05+ strangely placed exhaust

[CoTacoTRD]

OK. So on Saturday all previous plans fell apart and I was left with.... well nothing to do. So I decided it would be a good day to do the Rear Diff Breather extension mod on my truck. Headed off to my father's house (I don't have a garage and he is a mechanic so he has just about everything in his garage) and did the mod. I brought the breather up into the gas door encloseure to keep it high and dry but to also keep an eye on it from time to time.

That being completed I was rolling around under the truck on the creeper trying to figure out where to move the exhaust pipe that is bent and flattened under the crossmember on these trucks. As I started looking around I believe I have figured out why Toyota did this. At the point where it crosses over the fuel lines run down the inside of the frame rail. Also it crosses over at a point where you can remove the T case and everything else without removing the exhaust. The only place I can see to run the exhaust better would be to run it down the drivers side within 3"s of the fuel lines and then cross over the the passenger side at the the carrier bearing on the two piece drive shaft. This should allow me to access the carrier bearing still but actually keep the exhaust in the frame rails and not hanging down. One extra hanger would need to be welded to the inside of the frame as I turned to go under the carrier bearing.

My only question is about the fuel lines. I see that they are still a metal line but now wrapped in rubber. The portion of the exhaust that would run near them is after the cat on the drivers side. Do you guys feel that there would be any issues between the exhaust and the fuel lines if I ran it this way caused by heat from the exhaust?

I know I should have gotten pics but forgot the camera.

[00regcab]

Exhaust will get hot enough to POSSIBLY boil the gas, you can get some 'heat shield' stuff that has an adhesive back on it, unbolt the fuel lines from the frame rail (to pull them away from the rail), and possibly wrap a layer or two around the lines and you should be good. But im not 100% sure on that.

[fjcruzer]

First thing that comes to mind is collision safety. Crash: break fuel line in proximity to really hot exhaust: BOOM!

But yeah, pics would be nice :) I've been wanting to figure out the same thing for the FJ, but have been too lazy to map it out.

[00regcab]

I dont think the exhaust would be hot enough to spontaneously combust if fuel was dumped onto it, but it is a possibility i suppose

[fjcruzer]

I dont think the exhaust would be hot enough to spontaneously combust if fuel was dumped onto it, but it is a possibility i suppose

Let's try it :D:flamethro

[00regcab]

Mythbusters anyone? :p

[Avsfreak1234]

discovery.com/mythbusters

Ive been wanting to email them about the drafting myth they did. I want to see if me tailgating soccer moms in their minivans improves my mileage as much as when i get in a semis blind spot :D

[ike]

Pretty sure the exhaust, especially around the cat is hot enough to ignite fuel vapors.

[CoTacoTRD]

The new exhaust if ran would start about 1' after the cat and the cat would stay in it's current location. Funny thing is Toyota didn't place any other heat shields after the cat as if it is the last spot of intense heat maybe? The fuel lines are inside the frame rail but actully attached to the bottom of the truck. I was thinking some more last night and could gain some more distance from the fuel lines by putting a small s in the line after the cat and moving the exahaust further toward the center of the truck. But then the exhaust hanger that would have to be installed would become more tricky. I guess one thing I could test is the tempature of the exhaust after a good drive right after that cat to see what sort of temps I am getting. Also would be good to get some pics so I will work on that once the ground dries this week.

[Jacket]

Isn't Bud's down in the Littleton area? I've heard that place does magic with exhaust work, and I'd be interested in hearing what opinions they have about the issue.

Good spot on the fuel lines - I hadn't noticed that before. Personally, I wouldn't put a hot exhaust near them. Any chance of running a pipe outside the frame rail (but above a slider)? I've seen some Land Cruisers set up like this.

[CoTacoTRD]

Isn't Bud's down in the Littleton area? I've heard that place does magic with exhaust work, and I'd be interested in hearing what opinions they have about the issue.

Good spot on the fuel lines - I hadn't noticed that before. Personally, I wouldn't put a hot exhaust near them. Any chance of running a pipe outside the frame rail (but above a slider)? I've seen some Land Cruisers set up like this.

I will have to check in with Bud's and see. I couldn't see a way to get the exhaust outside the frame rail unless it was moved from the header down. I don't really want to do that. But I also wasn't looking at that as an option. I need to get some pics up on this topic. Let me see what I can do.

[CoTacoTRD]

OK. Now for some pics:

This is the exhaust from the front and you can see where it crosses over to the passenger side under the T case and it actually hangs lower then the crossmember. The point on the left is where I would like to come straight back.
http://i243.photobucket.com/albums/ff242/cosport/Exhaust/DSCF2356.jpg
This shows you where the fuel lines are located on the drivers side.
http://i243.photobucket.com/albums/ff242/cosport/Exhaust/DSCF2360.jpg
This is further back and where I would like to run the exhaust back over to connect with the passenger side. I am thinking it can follow below that crossmember and still be between the frame rails. It should allow for access to the carrier bearing still.
http://i243.photobucket.com/albums/ff242/cosport/Exhaust/DSCF2366.jpg
When taking the pictures I noticed that the fuel lines actually continue right up behind the heat shield next to the cat. One of the hottest points on the exhaust. So obviously Toyota isn't concerned about the heat on the fuel lines provided I put some sort of heat sheild on it.
http://i243.photobucket.com/albums/ff242/cosport/Exhaust/DSCF2362.jpg
http://i243.photobucket.com/albums/ff242/cosport/Exhaust/DSCF2358.jpg
This shows that the fuel lines are still there at the point coming off of the header.
http://i243.photobucket.com/albums/ff242/cosport/Exhaust/DSCF2364.jpg

So if I come straight back off of the cat I will be between the frame rails, clear the T case no problem, and be about 4"s away from the fuel lines. So I am thinking I can take a heat sheild wrap and wrap the fuel lines just in case like Nate suggested. I can cut off the one exhaust hanger at the point where it turns now and if possible reuse it at the new point where it will turn. Then have slight dip under the carrier bearing to insure clearance but still be plenty above where it sits now and connect back in on the passenger side to a new MagnaFlow Exhaust. Then just have it bend over the axle and stop there instead of coming all the way out the side so it can get crushed.

So what do you guys think? Will this be OK? Or am I still looking for trouble being near the fuel lines.

What is the stuff that race car drivers use to cover their exhaust? Is that a heat shield? Could I use that to cover the exhaust along the fuel lines instead of covering the fuel lines themselves? Just a thought.

[ike]

Are you sure all of the lines near the exhaust are actually fuel lines, and not brake lines?

[00regcab]

You should only have 2 fuel lines.

1 feed, and 1 return

At least, this is how I've seen it

[CoTacoTRD]

I have traced all three back to the fuel tank. Now I know that on these Taco Toyota put some sort of pressurization system in to keep the line pressurized. Every now and then the fuel pump will kick in about 5 hours after the truck has shut off to keep pressure. That third line that is slightly larger then the rest could be electrical but yes they are the fuel lines.

[CoTacoTRD]

Are you sure all of the lines near the exhaust are actually fuel lines, and not brake lines?

I believe the brake lines in the second picture dipping into the frame and back out. Also in the forth picture as the squigally lines on the left side of the picture. They are smaller then the other lines pictured.

But you have me doubting myself so now I want to double check this. If I did have this backwards and the 3 lines on attached to the cab were brakes could that be an issue with the exhaust?

[ike]

If you traced them to the tank then they are fuel. on the older trucks there are two brake lines and a fuel line bunched together on the one rail, and i think it is the same on the other is the only reason i brought it up. You will want to sheild both. boiling brake fluid is no fun.

[CoTacoTRD]

Yeah but I am going to look again this weekend to be sure. But after seeing Toyota 700's vertical dual mufflers I am starting to rethink this and just have the new line come back to a second muffler like he did so long as they are small and don't hang down further. That would make for some good flow just don't know what it would sound like with 3 cyl. coming down the pipe. I want to keep it somewhat quite.

[RedRunnertc]

You can put a H-pipe in there when they get closer together to smooth out the sound some and dramatically increase the flow.

[mrdoug]

How are you guys dealing with the 02 sensors post cat when running dual exhaust?

[CoTacoTRD]

When I looked for them on mine there weren't any O2 sensors post cat because that was a big concern of mine as well. In the picture that shows the pipe coming down from the header I see what appears to be a second cat on that bank. So I am thinking that I have a total of 4 cats and that the O2 sensor is somewhere inbetween the two of them but there is nothing after the last set of cats.

H pipe or X pipe? I have seen both. I understand how they help smooth out the sound but what I don't understand is how they help with flow. Having exhaust come crashing into each other doesn't seem logical to increase flow.

Who has the answer?:confused:

[RedRunnertc]

You have to think about the flow as a series of pulses, not a constant flow. Because of the firing sequence, the crossover allows the pressure pulse from one side to kind of bleed off into the dead space between pulses on the other side, dramatically increasing the amount of exhaust flow that can be carried.

[CoTacoTRD]

^ That makes good sense. Thanks!