Exhaust piping size - OEM system/Cat delete question

[RickBlaine]

Gents,

My original exhaust has had it. I need to replace it this week. A local muffler shop is quoting me $180 installed for everything behind the catalytic converter (includes resonator and muffler).

1) I searched and my understanding is that the stock exhaust size for a 1991 Nissan 240sx (with automatic transmission) is 2 1/4 inches outside diameter (o.d).
http://zilvia.net/f/showthread.php?t=77119

If that size is incorrect please let me know the correct size....

2) Catalytic converter delete: I want to temporarily install a test pipe in place of the original catalytic converter. Will this throw any engine codes in a 1991 model? The 02 sensor is "upstream"- so I don't think it will, but I am not the expert here.

3) To add a MagnaFlow catalytic converter later (universal one- not CARB compliant), which nuts and bolts (stainless) will be the least resistant to rust so I can install/remove the catalytic converter/test pipe?

4) Please note that the car is 100% stock, with 103,000 miles, and does not burn a drop of oil. I have no plans to modify THIS car.

5) I am older, and do not want to attract attention. I was actually pulled over yesterday because my exhaust gasket between the cat and the rear pipe blew out- making lots of noise. Next week I start getting ticketed- and I do NOT want one of those 4" coffee can exhausts that local youths all get.

I need your help please! Thank you!

[ixfxi]

2.25 sounds right, its been ages since I had an NA 240SX. I recall at the time I upgraded to 2.5 inch and I had a Remus dual tip exhaust, I too wanted to look covert. Sounded OK, but overpriced muffler and crush piping didnt do much of anything for performance. Current setup with my SR is all 3.0 inch. I just yanked my 3" Magnaflow stainless steel cat and fab'ed up a stainless steel "test pipe" with flex section and wideband o2 port.

On an NA car, I really wouldnt advise being without a cat. It sounds shitty, it smells shitty. Unless you're turbo and blowing fireballs, keep the cat. Use all 304 stainless piping, flanges and fasteners - that will keep corrosion down to a minimum.

ps: I run an "angled" RSR GT2 coffee can exhaust, but... its powdercoated black. :-P

ps: I advise checking under the car to confirm your exhaust diameter. Use a caliper.

[Matej]

The catalytic converter is there so polar bears do not starve.

[Kingtal0n]

Just source another OEM exhaust system. The Factory exhaust on our cars is identical to the exhaust used on the JDM silvia- it will support 250rwhp with ease.

Absolutely no reason to use anything but on an N/A 2.4L engine

[RickBlaine]

Originally Posted by ixfxi

2.25 sounds right, its been ages since I had an NA 240SX. I recall at the time I upgraded to 2.5 inch and I had a Remus dual tip exhaust, I too wanted to look covert. Sounded OK, but overpriced muffler and crush piping didnt do much of anything for performance. Current setup with my SR is all 3.0 inch. I just yanked my 3" Magnaflow stainless steel cat and fab'ed up a stainless steel "test pipe" with flex section and wideband o2 port.

On an NA car, I really wouldnt advise being without a cat. It sounds shitty, it smells shitty. Unless you're turbo and blowing fireballs, keep the cat. Use all 304 stainless piping, flanges and fasteners - that will keep corrosion down to a minimum.

ps: I run an "angled" RSR GT2 coffee can exhaust, but... its powdercoated black. :-P

ps: I advise checking under the car to confirm your exhaust diameter. Use a caliper.

Thank you sir.

1) I will check diameter with a caliper (didn't even think of my caliper yet it is so obvious!) Just checked- the outside diameter of the exhaust pipe (just after the catalytic converter) is 2.25 inches.

2) I do remember that smell cars w/o a catalytic converter leave- it is not nice. The muffler shop has a cat- but it is a no name. I have a MagnaFlow coming in on Tuesday of next week. Thought I would test pipe it....maybe I'll just save a headache and get them to install their cat.

3) Thanks for tip on 304 stainless- I will have to ask what stuff they use. What do you mean by "crush"? Do you refer to crush vs. mandrel bending the pipe?

Any other advice or tips? I appreciate it!

[RickBlaine]

Originally Posted by Kingtal0n

Just source another OEM exhaust system. The Factory exhaust on our cars is identical to the exhaust used on the JDM silvia- it will support 250rwhp with ease.

Absolutely no reason to use anything but on an N/A 2.4L engine

Also an excellent idea.....There is a dude selling his used S13 exhaust (supposedly 80,000 miles on it)- but it is....used. If I check the integrity of the connections (gaskets and such) and it does not seem clogged, is $50 good to buy it? How much would you think a muffler shop would charge to drop the old and add the "new" S13 stock exhaust? I will call around in the a.m., but they are all closed now.

Thank you!

[ixfxi]

Originally Posted by Kingtal0n

Just source another OEM exhaust system. The Factory exhaust on our cars is identical to the exhaust used on the JDM silvia- it will support 250rwhp with ease. Absolutely no reason to use anything but on an N/A 2.4L engine

Originally Posted by RickBlaine

Also an excellent idea.....There is a dude selling his used S13 exhaust (supposedly 80,000 miles on it)- but it is....used.

The answer to the above is YES and NO.

Yes, technically you could just grab ANY stock S13 exhaust you find and install it, but then you are left with: a used exhaust. No glory in that, it just works. Performance and sound are, well... OE. However, you're still left with a janky 20+ year old exhaust thats mostly worn and rotten. And, heavy!

Now if none of that matters, then you step into the world of aftermarket. There ARE very high quality exhausts out there that will work great for NA *and* turbo, should you ever venture that route. Even if you dont care about performance, there's nothing wrong in my book with installing a nice quality component on your car. For example:

http://www.team-integra.net/forum/20...installed.html

^ RSR made, not sure if they still do, the EXMAG exhaust for our cars. This product was geared towards the sleeper crowd that want to blend in, but still have performance. The performance gains are found in nicely formed pipes known as mandrel bends. They are not crush formed (with kinks) like the stock exhausts or like muffler shop specials. I did not know or care about that many years ago, but now I do. Now I wouldnt waste my time with anything crush bent, and I very much like stainless steel - mandrel bent. This means buying something pre-made or fabricating it myself. With the wife's Miata I purchased a racing beat exhaust, mid pipe, headers, you name it. Beautiful construction.

So search away and I'm sure you'll find plenty. To keep the smells down I would advise running a cat. So basically, you need a cat-back setup.

Good luck

[ixfxi]

Here is a side-by-side photo of a stock exhaust (miata, just an example) vs a stainless mandrel bent setup.

[racepar1]

Originally Posted by RickBlaine

Thank you sir.

1) I will check diameter with a caliper (didn't even think of my caliper yet it is so obvious!) Just checked- the outside diameter of the exhaust pipe (just after the catalytic converter) is 2.25 inches.

2) I do remember that smell cars w/o a catalytic converter leave- it is not nice. The muffler shop has a cat- but it is a no name. I have a MagnaFlow coming in on Tuesday of next week. Thought I would test pipe it....maybe I'll just save a headache and get them to install their cat.

3) Thanks for tip on 304 stainless- I will have to ask what stuff they use. What do you mean by "crush"? Do you refer to crush vs. mandrel bending the pipe?

Any other advice or tips? I appreciate it!

I can for absolutely sure guarantee you that your muffler shop is NOT going to use mandrel bent 304 stainless. They will use crush bent mild steel piping, probably with the shittiest welds that could possible hold it together. $180 is way cheap. A nice stainless custom setup would run at least $500 and that's probably low. For your goals and needs a good condition stock setup would be ideal. HOWEVER, you do live in the rusty side of the country and finding a good one would likely be impossible.

As for the cat, why are you set on replacing it? Is there something wrong with it? If not it would be silly and useless to change it. Aftermarket cats suck ass, basically ALL of them. 9 times out of 10 you'll buy a new aftermarket cat and install it to pass smog. The next time you need to smog it (2 years later) it'll fail again. I prefer to run factory cats, even if they're used. I would LOVE to buy a brand new factory one, but the last time I priced one out it was $900 (my price, NOT retail) and there was only 1 left in the country. Since your car is a federal car running without a cat will not set a check engine light, BUT the EGR will not function. 240's have a backpressure transducer that will not apply vacuum to the EGR unless there is enough backpressure. Even brand new shitty aftermarket cats can sometimes cause this issue. CA cars have an EGR temp sensor to monitor EGR operation, federal cars do not.

[RickBlaine]

THAT is a work of art! Thank you for posting that.

[Bleakley]

I do have a stock 1992 exhaust. I've owned two s13's before this and was actually surprised how quiet it was - which is why I kept it stashed away in my storage unit. Car was from north Carolina so the exhaust def still has years left on it. If interested PM me.

[ixfxi]

Originally Posted by racepar1

I can for absolutely sure guarantee you that your muffler shop is NOT going to use mandrel bent 304 stainless. They will use crush bent mild steel piping, probably with the shittiest welds that could possible hold it together. $180 is way cheap. A nice stainless custom setup would run at least $500 and that's probably low. For your goals and needs a good condition stock setup would be ideal. HOWEVER, you do live in the rusty side of the country and finding a good one would likely be impossible.

As for the cat, why are you set on replacing it? Is there something wrong with it? If not it would be silly and useless to change it. Aftermarket cats suck ass, basically ALL of them. 9 times out of 10 you'll buy a new aftermarket cat and install it to pass smog. The next time you need to smog it (2 years later) it'll fail again. I prefer to run factory cats, even if they're used. I would LOVE to buy a brand new factory one, but the last time I priced one out it was $900 (my price, NOT retail) and there was only 1 left in the country. Since your car is a federal car running without a cat will not set a check engine light, BUT the EGR will not function. 240's have a backpressure transducer that will not apply vacuum to the EGR unless there is enough backpressure. Even brand new shitty aftermarket cats can sometimes cause this issue. CA cars have an EGR temp sensor to monitor EGR operation, federal cars do not.

aaron is correct on a lot. costs for an SS setup can be high, very much so if its custom made. If they are pre-made however, it can be affordable. btw aaron, there are good muffler shops that make custom SS exhausts - i'm sure we agree though its pricey.

as for the cat, i ran the magnaflow (non CA type) and not only did I pass here in socal, i passed with my SR20DET, and I want to say not just once... i believe 2 times. most of the cats are ceramic-type, but they also sell more expensive metallic type cats. im sure they are pricey.

this thread is funny. reminds me of what forums USED to be like before the influx of fucking brain-dead ex-honda driving zombies we've had for the last 10 years.

[Matej]

The HKS Sport appears to be a nice affordable low-key exhaust, despite being 3". I am not sure how loud/quiet it is behind a catalytic converter. Too bad HKS does not offer a 2.5" version with a resonator on the mid-pipe, but it still seems to be the most sensible exhaust available for those who want something in between the stock peashooter and an annoying cannon, since the aftermarket is mostly aimed at Hoonigans.

[racepar1]

Originally Posted by Matej

The HKS Sport seems like a nice affordable low-key exhaust, despite being 3". It would be even better if HKS offered a 2.5" version with a resonator on the mid-pipe, but it still seems to be the most sensible new exhaust available today, since the aftermarket is mostly aimed at Hoonigans.

Yeah, I've got a similar exhaust on my S13, RSR ex-mag. It is in NO WAY even REMOTELY close to being considered SORTA-KINDA quiet. My Apex N1 one-piece was actually quieter. But, like the OP, I got tired of the big ass canister hanging off the back of the car. I think I'm going to add a resonator to the ex-mag...

OP might wanna look into the BRM stuff...

http://www.brmexhaust.com/1989-1994-.../s13-240sx.htm

Probably won't be super stock quiet, but it's a mandrel bent catback system with low-key looks. It's also available with 2.25, 2.5, or 3 inch piping. The price isn't that bad either...

[e1_griego]

^Catless with an SR mine was pretty quiet just idling and cruising around, and sounds decent when you get on it but not quiet, I agree.

Not sure how it sounds on a KA, though I sold mine to a local kid with a KA. Should make him stop by and record it to share.

[racepar1]

Originally Posted by e1_griego

^Catless with an SR mine was pretty quiet just idling and cruising around, and sounds decent when you get on it but not quiet, I agree.

Not sure how it sounds on a KA, though I sold mine to a local kid with a KA. Should make him stop by and record it to share.

It's way louder on a KA. Not so bat at cruise/light load, but when you get on it it gets pretty damn loud. That's very typical though. EVERY exhaust is louder on a KA than an SR.

[Matej]

All the old school OEM-looking exhausts were quiet. They would probably sell better now than they did back then.
Fujitsubo, Kakimoto, Nismo, old HKS, etc. I had an ancient twin-tip exhaust with 2.75" piping for a CA18DET that was quieter than stock on the KA, but I was never able to find out what brand it was.

[e1_griego]

Originally Posted by racepar1

It's way louder on a KA. Not so bat at cruise/light load, but when you get on it it gets pretty damn loud. That's very typical though. EVERY exhaust is louder on a KA than an SR.

Yeah, fair. Hooray turbo mufflers.

I had some old school (what I think was) Kakimoto on my sohc back in the day and it was quiet and sounded decent. I paid like $150 for it used, and it was awesome. Big resonator and muffler.

[ixfxi]

Originally Posted by Matej

Here is a dick tip for ya... (sorry, been listening to too much of the Maddox podcast)

you can easily take the above exhaust and have a resonator added to the mid-pipe.

Thats the one thing people under-estimate, the resonator. 3" piping is not really a big deal, though for NA I think 2.5-2.75 would be better. But a resonator. Install a large resonator and you'll be good to go.

[Bleakley]

Originally Posted by ixfxi

Thats the one thing people under-estimate, the resonator. 3" piping is not really a big deal, though for NA I think 2.5-2.75 would be better. But a resonator. Install a large resonator and you'll be good to go.

+1, exhaust with a resonator will almost always sound better than an exhaust without one.

[slow40sx]

I went with an ISIS type-E on my daily 240, its very very quiet at idle like stock quiet and cruising it drones a bit but its not loud by any stretch, when you stomp on it its a little loud, not unbearably loud though, the police here are exhaust Nazi's and I've dailied this thing for 2 years 30 miles round trip to and from work everyday never been pulled over, the actual sound of it is ok. It doesn't sound particularly good. Although, I personally hate the sound of a KA. I might throw it on my SR 240 one day just to hear what it sounds like, but here's a pic of it for ya, its nicely designed, tucks up pretty nicely and its stainless steel so it will last, and if its too shiny for ya, you could always paint the muffler black, I was thinking about doing that actually

[Kingtal0n]

I run an OEM Exhaust with one of these


^ ^

it posses a diagnostic feature as well as recreational.

[Bleakley]

Kingalton, what is that? Can't really make it out.. Exhaust cutout/dump?
@slow40sx - I have an Apexi N1 Dual that I bought for the sound and my GOD does it hang low, looks Fricken stupid. Idk if it's the circuit sports downpipe I've got on there right now or what, but it needs fixed.

[Kingtal0n]

Yes. I wanted one for years and finally did it, and it has been hands down the most fun modification I have ever made.

I really, really love to listen to the engine, as much as anybody else- except that I prefer to listen to what is really coming out of the engine before it goes through all the twisty turny sound-changing materials of an exhaust system.

Else, I prefer to listen to my radio, i.e. hear nothing from the engine whatsoever like the car is completely bone stock.
Both settings (loud and quiet) have diagnostic value. With an OEM noise level engine, I can hear every tick tock the engine makes to verify it's condition.
With the downpipe open I can hear the act of combustion/compression and hear all cylinders firing correctly with an even tone.


I must have my cake and eat it too!

[slow40sx]

Originally Posted by Bleakley

Kingalton, what is that? Can't really make it out.. Exhaust cutout/dump?
@slow40sx - I have an Apexi N1 Dual that I bought for the sound and my GOD does it hang low, looks Fricken stupid. Idk if it's the circuit sports downpipe I've got on there right now or what, but it needs fixed.

The first 240 I bought in 06 came with apexi dual N1 on it and it hung low as fuck too lol, I put hose clamps on the hangers to pull it up higher, still hung low as fuck, then I traded the car lol

[Matej]

Originally Posted by Kingtal0n

Both settings (loud and quiet) have diagnostic value. With an OEM noise level engine, I can hear every tick tock the engine makes to verify it's condition.
With the downpipe open I can hear the act of combustion/compression and hear all cylinders firing correctly with an even tone.

You should put a cutout on each cylinder so you can see the diagnostics.

[Bleakley]

Originally Posted by slow40sx

The first 240 I bought in 06 came with apexi dual N1 on it and it hung low as fuck too lol, I put hose clamps on the hangers to pull it up higher, still hung low as fuck, then I traded the car lol

So unfortunate... Was definitely looking to remedy the situation by somehow getting it to tuck in a little closer.

[ixfxi]

Originally Posted by Matej

You should put a cutout on each cylinder so you can see the diagnostics.

yes, and stick your eat on each cylinder to test compression and confirm proper mixture

[Kingtal0n]

Originally Posted by Matej

You should put a cutout on each cylinder so you can see the diagnostics.

you dare mock the value of this diagnostic approach


we should all run around with really loud cars so that we cannot hear our engine's internals. That makes more sense.

[ixfxi]

Originally Posted by Kingtal0n

you dare mock the value of this diagnostic approach


we should all run around with really loud cars so that we cannot hear our engine's internals. That makes more sense.

thats what exhaust silencers are for. that, or valved exhausts.

the dump pipe approach is OK but i dislike the added plumbing added to the system.