if i take the cat out of my car what would be the difference in power feel and noise.

also i was looking through the timing post on here and they all say to move it to about 8 degrees advance but when my z is at 8 degrees it feels hesitant to about 3000 rpm. so i have it set at 12 degrees and it feels a lot better when accelerating.

 

You are talking about replacing the cat w/ a test pipe right? Exhaust will be slightly louder, maybe 1hp gain by itself, and the car won't pass emissions.

8 degrees is stock setting... 12 degrees is a better setting for cruising around. Shady runs his N/A @ 15 degrees.

 

ok i'll play around with the timing but do u know how restrictive the original cat are?

 

I'm not sure what kind of answer you are looking for... a lot? a little? 349875 google meters of back pressure? If you are looking for an actual measurement, I don't have one. Each motor will act slightly different. If you want numbers, dyno your car, remove the cat, and dyno it again. Like I said before, just removing a cat won't do much. But... a header and larger exhaust all the way, will help.

Remember this... there's a give & take with exhaust mods. We have many threads talking about that.

 

If anything you'll probably notice more gain from removing the cat on a turbo. I've always heard a larger more free flowing exhaust makes better gains on the Turbos, I've never heard much in the way of the non-turbos.

 

ok well i'll just leave it on until i can do my hole exhaust then, who else besides motorsport and monza makes an exhaust or do you have to get it custom with the other companies

 

Those are pretty much your only options for exhaust systems. These cars are too old and the market demand isn't large enough for companies to spend time on R&D for a product.

 

ok well im going to look through youtube to see what i like, any recommendations for mufflers

 

what do u guys know about the n1 mufflers

 

or i guess its k2 motors mufflers

they have a nice sale on the mufflers right now too

 

Why not stick to name brand items that have been proven to be quality parts?

Flowmaster... Borla... Magnaflow... Bullet... HKS... etc...

For the same cost as a kit you can order online, and wait for it to arrive, you could take your car to a local trusted muffler shop and get a nice exhaust system.

 

http://www.youtube.com/watch?v=v7MHhDbh-9w

thats a magnaflow(dont know which one but its the straight through design)its the only magnaflow that the guy found to fit in the space of the 2+2... AND IT WAS CHEAP!!!

it would sound better but i have a big *** exhaust manny leak

 

I just finished putting in the catback exhaust from MSA:

http://www.thezstore.com/page/TZS/PROD/PEC06/15-6027

It is 2.5" mandrel bent tubing with a "super turbo" oval muffler, which I assume is similar to a Dynomax turbo oval muffler. It came with absolutely no directions whatsoever.

Installation consisted of cutting the stock exhaust just rear of the diff, then removing the stock exhaust from the cat. (My cat has been extensively modified with a crowbar to be extremely free flowing - you can see right through it!)

The new exhaust is 3 pieces of pipe and the muffler. The longer, straighter piece has a bracket which I attached to the existing body mount just forward of the diff, using the same piece of rubber that was used for the old exhaust. The bent piece goes from that piece to the muffler, which I attached using one of the hangers they sent, clamped to the back of the muffler, attached to the body mount at the very rear of the car. I attached the muffler with the offset attached to the pipe and the centered portion facing the rear of the car.

The pipe that attaches to the cat had to be cut down to 5 inches long. I assume it is much longer than necessary so that it will fit the 2+2 model as well, but this caused me a lot of confusion - it's not long enough to replace the cat, but way too long to fit the coupe without cutting. I clamped everything up. The pipe was making contact with the diff, so I performed ghetto/redneck surgery by cramming an extra piece of mounting bracket rubber in between the diff and the pipe. I stuck the chrome tip in the back of the muffler and fired it up. It sounded pretty much like this video on youtube (not mine):

http://www.youtube.com/watch?v=dVvNsWRh7Mo

Very throaty at low RPMs, but quiets down as you rev up - it doesn't do that nice "braaap" sound. I took it out for a drive, and it was honestly too loud for my neighborhood, plus it droned horribly at 2000 RPM. I read a few more forum posts and decided to add a 12" tailpipe after the muffler. I just went and bought a 24" 2.5" ID piece from Vatozone, cut it to length, and clamped it on. This brings my chrome tip about 1/2" outside of the bumper. That made a huge difference - it's a lot politer when driving out of the subdivision at 25 mph, and the drone has been quieted, and pushed down to 1800 RPM.

Was it worth it? Not really. The sound is kinda cool, but it's moreso at lower RPMs - at higher RPMs, the pipe stops resonating and it's maybe even quieter than the stock. Installation was sort of a pain, but kinda fun, I guess.

As to performance - I ordered the kit and installed it without really reading anything about exhaust system theory. A larger, free flowing exhaust on an N/A engine is going to help you out in the high revs, when you're trying to shove as much air through the engine as possible. At low revs, it's actually going to hurt you. People call it "backpressure", but as I understand it, you need a smaller pipe at low revs because that will speed up the flow of air - at low revs you're not really pushing that much air through, so you need a smaller pipe to keep that air moving quickly away from the engine - kinda like putting your thumb over the end of a garden hose to speed up the water.

On a turbo, I understand that you're moving more air most of the time, so a bigger pipe is going to help you.

At the RPMs I drive at (2-4K), the exhaust is probably hurting my torque numbers. If you go around at 4K and a lot of the time, it might help. The cost of the system was $130, and it involved a lot of swearing while laying on my back under the car. A pro could probably do the job for not too much more, in almost no time at all.

It does sound cool when you start it up, though.

 

Oh, and the original question - the effect of removing the cat. I completely gutted my cat with a crowbar, like I said. It didn't do jack for performance, but it did give the car a much throatier, "bbRAHM-brum-brum-brum" nice idle tone. And it was completely free. But you're in California, so I guess make sure you can pass the test without it first (I know I've seen threads with tricks on passing even without a cat). Bang-for-buck, it's completely free, it can be done in an hour or so with nothing more than a wrench and a big iron stick. And if you want to put a regular or high-flow cat back in, no problem.

I also have my timing advanced to higher than 10 degrees - I tried setting it back to 6-8 degrees and found the same thing - kinda sluggish in the low RPMs, which, let's be honest, is where most of us city folks are driving most of the time.

 

how did you clear the cat out? just beat the center out with a crow bar? sounds like my next week end project...

F#$K the environment!!!!!!!

 

OH!!! I JUST GOT AN INGENIOUS AND PARTIALY STUPID IDEA!!!!

you know those servo powered exhaust bypass flange things? wire that bit up to some kind of shift light, then use a smaller diameter at low revs and larger a higher revs... ima genius!!!!

probly wouldnt be worth the time though..

 

Yep, that's pretty much the procedure. Harder than it sounds, that stuff is pretty tough. But after you get some good chunks knocked out, it starts coming out. Looks like charcoal briquets. Try to wear a dust mask or at least breathe in the other direction. There's also some fabric or something lining the chamber that needs to be pulled out.

Be warned, your exhaust is going to start stinking...

I like the variable exhaust diameter idea, but I'm sure there's some reason that it hasn't been done. Someone else was thinking the same thing:

http://www.halfbakery.com/idea/Rotat...riable-Exhaust

I had never heard of the valve to dump exhaust straight out of the header until I saw this on youtube:

http://www.youtube.com/watch?v=ZccI7aQOKnQ

So you can go down to the Sonic and let everyone know the size of your exhaust tip....

EDIT: I guess it's not straight out of the header, but just a different, louder system that it switches to.

 

my exhaust already stinks so i might think about this, and as for me thinking i had a new revolutionary idea.... I FAIL AGAIN!!!!

 

If you want a test pipe, track pipe or what ever you kids are calling it now days heres what you do. Find a 280 on craigslist thats getting parted out and grab the exhaust flanges from either side of the cat. Next go down to your local parts store and get a piece of exhaust tubing(same diameter as your exhaust) off the shelf. Take the tubeing and flanges down to your local muffler shop and tell them you want those flanges welded on the peice of tube. If you do this yourself make sure you test fit before doing your final welds. Presto. Track pipe and you can still use your cat to pass emissions, bolt on, bolt off. Besides a OEM cat goes for about $45 if you can find somebody that buys cores. No point in destroying a good cat.

 

ok everything iestyn.lewis just said, you ruined jk

 

2 scorpion i have a 1982 280zxt i also had a 1983 280zx n/a i removed both cats from both cars took about 2 hours or soo removing the honey comb inside the stock cats.. then stuck the cats back on an let me tell u it made a huge improvment in speed and at the gas pump but... the loudness with the stock exhaust isnt really cool.. so i bought me a HKS exhaust straight threw on my turbo 280zx an wow ! the n/a/ though i did the same to the cat but i went to autozone and got one of there mufflers... 99.99 plus tax... " its was my x gurlfriends car " but never the less it sounded like a roaring beast ! like a v-8 glass packed.. maybe a little less loud...

 

I ran my '82 N/A at 14 degrees on the timing...pulled past 6,400rpm. The exhaust...leave the cat and remove everything aft of it...it's loud but cool sounding and the drone inside the car at 70mph will make you go nuts.

 

ok i'm glad i found this thread as i was going to start one to do with timing. when i checked mine for the first time today it was already running at 14 degrees! due to currently cheap fuel (thank you global economic crisis) i'm running on ultimate which on our scale is 98RON well i pushed it all the way to 20 and have run it to 6500 and gone up hills from 15mph in 3rd 4th and 5th and no ping at all

 

I put on the MSA header and exhaust on my 81 non turbo coupe. It sounds pretty good. I'll try to get a sound sample on here. I did drop the cat and plugged the egr valve. The car has a lot more top end power and some pretty good low end. Got pulled over last weekend and the cop clocked me at 130 which i got up to that pretty fast. Smoked a honda GO DATSUN Also it bumped up my gas mileage as well. My state doesn't do smog so I have no worries.

 

i was looking up online for mufflers and found a piece called apexi n1 muffler, from k2motors.com. i looked it up on youtube and found it on a turbo 280zx, it sounded good and when i talked to the guy he said its been a good muffler for him, so i might be getting one of those.