2002+oem headers on a 91

J

JD Cross

Legendary Member
Joined
8 July 2002
Messages
2,492
Does anyone know what's involved (and if it's worthwhile) to upgrade from 91oem headers to 2002+oem headers?
Will the 91 exhaust bolt right one to the 2002 units or is the spacing different?
Thanks
Jim
 
I also heard that if you go with na2 cats the na1 sway bar gets in the way.
 
I was wondering this same thing.

now is it worth it to swap the na2 exhaust into a 92?

I mean tehy say you gain about 18hp but I am not sure.

if so then i am gonna do it right now.

so headers, full ehaust down to the muffler and the sway bar from the na2

is that right?
 
I don't have ready access to the various threads on this subject so I can't post links at this time but a search on Prime will unearth a treasure trove of information. I am doing this on my /94 -- hopefully full system off an /04 -- headers, cats, muffler and yes, I believe that the rear sway has to be changed for a NA2 one to clear the later year model cats. Hi Paul!

Best,
Jeff
 
The headers are definatly worth swapping as the 91 doesnt have proper headers but cast iron manifolds.

I swapped mine for some aftermarket headers, but you see the difference on this pic here:

SP_A0128.jpg
 
It needs to be noted that the '00-'02 headers are different than '97-'99 - you can use any year but will need the matching cats too.
 
Angus
about how much hp will it add if I take everything off Jason's 2002 and put in on my 92

18-26 like SOS says?

wanna know if it worth it to do? I mean bone stock 92 could use a little extra HP lol

have been thinking about doing it, if it adds anything

in my book its worth it
 
angus said:
It needs to be noted that the '00-'02 headers are different than '97-'99 - you can use any year but will need the matching cats too.
Click to expand...

If the car is a 91 - 94 and you change the cats to 95+, you will also need to change the rear sway bar.

The sway bar design was changed in 95 because the postion of the cats moved.

I know this for sure because I just got my 1992 back from Larry B today.
He installed 1998 OEM Headers connecting to 1996 OEM Cats and then on to a ARK DT-S exhaust (Same stlye as the 91 - 94 exhuast)

I did notice a little extra low end power and also the exhaust note changed.
It is not as loud and it is a deeper baratone sound. It is even better then before.
I did not get a chance to try it in the higher RPMs. (I was following the wife home)

The easiest/best way to upgrade a 91-94 NSX to headers is to get 97 - 99 headers and get the SOS adapter kit.
http://www.scienceofspeed.com/produ...s/NSX/ScienceofSpeed/factory_header_adaptors/
 
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The reason I am asking is I have a 1992 NSX bone stock.

I also have a fully working 2002 NSX.

I know it will fit.

I want to know if I put the complete exhaust from a 2002 on my 1992 will it add HP?

I have all the parts
2002 OEM headers,
bolts,
gaskets,
2002 OEM cats,
2004 OEM Muffler
2002 OEM sway bar
will it work and give me more HP?

has anyone ever put complete 02+ exhaust system on a 92?
 
Last edited:
It will work and it will give you more HP!

The 02 sensor cover is also different, but you have that also.

The 2002 system will have 4 02 sensors, but of course you will only plug in 2 of them.
 
Last edited:
The 2002 REAR header is not the same as the 1998:). You will need to use SOS adapters and modify the rear adapter to correct for the length change on the 2002 rear header. The rear header is shorter by 20mm.

Regards,
LarryB
 
We have stock 2002 headers (with '92 cats and aftermarket muffler) on our '92, and not only will you gain a bit of power......you'll save a bunch of weight over the hefty cast iron manifolds.
Cody installed ours, and made it all fit around the swaybar (had to add a rear 02 sensor extension wire too).

Brian
 
My understanding from prior Prime threads is that a complete /02 through /05 system (headers, cats, muffler) is a direct bolt on with the exception of having to use a later year sway bar and extending the 02 sensor wires and plugging the 2 extra holes for the O2 sensors that the NA2 has but the NA1 does not. Can someone confirm that my understanding is correct? Larry?

Thanks,
Jeff
 
LJZ said:
My understanding from prior Prime threads is that a complete /02 through /05 system (headers, cats, muffler) is a direct bolt on with the exception of having to use a later year sway bar and extending the 02 sensor wires and plugging the 2 extra holes for the O2 sensors that the NA2 has but the NA1 does not. Can someone confirm that my understanding is correct? Larry?

Thanks,
Jeff
Click to expand...

Yes you are correct.....the whole 02+ system is a bolt on. The is one difference though, I think you need the right (passenger USA) side exhaust or cat hanger. It's not on the earlier cars. You do need LEV Cats with the 02+ header. Eariler cats are not a direct fit...

I did the same to my 96 (slightly different exhaust set up in the UK) . You will just plug up the two post-cat O2 sensor holes....

You're thinking in the right direction.....and you do gain 10-15hp for the work too!!
 
Hagasan, thanks from one member of the Commonwealth (I'm an expat Cdn living here in the U.S.) to another. Much appreciated.

Best,
Jeff
 
DC Sports used my car to fit a prototype adaptor for the headers. I have a 92 and I believe I have the newer headers... They dyno'd it and it showed an increase of about 16hp.
 
RJD1022 said:
If the car is a 91 - 94 and you change the cats to 95+, you will also need to change the rear sway bar.

The sway bar design was changed in 95 because the postion of the cats moved.

I know this for sure because I just got my 1992 back from Larry B today.
He installed 1998 OEM Headers connecting to 1996 OEM Cats and then on to a ARK DT-S exhaust (Same stlye as the 91 - 94 exhuast)

I did notice a little extra low end power and also the exhaust note changed.
It is not as loud and it is a deeper baratone sound. It is even better then before.
I did not get a chance to try it in the higher RPMs. (I was following the wife home)

The easiest/best way to upgrade a 91-94 NSX to headers is to get 97 - 99 headers and get the SOS adapter kit.
http://www.scienceofspeed.com/produ...s/NSX/ScienceofSpeed/factory_header_adaptors/
Click to expand...

You have learned well, grasshopper. :)
 
shawn110975 said:
Angus
about how much hp will it add if I take everything off Jason's 2002 and put in on my 92

18-26 like SOS says?

wanna know if it worth it to do? I mean bone stock 92 could use a little extra HP lol

have been thinking about doing it, if it adds anything

in my book its worth it
Click to expand...

The 2003 OEM full exhaust (header, cats, muffler) on my 1995 NA1 NSX yelded 14.6HP and 9 ft-lbs of torque. The 2003 system bolts right up and replaces the entire 1995 OEM system. The main thing is the O2 sensors need to be extended, but otherwise it goes in completely with no issues.

Still haven't found out what I did with all the pictures but here is my original post.
http://www.nsxprime.com/forums/showthread.php?t=86686

An interesting thing I found out was the diameters of the 1995 exhaust were EXACTLY THE SAME for the 3.0L to the 3.2L. INFACT, the piping diameter coming straight off the block on the 2003 Header is actually slightly smaller than the exhaust manifold off the 1995!
 
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These are my costs, had I known it was going to be as expensive as it was to keep it OEM I may have considered a nice gently used set of CompTech headers.

If you are getting OEM headers consider the following:

1. Spend $ on aftermarket headers
Labor is the same or more if you use factory headers.
2. The factory OEM headers are tack welded and can crack at the seam, I brought my headers to turbochargers.com in Houston and they put a bead weld all the way around.
3. If you do decide to use Factory Headers, Jetcoat them (ceramic coating)
Jethotcoatings.com (My headers have still look great after 18 months).
4. Install them yourself
Just saw a great write-up posted in the DIY forum

Here were the costs involved (it was GROSSLY more expensive than I had anticipated when all was said and done).

NSX Prime Used Heades 19K Miles $350

SoS EAP-665 1997-99 Header Conversion Kit ($274), O2 Sensor Extension Harness Kit ($79) + Shipping ($8) Total $361.

Delray Acura Zanardi Rear Sway Bar (required if you plan on using catalytic converters from 1997) ($82.39) + Shipping ($8.95) Total $91.34

Turbochargers.com Labor to weld headers Total $150.

Jet-Hot Ceramic Coating ($235.00) + Shipping ($34) Total $269.

Gaskets
(2) 18115-PR7-A02 Gasket, EX, MAN ($53.84), (2) 18212-SA0-003 Gasket, EX PIP ($19.04) (2) GSKT 52.5MM-53 ($28.86) Total $101.74

David McDavid Acura Labor $735.00

Headers + Installation $2,058.08

After installing the headers I decided that I also wanted a CompTech Exhuast.

I purchased the Comptech Exhaust for $944.09 shipped, and dealer installation was $225.00.

Exhaust + Installation $1,169.09

Grand Total $3,227.17
 
coating them? if Honda welded them I trust them. so I would not have had them coated kinda overkill.

Any one going the DIY install route could have saved tons of cash.

as for the gains, I dont mind the labor but for 14.6 Hp gain. I am thinking
when I have my engine dropped I will do it.

but are you satisfied with the increase? I mean when you drove it after this install did you notice an increase? that what I am looking for.
 
Shawn I noticed a definite increase in pull above 6500 rpm. I have 97 headers on my 91 with a B&B/RM exhaust and stock cats.
 
shawn110975 said:
coating them? if Honda welded them I trust them. so I would not have had them coated kinda overkill.

Might be overkill but I felt the price was reasonable for the possible advantages which may include:
Ceramic-coated headers produce less heat, because the ceramic acts as barrier between the headers and the engine, which may translate to better performance, they protect the headers from rust and corrosion and if headers are coated inside as well it allows the hot exhaust gases to escape more quickly creating less turbulence due to the smoother surface.


Any one going the DIY install route could have saved tons of cash.

Yep, but I have neither the tools nor the time and I have had good luck with the work my dealer has performed.

as for the gains, I dont mind the labor but for 14.6 Hp gain. I am thinking
when I have my engine dropped I will do it.

I wish I had done a dyno to get true before and after results but I never got around to it, I think you are correct on the HP gain seems like most people on PRIME have reported around a 15 HP gain for headers and exhaust.

but are you satisfied with the increase? I mean when you drove it after this install did you notice an increase? that what I am looking for.
Click to expand...

I am sure you have seen the boat anchor (exhaust manifold). $3K for Headers and Exhaust was a lot to pay for about 15 HP, but I had not planned on doing forced induction.

I wanted to post the costs, and part numbers to help others considering the upgrade. Its always better to make an informed decision. You can also use my numbers as a guideline to determine how much the upgrade will cost you, e.g. if you don't want ceramic coating subtract $xxx, if you plan to D-I-Y subtract the labor costs.
 

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