Removing cat for better mileage - good idea?
 

I have a 300D, turbocharged 617 engine. I've heard rumors about other cars that taking off the catalytic converter helps improve fuel mileage. Is this accurate? I talked to one of my car buddies about it, he said it might help. I also had someone suggest to me that I completely remove the exhaust system, muffler and all, and run straight pipes all the way back. I told the first car buddy about the straight pipes idea- he said it was no good because the engine needs backpressure. I agree. However, I completely forgot to tell him that it was a turbocharged engine. I would think that a turbo would provide great backpressure, without the muffler or cat getting in the way. What do you all think? Don't anyone get mad at me for polluting- the car will be run on SVO and biodiesel exclusively. :D


Cliff's notes:
What advantages would I get by removing the catalytic converter only on a turbocharged 617?
What advantages would I get by removing the stock exhaust system up to the turbo and installing full-flow pipes?

look on the door post.. it says non catalytic converter equipted... mine does.. 85 300D-T om617... just two mufflers under there..

advantages of a free flow exhaust.. loud noises..
gotta love that turbo whine
disadvantages.... loud noises

And you'll see no advantages from replacing the exhaust with a full flow system, it'll just be louder, that's all.

Odd, that's new to me. I'll have to check that out.

What, that's not an advantage? :D

Just kidding. I hate obnoxiously loud vehicles. If it gets me better mileage, though...

probably wont get you better milage.. but if you forget about this thread the placebo effect happens

First, its true, there is no catalytic converter, most diesels don't have them, because the sulfur in diesel fuel would destroy them anyway.

Engines don't really need backpressure, but even if they did, the turbo provides more than enough.

MB diesels are breathing more air than they need as it is, so bigger intakes and bigger pipes don't make much of a difference, if any difference at all. You shouldn't put on a straight pipe and expect to get an increase in mileage. It'll just get louder.

To improve mileage, make sure your filters are good, there are no fuel leaks, either at the tank, or around the injectors, or at the primer pump, make sure the valves have been adjusted, and that your injection pump is properly timed. A properly functioning turbo will also help your mileage, so check to make sure its producing enough boost.

Anyway, these things should give you something to do for now. Enjoy your car!

peace,
sam

I just went out and looked- yet, "NON-CATALYST". I took a peek under and saw the two mufflers, too. I'm still on the fence- I've heard from handful of car people that it's a good idea, but the fact that they're not cat is certainly a revelation. How loud is a 617 sans exhaust?

the car people probably own gassers...

a 617 with no exhaust.. well.. ask forced induction.. i think he is running it right out the side

Mixed story on the car people- one is gas only, the other tunes and races diesel pickups. He's the one who told me to go for the straight pipes. So it's a bit of a mixed message. There's more important stuff to do on my car right now. I'll take care of the basics before I go ahead and do something like this.

It will likely be too loud for you with just straight pipe. A single high-flow muffler is all you need if you are fabricating a new exhaust system. Probably won't get you any extra power or improve MPG's but it will definitely lower EGT's and let the turbo spool up a little faster. Not a lot of bang for your buck. I wouldn't bother unless you need an exhaust system. If you do need an exhaust system then go ahead, why not. RT