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...
