Minimum distance from fuel hose to header?
Posted by kabobkebabkabob@reddit | projectcar | View on Reddit | 33 comments
I have probably 1.5" distance between the exhaust manifold and my fuel hoses. The hoses are wrapped with heat wrap. I had a janky additional heat shield between them before but decided it was a detriment.
I've been running it like this for 2000 miles without issue and that area is open in the wheel well since I pulled the bib. But would like to hear more thoughts
Elitepikachu@reddit
That shit is fine, ive seen people run way closer than that. If you're really concerned add a small piece of that reflective shit dynamat makes or just wrap the headers.
kabobkebabkabob@reddit (OP)
Everyone goes crazy about wraps destroying headers so I will probably ball out and get them ceramic coating. But I can get about 2-3" clearance from the hard line with a little downpipe reroute then 3-5" for the rubber after that, which hopefully I can get some steel braided hose for then heat wrap them on top.
Elitepikachu@reddit
Honestly dude I say just send it. Keep in mind fuel flow through that line quickly, it is essentially water cooled. It wouldn't hurt to move the line but I doubt you'd actually change much. I'd go measure the temps on it before doing anything personally.
I've got a v6 swapped spitfire at home. The brake lines are in a weird spot and basically I have a brake line that runs within an inch of the drivers side exhaust manifold. At first I thought I would be a major issue but I measured temps for that spot on the line at only like 25° hotter than the rest of the line. I put some of that very good foil over it and even after heavy driving in hot environments that part of the line is only 5-10° hotter and I dont have any heat soaking issues with it.
Adding some reflective insulation is your best bet if you wanna do something IMO.
kabobkebabkabob@reddit (OP)
I have a brake line U-bend out of a junction coming about 1/4" or so from the downpipe flange as well. The flange is the real issue there. It hasn't been a temp issue at all (it's heat taped as well) based on my infrared gun and ofc using the brakes extensively.
Anyway, I can get two birds stoned at once by relocating the flange farther down the downpipe. It'll clear all the lines better and then it looks like I can just use a compression fitting to extend the hard lines a bit to get to my old brake hoses.
Elitepikachu@reddit
Do NOT use compression fittings on your brake lines. That's an easy way to put yourself into the wall. Just make a new line or get a longer hose.
kabobkebabkabob@reddit (OP)
I know. These are fuel lines
FalseRelease4@reddit
You could plumb in hard metal lines and use braided steel hoses for connections at either end, just plain hose and a wrap sounds janky, also you should put some shields on that exhaust
kabobkebabkabob@reddit (OP)
Factory shield didn't fit. Not sure I can get the compound curves needed out of diy
FalseRelease4@reddit
All you really need is a metal wall that creates an air gap between the exhaust and between the wall and the sensitive components, the OEM parts are complicated because they need to make hundreds of thousands with as little effort as possible, for a one off you can keep the forms simple but put in a lot of welding time and whatnot to get a functional result because youre only making these for one engine
Threedawg@reddit
The stock Fiero is about that far.
Do with that information what you will.
vVSidewinderVv@reddit
Fuel leaks were never really part of the issue of why Fiero's caught fire. It was usually caused by oil leaking onto a hot exhaust or a melted wiring harness. The iron duke engine also had a very low oil capacity (3 quarts) and weak connecting rods. Oil loss would cause engine catastrophic engine failure and possibly fires. The last reason was parking a hot car over dry grass.
That said I would still at the very least insulate that fuel line. Boiling fuel in the line is no good either.
Threedawg@reddit
Well yeah, but that makes the joke less funny
Threedawg@reddit
I know, the comment was made in jest
MagicTriton@reddit
That is scariest sentence one could say
Shot_Investigator735@reddit
The issue, if any, will be heat soak.
When running, flow through the lines helps cool. Upon shut down, no flow, and the heat shifts in the engine as it heat soaks. You may be able to have your fans run for a few minutes after shutdown. Headers cool down much quicker than cast manifolds.
I would add another heat shield, and wrap that area of the header, then call it good if it is a metal fuel line.
kabobkebabkabob@reddit (OP)
Thank you. Sounds like I need more, since it's the rubber hose section at that distance. Where I can even route it however, idk.
Shot_Investigator735@reddit
Run metal for that section, put the rubber flex elsewhere.
kabobkebabkabob@reddit (OP)
Also - is the only way to add hard line length by re running it all the way back from the tank? The ends of it are currently flared fittings to the hoses.
Shot_Investigator735@reddit
A union can be used to join two sections, you'll need an appropriate flaring tool if it's not flared with a threaded fitting. Sometimes large diameter steel line is a pain to flare. You could always go further back, add a short rubber section, then a new steel section, then rubber again.
kabobkebabkabob@reddit (OP)
Now that's an idea. Cheers
Threewisemonkey@reddit
This may be a dumb idea, but is there a way to route it through the engine bay body panel? It looks like maybe you could enlarge those holes and fiddle the hose on the other side.
I probably would’ve wrapped those headers but a little late now, I don’t imagine those are coming off easily without lifting the whole engine
kabobkebabkabob@reddit (OP)
I've thought about that to an extent but that's the wheel well, so there's not much available in that direction.
Surprisingly, I can pull the headers without having to lift the engine. I suspect I could even wrap them in while still in the vehicle.
Threewisemonkey@reddit
Do the tires and suspension go full travel and bottom out? A hardline tight against the inside of the wheel well isn’t ideal, but the sheet metal would be a solid heat shield. Just trying to brainstorm with you here lol
kabobkebabkabob@reddit (OP)
I agree with ya there. Might could work but it's a 4x4 and I just don't know what all goes on in that fender when I'm wheeling lol
Poil336@reddit
I've run them that close
Warren1317@reddit
Bro, you want all your lines (may they be fuel, electrics, or brake lines) as far away from the exhaust as possible. No excuses to run something that burns next to something that heats up. Sure, while you build it, they ain't touching, but think about driving that car, hitting bumps, etc, with the vibrations or, even a collision, everything will move even from just a inch, and that can be a huge problem.
Other issue is that your fuel gets less dense as it heats up, so it can cause erratic fuel management, so less performance.
kabobkebabkabob@reddit (OP)
Do you have a minimum clearance reference? This is as far as it gets right now. Very few potential paths.
Warren1317@reddit
You know how engine bays have got cold side and hot side? It's much easier on straight engine. If you check a E36 or E46 engine bay, you see that the engine is engine to like 45° degrees, with the exhaust shoved under the car. The rest of the engine bay is the cold side, with intake manifold etc. You want the fuel line on this side obviously.
Now, thing is, you got a V8 engine, so the bottom of the engine would be your hot side with the exhaust headers. While the top would be the cold side.
You can't really have the fuel lines go on the side because of the exhaust, nor in the center because of the bell housing.
It's a bit complicated to help because idk the layout of time engine bay, but have you considered wrapping your exhaust, plus using heat shield, and making sure your fuel lines are going as far away as possible? Can't throw away numbers like that about safe distance, it depends on so many things
kabobkebabkabob@reddit (OP)
I'm aware of all of that though I do appreciate it. All factory lines are pulled as far as they can realistically go and I still need to further finesse a brake junction. I can maybe skim another inch out of the fuel hose but I think I'm gonna have to do like another commenter said and re run new line from the tank to get it all the way past the header.
I have considered an exhaust wrap though I've heard mixed things. I have some wrap from an old bike project laying around.
Waltersobchak1911@reddit
Dawg, spend $50 and an afternoon and just move the fuel line. Laziness = your car burning down. Why take that chance?
kabobkebabkabob@reddit (OP)
Lol you might be surprised at how difficult it is to find adequate clearance to get things where they need to go on a 32v dohc V8 swap into a small bay.
But that's why I'm here asking. If I need to do it, I'll do it. But information out there varies wildly.
zeed88@reddit
I don’t know which one is the fuel line but you need to shield the exhaust from everything else, fuel and brake lines and electric and plastic stuff
kabobkebabkabob@reddit (OP)
I will be adding to those now that I've removed the previous metal shield.