Eliminating Precats on an M103
 

If someone wanted to remove their precats, ( for race track purpose only) how would it affectively be done? would you have to cut out that portion of the exaust or could you just poke them out?
Thanks,
Adam

well...

1) you could order nice , new, and expensive stainless steel, euro spec downpipes from timevalve,

2) you could try to source the OEM euro downpipes, (probably marginally cheaper but more difficult),

3) you could cut them out and have a straight section of pipe substituted in, (probably not a good idea since it will be quite difficult to re-align the mounting points)

4) you could get a custom set of downpipes fabricated

or,

5) you could get a big drill or hammer and punch and a few hours of blood sweat and tears and drill or hammer the damn thing out.

I went with option 5.

Fortunately my car still passes the emissions tests, but the results compared to last year are nothing short of atrocious and i burned out a good (read expensive) Metabo 1/2" power drill in the process.

Adam- I have a set of pipes with the pre-cats already punched-out for sale. I'll let it go for $75.

If you're interesed let me know. You will need to make a CUT just before the catalytic converter, and then weld it back on.

:-) neil
1988 360TE AMG
1993 500E

Thanks for the info guys!
So, Im guessing it's quite a job to pound those suckers out. Neil, how is the condition of your set? Are the precat housings completely missing or were they just poked out from the down pipes? This was a job i was going to do myself today but lack of a lift made me pass on the job. since this is going to intial some cost..... what kind of preformance gains will i get from this mod?
Would i get $200 worth of extra performance?
Thanks!
Adam

The pre-cat insides were gutted with a very long air-chisel. Fitment is thus exact. I never dyno'd the 300TE when it had them, but it sure made throttle response better and it felt better at highway speeds or under full acceleration.

Hope that helps,

:-) neil

Adam- are you still interested?

:-) neil

I have a question. Do the early European 300E's ('86-'88) have precats? I want to know the specific differences between the Euro and US cars.

Neil,
Thanks for your offer, I really have too many projects going on right now. If you still have them in a few months I may be interested.
Thanks!
Adam

Neil----------- I have an '87 300E. Will your pipe fit my car ? Is it very labor intensive to take out my old pipe and fit in yours? I plan to have my mechanic do this. How many hours work do you estimate this will take? Do you know if European cars had these precats? Early Euro 300E's have 188HP and I'm wondering if the precats have anything do with the fact that US 300E's have 177HP.

Yes, the will fit. However, since it is one piece, you need to drop your exisiting exhaust, cut it right after the 02-sensor, and then weld on my piece with the precats punched out.

I'd figure a pro with welding skills could do it in about 2-2.5 hrs.

Some Euro's had cats & precats, some didn't. Most likely the issue is fuel & ignition timing due to the strict USA emissions.

:-) neil

I found that a reciprocating saw with a long blade would easily cut the "cat" stuff. First drill a hole for the saw blade, then cut the stuff into chunks and remove it, then finish up with a chisel around the sides. Much harder than I thought it would be but well worth it.