs. Remember, once the fuel uncovers the pick up tube, you lose fuel pressure instantly even though the lines ahead are full. I even had one instance when it restarted after the turn with a big backfire that blew off 3 of the 8 stack filters. I will be installing an accumulator tank in the rear center of the fuel tank. It has the baffles on 3 sides to allow fuel in from 3 directions. The pick up tube goes directly to the accumulator tank. I would check into this issue and how your tank is baffeled inside and how it will help prevent you from having a repeat of my problems. Other than this small problem, I love the EFI system and the reliabilty it gives.

Bill

Is this a dedicated race car? Are you sure you want a fuel cell? They require maintanace and can cause more problems over time than they are worth for a street car. Also some brands of stainless line can have an annoying fuel odor (not leaking) so I would recommend plumbing the majority of your car with hard lines.

No this is a tame street car in wolfs clothing. It has more like an aluminum fuel tank with fittings in the top I will Have to add fitting to the bottom rear for the pickup.
Now here is where I'm about as dumb as a box of rocks. I will be plumbing my fuel system for my stock Mark VIII 4.6l from scratch. Everything from tank to rails is aftermarket, so I will not need to incorporate any stock parts into the system. Which of the following diagrams would you chose to plumb this system? (Thanks Wayne for the illustration.)
http://www.ffcobra.com/photopost/dat...um/VCPFuel.jpg
Now version A & B look rather simple but I worry about fuel not being able to get evenly to all the injectors, am I off base here. Version C seems like the last in line might get hungry when you push the loud pedal. Version D looks the best but I really don't want all those hoses under the hood if I don't need them. Man I suck when it comes to this stuff someone please help.
Patrick

version C
 

Patrick,
My son and I did version C on our 289FIA EFI system. We thought it best because it kept everything behind the regulator at the designated pressure, we run 45 pounds of fuel pressure with 24 pound injectors, and like you, liked because it eliminated some of the lines around the engine to make for a cleaner install. We are very familiar with the diagrams posted as we bought our stack system from Wayne at Very Cool Parts. While we ran -6 hard lines from and returning to the tank, all flex lines from the end of the hard line, fuel rails (which were the equivalent diameter of -8 and treaded for same), and flex line to the regulator were -8. We felt that this larger diameter around the injectors may even act as some sort of a mini reservoir to draw against when a large demand (WOT) was called for. We have had no problems with this end of the system.

Bill

Re Sketches

Fuel Pump should be mounted behind the fuel cell. A fuel pump likes to PUSH gas, it does not do that great a job of sucking .....

Fuel pump should be mounted lower than the fuel cell with the pick-up mounted on the bottom. Again, its easier to PUSH rather than suck the gas.

Does fuel cell have a dedicated vent?

Where is fuel filter?

Avoid any and all sharp 90 degree fittings.

Minimize the amount of fittings inside the trunk. The ideal number is 0.

Never run fuel line inside passenger compartment.

i think "c" would be the ticket, if you're worried about fuel starvation "d" would be the one.

on some of the higher perf 351's since 1 & 5 fire consecutively there is concern about starving the second cylinder of fuel if the "round the front routing" is used.

i would suggest a 100 micron filter before the pump and 40 micron after.

C is the best choice Pat
 

fasterpatrick Pat here's the thing with both "A" and "B" fuel systems. Both the deadend lines. Over time small particals in the fuel will end up in the ends of these fuel lines and go into the injectors. I have seen this happen more than once. Sometimes just an injector cleaning works and sometimes you have to replace these injectors. I like the regulator after the last injector. This one works the best to keep a consistant pressure to all the injectors no matter weather you are cruising or at WOT. You can get a lean condition with a or b setup. System "D" is the best of the 4 but too much extra fuel line in the motor compartment. I have run system "C" for 10 ten years and had no problems. Down the road you may add a supercharger or turbo, "C" or "D" will handle this better. Dead lines are simplier now for GM, FORD, and DODGE to do on these cars. They also rely on the filtler in the gas tank to keep the lines and injectors clean. I have double filters on my system with socks on the inthe tank pumps and small 20 micron filters in each line. Today you run 24 lb injectors, add a power adder and you are looking at 38-42. Do you have a fuel tank built for the car??? If not install 1 or 2, 255 Walbro pumps in the gas tank or get one with the fuel pump and filter in the tank already. You will need relays for the fuel pump with 30 amp fuse. This works better than most external fuel pumps Weldon pumps are the only ones that can lift fuel 24" if needed with good vacuum. You will need a sump of the tank with 1-2 outlets to the external pump. I am not a fan of having elbows and fuel lines hanging out the back of the car. Depending on what state you are getting the car inspected in this may not be LEGAL for street usage. Need to check your state laws. External pumps have problems with high "G" turns. I have problem when my fuel tank gets down to 1/4 of a tank with fuel starvation. 1/2 tank no problem and this gas helps with traction and keeping a load on the rear tires. Where is the fuel pump located one the car the motor came out of?? In the tank? there is a good reason. IMO and having this system, "C" is the best. I also believe in larger fuel lines. 1/2 inputs and 3/8" returns. These lines will also cover for any contections or elbows needed for the system. You will never run your motor out of fuel supply and pressure with this size. Over engineer is the best advice I can offer you for building your car.%/;):)Rick L.

Well, I have received the major components for my fuel system still need to order line and fittings. I think will have to plumb a new fitting into the bottom of the tank for the pick up or do you think the fuel pump would draw fuel the whole 12" that the tank is high. my thought was to mount the pump below the tank and hope the the siphon theory would help draw fuel to the pump.
http://www.ffcobra.com/photopost/dat...215_Small_.JPG
http://www.clubcobra.com/photopost/d...907_Small_.JPG
I hope these pictures help explain my situation and how I'm going about this project.
Patrick

Why are you mount the fuel tank so high??
 

fasterpatrick Pat Why are you mounting the fuel tank so high in the chassic. Not sure how many gallons it holds but if it's 15 gallons, thats 105 lbs of high wieght in the car. That is not a good place if you want to autocross or roadrace the car. The other question is if you are going to mount the fuel tank that high, just add a bung to the tank near the bottom. About 1" from the bottom seam. How are you going to drain the tank if say you get a bad tank of fuel?:confused::eek:I have seen this happen when gas was $4.22 per gallon. Did you look at old style GM gas tanks? They are wedged in the back and give good ground clearance coming in or out of a trailer. ERA tank is 20+ gallons, sits very low in the car. There is still a full trunk for storing things. I do have my battery also in the trunk. Rick L. Ps Pat I started withthe same pump as you(fuel) THIS is not a good vacuum pump for fuel. Works great as a gravity feed pump. It will support 1,000 HP. Paxton, Stewart, and a couple of others use the same pump with their names on it. Weldon is a better one. I started with this pump. I went to internals.