Catalytic converters, aftermath…

So, what did we accomplish?

  • The exhaust is 7kg lighter
  • It can now take a beating since the the core is metallic and not ceramic
  • It flows better (no idea if it will make a difference)
  • The sound is more sharp, metallic like

Will be posting a “soundvideo” as soon as we can get it out of the garage, was a snowstorm 3 days ago. Waiting for spring…

Final chapter, catalytic converters

Get the lambdas mounted, used some copperpaste on the threads, will probably not make any difference, but felt good:

Since a few years I always mount my exhausts with stainless steel bolts and washers and lock nuts made from copper, absolutley brilliant, they will look brand new when the car is in a museum, I also prefer Allen bolts or Torx, but not always possible

Also stole the mount from the old catalytic converters:

I am happy with the result:

Also managed to weld the crack in the rear part of the system, need to do something about this next year, two cracks and almost no material to weld, but it is fine for now:


Catalytic converter, finish straight…

Time to get going again, cut away and replace the second catalytic converter:

Make one end of the bend oval and a lot of adjustments for the angle:

Get everything back in the car for trying out the fit, again….

A lot of TIG welding and some grinding later, you can also see that the catalytic converters have Weld bungs for the Lambda, I could not use these, fortunately they came with plugs, I had to buy new ones and weld them in on the bends so the wires would be long enough:


Welding the catalytic converter

Get everything back under the car for tryouts:

I use an ordinary electric welder with stainless pins to spotweld in some places, later I use a TIG to weld it completely around. I am still learning the TIG, my welding is not the best, but at least no leaks.

Started TIGgin:

It is good enough for an exhaust:


Old VS New:

Lets leap forward to next task…

…catalytic converters. I hate pre 2000 catalytic converters. They are bulky, heavy, usually have a ceramic core, restrictive and most of all ugly, I basically hate everything about ceramic core catalytic converters. I have written quite much about the subject in a previous post, so let’s skip to the actual task.

Raise your car, the water is not from this one…:

These are the culprits:

Loosen everythin at the end:

Make sure to unscrew the conntectors for the Lambda sensors, you don’t want half your exhaust hanging in those wires:

Separate the front from the downpipes:

Get everything in the middle out of the way:

And you will end up with this:


Catalytic converters

The new catalytic converters have arrived. The Original ones are heavy, bulky and have a ceramic core. During the 90’s this was the way to go, I am sure there was metallic core ones around, but they were probably too expensive. The ceramic core does not like vibrations, it comes loose, cracks and gets blocked up. Catalytic converters are very hot and when driving in wet conditions they might get sprayed, well, everyone can imagine that it is not good to have parid cooling aswell.

Conclusion, there has happened a lot in this area in almost 20 years.

If you want to find out if your catalytic converters are blocked you can unscrew the Lamda sensor (also called Oxygen sensor) in fron of the catalytic converters and use a fuel pressure gauge to measure the exhaust pressure. Should be basically none up to 2000 rpm, this can also be felt with just the finger, if pressure = blocked.

On this car, I have not measured, we want to save weight and make it better, besides, I have my suspicions that at least one of them are blocked, so we will just replace them. Need some 63 mm piping (2,5″), a straight piece and 3 pieces of 30 degree bends. Of course stainless steel and some welding equipment for this. 2 pieces of catalytic converters, basically I treat the engine as 2 straight 6 cyl engines of 3l (in this case 3,6l, but it passed inspection with original ones, so…) when dimensioning them. Decided to go for 100 CPI (100 Cells Per square Inch) “race” catalytic converters. I like the ones that is made from a pipe and not two pieces of flat metal joined together. Also, these ones have the Lambda sensor thread already fitted, makes it a lot more easy.

We will get back to this later.