NA2 Exhaust install in NA1

I am installing a complete NA2 exhaust system in my 91 NA1. I have the headers, heat shields, O2 sensors installed and connected. I swapped the O2 sensor location since neither one was long enough for the new headers. I made the extension pig tails out of two used O2 sensor harness connectors from the salvage yard. One was about 8 inches and the other was about 6 inches.

I am currently at the point of installing the NA2 cats. The rear sway bar is in the way. Am I going to have to find a NA2 rear sway bar, or does the NA2 use different brackets? How about the hangars for the NA2 cats? The NA1 cats don't have any hangar mounts on them. I would like to do it right.

Brad

I know you want to do it right, but one alternative if others here don't come up with some fixes is to just remove the rear sway? Try it at least, I personally like it.

Hey Brad- strut bar's on the way...

Mac Attack said:

just remove the rear sway? Try it at least, I personally like it.

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I have heard of doing this. I will give it a try. I was looking at that possibility when I was laying under the car yesterday. If I remove the sway bar, what do you do with the link that attaches the sway bar to the strut?

Brad

Buy SOS adapters and keep NA1 exhaust. That is what I did. If NA2 headers are from 2000 to 2005 one of the adapters will need minor fix. Larryb installed 2002 headers on my 94 nsx. He is a good guy. You can PM him. NA1 engine likes NA2 headers.

davidg said:

Buy SOS adapters and keep NA1 exhaust. That is what I did. If NA2 headers are from 2000 to 2005 one of the adapters will need minor fix. Larryb installed 2002 headers on my 94 nsx. He is a good guy. You can PM him. NA1 engine likes NA2 headers.

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The headers came off of a 98 model. I picked up a pair of NA2 cats since I didn't want to have to do all of the adapter stuff. I was just going to go OEM for the whole system till I found a used, very little, ARK DT-X exhaust up in the Seattle area and was able to pick it up. It had the adapters with it for the NA2 style connections. The problem I ran into was the hangars for the NA2 cats and the NA1 rear sway. I think that I have both of them solved. I'll even attach a pic of the headers.
Brad

Nice parts. Keep the sway bar.

Brad,

Those exhaust parts look like junk. Send them to me and I'll test them for you.

Did you jet hot coat the headers or something, can't imagine they look like that from honda.

1995-2001 have a different sway bar to clear the updated exhaust.

I know I have a set here, let me check if they are 1995+, I recall them coming off a 1996. If they are the correct fitment, you can have them. They are not stock bars, they may be Dali.

Regards,
LarryB

amengineering said:

Did you jet hot coat the headers or something, can't imagine they look like that from honda.

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That would be nice if they came from Honda like that......Brad had them coated a couple of months ago. Nice, huh?

amengineering said:

Did you jet hot coat the headers or something, can't imagine they look like that from honda.

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Yes, they are JET HOT coated. I am now a dealer for them so if anyone wants to do any ceramic coating with them let me know I can save you 15% off of list. Drop me a PM. They really are nice. It's just too bad that once I put them on nobody will see them. Oh well, I'll know they are there.

Maybe I will have to put some hydraulics on my car just so I can show off the headers and exhaust!!!! LOL, LOL.......NOT!!!!

Brad

Larry Bastanza said:

1995-2001 have a different sway bar to clear the updated exhaust.

I know I have a set here, let me check if they are 1995+, I recall them coming off a 1996. If they are the correct fitment, you can have them. They are not stock bars, they may be Dali.

Regards,
LarryB

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Larry,
I really appreciate the offer, I think that I am going to go with a Zanardi rear sway bar. I have a NSX-R front sway bar and from what I hear the Zanardi rear bar would provide good balance for the car. Thoughts????
Brad

I am about to do the same with the 97+ headers. How much did it cost to coat them or how much would it cost me? I have a problem with bolting rusty parts to a car even if you can't see them. I was at least going to spray them with a ceramic paint but after seeing those I think I have to do that, plus its actually functional and I could lose the heat shields. I think I am going to make the test pipes and header extensions so I would need those coated too. Anyone got a set for cheap that fit? I don't really want to waste time with the dali ones if they don't fit right and don't want to pay that much for the SOS ones. Good luck with the project.

OLDMNSX said:

Larry,
I really appreciate the offer, I think that I am going to go with a Zanardi rear sway bar. I have a NSX-R front sway bar and from what I hear the Zanardi rear bar would provide good balance for the car. Thoughts????
Brad

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I have almost the same setup as you. I have a NA2 header set, w/ NA2 cats and a custom exhaust made for 95+ NSX (which fits the same as 97-99 NSX).

As you found, the 91-94 rear sway gets in the way. Get the rear Zanardi bar to solve this problem.
I currently run the front Type R bar w/ the rear Zanardi bar. It's a good combo.

Regarding exhaust hanger/brackets. You are correct, your NA2 cats have additional hangers. You will have to buy two more brackets and bushings (not sure thats what they are called) to have a complete OEM look. That's what I did. Those extra parts will cost you around $60-$80 total. Go to the Delray Acura parts website and look up the parts w/ their online catalog.

amengineering said:

I am about to do the same with the 97+ headers. How much did it cost to coat them or how much would it cost me? I have a problem with bolting rusty parts to a car even if you can't see them. I think I am going to make the test pipes and header extensions so I would need those coated too. Anyone got a set for cheap that fit? I don't really want to waste time with the dali ones if they don't fit right and don't want to pay that much for the SOS ones. Good luck with the project.

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I am up in Washington State for the weekend, I will look and see what it cost to do mine when I get home. Don't hold your breath. It was a couple months ago. It seems to take me forever to get anything done on my car.

Are your going to have the outside of the flange to header tube weld continued around the complete tube and then grind off the weld that is on the inside of the tube? Look at the picture of my headers. I will try to find the picture of the inside of the tube to post. Pretty self explanitory.

Brad

OLDMNSX said:

I am up in Washington State for the weekend, I will look and see what it cost to do mine when I get home. Don't hold your breath. It was a couple months ago. It seems to take me forever to get anything done on my car.

Are your going to have the outside of the flange to header tube weld continued around the complete tube and then grind off the weld that is on the inside of the tube? Look at the picture of my headers. I will try to find the picture of the inside of the tube to post. Pretty self explanitory.

Brad

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I don't even get the car for 2.5 weeks so no real game plan yet. I guess I am not sure what you are taking about. I don't have the headers in hand yet though. Is this something that needs to be done or some way to make them stronger? Did you make the test pipes the header adapters from one piece? Any reason you would not want to do this? I just don't like so many different exhaust connections. Any other sugegstions?
thanks,
andy

amengineering said:

I guess I am not sure what you are taking about. I don't have the headers in hand yet though. Is this something that needs to be done or some way to make them stronger? Did you make the test pipes the header adapters from one piece? Any reason you would not want to do this? I just don't like so many different exhaust connections. Any other sugegstions?
thanks,
andy

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Andy,
When Acura made the NA2 headers they took the header flange (flat piece that bolts to the engine head) and tack welded each pipe, in two spots, to the outside of the flange. Next they welded a complete bead, full circle, on the inside of the exhaust tube to the flange. This weld is in the exhaust gas path and is about 3/16 in tall. This weld bead will disturb the gas flow and will restrict the exhaust gases coming from the engine. I couldn't see putting them on that way. Maybe it doesn't matter, but I think so. I can't seem to find my pictures of the inside of the headers before and after grinding all of the weld out. That was bout the time I started having camera problems.

I don't have test pipes, only the NA2 cats, so it will all bolt up without any problem.

Brad

OLDMNSX said:

Andy,
When Acura made the NA2 headers they took the header flange (flat piece that bolts to the engine head) and tack welded each pipe, in two spots, to the outside of the flange. Next they welded a complete bead, full circle, on the inside of the exhaust tube to the flange. This weld is in the exhaust gas path and is about 3/16 in tall. This weld bead will disturb the gas flow and will restrict the exhaust gases coming from the engine.
Brad

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That's exactly what I found w/ the NA2 headers I put on my car. All of my exhaust work was done by Hoover and team at TurboHoses. Since I was kickin it w/ the pros, we decided to fully weld the outside of the flange and grind down the inside ridge just like you did. That made the header stronger and the flow better.

Here are some pictures of the inside, exhaust path, weld removal and of the additional weld on the outside of the flange before I had them JET HOT coated. I also had the flanges machined flat at my local machine shop. That was expensive, $90 for both. He said that they needed it.

Brad

Hey Brad,
Quit sitting around wasting time posting stuff on this site :smile:. Hurry up and install that stuff for cryin' out loud. I wanna know how it compares to my Comptech stuff.

By the way, it was good to see you again....hope you enjoyed the ride in the NSX.

-Matt

Did you weld them up or take them somewhere? That's probably a good idea to have it machined flat again, probably wouldn't have thought to do that, thanks. Ever find out the price on the jet hot coat? Did you do the inside too?

MANIACura said:

Hey Brad,
Quit sitting around wasting time posting stuff on this site :smile:. Hurry up and install that stuff for cryin' out loud. I wanna know how it compares to my Comptech stuff.

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YEA, YEA, YEA!!!!!:wink:

MANIACura said:

By the way, it was good to see you again....hope you enjoyed the ride in the NSX.

-Matt

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As usual it was good to see you and your family. It was fun getting to drive your car. The SUSHI was wonderful too. We will have to go there again.
Thanks,
Brad:smile:

amengineering said:

Did you welf them up or take them somewhere? That's probably a good idea to have it machined flat again, probably wouldn't have thought to do that, thanks. Ever find out the price on the jet hot coat? Did you do the inside too?

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I took them to a local muffler shop for the welding. $35 if I remember right. WOOPS, I still need to look for that JET HOT receipt, I'll do that. It's in the pile of receipts of NSX stuff in the garage. I sometimes hate to look at that pile. $$$$$$$$$$$$$.

Brad

amengineering said:

Ever find out the price on the jet hot coat?

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The list price for both of the NA2 headers was $235 plus $54 return shipping and handling. The $54 is a flat rate. I delivered the headers to them on one of my trips to Phoenix. They do a really good job packaging them for the return, really sturdy boxes. Take 15% off the $235, I can't help you with the shipping.:wink:

amengineering said:

Did you do the inside too?

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Yes, they were done both inside and out. To do both was only about $20 more, why not?:biggrin:

Brad