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What cat for 91 Hatch with B18

Discussion in 'Civic and CRX - EF' started by luciusad2004, Nov 1, 2010.

  1. luciusad2004

    luciusad2004 Member

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    Hey guys.

    I'm gonna be having a new exhaust built for my 91 hatch and I'm looking to get a new catalytic converter. The car has an LS integra swap in it. (b18a1) The mechanic said he could just run straight pipes but i don't want to run in to any issues with inspections. I was looking at the high flow car sound cats (The Official Site of MagnaFlow Catalytic Converters by Car Sound they seem to be the most recommended hi flow cats whenever the subject comes up.) but wasn't sure what to get. Should I get a cat to match my chassis or to match my engine?

    I also noticed that they sell "universal" cats without the flanges and what not on them and that a lot people seem to be running the larger universal cats. Should I just get larger cat to match my pipe sizing? I found some integra forums via Google were everyone was recommending the 9400 series cats.

    Thanks for any input.
     
  2. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Carsound is good- I've used them in the past. You can run universals if you're not worried about just bolting up to your current exhaust- and since you're swapped to a different engine, there's not necessarily a guarantee that a standard size will fit. You'll have to see what kind of cat you have already in terms of fitment, then match it. Since you're having an exhaust built for your car, it wouldn't hurt to go ahead and get a universal that works for your emissions system, then add the right size flanges. Match the pipe diameter to your exhaust. Hopefully the collector on your header is large too.
     
  3. luciusad2004

    luciusad2004 Member

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    Thanks for the input.

    I'm looking to get the DC sports header for the LS Teg. I'm on a pretty tight budget to be honest. My cars past due for inspection and the exhaust is leaking everywhere so i just need to get it taken care of as soon as I can. I'm only looking to get a cat because i'm having the whole thing replaced anyway and mine's probably bad. Pretty much because i figure the mechanics gonna wanna just run straight pipes right through if i don't have a new cat ready for him.
     
  4. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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  5. luciusad2004

    luciusad2004 Member

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    One more quick questions.

    So as long as the cat physically fits under my car and has all the proper emissions equipment (o2 bung, breather tubes, etc) it should work right? I'm just really confused over what one to look for.

    If i search for my car (My chassis and the the car my engine came out of both use the same universal cat) they recommend a 53000 series cat. I was looking at this as it would be the same thing they list as made for my vehicle except with the 2.5" piping instead of 2"

    A lot of people around the net are saying they run the
    bigger 93000 (here) or 94000 (here) series cats.

    Is there an advantage to the bigger cats that I'm not seeing? Do they flow better? I don't see how it would considering its got a couple extra inches of material inside of it. Is it really necessary for my tiny 1.8L engine? If I plan on boosting some time in the future, would the larger cat be a better choice?
     
  6. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Sometimes you have to match the cat type up to the newer cars.

    Larger diameter = better flow
    Longer length = more cleaning

    That's about it as far as I can tell. Answer to your first question is yes. Most Civics are pretty close to passing the sniffer without a cat anyway, especially at 1991 standards- even with a swap.
     
  7. invisibledemon

    invisibledemon Bored Moderator VIP

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    unless you are going to end up boosting this car or making huge amounts of hp, the universal cat with suit you just fine.
    being that you are obd-0, the cats for your car are not as restricting as the obd-2 cats.
    the guy making your exhaust should be able to cut the flanges off of your old cat and put them on the new one to keep it as a bolt on cat. that way, later on you can change out to a test pipe if you wish to.

    ****Do not, absolutely dont, have the cat straight welded in.
    its annoying and inconvenient at times when modifying. if he says he cant weld on the flanges, go find a better exhaust guy.


    if, you do not currently have a cat to get the flanges off of, they should be able to match you some up at the shop, if they cant, then go on ebay and buy a cheap test pipe to hack the flanges off of.
     
  8. luciusad2004

    luciusad2004 Member

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    It looks like the collector on my header will be 2' with a stock size flange. if i get the direct fit cat it'll match right up and have all the flanges already on it. They aren't that much more money either. The in/out pipes will just be a half inch smaller than the universal cat. Would the flanges off the old cat work with bigger pipes? Wouldn't they be to small? Is it worth it to get the bigger piping or would the direct fit just make it easier on me?
     
  9. invisibledemon

    invisibledemon Bored Moderator VIP

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    direct fit would be easiest.
     
  10. luciusad2004

    luciusad2004 Member

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    I think im going to go that route then and just get an Direct fit Teg cat. If my header were 2.25 or 2.5 I might have gone bigger but it's not. My buddy keeps talking about just running pipes but i want the car to be street legal.

    Plus i keep reading that these things don't hold up well if I boost. This way i can easily replace it with something a little more heavy duty when i boost or if it otherwise fails.
     
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