dual exhaust

Does anyone use dual exhaust? i am wanting to get duals on my 240, but seems like a little work with the gas tank in the way.

You mean like a tip on each side? Why?

You mean like a tip on each side? Why?


ya why... dont you wanna be like everyone else!?? :rolleyes:

duals are pointless on an inline motor

plus a 240 with duals would look somewhat ugly i think.

just like when you see the super cool cavaliers with dual exhaust.

Only Inline Engine car that duals look good on is a Lowered S2000 with a decent sized can exhaust on both.

And the 350Z/G35.

And the 350Z/G35.


350Z/G35 are 3.5L V6, not inline.


SRT-4's are nice with duals, and they sound hella nice IMO

Oh, right, sorry I thought he meant like longitutinally mounted. (btw, I know I spelled it wrong.)

Oh, right, sorry I thought he meant like longitutinally mounted. (btw, I know I spelled it wrong.)


it deonst mtater as lnog as we knoe waht you maen!

longitudinally. l-o-n-g.... j/k
d-i-c-t-i-o-n-a-r-y

just get the apexi n1 duals

the n1 dual canister is what you need, it sounds pretty sweet on NA and turbo cars..

the n1 dual canister is what you need, it sounds pretty sweet on NA and turbo cars..


i love mine N/A, cant wait to go turbo and hear it then...

yeah if i can ever find an S13, im hoping to pick up the N1 dual because of that same thing, its great NA and turbo..

i love mine N/A, cant wait to go turbo and hear it then...

hows it sound? how much did you get it for? whered you get it?
i might get one from a friend, never been used. hes asking 215. i think its a steal

yeah thats definitely a steal. but you should understand WHY it would be pointless to use fully dual exhaust on an i-4.. if a 3" exhaust is putting out X litres every 100miles at 2k rpm, you'll need 2 1.75" (or less) pipes to have the right backpressure. how do you think that would sound?? and even the s2000 isn't a fully dual exhaust. its 2 pipes coming out of 1 muffler.

if you're thinking about having 2 tips (one on driver's side, one on passenger's), its gonna cost you 4X as much just to modify the underneath of your car to have the right length pipes. if you want twin tips, get the apex'i N1 dual. if you want a regular performance exhaust, get the N1. (imo)

There is no "right" amount of backpressure. Not in N/A motors or forced induction motorrs. Backpressure is a negative pressure in exhaust flow that results in exhaust gases(read: already burned, completely useless for combustion) and forced BACK into the combustion chamber, thereby forcing the piston to do extra work pushing that exhaust gas out of the chamber, causing less power to be made with each effective stroke. There is no such thing as an exhaust that is too big. There is a point, however, where maximum flow is reached and increasing pipe diameter would serve no purpose.

Summary: Think about it, the basic idea is to put air and fuel into the combustion chamber, compress it, blow it up, spew it out and start over. Why would you want fuel and air that has already been drained of its usefullness coming back into the combustion chamber?

There is no "right" amount of backpressure. Not in N/A motors or forced induction motorrs. Backpressure is a negative pressure in exhaust flow that results in exhaust gases(read: already burned, completely useless for combustion) and forced BACK into the combustion chamber, thereby forcing the piston to do extra work pushing that exhaust gas out of the chamber, causing less power to be made with each effective stroke. There is no such thing as an exhaust that is too big. There is a point, however, where maximum flow is reached and increasing pipe diameter would serve no purpose.

Summary: Think about it, the basic idea is to put air and fuel into the combustion chamber, compress it, blow it up, spew it out and start over. Why would you want fuel and air that has already been drained of its usefullness coming back into the combustion chamber?



this thread and arguement has occured a million times, if u lose backpressure, you lose tourque, i dont knoe why but you do.


i paid 579 for my s14 off nopi international, i wish i could have got one for $2** but if i had to choose i would spend the 579 again over stock, it sounds great, nice and deep and backfires just a bit at the right RPM's, at WOT its awesome.

http://www.zilvia.net/faqs/exhaust/n1/n1.asp <--sound clip, check it

I'd wanna get it to, but seems pricey for mild steel.

well i was really askin how the duals installed. on passanger side my gas tank is right in the way. and i dont plan on putting 2 cannon 3.5" tips on it. and will it cost alot is my real question.

bleh no edit. well anyway. this is what i am thinking of putting on. 2 of these.
http://cgi.ebay.com/ebaymotors/HKS-DTM-ROUND-3-TIP-MUFFLER-NISSAN-240SX-S13-S14-200SX_W0QQitemZ7999441154QQcategoryZ33636QQrdZ1QQc mdZViewItem well not this exactly but something like it.

ok to clear it up...the only torque you would lose with a bigger exhaust is torque acquired from the resonance tuning of the pipes

you can get max torque out of the engine with a wide open exhaust, but a few more ftlb can be gained by using a resonance tuned exhaust OVER what your engine can make. most high quality exhaust systems use this method to boost low end torque so they dont make less hp than a wide open system(read: high quality as in not tsudo, ect :gay:

I still don't get why you wanna do it.

im gunna say its not worth the money you will put into it

Im gonna have to say that its not really the resonance that cause you to get tq. Its back pressure that gives you the low end torque.. Now too much back pressure and you have a bad problem. Sure Resonance can mean back pressure but resonance can be achieved without backpressure.

maybe its not a specific size that gives the 'right' amount of bp, but there is a point where you can have too little or too much so that you're not producing efficient power. i'm not sure if the physics of dual exhaust on a 240sx evade the PRINCIPLES of physics but i don't see how it would help. unless you want to go rice can dual exhaust with one pipe from the engine, then ok, make sure the rice doesn't stick to the pot.. just go with any cat back for over $300. that way you know you're buying a quality product. i suggest the apexi n1 or n1 dual.

yea i planned on putting a header and splitting it about half way past the car. i just like the dual exhaust look. plus i was thinkin about doing a vg30dett or a rb swap.

yea i planned on putting a header and splitting it about half way past the car. i just like the dual exhaust look. plus i was thinkin about doing a vg30dett or a rb swap.


rb's are straight six, no need for duals

no backpressure does NOT give you torque

i wish i could cast the spell of wisdom upon all those infected with that old school domestic ricer myth

if you still insist that it does please try to explain it with physics or some logical manner. dont use the sucking thru the straw theory cuz thats total bs

Resonace Tuning is for headers... dont kid yourself into thinking that any part for a KA or SR is resonace tuned.



The case of backpressure is guilt by association in that stream velocity is what makes torque. to get velocity you need pressure. Velocity makes torque by giving the exhaust momentum and it creates a scaveging effect inside the cylinder at a certian piston speed. the speed this happens is determined by piping diameter... large exhausts will stagnate at low speeds and will start to scavenge at a higher RPM but smaller exhausts will scavenge at a lower RPM but then choke at a higher RPM.

or you could be like the indy v8 guy and put sidepipes on it :icon16:

Resonace Tuning is for headers... dont kid yourself into thinking that any part for a KA or SR is resonace tuned

im sorry your right i meant stream velocity that creates the scavenging effect, not resonance tuning. mistake in terms


The case of backpressure is guilt by association in that stream velocity is what makes torque. to get velocity you need pressure. Velocity makes torque by giving the exhaust momentum and it creates a scaveging effect inside the cylinder at a certian piston speed. the speed this happens is determined by piping diameter... large exhausts will stagnate at low speeds and will start to scavenge at a higher RPM but smaller exhausts will scavenge at a lower RPM but then choke at a higher RPM.


i wonder then, why have i seen many cars run a 3" side exit off the header with no cat, then dyno showing increase hp + tq low and high end?

as varied as near stock civics and tuned turbo motors all show the same effect

i wonder then, why have i seen many cars run a 3" side exit off the header with no cat, then dyno showing increase hp + tq low and high end?

as varied as near stock civics and tuned turbo motors all show the same effect

A) dynos are full throttle - part throttle is where a properly sized exhaust will shine

B) Theres a Restriction up stream - the header prolly narrows to 2.75 or something and gives a venturi effect giving good velocity in the header and then it probably stagnates in the pipe taking off the exhaust loses the stagnation but keeps the venturi.

C) Compared to stock a 4in pipe would make power... turbulent flow caused by diameter changes (crush bent) kill flow and velocity quick. on turbo cars, however, tuners establish turbulent flow (using a large step in piping diameter right after the turbine) so the exhaust is pushing a semi straight column of exhaust instead of a spiraling column (to make the shortest distance to the exit)

There's a little thing called the street, maybe you are permanantly on full throttle, but normal people sometimes only go part throttle and it would be nice to have enough torque to make it to the next red light.

http://img62.exs.cx/img62/7305/napoleondynamite2ls.jpg

IDIOT!! GOD!!!!

lol but i actually agree with sr20det on this.
why would you need power on part throttle? you dont need to get to the light that quickly, and if you did youd be at full throttle anyways.

lol but i actually agree with sr20det on this.
why would you need power on part throttle? you dont need to get to the light that quickly, and if you did youd be at full throttle anyways.

You want enough power to move the car without going to full throttle. NA engines that have no power before 6k RPM have a hard time doing that.

That engine with no HP til 6000 RPM would make the ultimate sound clip.... Vrrroooooooooooooooooooooooooooomm..Eerrrrrrrrrrrr rrrrt..*Shift*....Vroooooooooomm..Eeerrrrrrrrrrrrr rrrrrrrt *Shift* it would sound like you had so much topend power lol...or just crazy turbo lag.

im not even going to comment on the exaggeration(sp?) that you just put out there.
because it was an exaggeration.

nice job following through on your commitment to not comment.

and i think on a KA you can get away with any size exhaust pretty much I have the apexi gt which is huge but i didnt really notice a whole lot of difference either way around town but on the freeway it was better. but i have heard from honda people that they feel the hurt down low when they get exhaust thats big so maybe the theory is true but the 2.4 seems to be able to deal with 95mm just fine.

Jeez.

You tune for the RPM range you want to make power. Not the gas pedal range.

And for those of you who need power from 900rpm on, ever heard of downshifting? Better yet, just get an SRT4. They make 2000000psi at idle.

Not even the largest compressor woudl take until 6k to spool if you used a small enough turbine housing. People alway assume that with larger compressors such as the TO4R and TO4S that you will never spool until 6k+. Its not true. w/.58 turbine housing, spool time would be minimal.

And lag is not from the time you hit the gas till the turbo spools. It is how long it takes the turbo to make boost in its "proper" RPM range. I get full boost at 4k, so if I am at 15" HG and I hit the gas, from the time my foot hits the floor at 4000rpm till the time it makes full boost at 4XXXrpm would be considered "lag". Anytime before 4000rpm is considered Sizing error if you wanted boost sooner.

I said NA engine, not turbo engine.

why do you need power when not at full throttle?. do you put it to the floor when you pass someone? or when you hit a green light? just cause your not racing dont mean you do not need power thru your low end too.

...your missing the point.

ive never driven (or seen) a car that would lose so much power from a oversize exhaust that it couldnt pass someone without downshifting. unless it couldnt in the first place.

and really why would you want to go so fast thru green lights if you arent racing...

You tune for the RPM range you want to make power. Not the gas pedal range.

to add to the partial throttle, just to settle things...

if your at part throttle, and you want to be accelerating at x speed. but your only going at y speed, why not press the pedal a little bit farther to get the desired x acceleration?? your still not hitting WOT.

i think the point here is driveability i.e. you dont want to have to wait for power.

i think the point here is driveability i.e. you dont want to have to wait for power.

Then get a V8....

no im not agreeing with anyone on here it just seemed like people were missing the point.

1 entry found for backpressure.
back·pres·sure
Residual pressure opposing the free flow of a gas or liquid, as in a pipe or an exhaust system.


Source: www.Dictionary.com

Now that we're all on the same page, try reading an article on the subject. Hey, imagine that. Actually learning about something from people who know what they're talking about instead of regurgitating myths you heard from "that guy with a fast car X". DO NOT POST ANYTHING ELSE IN THIS THREAD UNTIL YOU READ THIS ARTICLE. (http://www.momsracing.com/tech/exhaustScavenging.pdf#search='backpressure%20exhau st')

Please, read it. This is from people who know engines, who know cars, and who have scientific data to back up they're opinions on the subject. A quote from the article:

"...Wollongong (Australia) mechanic Kevin Davis has done extensive testing of varying backpressure on a number of performance engines...He initially expected to use [his patented system] to cause some backpressure at low loads to 'help torque'. However, he soon changed his mind when any increase in backpressure proved to decrease torque..."

This guy developed a patented system to tune backpressure and backpressure only in an exhaust system and found that ANY increase, even as small a 1.5psi - which almost no exhaust on a street car could produce an amount that small - caused peak torque to drop by 4% and peak power by 5%.

Someone, anyone, look at this article and THEN explain to me why backpressure is good for ANY ENGINE UNDER ANY CIRCUMSTANCES. You can't, because you're wrong. Sorry if the truth hurts, thank you and good night.

Click here (http://www.geocities.com/MotorCity/7177/exhausttheory.html)

Read that for all of you "Backpressure is T3h Good for T3h T0rQu333!!111" people... I mean honestly.. You pressurize air into the intake side of the engine and then what? pressurize exhaust back in? Yea okay. Whatever you say...

1 entry found for backpressure.
back·pres·sure
Residual pressure opposing the free flow of a gas or liquid, as in a pipe or an exhaust system.

Dictionary.com - telling people things they already knew since 1999.



Now that we're all on the same page, try reading an article on the subject. Hey, imagine that. Actually learning about something from people who know what they're talking about instead of regurgitating myths you heard from "that guy with a fast car X". DO NOT POST ANYTHING ELSE IN THIS THREAD UNTIL YOU READ THIS ARTICLE. (http://www.momsracing.com/tech/exhaustScavenging.pdf#search='backpressure%20exhau st')

Uhhh... Maybe I should post up the link to that guy saying narrow tires are better for traction... you know... since everything on the internet is true... :gay:



Someone, anyone, look at this article and THEN explain to me why backpressure is good for ANY ENGINE UNDER ANY CIRCUMSTANCES. You can't, because you're wrong. Sorry if the truth hurts, thank you and good night.

Ummm who are you agian?

For the most part when people are refering to backpressure they are refering to flow velocity. (yes, despite your working knowledge of dictionary.com we do know what were talking about)

Why people talk about backpressure being good on N/A cars is because that an exhaust that chokes on the topend is not stagnating on the lowend. however in the case of the 240SX for some reason (I assume because the Header establishes flow velocity since all of them have 65mm diameters.) a 3in exhaust will make power with minimal to no loss at 100% throttle HP / Torque.


whttrshpunk FAIL

OMFG...did you not see the part in that little link you posted where the Power started to decrease in its Power Gains the larger the I.D. of the tubing? and that was on a V8 with high displacement. Smaller engines will have a harder time to fill that Tubing....also this guy claims over 200HP gain from exhaust system change...

Hmm lets see also John Grudinsky states that has seen backpressure help a 4-Cyl in the low-end but choke out in the top end...He said it was due to the timing.

I think you need to read the whole thing."Thank You and Goodnight"

Any technician with any dyno experience will tell you that the best mufflers are no mufflers at all!
so how is this saying that oversized exhausts are not good? no muffler = muffler with infinity diameter

The outer casing is sized just-so, so that high-pitched engine sound (what we deem "noise") is reflected back into the core of the muffler… where those sound waves meet their maker as they slam right into a torrent of more sound waves of like wavelength coming straight from the engine.

now this just reeks of ignorance. maybe they should explain how they got the sound waves to bounce back and cancel against the sound waves coming, WITHOUT DOIN THE SAME TO THE EXHAUST FLOW

Whoa, bet you didn't know that!

this guy cracks me up. and not in a good way.

If you think about it, you'll realize that since stock exhausts are so good at restricting that they'll actually ram the exhaust pulses together and actually make pretty darn good low-end torque!

he does such a good job of explaining this one! :rolleyes:

According to the flowbench, two of the best flowing units you can buy are the Walker Dyno Max and the Cyclone Sonic. They even slightly out flow the straight through designs from HKS and GReddy BL series. Amongst the worst, are the Thrush Turbo and Flow Master mufflers.

some proof, homie?

OverBoost.com

ahahahhahahahahahha OMFG and i thought this was going to be written by someone respectable, not a group of RICERS!

:lol2::lol2: :lol2::newbie:

Yea slideways..., its on stealth316 which is way below the level of car gods such as yourself. Slow down and actually think about what you are reading for a second and you'll see that most of what you asked was insinuated either earlier in the read or you should already know it(hint: this article is useless to you).

Overboost.com makes shitloads of money while you make shitty posts. Hmmm, who's the ricer here?

apc makes shitloads of money...does that make them respectable? apc makes more money than overboost. maybe i should talk to them for all my backpressure questions.

im not doubting this theory it was just a very poorly written article with no proof and very shaky logik

Hypocracy.

not hypocracy
just doubt
i think backpressure is always bad
i dont know every last detail though so if someone can convince me that it can help, then ill believe
it just has to be a well written article that has actual logikal proof to go with its statements

Dont be so arguementitive. I've explained well enough why backpressure is associated with torque and you've chosen to ignore it and focus on obsure qoutes

For the most part when people are refering to backpressure they are refering to flow velocity. (yes, despite your working knowledge of dictionary.com we do know what were talking about) Why people talk about backpressure being good on N/A cars is because that an exhaust that chokes on the topend is not stagnating on the lowend. however in the case of the 240SX for some reason (I assume because the Header establishes flow velocity since all of them have 65mm diameters.) a 3in exhaust will make power with minimal to no loss at 100% throttle HP / Torque.


Oh yes, you explained it so well with such solid physical evidence and logic. I especially liked the part where you said "for some reason". At least I have a reason and a well written, documented article from a respected racing company's website to back up my opinion, you're just an argumentative, belligerent retard who refuses to just say "Hey, you know what? You make a good point. Maybe I didn't know as much about backpressure as I thought I did."

You see there is nothing wrong with not knowing, the danger is in refusing to learn.

Oh yes, you explained it so well with such solid physical evidence and logic. I especially liked the part where you said "for some reason". At least I have a reason and a well written, documented article from a respected racing company's website to back up my opinion, you're just an argumentative, belligerent retard who refuses to just say "Hey, you know what? You make a good point. Maybe I didn't know as much about backpressure as I thought I did."

You see there is nothing wrong with not knowing, the danger is in refusing to learn.


Bwhahaha I read bits of that article... what an Idiot. he made a huge exhaust for Zero Pressure and then pluged it... so not only is it stagnating... hes plugging it up right at the end... wow... thats an exact simulation for an aftermarket. espescially since the KA's header as I explained earlier is 65mm which I suspect creates a venturi effect when on a 3in exhuaust...


Have fun calling me ignorant on the basis of some shithole link you found on the intra web