[Simpoge39]

I am currently getting a custom 3" exhaust done, the person doing it was saying it would be best to go 3" and when the split comes for the dual he was going to make it 2.5. He said this would cause more velocity for the exhaust moving out and would actually balance out since it is dual. He said I would not loose any power. Does this seem right? Or should I just do 3" all the way.

 

[bloodycliff]

3 all the way..

although

best bet is to do a single out 3in
but the duel does have a bit of powerloss...but it will hardly be noticable

 

[breeechan]

2 2.5" pipes still flow around 30% more than a single 3. 3 to 2.5 dual is fine.

 

[Simpoge39]

2 2.5" pipes still flow around 30% more than a single 3. 3 to 2.5 dual is fine.

But would it be better to do that or keep it 3" all the way?

 

[nealdog]

I am currently getting a custom 3" exhaust done, the person doing it was saying it would be best to go 3" and when the split comes for the dual he was going to make it 2.5. He said this would cause more velocity for the exhaust moving out and would actually balance out since it is dual. He said I would not loose any power. Does this seem right? Or should I just do 3" all the way.

thats is a confusing quote to me, is he trying to say that a 3inch exhaust would flow to much? or two little, im a bit lost at that
.... if he is saying you will flow to much he's a bag of stupid.
.... if hes saying it will flow two little he's a bag of stupid
.... if hes implying that 3" exhaust will flow to much and the restrictions of the 3"- 2.50" split into a dual, will even out the flow he's a bag of stupid {the only thing that split might even-out would be the exhaust pules, creating a smoother sound}

The idea of a good exhaust is to direct expelled gas's to a different location with the least amount of restriction. Restrictions are a flow killer, and so are under-sized tubing. Any one that says you need a little bit of back-pressure is a bag of stupid {yes i've ran into people that say that, and this is also a flow killer}.
i wont go further because im assuming you are a fairly intelligent individual, and know the rest.



P.S. not trying to be a dick if thats how that sounded

 

[carbonshark]

i believe the statement about higher velocity was just an explaination of why it would be ok to drop down sizes. it would have a nozzle effect and speed up the air moving through it.

the idea of back pressure comes from the notion that exhausts having constant flow are more efficient--its smoother going down the pipes if there is steady flow (or laminar flow). if an exhaust is too large and creating no back pressure, the exhaust air being "stopped" for a millisecond or two and then continuing flow casues an unsteady flow (turbulent flow) and loss of effeciency--meaning less miles per gallon and a slight drop in horsepower.

depending on what PSI you are running, assuming its a 4 cylinder engine--the front half being 3 and the back being 2.5 would give a better sound because the exhaust going through the muffler would be faster--meaning a smoother/nicer exhaust note with less chance of ricing out at higher rpms. but then again that also depends on brand of muffler.

 

[Tibanator]

3in straigh pipe single exit would be pretty nice u will love it trust me, and how often do u see a tib around town with a single exhaust to? not mnay makes youre that much more differnt

 

[Simpoge39]

I personally think dual looks more mean.

 

[Simpoge39]

i believe the statement about higher velocity was just an explaination of why it would be ok to drop down sizes. it would have a nozzle effect and speed up the air moving through it.

the idea of back pressure comes from the notion that exhausts having constant flow are more efficient--its smoother going down the pipes if there is steady flow (or laminar flow). if an exhaust is too large and creating no back pressure, the exhaust air being "stopped" for a millisecond or two and then continuing flow casues an unsteady flow (turbulent flow) and loss of effeciency--meaning less miles per gallon and a slight drop in horsepower.

depending on what PSI you are running, assuming its a 4 cylinder engine--the front half being 3 and the back being 2.5 would give a better sound because the exhaust going through the muffler would be faster--meaning a smoother/nicer exhaust note with less chance of ricing out at higher rpms. but then again that also depends on brand of muffler.

I decided to go with 3" so I won't have to change it when I up the boost. It's vibrant resonator (small one) and two flowmaster 40 series

 

[Montmont]

I personally think dual looks more mean.

Agreed. Duals look so much nicer than a single.

 

[carbonshark]

the flowmasters will keep it deep...give those tips a slight angle up, get everything broke in then crank up the boost and enjoy it. Be sure to put up a decent quality exhaust vid too!

 

[VoodooXTC]

Unless your looking for 500 hp, I wouldn't go bigger then a single 2.5". Hot gasses will travel faster through a 2.5" pipe then through a 3" pipe. Look you the PDF for Corky Bell's Maximum Boost, there is a section on exhaust.

A 3" splitting into a dual 3" has no business on a 2L car. If you are set on having a 3" down pipe that splits to duals, go with 2.25" pipe after the split. Dual 2.25" will flow equal to a 3.18" exhaust and be less raspy.

 

[Simpoge39]

Yes, I also forgot to mention I'm getting a 62/62. It has a 3" outlet and I didn't want that backing up at all. I want it to release its gas easily.

 

[RetfirDMX]

i think 2x2.5 out of a 3.0 will give the exhaust a good velocity and help make a little mid/low end so you're not sluggish until you hit 5k rpm/max boost

 

[VoodooXTC]

Yes, I also forgot to mention I'm getting a 62/62. It has a 3" outlet and I didn't want that backing up at all. I want it to release its gas easily.

Out of curiosity, how come your getting a turbo rated for 700 hp? What are your hp goals? Are you gonna DD the car or is it just a track car? Do you have a built motor? Answer these questions and I will help you pick a more suitable turbo for your needs/wants.

i think 2x2.5 out of a 3.0 will give the exhaust a good velocity and help make a little mid/low end so you're not sluggish until you hit 5k rpm/max boost

No, smaller diameter piping gives better velocity.

 

[Kman Tib]

No, smaller diameter piping gives better velocity.

This I think is a little contractictory in way of turbos on a engine. If this were all true then why the heck don't people run a little dinky 1.5"? Velocity I don't think needs to be looked at to much extent for turbo, actually I would more believe that less velocity but more volume means better for the functioning of the turbo which means obviously a larger pipe, to a point, you obviously don't want to go overly huge. Yes that statement is true cause pushing a given amount of water through a pipe at a given pressure - the water will come out at a faster speed (velocity) of a smaller pipe than it would of a larger pipe however it will take longer to finish the given amount out of the smaller pipe than it would the larger - that's because of back pressure which is not good for turbo setups, more back pressure means less efficient. You want to get rid of the exhaust gas as quickly as possible so not have much back pressure build up, if any at all. That's the point and way of letting the turbo "breathe".

So with that said I would say 3" single or the 3" to split 2.5" would work fine - the split to 2x 2.5" would obviously split the volume from what the 3" was carrying so I don't think would cause any back pressure build up.

But this is my opinion, hopefully I got accros in words all of what I'm thinking in my head :3_wink:

Edit: I use figuratively cause we can see it, obviously we're dealing with gasses tho.

 

[VoodooXTC]

This I think is a little contractictory in way of turbos on a engine. If this were all true then why the heck don't people run a little dinky 1.5"? Velocity I don't think needs to be looked at to much extent for turbo, actually I would more believe that less velocity but more volume means better for the functioning of the turbo which means obviously a larger pipe, to a point, you obviously don't want to go overly huge. Yes that statement is true cause pushing a given amount of water through a pipe at a given pressure - the water will come out at a faster speed (velocity) of a smaller pipe than it would of a larger pipe however it will take longer to finish the given amount out of the smaller pipe than it would the larger - that's because of back pressure which is not good for turbo setups, more back pressure means less efficient. You want to get rid of the exhaust gas as quickly as possible so not have much back pressure build up, if any at all. That's the point and way of letting the turbo "breathe".

So with that said I would say 3" single or the 3" to split 2.5" would work fine - the split to 2x 2.5" would obviously split the volume from what the 3" was carrying so I don't think would cause any back pressure build up.

But this is my opinion, hopefully I got accros in words all of what I'm thinking in my head :3_wink:

Edit: I use figuratively cause we can see it, obviously we're dealing with gasses tho.

You are right, smaller diameter pipe has higher velocity helping with turbo spool. Larger diameter piping has less back pressure helping the turbo breathe better up top. The key is finding the right balance between the two.

A 3" exhaust that splits to dual 2.5" on a 2.0L will flow great but sound absolutely horrible and kill spool time. Like I had said earlier, a 2.5" single exhaust will flow enough to support around 500 hp.

 

[Simpoge39]

You are right, smaller diameter pipe has higher velocity helping with turbo spool. Larger diameter piping has less back pressure helping the turbo breathe better up top. The key is finding the right balance between the two.

A 3" exhaust that splits to dual 2.5" on a 2.0L will flow great but sound absolutely horrible and kill spool time. Like I had said earlier, a 2.5" single exhaust will flow enough to support around 500 hp.

It has been done, I just need to find a good video recorder, my phone does not record sound too well. The outcome! It is 2.5 to 3" for now, The downpipe starts at 2.5'' but this will be changed very soon. The car sounds excellent! No rasp no rice, nothing but good. I have to say it sounds like a quite V6. It is amazing I love it. I will post vids up very soon.

 

[Kman Tib]

You are right, smaller diameter pipe has higher velocity helping with turbo spool. Larger diameter piping has less back pressure helping the turbo breathe better up top. The key is finding the right balance between the two.

A 3" exhaust that splits to dual 2.5" on a 2.0L will flow great but sound absolutely horrible and kill spool time. Like I had said earlier, a 2.5" single exhaust will flow enough to support around 500 hp.

Cool, I see what you're saying with the velocity now and I know it's to find the balance between the 2. But I've still yet to see a 500hp 2'0l turbo running a 2.5" exhaust so that's where I'm a little lost. But I guess it probably also has a little to do with the turbo choice as well.


OP hurry and get some vids and pics up.

 

[VoodooXTC]

It has been done, I just need to find a good video recorder, my phone does not record sound too well. The outcome! It is 2.5 to 3" for now, The downpipe starts at 2.5'' but this will be changed very soon. The car sounds excellent! No rasp no rice, nothing but good. I have to say it sounds like a quite V6. It is amazing I love it. I will post vids up very soon.

I would stick with that, you like how it sounds and I'm sure the car moves pretty good.

Cool, I see what you're saying with the velocity now and I know it's to find the balance between the 2. But I've still yet to see a 500hp 2'0l turbo running a 2.5" exhaust so that's where I'm a little lost. But I guess it probably also has a little to do with the turbo choice as well.


OP hurry and get some vids and pics up.

My Talon, 2.0l, only has a 2.5" exhaust and it's making over 400 at the crank with a 16g turbo and 21psi. Plus the spool time is rediculously quick.