incomplete

UPDATE!

so, after doing my homework i found that there is only one aftermarket cat that is legal for our cars in CA:
http://www.summitracing.com/parts/MPE-36106

i have that, some piping and adapters in the mail now!

---------original post---------

long story short:

my current cat is a 2.25", and is completely monkey-patched in to my exhaust pipes (3").



i also want to install a wideband, but don't feel like disassembling everything to get the downpipe off.

here's the solution i'd like to run by you guys:

1) cut out and replace the old cat w/a new 3" one, and replace that horrific shim job w/new 3" pipe segments.
2) move the wideband o2 sensor back a few inches so that it's installed on the new exhaust piping

questions:

* will (2) affect my A/F readings? i can't see how a few inches could mess things up all that much, if at all
* the car will be streeted, so i will need a cat that will let me pass CA smog. does anyone have any recommendations? i was digging around summit racing and found a bunch that are about $1k cheaper than pelican parts.

fortysixandtwo

Moving the wide band back should not change the reading.
For CA smog, assuming your area has the same regulations as the LA area, you will need to get an approved converter for the car. This means you're stuck with picking from a list the government came up with, and I do not believe any 3" converters are on that list.

schip43

Maybe a Diesal truck or a truck V10 cat? No idea just throwing it out there.

V2Rocket

Walker brand cat has a 2.5" inlet/outlet, you might be able to get that expanded closer to 3" at a good exhaust shop. This is the CARB approved cat for a 951.

http://catalog.walkerexhaust.com/cat...dStatus=ACTIVE

incomplete

i clicked through, and it shows specifically that it's for the 944 N/A. wonder if this would be a big deal? no price either, but i guess i'll call tomorrow and check on both of these things.

also: i've got a great shop lined up to do the work, so i'm not worried about making things 'fit'.

thanks for the lead! this is the last thing blocking my smog (though i could just do it w/o the AFM).

incomplete

word.

btw, the CARB site is literally the worst design i've seen or used since 1998. wtf.

V2Rocket

their NA converter is round. i know because i have one. i was just clicking through their site yesterday because i am considering a 951 catback. that one i linked to (or attempted to link to, part 80508) is listed for an 86 951.

bw993

Magnaflow makes a CARB CAT for the 951. I think the number is 36106 and it's 2.5" inlet.

Tom M'Guinn

Plain English description of new rules here:

http://www.bar.ca.gov/80_BARResource...C-summer08.pdf

Lots of good info in the magnaflow catalog:

http://images.magnaflow.com/02catalo...ca_catalog.pdf

As I read it, the 951 takes a PC-1 (passenger car, one converter per cylinder bank), CARB-approved converter or an approved direct fit replacement. Based on that, if you don't use a direct fit replacement like the one sold by DEC, it looks like you could use a universal Magnaflow 36009, which is shown on the CARB-approved list here:

http://www.arb.ca.gov/msprog/aftermk...xemptcat09.pdf

Info about the converter here:

http://www.magnaflow.com/02catalytic...alCARB/360.asp

It's about $210 at summit:

http://www.summitracing.com/parts/MPE-36009/

This is a 3" converter. The CARB list linked above only references the type of vehicle (PC-1) for pre-OBDII cars, and does not reference the specific car or original pipe size. However, see the first question on page 4 of the CARB Q&A linked below that says you cannot adapt pipe diameters.

http://www.arb.ca.gov/msprog/aftermk...tallcatq&a.pdf

Since the exemption for that converter only lists PC-1 cars and doesn't specify a particular model, it's not clear if the no-adapter rule applies to pre-OBDII converters. The 3" pipe might violate another regulation against pre-cat exhaust mods though. Chances are slim you'd be failed for the pipe diameter only but if you wanted to eliminate doubt, you could use the 36006, which has a 2.5" inlet/outlet or try calling ARB at their 800 number.

Be sure it is installed in roughly the same locatation as the stock converter and that the CARB stamp is facing down and visible:

http://arb.ca.gov/msprog/aftermkt/de...o/D-193-86.pdf

incomplete

dude. beer's on me. date and place, please?

ps - someone sticky this?

Tom M'Guinn

Just hope it helps. I've spent a lot of time trying to make sense of the new rules, although I largely punted last month and just installed a DEC direct-fit, which passed smog with super low numbers. It's an ill-fitting, poorly-constructed converter though... Sorry I wasn't able to stop by the other weekend -- trust you got the DME/KLR boxes you needed. If not, just let me know. As for beer, maybe a south bay get-together is in order one of these weekends...?

incomplete

you're streetable? i'll post something in a couple of weeks.

Tom M'Guinn

Yes, car is up and running -- at least until my next experiment -- and 100% street car.

ibkevin

PM me if you have more questions, we'll talk. I went through the wringer on one of my inspections.

Kev

incomplete

UPDATE!

so, after doing my homework i found that there is only one aftermarket cat that is legal for our cars in CA:
http://www.summitracing.com/parts/MPE-36106

i have that, some piping and adapters in the mail now!