Does It Make A Difference If My Exhaust Is Twin/single?

[Awesome]

I had a bet with a mate.. and he believes theres a power difference if theres a single exhaust..

We're talking about the tip of the muffler..

Quoted by someone on the forum.. -->

Because twin or single its going to make absolutely no diffrence. Its far too late in the exhaust system for it to have any effect of noise or "performance" or anything of the sorts.

...............

please share your opnion..

Does it really make a difference if the exhaust tip is single or twin?

[WYTSKY]

could have just asked the question in here.... http://www.skylinesaustralia.com/forums/Tw...le-t242824.html

(where you got that quote from)

anyway... its n/a power I am assuming you are talking about? not going to be a single difference... maybe max 1kw/2kw depending on overall setup, but if you have a good system (manifold to back of car) it doesnt matter what the tip is going to be...

but for argument sake lets look at the math of it....

if you have twin exhausts, each coming out to 2 2.5inch tips = 2*2.5 = 5 inchs of good 'ol super cheap auto chromey tip

or if you want a cannon that has a single big 5 inch tip = 1*5 = 5 inchs of good 'ol super cheap auto chomey tip

see what I mean... its not really going to make any difference.... get a 500kw dyno monster that needs all the flow it can get and then yes... different setups will impact on the cars performance.

Adam

[N-DAWG]

What Adam said covers the answer.

On another note though, the oval twin tip mufflers are apparently known to drone quite a bit on N/A Skylines, as I've been told by one of the guys at Rob Bliss Exhaust in Brisbane. That was the advice I was given when I was asking about a twin tip set up, simply for a factory looking system.

I don't like to be the one to say it, but if you do a search through these N/A forums you'll find that N/A Skyline Exhaust systems have been pretty much done inside out...

[mitchy_]

could have just asked the question in here.... http://www.skylinesaustralia.com/forums/Tw...le-t242824.html

(where you got that quote from)

anyway... its n/a power I am assuming you are talking about? not going to be a single difference... maybe max 1kw/2kw depending on overall setup, but if you have a good system (manifold to back of car) it doesnt matter what the tip is going to be...

but for argument sake lets look at the math of it....

if you have twin exhausts, each coming out to 2 2.5inch tips = 2*2.5 = 5 inchs of good 'ol super cheap auto chromey tip

or if you want a cannon that has a single big 5 inch tip = 1*5 = 5 inchs of good 'ol super cheap auto chomey tip

see what I mean... its not really going to make any difference.... get a 500kw dyno monster that needs all the flow it can get and then yes... different setups will impact on the cars performance.

Adam

ROFL...

2x 2.5" pipes IS NOT the same as a 5" pipe.

5" == 12.7cm == cross sectional size of 126.67cm^2

2.5" == 6.35cm == cross section size of 31.67cm^2 x 2 == 63.34cm^2

thus, 4x 2.5" pipe is equivilent to a 5" pipe.

the tip size will only make a difference if the original is too restrictive

[342Four]

the biggest exit AFTER teh muffler the better

too big and droney and noisy as fuck - something like a 3" single exit or a twin 2.5" depending on taste would sound alright

the biggest restriction in teh whole exhaust should be the muffler - theres a reason for that - its called legalities regarding noise lol

the ultimate would be straight pipes - but thats noisey as fuck

Edited November 3, 2008 by 342Four

[GTS4WD]

Gosh who ever you quoted that from is an AWESOME bloke!

You have your answere in your first thread.

Twin or not. There is no difference. I dont care. There just isn't.

Its too late in the exhaust system. The gass is being pushed out, the tips are ALWAYS bigger than the rest of the system etc. etc. etc.

its only for the look.

Do I need another "In Before the Lock" photo too?

Is it school holidays already?

Edited November 3, 2008 by GTS4WD

[WYTSKY]

haha... well said Chris....

and Mitchy.... I am glad you found my post that amusing that you rolled on the floor laughing outloud while reading it... please put a youtube vid up to show you did it or dont comment saying that crap.

god knows where you pulled the cross sectional values anyway..you went from 12.7cm to 126.67cm how?

regardless, if you really believe a twin TIP (NOT the whole system) is going to make that much difference please show me comparission dyno threads. but from what my mates and I have tested... a single big TIP or two tips each half the size of the big one is not going to make the slightest difference for a road car.

and because Chris seems to be the guy to quote off it seems appropraite that I repeat his words so that you may understand.

"Twin or not. There is no difference. I dont care. There just isn't.

Its too late in the exhaust system. The gass is being pushed out, the tips are ALWAYS bigger than the rest of the system etc. etc. etc."

[342Four]

^^^^dude its called math

5" is 12.7cm

area of a circle equals Pi*R(sqaured)

radius is half of 12.7cm = 6.35cm

that squared = 40.3225 square cm

times THAT bi Pi and you get 126.7 square centimeters cross sectional area of a 5" tip

to get the equivalent area from a 2.5" tip you need 4 2.5" tips (cross sectional area of a 2.5" tip is 31.7 square centimeters)

a tip CAN be too restrictive

imagine a 2" tip on a 3" exhaust

its like trying to blow up a balloon with a straw - ur going to get tired, and the balloon is not going to get very full

[666DAN]

There is a big difference between them....Police see a cannon and get interested in your car very quickly A factory looking twin system doesn't get any real attention in comparison

[GTS4WD]

a tip CAN be too restrictive

imagine a 2" tip on a 3" exhaust

its like trying to blow up a balloon with a straw - ur going to get tired, and the balloon is not going to get very full

Yes.. this is true. But even the supercheap items have the tip welded to the muffler so its impossible to mess this one up.

All mufflers have a tip larger than the entry point.

[WYTSKY]

Im not arguing with you the math of a FULL system, I know theres a big difference... but as if you have a 3inch system with a 2inch tip... unless you welded it together yourself you couldnt buy it like that.

[GTS4WD]

I suppose you could weld the tip of the miffler to the exhaust and leave the inlet as the tip.

So as the muffler is 3inch to a 2 inch tip. or something of the sorts.

Back to the thread,

IBTL

[Eug]

adam, what mitch said about calculating the area of the exhaust (i.e. cross section) is 100% correct.

some of you guys are going around in circles. firstly you need to understand what the muffler is for.

the muffler is basically a point where the flow of exhaust gases are muffled by distrupting the airflow. the gases are passed through a series of perforated pipes in various baffled chambers. they are then expelled outside and voila! quiet exhaust. i suggest some of you go and open a muffler up if you get the chance and understand how the internals work.

the biggest exit AFTER teh muffler the better

too big and droney and noisy as f**k - something like a 3" single exit or a twin 2.5" depending on taste would sound alright

the biggest restriction in teh whole exhaust should be the muffler - theres a reason for that - its called legalities regarding noise lol

the ultimate would be straight pipes - but thats noisey as f**k

i would say 99% correct ashley! good work. the other 1% i will explain a little later.

the other 1%. even if the end pipe of the muffler (i.e. tip) is the biggest, which will help to some degree. it also comes down to the design and sizing of the internal pipes, perforations and camber sizes.

so the million dollar comment is: you can not just look at the tips alone. it ultimately comes down to the research and development behind the product it's internals and how well the muffler as one entire package is able to maintain good flow properties and keep the exhaust volume under legal limits.

and yes ash, straight pipes would be the sweet sweet ultimate.

edit: see pics for a better understanding

[342Four]

a straight through muffler is exactly as it suggests

a good quality straight through muffler you should be able to look right through it from exit to entry (unless of course you have an offset exit/entry)

the muffling on a straight through is done by a baffle chamber AROUND the exhaust - perforations or the like in the pipe in the muffler allow flow to diffuse into the chamber and muffle the sound

thats essentially how a cannon works

the muffler in the last pic by eug is a typical factory exhaust muffler - sound is very quiet, but very very restrictive - the exhaust gases have to change direction 3 times and in a small body this is going to choke the gases BIG time and slow everything down and not flow well at all

[342Four]

lol here is a crappy photoshop pic

the bottom one is a common aftermarket muffler - exhaust comes in from right - goes out main pipe and diffuses into exit pipe

they usually flow alright and arent too restrictive

the top one is an straight thru highflow item - gases diffuse into baffle chamber around the pipe

generally the bigger the baffle chamber the quiter it is, but also can very droney as the gases start to 'echo' a lot more

[WYTSKY]

adam, what mitch said about calculating the area of the exhaust (i.e. cross section) is 100% correct.

so the million dollar comment is: you can not just look at the tips alone. it ultimately comes down to the research and development behind the product it's internals and how well the muffler as one entire package is able to maintain good flow properties and keep the exhaust volume under legal limits.

Thanks for the lesson! definetly understood much better now! 

Thanks mitch for trying to explain it... I just didnt understand how you went from 12.7cm to 127.xxx ... but as soon as someone said pieR^2 I got it.

Least I learnt something today! 

regards,

Adam

P.S isnt it funny how "awsome" hasent even replied to his own thread?!

[G0DZLR]

What Adam said covers the answer.

On another note though, the oval twin tip mufflers are apparently known to drone quite a bit on N/A Skylines, as I've been told by one of the guys at Rob Bliss Exhaust in Brisbane. That was the advice I was given when I was asking about a twin tip set up, simply for a factory looking system.

I don't like to be the one to say it, but if you do a search through these N/A forums you'll find that N/A Skyline Exhaust systems have been pretty much done inside out...

do circular twin tip mufflers even exist? if so thats what id want to get if the drone is the case.

(saying that my exhaust drones alot and its round)

[N-DAWG]

Thanks for the lesson! definetly understood much better now!

Thanks mitch for trying to explain it... I just didnt understand how you went from 12.7cm to 127.xxx ... but as soon as someone said pieR^2 I got it.

Least I learnt something today!

regards,

Adam

P.S isnt it funny how "awsome" hasent even replied to his own thread?!

Which thread? He has too many to keep track of lol

i'm suprised to see this thread is still going, but with that said though, it's been quite an informative lesson on mufflers which is good to see!

[Awesome]

Crappy threads own dont they? ;]

[GTS4WD]

WOW..

way to complicate things boys!

Yes. This is true what is being said. Theoretically.

But in all honesty.

Take a step back!

This is not a defining aspect. There are far more important issues (Air temp, humudity, dyno, petrol, air flow, air quality etc.) that will be more influential in a "final figure" in terms a power figure or even the "seat of the pants" test. Your going doing to experience any diffrence. These very minor details are not going to have huge effects upon a vehicles performance (well not when your talking about ye ol faithful RB25). When you get to the world stage of V8's, touring cars F1 etc. these insignificant diffrences make a diffrence. But even then you dont have to worrie about mufflers.

So I suppose its just a thread for a thread's sake, an argument for the sake of arguing.

I suppose its an interesting thread as an idea. But little practicallity.

Simple is always best.

And simplest is straight. Either way its going (twin or single) to make bugger all diff.

And final word is:

Edited November 5, 2008 by GTS4WD