2005+ Tacoma: is aux fuel tank opposite existing fuel tank possible?

[ntsqd]

I've never liked the idea of tanks in series. In this scenario you either have a pump or a valve to allow fuel in the second tank to flow into the first tank. What happens if you overfill the first tank? A system like this requires your attention when you may need to be paying attention to other things. Quite some time ago I was told that this sort of system had been federally outlawed for passenger cars and light trucks (pick-ups). During the 70's fuel crunch enough folks managed to catch themselves on fire that it brought an unfavorable light to the design. Whether or not what I was told about the legality was correct or not I still see it unfavorably.

Tanks in parallel are a safer way to go. There are selector valves that divert both the supply and the return lines. These were commonly used on U.S. pick-ups with dual tanks. Series 80 LC's have an aftermarket tank available with a dual-fill filler tube. So opening one cap allows the filling of both tanks. This could easily be made by someone competent. In the case of the 80 series unit there is no nozzle restrictor. In a fabricated fill tube one could either place the Y below the restrictor and allow the primary tank to fill first and then 'spill' over to fill the aux tank, or a restrictor could be placed in each fill tube.

[fbksurferjoe]

I have an aux fuel set up that you might consider, I purchased a marine topside fuel tank and mounted it in my roof rack also in the roof rack i mounted a solid state electric fuel pump with an inlet and an outlet all enclosed in a nice aluminum box. The inlet uses a marine type connection to connect to the fuel tank and the outlet runs between my cab and camper all the way to my tank fill. A switch inside activates the electric fuel pump. It is worry free, low profile and the idea of it being top heavy I have not run into thus far. I can also fill while i am driving down the highway if i feel like it which is a nice feature. For under $300 i think it works pretty well. If you are interested ill snap a few pictures when i get a chance and post them up.

[alfio]

Originally Posted by slooowr6

on http://www.fjcruiserforums.com/. It's deep in one of the thread about man-a-fre aux tank. I don't have a link to that thread.

took some work but i found it: is this it? i think so. anyway, it answers what i was looking for

alfio

[Switch]

I just found this post http://forum.ih8mud.com/79-95-toyota...88-runner.html

There is a pic of exhaust running right next to fuel tank. Hard to tell how close exactly...

The tank is above the spare, which is an interesting approach in and of itself. I've looked at this location, just seems too small without leaving the spare too low.

[Switch]

So here's one option I've been looking at.

What I'm trying to figure out is the clearance for the exhaust pipe and the sheilding needed for the muffler in this location.



Here is another design I'm trying to figure out if will work (using two Hushpower mufflers)...
here's a sound clip of a Taco with 1 hushpower muffler, I think using two would work better
http://www.youtube.com/watch?v=cCvZHD3zReo

[Switch]

Also, here's the layout for the pollak fuel selector. I have not been able to find a write up of this installed in a Taco, but this would separate the two fuel tanks to prevent the CEL that have occured with tanks in series...

[keezer36]

This link from the manual looks to be the pressurization test which allows for up to 15 minutes to pass depending on how much gas is in the tank. I don't know how robust this pump is but 15 minutes seems like a good bit of time.

http://www.ncttora.com/fsm/05+/data/...ta/0050035.pdf

[Switch]

Originally Posted by Switch

So here's one option I've been looking at.

What I'm trying to figure out is the clearance for the exhaust pipe and the sheilding needed for the muffler in this location.



Here is another design I'm trying to figure out if will work (using two Hushpower mufflers)...
here's a sound clip of a Taco with 1 hushpower muffler, I think using two would work better
http://www.youtube.com/watch?v=cCvZHD3zReo

The way things are going, I think this thread is going to turn out to be a build thread. I went to a local muffler shop today (Allied Automotive) and spoke with their exhuast guru, Justin, about the two options above. He said that either could be done. We'd just have to use header wrap for the length of the exhust pipe to control the heat. He said the header wrap would knock a couple years off the life of a pipe due to corrosion. He thought that the dual Hushpower design we preferable because it would be the quieter of the two designs. He also said that the existing carrier berring would not be a problem becuase there is enough space to route the pipe between it and the existing fuel tank.

So it looks like I have an answer to a few of my questions:

1) How close the pipe can be to the tanks and drive shaft? How much can heat sheilding mitigate this?

A: There is enough space to locate two mufflers immediately after the cat, with a Y pipe above the drive shaft, and exhaust pipe runnign straight back from there to accomodate an aux tank.

2) If muffler is moved forward. Is that going to result in heat blowing over the tank and causing problems. How much can heat sheilding mitigate this?

and

5) Can two smaller mufflers be placed before the y pipe? (bonus eliminates that stupid low hanging crossover pipe).

A: With the existing Bent-Up gas tank skid (and a second one fabricated for the aux tank) heat from the mufflers should not be a problem.


6) Would this degrade performance?

Answer: I still don't know. From what I've been reading the best thing from a performance perspective would be to replace the left cat with the same part as the right cat so that they both have the same 2"diameter (the left cat out pipe is 2 1/2" in order to accomodate the stupid oversized crossover pipe). This would allow the installation of two Hushpower mufflers with 2" in/out so I'd have 2" pipes all the way to the Y pipe and only minor bends in along the way. From everything I've read this should improve performance, having fewer changes in diameter and fewer turns.
On the other hand without an H pipe before the mufflers, I may be sacraficing "scavenging effect". As I understand it the "scavenging effect" is a "precussion" rather than an "exhaust flow" consideration, it is not clear to me if the proposed design is flawed in this regard or not. I suppose I should just plan on getting dyno readings before and after to find out how much the performance was changed. If the H-pipe is really that important, it could certainly be added to the design under consideration. Like this:


For my application this may not matter that much since the biggest torque improvement I could get would be to go back to stock tire size or regear.

As a side note from everything I've read, the whole back pressure debate is moot for fuel injected engines, so I'm not to wraped up in that issue.

Note: If I go with this design for the exhaust, it might be possible to fit an OEM tank on the passenger side.

Assuming the exhust fitment problems are solved, I'm left with tank fitment and integration to OEM fuel system as the next big problem to tackle...