# Intake and exhaust



## nissandrew (Aug 23, 2005)

I'm just wondering what you guys are using for intake and exhaust. (ie. K&N, size of the exhaust pipe and muffler, etc.) I'm just trying to figure out what I want to do in the spring when I get my car finished up.
Also, what is your guys' opinion on these headers:
http://www.zcarparts.com/store/merchant.mvc?Screen=CTGY&Category_Code=PEC02

Thanks for your help.


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## ICP Sux0rZ! (Jan 10, 2005)

those header look nice

i'm using a K&N OEM replacement filter, gonna be switch to a FIPK evetually

i think most NA guys use 2.5" pipes, and turbo guys run 3"


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## Xorti7 (Dec 27, 2004)

ICP Sux0rZ! said:


> those header look nice
> 
> i'm using a K&N OEM replacement filter, gonna be switch to a FIPK evetually
> 
> i think most NA guys use 2.5" pipes, and turbo guys run 3"


Yea, 3" for the turbo. I just have the cat back. Im told a straight through design would have been better, but I have a magnaflow and it sounds great.

Dont waste you're time with the FIPK, just get the $55.95 Part #: RF-1011

http://z31.com/kn.shtml

The only difference is a few nuts and washers and a bracket thing you can make yourself (or most likely not even bother with; I didn't)


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## nissandrew (Aug 23, 2005)

So with my n/a motor, I could run a K&N filter, MSA headers, 2.5" exhaust...and what about the cat and the muffler? Suggestions?


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## AZ-ZBum (Nov 21, 2004)

It would be illegal to drive a Z31 with no cat on roadways in the US. Not that people don't do it...

As for the muffler, I haven't heard a MagnaFlow muffler I haven't liked.


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## nissandrew (Aug 23, 2005)

AZ-ZBum said:


> It would be illegal to drive a Z31 with no cat on roadways in the US. Not that people don't do it...
> 
> As for the muffler, I haven't heard a MagnaFlow muffler I haven't liked.


Lol, yeah, illegal isn't cool...are there alternatives with the cat, though?
As far as the Magnaflow, for those of you that own one or have heard one; What does it sound like? I'm trying to avoid the ricey fart can sound...thanks for the replies.


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## dono200sx (May 2, 2002)

nissandrew said:


> Lol, yeah, illegal isn't cool...are there alternatives with the cat, though?


Yep! I'm planning a Random Technology high-flow cat on my Z when I do my exhaust. From what I've heard they're made well and you won't lose hardly any power. I believe they were mentioned in several places at Nissan Performance Magazine Just do a search for Random Technology and you will get several hits. They can be had for around $ 350 plus tax/shipping. Which is still cheaper than a dealer. Hope this helps.

I've also heard that Catco makes good high-flow cats and they cost around $150 plus tax/shipping. But I think the Random Technology cats are made better.


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## hondakillerZX (Aug 16, 2004)

when people get a full exhaust like turbo back with a high flow cat does it make more emissions or less? i mean is it easier to pass smog with the bigger pipes or with the smaller pipes


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## ICP Sux0rZ! (Jan 10, 2005)

AZ-ZBum said:


> It would be illegal to drive a Z31 with no cat on roadways in the US. Not that people don't do it...
> 
> As for the muffler, I haven't heard a MagnaFlow muffler I haven't liked.


well in certain states that dont require testing (i.e. florida, texas, certain parts of south dakota, certain parts of colorado) u can legally run no cat, jsut gotta check with the local laws :thumbup: 


i cant wait to get to FL



hondakillerZX said:


> when people get a full exhaust like turbo back with a high flow cat does it make more emissions or less? i mean is it easier to pass smog with the bigger pipes or with the smaller pipes


depends, u can get highflow cats and mufflers that keep emissions to acceptable levels


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## MrFurious (Oct 30, 2005)

How many times do you get tested where you live? Just remove the cat, or get your exhaust after your test. We did have tests here, but they werent as stricked as Cali's. But we no longer have tests, but police have a law here about being able to do something about a car that doesnt look up to par. But unless your dragging parts or looking like you have a smoke screen shooting out. You wont get ticketed. Most of the laws by some of these states are rediculas. Because the only thing that is being restricted is the owner of the car. Some states wont even allow aftermarket intake. :banhump:


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## AZ-ZBum (Nov 21, 2004)

ICP Sux0rZ! said:


> well in certain states that dont require testing (i.e. florida, texas, certain parts of south dakota, certain parts of colorado) u can legally run no cat


No you can't you jackass. Federal law says that all emissions equipment required must not be compromised. Just because you don't have emissions testing doesn't mean you can remove whatever the hell you want.


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## Zen31ZR (Mar 24, 2004)

Actually, that would be somewhat incorrect. To prevent wildfires the converter can be removed..... A hot cat can ignite any dry grass and hay or wood that touches it. Forest service vehicles don't have catalytic converters, in this state. The muffler must be intact as a spark arrestor, however. The percentage of vehicles affected in pretty small, though. I'd agree that 100% of road going vehicles are required to have a functional cat and all their emissions equipment intact.


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## ICP Sux0rZ! (Jan 10, 2005)

if your not gonna get tested ever what the hells the difference? no one will know so who the F--- cares?


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## lostmenoggin (Sep 10, 2005)

ICP Sux0rZ! said:


> if your not gonna get tested ever what the hells the difference? no one will know so who the F--- cares?



Visual inspection.. If they look and see you have no cat, you may get a ticket or something.. depending on your local laws. I have that pacesetter catback exhaust with a punched out cat.. It's loud but I haven't gotten a ticket yet...


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## dono200sx (May 2, 2002)

hondakillerZX said:


> when people get a full exhaust like turbo back with a high flow cat does it make more emissions or less? i mean is it easier to pass smog with the bigger pipes or with the smaller pipes


 According to what I have read, it won't "create" more emissions. That's done by the motor. It will, however, let a little more flow through. That being said, you should be able to pass your emissions test without any problem so long as all of your emissions control equipment is in place. 

If they are giving you trouble about the size of your pipes, go somewhere else. They are jerking you around. 

BTW, it is illegal to drive your car on the road without a cat in Texas. A guy I know just got a ticket for it. He tried to fight it in court, but lost.


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## ICP Sux0rZ! (Jan 10, 2005)

lostmenoggin said:


> Visual inspection.. If they look and see you have no cat, you may get a ticket or something.. depending on your local laws. I have that pacesetter catback exhaust with a punched out cat.. It's loud but I haven't gotten a ticket yet...


if you aren't getting inspected, the only way a cop would know was if you were driving like an asshat, and had a riced out (and or heavily modified) car, in cali, engine mods of any kind are frowned upon, i see honda boys on the side of the road getting tickets alot, hood open, cop has a mirror looking under, dont get pulled over and you'll be fine, 

even then if u wanted to, empty out the cat run a test pipe and slide the cat shell over it and weld it to the pipe, hey look fake cat


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## Zen31ZR (Mar 24, 2004)

ICP Sux0rZ! said:


> if you aren't getting inspected, the only way a cop would know was if you were driving like an asshat, and had a riced out (and or heavily modified) car, in cali, engine mods of any kind are frowned upon, i see honda boys on the side of the road getting tickets alot, hood open, cop has a mirror looking under, dont get pulled over and you'll be fine,
> 
> even then if u wanted to, empty out the cat run a test pipe and slide the cat shell over it and weld it to the pipe, hey look fake cat


Yeah thats been done before. Lotta guys do that here. Most engines around 2.0 liters and smaller can pass without a cat if tuned right with a S-AFC. Dunno about 3.0, though


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## lostmenoggin (Sep 10, 2005)

ICP Sux0rZ! said:


> if you aren't getting inspected, the only way a cop would know was if you were driving like an asshat, and had a riced out (and or heavily modified) car, in cali, engine mods of any kind are frowned upon, i see honda boys on the side of the road getting tickets alot, hood open, cop has a mirror looking under, dont get pulled over and you'll be fine,
> 
> even then if u wanted to, empty out the cat run a test pipe and slide the cat shell over it and weld it to the pipe, hey look fake cat


very good. I think you might be getting it now. Thats bascially the same thing I was saying. I said visual inspection, meaning by anyone, but I was mostly referring to cops; not a state inspection. But you got the idea.. don't get pulled over. :thumbup:


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## ICP Sux0rZ! (Jan 10, 2005)

lostmenoggin said:


> very good. I think you might be getting it now. Thats bascially the same thing I was saying. I said visual inspection, meaning by anyone, but I was mostly referring to cops; not a state inspection. But you got the idea.. don't get pulled over. :thumbup:


well i know the dont get pulled over part, but theres always ways around it


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## hondakillerZX (Aug 16, 2004)

hey i live in california so do you guys think ill still pass smog with a 3'' turbo back, highflow and a borla muffler


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## ICP Sux0rZ! (Jan 10, 2005)

hondakillerZX said:


> hey i live in california so do you guys think ill still pass smog with a 3'' turbo back, highflow and a borla muffler


considering the amount of people with those, probably


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## hondakillerZX (Aug 16, 2004)

cool ill probably go through with it and just keep my old stuff just in case


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## hondakillerZX (Aug 16, 2004)

does low end torque suffer a lot with a 3'' turbo back


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## AZ-ZBum (Nov 21, 2004)

it improves.

http://www.az-zbum.com/backpressure.shtml


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## Zen31ZR (Mar 24, 2004)

From what I saw, there was no difference between running no pipe at all and running the catback I had, expect of course quieter.... Lost the most reinstalling the cat, actually. A turbo makes all the difference there, as Zbums site says. You'd probably notice it somewhat on an NA car, but not a turbo car. Turbos do lots of interesting things to exhaust gases, and also act as a nice muffler. In fact my VG30ET exhaust note was louder at idle (when the turbo isn't spinning very fast) than at 6500 rpm. You hear the spool-up whine, and then just the whoosh of a lot of air coming out after that. I've got a video I'll post up, someday when I have a host, of my car at the track, running downpipe only.


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## hondakillerZX (Aug 16, 2004)

AZ-ZBum said:


> it improves.
> 
> http://www.az-zbum.com/backpressure.shtml


thanks for the info dude. good stuff. is it true that milage gets better with a bigger exhaust ?


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## MrFurious (Oct 30, 2005)

I am not argueing here just stating. The reason why you loose low end HP on a new (aftermarket) free'r flowing exhaust is because of the lack of back pressure. Which is actually a plus, if you tune your. I will explain... Car manufactures figured out a few tricks on how to improve power with all of this emissions stuff and regulations. One way is by making the exhaust a little restrictive, thus causing not all of your exhaust to excape imbetween strokes of the motor. Why can this be a plus you ask? Because it gives you a richer fuel mixture (because of the unburned fuel in the exhaust) without you having to actually tune your car to have that fuel at the low end. This is a plus but only up to a certain RPM, once you get your motor reved up past a certain RPM that restrictive exhaust becomes a hindrance. Your exhaust no longer excapes at a beneficial rate thus causing a loss in HP. So, when you put on a new high performance exhast on a stock car that has been tuned with emissions in mind, your car will run lean at the lower RPM ranges, then will benefit at the upper RPM ranges. So what I am getting at is that when you start putting on performance parts, to get their full potential, you will need to tune your car.


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## Zen31ZR (Mar 24, 2004)

MrFurious said:


> I am not argueing here just stating. The reason why you loose low end HP on a new (aftermarket) free'r flowing exhaust is because of the lack of back pressure. Which is actually a plus, if you tune your. I will explain... Car manufactures figured out a few tricks on how to improve power with all of this emissions stuff and regulations. One way is by making the exhaust a little restrictive, thus causing not all of your exhaust to excape imbetween strokes of the motor. Why can this be a plus you ask? Because it gives you a richer fuel mixture (because of the unburned fuel in the exhaust) without you having to actually tune your car to have that fuel at the low end. This is a plus but only up to a certain RPM, once you get your motor reved up past a certain RPM that restrictive exhaust becomes a hindrance. Your exhaust no longer excapes at a beneficial rate thus causing a loss in HP. So, when you put on a new high performance exhast on a stock car that has been tuned with emissions in mind, your car will run lean at the lower RPM ranges, then will benefit at the upper RPM ranges. So what I am getting at is that when you start putting on performance parts, to get their full potential, you will need to tune your car.


Except for the fact that cars are self tuning within a certain range, which is fairly broad. You won't get lean or rich anywhere, because the ECU will adjust against what it sees for exhaust gases. Maybe thats how it would have been on carbed cars, but fuel injection has come a long way. Even the Z31 can adjust for changes in intake and exhaust, so you won't lose anything anywhere. Its when you go outside the stock ECUs maps ranges that manual tuning or another ECU becomes necessary.


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## MrFurious (Oct 30, 2005)

I dunno just how much adjusting the Z31 does. But some fuel injection systems dont even have an O2 sensor, just FYI. Plus fuel enjection systems were only made to adjust for one reason, and that is for altitude changes. Because a car tuned at sea level wont run at 10,000 feet or which ever altitude you choose. So I doubt when you put on new exhaust the car is going to perfectly correct its fuel map to the new exhaust. But I could be wrong.


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## Zen31ZR (Mar 24, 2004)

MrFurious said:


> But some fuel injection systems dont even have an O2 sensor, just FYI.


 Hmm, not anything with 4 wheels made to run on public roads in the U.S.  You might be referring to motorcycles with that statement, but they are the exception to the rule on a lot things. 

And no, the only reason to have fuel injection is not for altitude adjustment. A carbed car built to run at sea level _will_ also run at 10,000 feet, it just will not pass emissions at that altitude. To a point, carbs are also self regulating since they only expend as much fuel as there is air going through the venturiis. EFI is much more precise, but in reality carbs actually atomize the fuel better..... EFI is also easier to use with turbocharging. EFI is also the only thing that has a chance of passing current emissions standards. EFI also aids with driveability, allowing race motors with large cams built to live at 8000 rpm or more to idle decently at 1000 rpm or less...... You'd never get that kind of driveability from carbs, because those kind of engines barely pull any vacuum at idle speeds. There's a lot of reasons to use EFI. I'm just barely scratching the surface.


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## Zen31ZR (Mar 24, 2004)

84z31 said:


> do you smoke crack? do you even know what you are talking about?
> 
> the ecu does adjust the fuel mixture. that is why there o2 sensor.
> 
> read some information about bosch fuel injection systems used on 80's toyota's. not as complex as a nissan system but you'll maybe understand a little better. i think toyotas used bosch L- injection systems.


And Bosch CIS injection systems have been around since the early 70s. I had a '73 Volvo with CIS. Most BMWs since the 2002 have been CIS powered. Very simple system.


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## dales86t (Nov 1, 2005)

ever heard of mechanical injection? uses a mechanical pump and old school styles to help map air fuel ratios, look at saabs, porches, mazdas all back in the day cars. They dont use o2 sensors.


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## MrFurious (Oct 30, 2005)

dales86t said:


> ever heard of mechanical injection? uses a mechanical pump and old school styles to help map air fuel ratios, look at saabs, porches, mazdas all back in the day cars. They dont use o2 sensors.


http://www.boschautoparts.co.uk/pcPetr11.asp?c=2&d=1

If you look at Bosch's FI diagrams, their K-Jetronic system doesnt use a "Lambda Sensor" aka O2 sensor. 

All that is really needed in FI is... Fuel Pump, Fuel Reg, Injectors, TPS, MAF or MAP sensor, & ECU. The rest is for emissions. Or little things that they decided to add on.


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## MrFurious (Oct 30, 2005)

Now that I am thinking about it, do you really even need a MAP or MAF sensor with the combination of having a TPS and the ECU knowing your RPM?


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## Zen31ZR (Mar 24, 2004)

MrFurious said:


> Now that I am thinking about it, do you really even need a MAP or MAF sensor with the combination of having a TPS and the ECU knowing your RPM?


There's different types of injection systems. Other models the MAF also functioned as a sort of TPS, some only have an MAP. However, most of that was all OBD1 or before. If you are talking about modern injection systems, its just not like that anymore. 

The ECU does have to have a frame of reference for what the engine is doing. The engine might be at 6000 rpm, but is the throttle open or closed. How much air is the engine taking in, so that the correct amount of fuel can be applied. Its stuff like this that gives that little thing called "driveability", which is a very big deal. Do you want your engine to stall every time you roll up to a stoplight? Do you want the engine to stall because the injectors are still spraying the same amount at 6000 rpm with the throttle closed as they were at WOT? It's all about driveability and passing emissions standards, not for really any other reason.


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