NA2 Exhaust install in NA1

[amengineering]

So it would be about $255 with return shipping. How do I go about getting the 15% discount, tell them you refered me, or is it a prime discount or something. I don't get my car until the 26th so it will be a few weeks by the time I make the test pipes and get the manifold welded. I'm going to cut off the mounting tabs for the heat shield too. You didn't jet coat the test pipes, did you? I plan to do the header and test pipes. I would imagine it would be another 100 or so to get those done. Thanks for the help with this, let you know when I got evertything ready.

 

[OLDMNSX]

So it would be about $255 with return shipping. How do I go about getting the 15% discount, tell them you refered me, or is it a prime discount or something. I don't get my car until the 26th so it will be a few weeks by the time I make the test pipes and get the manifold welded. I'm going to cut off the mounting tabs for the heat shield too. You didn't jet coat the test pipes, did you? I plan to do the header and test pipes. I would imagine it would be another 100 or so to get those done. Thanks for the help with this, let you know when I got evertything ready.

Andy,
What we will do when you get ready is:
1. I will e-mail which plant location is nearest to you, that you will be shipping your headers to them.
2. You ship your parts direct to them.
3. They will confirm the price after seeing what you have. (The test pipes will be the question) I will send you a copy of the e-mail they send to me.
4. You pay me, I pay them, and they will ship your parts back to you and you save 15%. If you do PayPal you will have to add the 3%. If you send me a cashiers check as soon as I let you know there shouldn't be any wait. It takes one to two weeks anyway.

BTW, I put the heat shields back on mine. Thoughts?

Don't forget you will have to make some pigtails for the O2 sensors or buy some ($$). I made mine out of two O2 sensor connectors from the salvage yard. (FREE, just some time)

Brad

 

[OLDMNSX]

The Latest. On initial start up, CEL illuminated. Codes showed "Forward O2 Sensor". I swapped front with rear O2 and reset the ECU. Started the car, instant CEL. Codes showed "RearO2 Sensor". I purchased one new NTK O2 sensor, installed it in the forward bank, hardest one to change out. Started the car, NO CEL. I figured that my troubles were over. I ran the car for about 150 miles and figured that I would get a follow up emission check.

I went to the same place that I had the initial check with the old NA1 complete exhaust system, which was a "Pass with flying colors". Well to my surprise this latest check with the NA2 exhaust "Failed Misserably". One new and one old O2 sensor. I am going to get another new NTK O2 sensor to replace the old rear bank sensor and do another test.

Moral of the story is "Just because you don't have a CEL doesn't mean that the O2 senors are doing a good job." The emission test is the only way to tell how well your exhaust is testing.

You will get a CEL if either the O2 heater or sensor circuit have failed, but not if the sensor is giving the ECU an invalid reading. Something may have happened to the O2 sensor when I removed it. I didn't use anything, PB Blaster etc, to get them out.

Now the other thing could be a faulty CAT. The fault with that thought is that I had loaned my CATs to John and his car passed a emission test back in VA. I may have to get with him for a copy of his results to compare the results.

The tech said that he had never seen such a drastic swing on test results. He was amazed.

Brad

 

[MANIACura]

That sucks. You inspired me to get my emissions tested before I started to install my headers. Passed with flying colors as usual.

Header install: If anyone asks me to help them install their NSX headers I'm gonna punch them in the mouth.

You were right about not starting this project two days before a driving trip. The car is sitting on stands with everything out.....finally. Took me five hours to get everything out.....front and back. The car fought me ever inch of the way. You need a different extension/universal/socket/wrench for every stinkin' bolt. And they're all stuck of course. Broke one stud on the rear bank but got it out of the head easily. Two others backed out. Hope I can find these studs somewhere easily.

The stock 91 exhaust manifolds are absolute garbage and they weigh a ton. The headers are saving me 11 pounds.

Round 2 tomorrow.....

 

[MANIACura]

Round two complete. Me one, car zero.

Installation was way easier than removal. Took another 3 hours to put everything back in including clean-up.

Conclusion: If you have an NA1 car.....get rid of the stock NA1 manifolds. Whether you put NA2 headers on or aftermarket headers.....get rid of the stock NA1 manifolds. They must be the weak link in the exhaust.

My cars pulls harder than it ever has. Actually made me laugh out loud. I don't need a dyno.....it is a significant improvement.

The header/stock cats/Taitec GTLW combo sounds like pure heaven. Deep throaty growl that you can drive quietly in and out of the neighborhood but when you get on it......hold on baby! It screams.

No check engine lights or hiccups.

 

[sokudo88]

just want to share my experience. i just installed 97 stock headers on my 91, but used the same 91 cats. had to go to muffler shop to get some piping done since i alrdy have aftermarket exhaust. my mechanic extended both 02 sensors, plugged them up, and no CEL so far. im hoping everything is ok but when i first drove the car, wow.....big difference!!

 

[dablackgoku1234]

Just to recap here for those not mechanically gifted... in order to put an NA2 exhaust (say 2002+) on an NA1 car (say 1991), I would require the compete setup:

1) NA2 exhaust
2) 02-05 headers + o2 sensor reposition (700 bux)
3) 02-05 cats and bracket/bushing (600 bux) OR test pipe (?)
4) 02-05 rear sway bar (?)

is that correct?

 

[LJZ]

Just to recap here for those not mechanically gifted... in order to put an NA2 exhaust (say 2002+) on an NA1 car (say 1991), I would require the compete setup:

1) NA2 exhaust
2) 02-05 headers + o2 sensor reposition (700 bux)
3) 02-05 cats and bracket/bushing (600 bux) OR test pipe (?)
4) 02-05 rear sway bar (?)

is that correct?

I recently (November /09) acquired a completely stock /94 that now has 24K miles and would like to upgrade to NA2 headers and a different muffler (either NA2 muffler or ARK DT-X). I have a couple of questions after reading the posts above. First, one of the posts above indicates that post /99 headers need some minor modification to fit a NA1 -- can someone elaborate on exactly what needs to be done and if this is difficult (for someone, unlike yours truly, who really knows what they are doing) and/or expensive? If one installs NA2 headers on an NA1 you need the adaptors that are made by SOS, correct? I know about extending the O2 sensor wires. Is the NA2 muffler a direct bolt on if one installs the NA2 headers (or for that matter does aftermarket headers) but retains the NA1 cats? I'm told that the ARK DT-X is a direct bolt on to a stock NA1 system. Larry B, if you are out there would love to hear from you on this -- tried to PM you but not sure it went through. Thanks to all in advance for your guidance. :smile:

Jeff

 

[amengineering]

Working on this right now. They don't need modification, but people suggest welding the primaries on the outside of the flange and grinding down the factory welds on the inside of the flange smoother air flow. You can't use na1 cats with a na2 exhaust. The SOS header adapters are for using na2 headers and na1 cats. I cut the flange off a set of exhaust adapters and am welding on a 16"ish piece of 304 SS and rewelding the flange on the end of the 304, making real cheap 1 piece exhaust adapter/test pipes. I ordered new header gaskets but my old ones looked just fine. If you want to spend some more money you can also jet hot coat them. good luck

 

[Mac Attack]

Working on this right now. They don't need modification, but people suggest welding the primaries on the outside of the flange and grinding down the factory welds on the inside of the flange smoother air flow.

I wouldn't recommend welding the outside of the primaries on the flange. That way you'll have a weld on the inside and the outside. There is a big temperature difference across these welds which will lead to large thermal stresses and actually make them crack more than if you left them alone.

It's best to put some flex joints in instead if you're concerned with cracking.

You CAN grind down some of the inner weld though that protrudes in the exhaust flow.

Dave

 

[prelude]

I don't think you need sway bar if you use test pipes. The NA2 converters need NA2 sway and vice.

 

[amengineering]

"I don't think you need sway bar if you use test pipes. The NA2 converters need NA2 sway and vice."




My 1" dali bar clears by at least an inch or two. Cats would be a different story. Zanardi bar also works with na2 cats as well, I think I remember reading that somewhere....

 

[LJZ]

Dave, Prelude and Amengineering, thanks for the input. One last question (and here I'm probably disclosing a high level of ignorance) related to NA2 exhaust and NA1 cats -- is there no way to retain the NA1 cats if I want to switch to NA2 exhaust? Can some type of adaptor be fabricated or is this simply not possible given how the cats mate up to the exhaust? By test pipes I assume you are referring to substituting straight pipes to the exhaust for the cats, correct? Thanks again for your input.

Jeff

 

[Mac Attack]

is there no way to retain the NA1 cats if I want to switch to NA2 exhaust? Can some type of adaptor be fabricated or is this simply not possible given how the cats mate up to the exhaust?

I'm sorry - don't know the answer to that one. I put generic Magnaflow cats on mine when I did my headers that mated up to a custom muffler.

By test pipes I assume you are referring to substituting straight pipes to the exhaust for the cats, correct?

That's correct.

Dave

 

[amengineering]

" is there no way to retain the NA1 cats if I want to switch to NA2 exhaust? Can some type of adaptor be fabricated or is this simply not possible given how the cats mate up to the exhaust"




I suppose you could cut the flange off the NA2 exhaust, chop off the 90 and 45 degree corners, and weld the flange back on. Basicaslly cutting off a piece the size of exhaust adapters for NA1 exhausts.

 

[drew]

I recently installed NA2 headers on my NA1 with the adapters . I have the O2 sensor harness extenders.


How in the heck did you route the O2 harness? Seems very different than the NA1....

Thanks

Drew

 

[warrenw]

Is there an exhaust / Header / Cat compatability matrix out there?
I have a '91 and would like to get rid of the manifolds and replace with Acura OEM headers and exhaust of a later model. Not sure what bolts up, and what doesn't.
I have searched around and nothing found anything yet.
any help would be appreciated.

thanks.

 

[Honcho]

Here is a short matrix. If you keep all parts within the same year range, it will fit.

91-94
95-96
97-99
00-05

 

[pvmike]

Is there an exhaust / Header / Cat compatability matrix out there?
I have a '91 and would like to get rid of the manifolds and replace with Acura OEM headers and exhaust of a later model. Not sure what bolts up, and what doesn't.
I have searched around and nothing found anything yet.
any help would be appreciated.

thanks.

Warren, here's my experience:

http://www.nsxprime.com/forums/showthread.php?t=95399

To summarize for NA1 owners:

97-99 NA2 headers: You will need 97-99 cats and exhaust OR adapter pipes (like these from SOS) to connect to 91-94 cat/exhaust. 95-96 owners can simply bolt on 97-99 headers.

00-05 NA2 headers: You will need 00+ cats and exhaust. There is no substitute unless you custom fabricate the adapter pipes. The 00+ headers differ from the 97-99 in that the flange on one of the manifolds (lower one) is "clocked"/turned slightly (about 15 degrees), and it's also slightly shorter. So if you purchased the 97-99 adapter pipes above, one of the pipes will need to be cut, turned, and extended.

Also, you'll need to change your rear sway bar. The Zanardi rear bar will work.

This question gets asked a lot. This info should be stickied somewhere...