Isn't a 3 inch exhaust too big?

[maxima278]

I keep seeing magazines saying to use a 3 inch exhaust on a turbo'ed car. That just seems massive to me. I know that you can have too little back pressure. Just wondering if anyone has any knowledge about this

[IanS13]

Turbo cars don't need any back pressure, between the turbo and the head inside of the turbo manifold is much more back pressure than any car needs or like, on any normal car before the converter there should not be more than 1-2psi back pressure after that you don't need any more, meaning after the converter 0 back pressure is perfect but on stock exhaust system that is not the case. so if you can deal with the noise a 3" catback exhaust on a na 240sx is ideal

you may ask what qualifies me will, I am a exhaust tech that's what i do

[GhostDriver]

I guess a three inch is the accepted diameter for turbochargers but I think a 2.5 is fine depending on the unit.

[WeldingHank]

backpressure = bad. end of story.

[naed240sx]

Of course all of this depends on the car. Larger engines typically demand larger diameter exhaust systems. For the ka, as it has been discussed many times, you can use a 3" system for maximum gains, but 0 losses, even if you are NA. Forget backpressure, velocity is most important. The higher the exhaust velocity, the more scavenging that takes place.

higher velocity=more scavenging=more power

[BadMojo]

For the ka, as it has been discussed many times, you can use a 3" system for maximum gains, but 0 losses, even if you are NA. Forget backpressure, velocity is most important.

It's pretty much limited by how loud you want it to be. A 3" exhaust on an NA KA with aftermarket headers would, for me at least, probably be too annoying for daily driving, even with a resonator.

[0wn3r]

now feel free to say i'm wrong, but most people that go with 3" exhaust do so because (like said above) the turbo doesnt really need or want any back pressure... and pressure will = heat. you don't want to put any unecessary strain or heat back onto the turbo/engine.

[edit:] heyyyy it's welding hank! the first person from ONE i've seen on here

[redrocket]

its better to have a freer flowing exahust on a turbo because due to the back pressure caused by having a "smaller" exhaust system you gain turbo lag...............

on an NA vehicle the less back pressure helps the car in the upper RPMs but can cause the vehicle to loss some of its low end torque

[JimmyMethod]

Lock this thread... now...please...

[KDashy]

I remember a thread like this and I brought up the fact that exhaust gases come out in pulses and someone FLAMED me for it, unbelievable.

Nico members are generally smart but no one can agree on exhaust tech.

IBTL

[PantherRacer]

IBTLand scince a self proclaimed exhaust technician spoke, I say the person asking the question listen to them lol

[0wn3r]

I remember a thread like this and I brought up the fact that exhaust gases come out in pulses and someone FLAMED me for it, unbelievable.

Nico members are generally smart but no one can agree on exhaust tech.

IBTL

i dont really know what's wrong w/ this thread... no one is really disagreeing besides what badmojo said. but, in all, he just means on a stock system, the bad side to larger exhaust is going to be the noise... hence, why silencers are made to make smaller.

[lrb_2000]

3" catback + no cat on N/A = loud. That's what I have, plus stripped interior, oh boy.. it's loud as hell, and I love it lol...sounds good too, has a nice low tone to it, not like some ricer honda with 2" piping and a 4" tip.

[BadMojo]

3" catback + no cat on N/A = loud. That's what I have, plus stripped interior,

Is that why the driving cat in your sig is shrieking in pain?

[lrb_2000]

most likely... lol... it doesn't like to drive my car anymore.

[moneymike102]

i got a 3inch pipe wit no cat(testpipe) on my KA24E and my **** is louuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuddddddddddddddd

[eds13]

most likely... lol... it doesn't like to drive my car anymore.

[Nismo_Freak]

on an NA vehicle the less back pressure helps the car in the upper RPMs but can cause the vehicle to loss some of its low end torque

Low end torque loss isn't as a result of losing back pressure.

You will always make less torque with more backpressure.

It has more to do with the stagnation of the flow in a larger pipe, but the loss of low end torque you will ever see on a dyno is maybe 1 - 2 lb. ft. It's more mental than anything.

[Nismo_Freak]

Turbo cars don't need any back pressure, between the turbo and the head inside of the turbo manifold is much more back pressure than any car needs or like, on any normal car before the converter there should not be more than 1-2psi back pressure after that you don't need any more, meaning after the converter 0 back pressure is perfect but on stock exhaust system that is not the case. so if you can deal with the noise a 3" catback exhaust on a na 240sx is ideal

you may ask what qualifies me will, I am a exhaust tech that's what i do

Wow, someone that doesn't have their head up their crack when it comes to an exhaust.

To add to his post the 1-2 PSI of backpressure is a result of the catalytic converter and it aids in supplimenting proper EGR control. With no backpressure you will run into improper EGR function.

[Ni2s4s0aSnX]

No 3-inch exhaust is not too big.

[yessir240]

dont know about yall suckers but im putting that 6.5" on mines bwa ha with a folgers tilted 45 degrees what now Bishes.... bwa hhaha

[0wn3r]

bwa ha ... bwa hhaha

do you watch Bleach? lol

"teh spirits are alwayyys with-ahhhh YOU bwahahahaha!"

[JustinStrife]

I run a BRM 3" Exhaust w/ resonator and dual tip, with the stock Ka w/ just AEM intake, and I definetly noticed a pick-up in power. The KA can handle 3" easy. And if you plan on turboing, IMO you want that 3" all the more.

[drifter_for_life06]

isnt there someone here with a 4"?

i thought there was in my old exhaust S13 thread