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Discussion Starter #1 (Edited)
I've been trying to figure out a cheap replacement for the DX/LX 1-piece exhaust manifold cat. Honda really screwed us DX/LX owners over (intentionally) tossing in a cast iron header that is 100% gauranteed to crack around 100k miles. Buying an OEM replacement (which will crack again) will cost over 450 dollars, which is about 10x inflation. I wouldn't buy it even if it was selling for 50 bucks because the whole thing stinks. The EX doesn't have this problem since the cat is located on the bottom, and the header is connected to a downpipe. The stock cast iron header can be swapped with an appropriate steel header.

My goal is to add a steel header but that will mean I will need to find an alternate place for a cat. What are the easiest options?

http://i50.photobucket.com/albums/f334/magautoparts/Converters Regulators/18160-P2E-A12JPG1.jpg
DX/LX 1-piece header cat.

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98 civic ex coupe
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If you had to stay obd2 compliant its gona be a little bit of work. in order to run a cat in the downpipe you would need to lengthen and relocate your oxygen sensors. You have 2) one b1s1 for reading your air fuel ratios and the second oxygen sensor b1s2 is monitoring whether your catalytic converter is working efficiently. On a y7 if you got a header would your first o2 sensor be on top on the header? I have seen a few header like this you would not be getting accurate reading when the bung is off of one cylinder. the stock cast mani has the 02 in the middle so it gets an even reading of all cylinders.

I hear what your saying man. I replaced the mani/cat combo on my moms 00 lx. Ive prob done 15 of these at work. I think its the way the way honda designed the o2 sensor and manifold. They always seem to crack right at the 02 bung. You can find a cheaper aftermarket manifold and cat but sometimes they dont work well and youll set a cel for PO420 catalyst efficiency. My mothers is an aftermarket though and 3 yrs and 50,000
now and no cel.

Doing what you want to do would take a good amount of time and prob around the same amount of money as going with an aftermarket manifold/cat. But you wouldn't have the problem again if thats what your looking to do.
 

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nonvtak ftw
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Megan header - weld in cat or bolt a stock ex cat to the header and back the flange up on the catback.

password jdm 02 extension wire or do it yourself with wire and solder.
Do all this for less then the cost of replacing the stock converter manifold
 

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and if you wanted to stay stock. what makes you think that you can only get the stock manifold/cat at the dealer.. of course there going to be exensive... u can hit up ebay.. they have them for cheap brand new
 

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Discussion Starter #8 (Edited)

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Discussion Starter #9 (Edited)
If you had to stay obd2 compliant its gona be a little bit of work. in order to run a cat in the downpipe you would need to lengthen and relocate your oxygen sensors. You have 2) one b1s1 for reading your air fuel ratios and the second oxygen sensor b1s2 is monitoring whether your catalytic converter is working efficiently. On a y7 if you got a header would your first o2 sensor be on top on the header? I have seen a few header like this you would not be getting accurate reading when the bung is off of one cylinder. the stock cast mani has the 02 in the middle so it gets an even reading of all cylinders.

I hear what your saying man. I replaced the mani/cat combo on my moms 00 lx. Ive prob done 15 of these at work. I think its the way the way honda designed the o2 sensor and manifold. They always seem to crack right at the 02 bung. You can find a cheaper aftermarket manifold and cat but sometimes they dont work well and youll set a cel for PO420 catalyst efficiency. My mothers is an aftermarket though and 3 yrs and 50,000
now and no cel.

Doing what you want to do would take a good amount of time and prob around the same amount of money as going with an aftermarket manifold/cat. But you wouldn't have the problem again if thats what your looking to do.
Well that is what I'm looking for, which is a permanant fix. I was considering the V-TEC (SI?) 6th gen cat which looks exactly like the picture above, but it's split into 2 pieces where you see the weld. So I'm thinking maybe they designed it like this so that the owner can switch his iron header out for a steel one --easy swap. Still trying to find a pic...

Update: Nope, won't work. It's a VTEC-E version and it's a proprietary cast iron header. Junk.

 

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98 civic ex coupe
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go with grounded's idea. You get get a cheaper header. Lengthen your oxygen sensor wiring. It would be sweet if you found a reasonably priced y8 cat. But if you had to go with an aftermarket cat that wouldnt be bad. Ive never heard of the one you posted but it looks nice. I had a universal catco with an o2 bung and it worked great. Everybodys got there opinion on a flex pipe but i'd look into a small one with the setup your looking to make.

Do you have a catback. I dont see how a y8 cat would connect to your midpipe if its stock because you dont have a flange there like a y8 stock exhaust. You will probably need to have all this welded up. But it wont be very expensive or time consuming. And well worth it so you wont have another cast mani failure.
 

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Discussion Starter #11 (Edited)
go with grounded's idea. You get get a cheaper header. Lengthen your oxygen sensor wiring. It would be sweet if you found a reasonably priced y8 cat. But if you had to go with an aftermarket cat that wouldnt be bad. Ive never heard of the one you posted but it looks nice. I had a universal catco with an o2 bung and it worked great. Everybodys got there opinion on a flex pipe but i'd look into a small one with the setup your looking to make.

Do you have a catback. I dont see how a y8 cat would connect to your midpipe if its stock because you dont have a flange there like a y8 stock exhaust. You will probably need to have all this welded up. But it wont be very expensive or time consuming. And well worth it so you wont have another cast mani failure.
Yeah, that's what I'm doing for sure. Cheapest and most reliable. Someone on here is offering their 1-piece ractive header (non generic) but I'm not sure what size the down pipes are. 2" is OEM if I'm not mistaken.

Yeah, you're right, the exhaust pipe side will need to be cut and the cat will need to be welded. But to be honest with you, that doesn't seem like the best idea if I were to do it. I don't see why they can't just cut off the flange, then cut off the proper length of pipe, then weld the flange onto the pipe. So starting form the rear it would be: Pipe, weld, a bit more pipe, flange bolted to cat flange, cat, flange bolted to header flange.

I was told that the weld shop will just weld it all together, but that would be stupid. Cut the existing exhaust pipe to make room for cat, weld the flange on there and you've got an EX setup. Now, the cat can be removed whenever, and the header too.

Why wouldn't this work?

 

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That would work great. If you can get your hand on a y8 cat you could find the flange at the midpipe that connects the cat. Then you just weld the flange with a small section of pipe to your catback. Then you will be able to remove the exhuast and cat without cutting. You should be fine with the exhuast donut and spring bolts. flex section would be nice but its just extra insurance imo if you have an expensive exhaust or header. Sounds like you got yourself a sweet setup and it wont require too much parts or welding with the correct parts
 

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I was just figuring the welding if you got an aftermarket cat or a y8 cat were someone had unbolted it. You just gota find one were they can cut off a few inches behind the flange for the midpipe then your set.
 

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Discussion Starter #14
That would work great. If you can get your hand on a y8 cat you could find the flange at the midpipe that connects the cat. Then you just weld the flange with a small section of pipe to your catback. Then you will be able to remove the exhuast and cat without cutting. You should be fine with the exhuast donut and spring bolts. flex section would be nice but its just extra insurance imo if you have an expensive exhaust or header. Sounds like you got yourself a sweet setup and it wont require too much parts or welding with the correct parts
Okay, but are you saying I need to weld 2 of the flanges together? Because the flanges all hook up with bolts assuming I have an EX cat. So why would I bother having them weld anywhere other than the pipe? Because the way I have it drawn, the cat unbolts from the spring-bolt side and the header side. Unless... there is a problem with the spring bolts mating to the rear of the cat requiring the flanges to be welded?
 

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No flanges will need to be welded. I just meant you would buy a y8 cat were someone had cut off a few inches behind the flange at the midpipe connection. You then have the header installed and bolted up to the cat with the flanges and spring bolts. This gives you an idea of how close your cat and midpipe connection will be Then the guy whos welding has to see how much pipe he might have to add or take off to weld up to your midpipe. depending on what you have for a current midpipe. Or are you just getting a whole new catback bent up and welded. When I say welded I mean at the connection close to the flange for the mid pipe so you would be able to unbolt everything at the midpipe flange and at the spring bolts for the header connection
 

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Okay, but are you saying I need to weld 2 of the flanges together? Because the flanges all hook up with bolts assuming I have an EX cat. So why would I bother having them weld anywhere other than the pipe? Because the way I have it drawn, the cat unbolts from the spring-bolt side and the header side. Unless... there is a problem with the spring bolts mating to the rear of the cat requiring the flanges to be welded?
I said that wrong. Sorry i just meant you weld up a small section of pipe to your midpipe. So say you got a y8 cat were someone had cut the pipe a few inches behind the rear flange then you just have that welded to your midpipe and connect the two cat flanges with bolts and spring bolts for the header connection
 

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Discussion Starter #17
No flanges will need to be welded. I just meant you would buy a y8 cat were someone had cut off a few inches behind the flange at the midpipe connection. You then have the header installed and bolted up to the cat with the flanges and spring bolts. This gives you an idea of how close your cat and midpipe connection will be Then the guy whos welding has to see how much pipe he might have to add or take off to weld up to your midpipe. depending on what you have for a current midpipe. Or are you just getting a whole new catback bent up and welded. When I say welded I mean at the connection close to the flange for the mid pipe so you would be able to unbolt everything at the midpipe flange and at the spring bolts for the header connection
Why do you keep saying catback? I'm not getting a catback setup. I'm keeping exhaust stock minus the addition of a steel 1-piece header, an EX or EX style cat, and the cost of shortening and welding the exhaust pipe (mid pipe?) to make room for the cat. Or am I missing something?

And how much should the labor for cutting and welding cost? Isn't he going to have to take off the exhaust pipe to weld it?
 

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\/ apply baby lotion here \/
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Here's that Crack on the Stock y7 where OP has mentioned....


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I replaced it with a ebay Header (for a Ex)...


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All you need to do is Bolt the Flanges together then go to a Muffler Shop to Put a Cat. right after the end of the Header...
( I haven't done it yet :biggrin: )


You can see ^^^^ there's more than enough room to put a Cat there
It depends where you get a Cat. New or Used. A muffler shop won't charge you more than $25 to do the Job + the Cat.
 

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that is what i told him 500 times, pata.

he then kept asking me why it wouldnt bolt up with the stock shit. well the aftermarket header isnt a STOCK piece, so of course modification would be needed to install a cat.
 
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