A Custom-Built Stainless Steel Exhaust System

Last time we showed you what engine mounts were used and how the tail shafts were modified to fit.

Finding A Path

You might remember that Dave cut away the left corner of the transmission tunnel at the firewall. This was done to make room for the exhaust system. With the front tail shaft fitted, this area gets pretty tight.

The firewall cut away to allow room for the exhaust system and fuel lines.
The firewall cut away (bottom right of picture) to allow room for the exhaust system and fuel lines.

You also have to think about fuel lines and brake lines. Where will they run and how do you keep them safely away from the heat of the exhaust pipes?




There is one huge advantage with having independent suspension. Because the front diff is in a fixed position, you don’t have to give the tail shaft room to move up and down. So the exhaust can be mounted close to the tail shaft and even run underneath it.

This is how the exhaust system runs:

  • The right hand exhaust drops down and runs straight back to the muffler.
  • The left hand one drops then crosses under the front tail shaft to meet its mate.
  • They both come together then run into a muffler.
  • Out of the muffler, they split again and the two tailpipes exit out the side, in front of the rear wheel.
The finished exhaust system fits in neatly.
The finished exhaust system fits in neatly.
The muffler was mounted used existing parts. Pajero Exhaust System.
Those tailpipes look good sticking out the side!

Building The Jigsaw Puzzle

By doing this, Dave has made a path for the fuel lines. He’s kept the exhaust system over to the right side and the fuel system well away from the heat of the exhaust.

And by cutting away the corner of the transmission tunnel at the firewall, he’s allowed space for the fuel lines to sneak up behind the exhaust. They’ll of course be heat shielded as well.

The brake lines will run along the right had side, tucked up in under the body. So they’ll be far enough away from the exhaust heat.




Keeping Cool

The one place that’s slightly concerning is the gearbox. The left hand exhaust runs under the gearbox. There was really no other option. With twin fuel pumps to be mounted on the underside of the body to the left of the gearbox (directly under the new fuel tank outlet), the exhaust had to cross under the gearbox early. Again, heat shielding will be used here.

The exhaust system runs under the gearbox.
The exhaust system runs under the gearbox. Unavoidable, so it will have to be heat-shielded.

Another consideration was bash plates.

Although it’s hard to see in the photos, the lowest point of the exhaust system is just a tiny bit lower than the rear crossmember. So fitting bash plates won’t be difficult. Of course, they’ll need to be ventilated so heat doesn’t build up under the floor.

What’s It Made From?

The exhaust pipes are 2-½” (65mm) 304 stainless steel tubing. The muffler is a 3-½” stainless steel light truck, straight-through muffler.

Why this material? Well, Dave happened to have some lengths of 2-½” stainless tube and a stack of tube bends. The truck exhaust muffler was available at a discount, through a contact who repairs trucks for a living.

Remember, this is being built to a budget…




Mounting The Muffler

The original mounting brackets were cut and adapted to suit. We picked up existing captive nuts in the body and bolted the brackets on. Dave had a box of rubber isolators which we raided. Some 12mm mild steel round bar was used to make up mounting arms.

The muffler fitted and ready to go. Pajero Exhaust System.
The muffler mounted in place.
Details of the muffler mountings. Pajero Exhaust System.
Looks a bit like a three-legged spider.

The finished product looks pretty good, considering it was basically made up from bits lying around the workshop. I wonder how loud it will be…

Next time: Designing and building the air intake box.

Questions or comments? Ask away in the Comments section below.

Any errors or omissions are mine alone.


Want to know more about off road racing? Then go here.



SaveSave

Leave a comment