dual exhaust

[D-Bo]

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)

[whttrshpunk]

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?

[xcusememisswyn]

Originally Posted by whttrshpunk

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

[240SXSlideStar]

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

[Adam_rex]

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.

[Adam_rex]

bleh no edit. well anyway. this is what i am thinking of putting on. 2 of these.
http://cgi.ebay.com/ebaymotors/HKS-D...QQcmdZViewItem well not this exactly but something like it.

[slideways...]

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

[240SXSlideStar]

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

[sidewayzS13]

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

[monooxide]

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.

[D-Bo]

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.

[Adam_rex]

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.

[xcusememisswyn]

Originally Posted by Adam_rex

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

[slideways...]

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

[R.W.240]

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.