Planning Fuel System

[John McIntire]

Ok guys, here it goes. I've been planning out my fuel system in my head. Let me know if this will work. I plan on coming out of the fuel cell and running the feed up the passenger side frame rail up to the back of the passenger side fuel rail. From there it'll run up the fuel rail towards the front, crossover to the front of the drivers side fuel rail over the thermostat housing. Then at the back of the drivers side fuel rail, I plan on installing a regulator, and then have the return line run back down the drivers side fuel rail to the fuel cell.
With this design, The fuel rails will always be under pressure and second, it kind of cleans up the install a bit. I'm not too worried about fuel rail "shock" because I'm running sequential.
Let me know what you think!
John

[John McIntire]

36 views and no opinions? I'm open to all info and suggestions!
john

[ProStreet R/T]

fuel shock? whats that?

If thats how you want to route it, it will work fine. I personally run the feed/return lines together just to keep it easy, but w/e floats your boat.

How much HP are you planning to make? What size feed/return lines?

[Fuelie Fan]

I think what he is referring to is fuel rail harmonics. It's why returnless systems still have to run dampers in the fuel rail (that thing that looks like a regulator, but isn't)

What you described should be fine. It could be improved with a second crossover, but probably not necessary. Also, I tend to agree that it's cleaner if the lines are run along the same path, not on opposite sides of the car, but that's personal preference.

[DeltaT]

I like it. I ran the fuel return line, well insulated, over the tranny and back the same side as the feed, but I'm getting some pretty warm fuel back and am thinking of moving it to the driver's side rail.

I think you can still get harmonics or fuel shock at higher rpm with sequential, since the pulses are so long they start overlapping. At 6000rpm the fuel pulse can be happening over 80% of the time, depending on your injector size.

Jim

[John McIntire]

Thanks for the responses guys! Yeah, I guess I could run the return back on the passenger side, but I just figured that since i was over on the drivers side anyway, I would just run it back that way.
As far as fuel shock, I never really thought about it in the upper RPM ranges. My engine redlines at 6 grand, and I dont spend too much time up there anyways.
Thanks again, and let me know if you have some more ideas!
John

[EFI69Cam]

Insulate and keep fuel lines as far away from heat sources as possible. I almost rolled my car off a cliff from frustration at vapor lock caused by exhaust heat.

[Fuelie Fan]

EFI, especially MPI and sequential systems running at 3+ bar, isn't as senstive to vapor lock but it certainly does happen. One of our customers had serious issues in a 240Z he converted and it ended being a heat issue, so yes do avoid heat sources as much as possible. Good point.

[DeltaT]

Or you could do it the way I ran mine:

A -10 from the fuel cell to the pump

-10 from the pump up the pass. frame rail to a Y-block

Two -8 lines: One to the front of each rail. No crossover.

Two -8 lines: One each to a port on the regulator

One -8 Return line back to fuel cell

This pretty much eliminates the 'fuel shock' problem, because each line has their own feed.

Jim

[ProStreet R/T]

Or you could do it the way I ran mine:

A -10 from the fuel cell to the pump

-10 from the pump up the pass. frame rail to a Y-block

Two -8 lines: One to the front of each rail. No crossover.

Two -8 lines: One each to a port on the regulator

One -8 Return line back to fuel cell

This pretty much eliminates the 'fuel shock' problem, because each line has their own feed.

Jim

And that ladies and gentlemen, would be the RIGHT way to plumb a fuel system. Dual feed in/out with the regulator on the return side.

[Fuelie Fan]

This is not much different, functionally, from running crossovers front and rear, it just brings the junction points away from the rail. It's an improvement I suppose, but not sure it's really necessary. Just as long as your system doesn't have a dead-head where standing waves can form, you'll be fine. Plus, if you were to have problems with harmonics, it's a lot lighter and cleaner to add a damper than all that extra line.
Also, your lines sound pretty oversized (unless you're making 4 digit horsepower!)

[DeltaT]

I built everything to be able to upgrade to a YSI blower at the track, which will put it within striking distance of the 4-digit mark. Plus I have 2 stages of nitrous plumbed but not wired yet. Better a little large. You never hear about someone having a problem because their fuel system has excess capacity, right? But you sure hear about the reverse.

I like the German philosophy - overbuild and understress. Emphasis on reliability.

Jim

My Site: http://home.mindspring.com/~jim_fisk/id1.html

[GetMore]

I like the German philosophy - overbuild and understress. Emphasis on reliability.

Except for electrical systems, where the wiring is just big enough. The Germans must be short on copper.