suggestions for exhaust

[Parsonator73]

what do you guys suggest for an exhaust on a 4 cylinder? i want something that sounds better than stock but i'm on kind of a tight budget.

 

[jax4bangin]

flowmaster or magnaflow... if u want deep tone run 3 inch pipe out of the muffler.. who dont want deep tone right?? lol

 

[Wicked_Sludge]

the only good 4 banger is a quiet 4 banger.

but thats just this observers opinion.

3" is WAY to big for a 4 cylinder, you will kill your bottom end with it.

 

[Parsonator73]

so what isn't too big?

 

[Wicked_Sludge]

personally, i wouldnt go over 2" (which happends to be stock) on a street driven truck, in order to maintane as much bottom end torque as possible. if you want to move the already high powerband up even further, you could probably get a few more peak HP at the expense of off-the-line power with 2.5".

 

[Jason]

Good exhaust for a 4 cyl? Hmmm. Stock?

 

[jax4bangin]

i have ran all sizes from 2 1/4 - 3", magnaflow and flowmaster.. and i am a teenager so no doubt i like makin a lil noise but i have settled on my current setup because i downsized the pipe before the muff(from 2.5 to a 2.25) to increase bAck pressure also on a chamber muff(more back pressure than straight through magna) and the 3" tail pipe is only to give me a deep tone.. i have actually felt in ancrease in power over stock after downsizing the pre-muffler piping

 

[Wicked_Sludge]

backpressure on a 4 stroke engine is a bad thing. your loss of power with a larger pipe has nothing to do with "too little backpressure".

 

[jax4bangin]

enlighten me, if too little backpressure doesnt cause lack of low end power then y is it bad to run larger diameter piping?

 

[Wicked_Sludge]

on a 4-stroke engine, NO backpressure is a good thing...but completely eliminating it is near impossible.

running too-large an exhaust pipe reduces exhaust gas velocity, which allows the exhaust to slow and cool inside the pipe, effectively "plugging" the pipe and INCREASING backpressure.

with a properly sized pipe, you maintain gas velocity...and as each exhaust pulse travels through the pipe, it creates an area of low pressure behind it, which helps to pull the next pulse out of the combustion chamber and down the pipe....this occurs in a continuous cycle, acting like a sort of "reverse supercharger", if you will, pulling the exhaust out of the engine. this effect is known as scavenging, and is very important for proper performance.

so, using too large of a pipe will increase backpressure by allowing the exhaust pulses to slow down and build up inside the pipe, and it also destroys proper exhaust scavenging. the double wammy is enough to really decrease performance.

 

[jax4bangin]

dang dude i had no clue bout that plugging effect.. thanks for that info.. but i seriously dont feel a loss of power at all or decrease in mileage.. so idk wats up

 

[Wicked_Sludge]

i have actually felt in ancrease in power over stock after downsizing the pre-muffler piping

scavanging explains why decreasing your pipe size provided a boost in power.

piping after the muffler is less vital than the piping before the muffler, thats why your 3" taipipe hasnt reduced your power noticeably (it IS reducing it, i assure you).

 

[Ozwynn]

I think it was noV8whydrive that told me Idealy you want 7psi BP for proper exhaust scavenging.

that being said ...... go uncorked and add a turbo with a 3" pipe from the axle back

oh yeah, you need a tri-y header to go with it.

 

[Wicked_Sludge]

woah. 7 PSI is WAY too high for any engine.

ford specifies around 5-6 PSI as a "problem"...but many engines experience driveability issues even before that.

 

[Ozwynn]

Like I said...... I would go uncorked with a turbo. thinking of that ....... I can't rmember what side it was but i was looking at a motorhome with a V-10 and one side exhaust was more restricted than the other......... it had an extra bend in it to clear something.....