Help: Cat Bypass on '86 3.2

[ntrylvl]

Hi all,

So I'm a veteran of several Porsches, but I have FINALLY added one of the wonderful air cooled sixes to my stable.

I am looking to install a cat bypass on my '86 Targa BEFORE I install my SW chip (which I received today). I would like the group's opinions on which bypass to order. Additionally, what gaskets and/or hardware do I need to order from our host to complete the BOM for the project? Finally, are there any special considerations (oxygen sensor, etc.) regarding the installation itself? Anything special to look out for or be aware of?

Thanks in advance for your help!

[DRACO A5OG]

Get a Inexpensive Bursch with O2 Bung. If you don't like it you can go back to OEM Cat.

BTW is your SW chip a CBP Chip?

[ntrylvl]

Thanks, Draco. Yes, the SW chip is a CBP chip. I spoke with Steve before ordering it, and I let him know that I would be running primarily with the bypass, but sometimes without it if necessary. He pointed me at the CBP chip. I will check out the Bursch.

Chris

[DRACO A5OG]

If you can buy it used so you won't be out of pocket so much. Don't bother repainting it, it will burn off.

I love my CBP with SW Chip.

Yours may back fire but it is very infrequent. The added HP and Torque is priceless.

Oh one more thing. Be prepared to chisel the rust welded bolts off. Dremel is good but takes too long and you will go through many disks.

[ntrylvl]

Thanks for the heads-up. I am looking forward to the new setup. Backfires don't bother me; I'm also a 914 owner

Noted on removing the bolts. Can't wait.

One question: do I need just two gaskets, and if I order the CBP new, does it come with hardware...or do I need to find that separately?

[DRACO A5OG]

Actually, I like the backfire, makes me feel like I'm in a F1 race, LOL

You will need all three gaskets: driver side, cross over and to muffler.

I am not sure if Bursch comes with hardware new, because I bought mine 2nd hand, I bought new bolts and copper nuts.

Get some copper-based anti-sieze so you can remove the CBP for smog.

BTW, not the bolt but the nut. Once you get it chiselled loose, it will unscrew easily. don't mess with the bolt, you don't want to bend it

[Zef]

The Bursch don't come with hardware..Go to a local muffler shop and get them there...And for the backfiring concerns...I have a Bursch CBP...a Monty Free Flow 100 mm and a SW chip...never experienced any backfire with that set up.

[old man neri]

Originally Posted by DRACO A5OG

BTW, not the bolt but the nut. Once you get it chiselled loose, it will unscrew easily. don't mess with the bolt, you don't want to bend it

You would be surprised how bad they can get. On mine there was nothing to chisel loose. Just torch stuff away. Here are some pics.

These are the only two bolt heads that survived on mine.



Shot part of the bolt. I think it's the head that was torched off in this case.


This is what it looked like before the 4hr ordeal



OP: I got a used fabspeed one and I like it. I would just make sure that yours has a place for the O2 sensor. Buying a used one is a great way to save money.

Also, if yours looks like mine did it might be worth it to just spend a few $$ and get a muffler shop to pull your old one.

[gtc]

I have a used Fabspeed for sale if you're interested... $210 shipped. Quite a bit nicer than the mild steel bursch units. Let me know if you're interested.

[ntrylvl]

Graham,

Yes, I would be interested. Thanks for bringing this up. Is it in good shape, and why selling? Will send you a PM.

Thanks,
Chris

[cljsf]

I've just gone through a similar decision process. I bought a used Fabspeed for $185, though I collected it from the seller, so gtc's offer is inline with what I paid. I am yet to fit it, so can't comment on removing the old bolts.

From what I understand, a cat bypass is noisier than a pre-muffler. The cat bypass is a simple straight pipe, whereas a pre-muffler has a shroud around it that provides some noise dampening. I didn't want to completely piss off my neighbors so went for the pre-muffler. The choice there seemed to be Fabspeed or Dansk, though Ben @ M&K now does one too. I didn't want to spend $500 on a new Dansk, and couldn't find a used one, so bought the Fabspeed. I understand that the early ones had some fit problems with the flange holes not drilled in the right places but I believe they have fixed that now. If you buy a used one, you might inquire as to the fit.

You will need all three gaskets. I bought new ones from a Bay Area Porsche parts shop (Parts Heaven) but Pelican sells them too. No idea about buying them from a general muffler shop; perhaps they cut to fit?

Regarding replacement nuts/bolts, there is much written on this site about them. Will Ferch seems to be the expert and I followed his advice. I bought marine stainless steel bolts with silicon-bronze nuts. Apparently, these will not bond to each other, making the biennial removal for your smog test an easier task. The part numbers were listed on one of Will's posts and I ordered them from McMaster-Carr. Cost me $30 shipped and arrived in three days. PM me if you want me to forward you the specifics to save you from searching for them.

As for not fitting yet, I am pre-occupied with trying to resolve a charging/alternator issue. The pre-muffler is next in line once that is taken care of.

Charlie

[alf]

Originally Posted by gtc

I have a used Fabspeed for sale if you're interested... $210 shipped. Quite a bit nicer than the mild steel bursch units. Let me know if you're interested.

I am local and would buy it if Chris passes

[ntrylvl]

Thank you everyone for all of the info. I bought Graham's used Fabspeed, and I am looking forward to installing it. I don't THINK my bolts/nuts will be TOO difficult to remove based on my quick glance, but I'll see when I crawl under there....

Chris

[ntrylvl]

Graham,

Thanks again. Project complete!

Chris