Hi Guys,

Wondering if I could get some feedback on going the dual exhaust option.

From a performance standpoint, I am wondering wether having dual exhausts would actually result in a loss of power.

If you think about it, you are effectively doubling the volume of the exhaust after the split. Does this result in a loss of back pressure?? If there is a drop in back pressure, can this be rectified through using a different type of exhaust, i.e. not a straight through design??

Anyone got any ideas or experience with this?

hey mate, you still love me :P

if i was going to do twin exhausts it would be for looks only, having twin 2.25/2.5 pipes for a magna is too large. so yeh i would chuck a fakey on if i was desperate for that look.

minimizing back pressure is good but you still have to have the correct size piping to keep the gases flowing quickly, know what i mean?

thats how it works as far as i understand......... lol

brendan

what difference would it make coming into 2 cats and two pipes rather than a split after the cat?

I have twin exhaust which is split before the muffler. I noticed no performance decrease, but rather an increase in high revs. It accelerates harder now after 4500rpm.

I have twin exhaust which is split before the muffler. I noticed no performance decrease, but rather an increase in high revs. It accelerates harder now after 4500rpm.
Cool. So what sort of setup did you have before the dual pipe setup? was it just the stock muffler?

If you think about it, you are effectively doubling the volume of the exhaust after the split. Does this result in a loss of back pressure?? If there is a drop in back pressure, can this be rectified through using a different type of exhaust, i.e. not a straight through design??

Anyone got any ideas or experience with this?
You would need to go probably 2.25" piping with baffled mufflers to keep back pressure.

Its something i wouldnt do as the guys down at Daalder basically said, theres no point as you will lose too much back pressure.

Yeah, had just original exhaust on car before.
The original pipe on my TH was 2.25" but went up to 2.5". Got Berklee PEX muffled resonator, and 2 straight-through Berklee PEX mufflers, with twin tips :) Sounds very nice.

I had a straight through resonator first but droned too much. So muffled version still drones a little, but way better. If you dont want droning...leave the resonator alone and just change muffler and tip. My setup was around $800 including labour. Oh, and i won the 'Phattest Exhaust Note" on Sunday on our last cruz. ;) hehehe **** all over the 4" cannons. hehehe

Yeah, had just original exhaust on car before.
The original pipe on my TH was 2.25" but went up to 2.5".
So the original piping on a TH magna is 2.25"?? Did you upgrade the diamter from Cat back or all the way to the headers??

These Berklee mufflers sound like the way to go! Im thinking of just doing the muffler and tip, and a few people seem to have good results with them.
Is there a part number, or do I just ask for a Berklee PEX straight through muffler? Who sells them in SA?
Pete

I have twin exhaust which is split before the muffler. I noticed no performance decrease, but rather an increase in high revs. It accelerates harder now after 4500rpm.

Im the same.. before muffler and two pipes one each side..
I had no loss but better hi revs.. :D

ok fellas if you want to go twin exhaust for the best power you would branch it after the back wheels or befor it doesent really matter but when you branch it use twin 2 inch piping cuase twin 2.25 is still too big think about it thats 4.50 inch exhaust if you put them together so twin 2 inch is fine any thing under that is ok as well but your getting a bit small for a nice looking rear muffler to go with it

the exhaust im getting im branching it after the rear wheels with twin 2 inch pipes and 2 suppercat cannon mufflers.

Ps or if you can afford it go duel 2 inch pipes all that way from the headers with duel cats duel every thing thats were you get some very nice gains cause you dont have two sides fighting for one pipe you have both independent pipes and not to mention you have a very nice sound this way cause one pipe puleses different then the other and they sound sweet :D

the exhaust im getting im branching it after the rear wheels with twin 2 inch pipes and 2 suppercat cannon mufflers.


Got it minus the cannons.. lol


Ps or if you can afford it go duel 2 inch pipes all that way from the headers with duel cats duel every thing thats were you get some very nice gains cause you dont have two sides fighting for one pipe you have both independent pipes and not to mention you have a very nice sound this way cause one pipe puleses different then the other and they sound sweet :D

Doing that when i do the full exhaust system after July... lol lol

Got it minus the cannons.. lol



Doing that when i do the full exhaust system after July... lol lol

i know you allready have that ego :P just letting every one else know :D

i know you allready have that ego :P just letting every one else know :D


Im gunna do full duallies when i get my tax money... :bowrofl:

cuase twin 2.25 is still too big think about it thats 4.50 inch exhaust if you put them together so twin 2 inch is fine

Not true!

Area = PI * r^2

so area of a 2.25" pipe..

PI * (1.125 * 1.125) = PI * 1.265 = 3.97

Two pipes = 7.95 in ^ 2

4.5" pipe..

PI * 5.062 = 15.904 in^2

So two 2.25" pipes is still only half the area of a single 4.5" pipe.. more like one single 3.2" pipe.. (the cross section of a 3" pipe is 7.068 square inches)

Not true!

Area = PI * r^2

so area of a 2.25" pipe..

PI * (1.125 * 1.125) = PI * 1.265 = 3.97

Two pipes = 7.95 in ^ 2

4.5" pipe..

PI * 5.062 = 15.904 in^2

So two 2.25" pipes is still only half the area of a single 4.5" pipe.. more like one single 3.2" pipe.. (the cross section of a 3" pipe is 7.068 square inches)

Grrrrr..... I hate smart people.. lol lol

So two 2.25" pipes is still only half the area of a single 4.5" pipe.. more like one single 3.2" pipe.. (the cross section of a 3" pipe is 7.068 square inches)

still to big duel 2 inch is fine no loss of power at all with that set up if any thing you may gain it but only time money and a dyno is going to tell you that

Got it minus the cannons.. lol



Doing that when i do the full exhaust system after July... lol lol
sell ya dual system to me after u get the new one :D

Not true!

Area = PI * r^2

so area of a 2.25" pipe..

PI * (1.125 * 1.125) = PI * 1.265 = 3.97

Two pipes = 7.95 in ^ 2

4.5" pipe..

PI * 5.062 = 15.904 in^2

So two 2.25" pipes is still only half the area of a single 4.5" pipe.. more like one single 3.2" pipe.. (the cross section of a 3" pipe is 7.068 square inches)

Glad I read thru, was gonna say the same, saved me the trouble :P

read this

"Backpressure: The myth and why it's wrong.

I. Introduction

One of the most misunderstood concepts in exhaust theory is backpressure. People love to talk about backpressure on message boards with no real understanding of what it is and what it's consequences are. I'm sure many of you have heard or read the phrase "Hondas need backpressure" when discussing exhaust upgrades. That phrase is in fact completely inaccurate and a wholly misguided notion.

II. Some basic exhaust theory

Your exhaust system is designed to evacuate gases from the combustion chamber quickly and efficently. Exhaust gases are not produced in a smooth stream; exhaust gases originate in pulses. A 4 cylinder motor will have 4 distinct pulses per complete engine cycle, a 6 cylinder has 6 pules and so on. The more pulses that are produced, the more continuous the exhaust flow. Backpressure can be loosely defined as the resistance to positive flow - in this case, the resistance to positive flow of the exhaust stream.

III. Backpressure and velocity

Some people operate under the misguided notion that wider pipes are more effective at clearing the combustion chamber than narrower pipes. It's not hard to see how this misconception is appealing - wider pipes have the capability to flow more than narrower pipes. So if they have the ability to flow more, why isn't "wider is better" a good rule of thumb for exhaust upgrading? In a word - VELOCITY. I'm sure that all of you have at one time used a garden hose w/o a spray nozzle on it. If you let the water just run unrestricted out of the house it flows at a rather slow rate. However, if you take your finger and cover part of the opening, the water will flow out at a much much faster rate.

The astute exhaust designer knows that you must balance flow capacity with velocity. You want the exhaust gases to exit the chamber and speed along at the highest velocity possible - you want a FAST exhaust stream. If you have two exhaust pulses of equal volume, one in a 2" pipe and one in a 3" pipe, the pulse in the 2" pipe will be traveling considerably FASTER than the pulse in the 3" pipe. While it is true that the narrower the pipe, the higher the velocity of the exiting gases, you want make sure the pipe is wide enough so that there is as little backpressure as possible while maintaining suitable exhaust gas velocity. Backpressure in it's most extreme form can lead to reversion of the exhaust stream - that is to say the exhaust flows backwards, which is not good. The trick is to have a pipe that that is as narrow as possible while having as close to zero backpressure as possible at the RPM range you want your power band to be located at. Exhaust pipe diameters are best suited to a particular RPM range. A smaller pipe diameter will produce higher exhaust velocities at a lower RPM but create unacceptably high amounts of backpressure at high rpm. Thus if your powerband is located 2-3000 RPM you'd want a narrower pipe than if your powerband is located at 8-9000RPM.

Many engineers try to work around the RPM specific nature of pipe diameters by using setups that are capable of creating a similar effect as a change in pipe diameter on the fly. The most advanced is Ferrari's which consists of two exhaust paths after the header - at low RPM only one path is open to maintain exhaust velocity, but as RPM climbs and exhaust volume increases, the second path is opened to curb backpressure - since there is greater exhaust volume there is no loss in flow velocity. BMW and Nissan use a simpler and less effective method - there is a single exhaust path to the muffler; the muffler has two paths; one path is closed at low RPM but both are open at high RPM.

IV. So how did this myth come to be?

I often wonder how the myth "Hondas need backpressure" came to be. Mostly I believe it is a misunderstanding of what is going on with the exhaust stream as pipe diameters change. For instance, someone with a civic decides he's going to uprade his exhaust with a 3" diameter piping. Once it's installed the owner notices that he seems to have lost a good bit of power throughout the powerband. He makes the connections in the following manner: "My wider exhaust eliminated all backpressure but I lost power, therefore the motor must need some backpressure in order to make power." What he did not realize is that he killed off all his flow velocity by using such a ridiculously wide pipe. It would have been possible for him to achieve close to zero backpressure with a much narrower pipe - in that way he would not have lost all his flow velocity.

V. So why is exhaust velocity so important?

The faster an exhaust pulse moves, the better it can scavenge out all of the spent gasses during valve overlap. The guiding principles of exhaust pulse scavenging are a bit beyond the scope of this doc but the general idea is a fast moving pulse creates a low pressure area behind it. This low pressure area acts as a vacuum and draws along the air behind it. A similar example would be a vehicle traveling at a high rate of speed on a dusty road. There is a low pressure area immediately behind the moving vehicle - dust particles get sucked into this low pressure area causing it to collect on the back of the vehicle. This effect is most noticeable on vans and hatchbacks which tend to create large trailing low pressure areas - giving rise to the numerous "wash me please" messages written in the thickly collected dust on the rear door(s).

VI. Conclusion.

SO it turns out that Hondas don't need backpressure, they need as high a flow velocity as possible with as little backpressure as possible.


its told by honda boys so im not sure if they know wat they are on about but i can see the good points.

brendan

good try cthulhu, I was impressed you tried to use some maths in this, but just as I was to reply to that with some engineering principles, TM-SE-RED comes up with the gem that has completely taken the words out of my mouth. Now I have nothing to add unless you guys are so intrigued that you want me to start talk about how velocity is related to area size, then work from the first principal with explaination of finite element matrix to heat transfer and fluid motion, etc. :P

Gosh, good old engineering days, how I miss it. :nuts:

So the original piping on a TH magna is 2.25"?? Did you upgrade the diamter from Cat back or all the way to the headers??

Nah, cat back...

These Berklee mufflers sound like the way to go! Im thinking of just doing the muffler and tip, and a few people seem to have good results with them.
Is there a part number, or do I just ask for a Berklee PEX straight through muffler? Who sells them in SA?
Pete

Im not sure what the part numbers were, but i can find out tomorrow for ya.

hey mate, you still love me :P

if i was going to do twin exhausts it would be for looks only, having twin 2.25/2.5 pipes for a magna is too large. so yeh i would chuck a fakey on if i was desperate for that look.

minimizing back pressure is good but you still have to have the correct size piping to keep the gases flowing quickly, know what i mean?
thats how it works as far as i understand......... lol

brendan

bite your asses, i said it first :P

So i was right with backpressure being a load of rubbish...

For a dual exhaust to work effectively (ie. performance), pretty much what Whitemagna said, you'll want twin piping one coming out from each header, which means you will need two of everything. However due to the V-design of the engine, you'll also want an X-pipe put in place. Something similar is the H-pipe design which has the same principles, but I think the X-pipe is better then the H-pipe.

Do a google search on these if you don't know what they are.


I did plan on getting a dual exhaust setup as described above, but I think I'm going to try out D&T Performance single exhaust design, where the custom header piping branches into one at the cat (Yes the cat has two inlets and one outlet).

But I'd like someone to do the above, i've never seen a Magna with that setup before.

The "H" pipe design gets a bit of use too..

Oops, I meant H-pipe, not Y-pipe.... :redface:

I have nothing to add unless you guys are so intrigued that you want me to start talk about how velocity is related to area size, then work from the first principal with explaination of finite element matrix to heat transfer and fluid motion, etc. :P
I'm sure the guys would love to know what's the right diameter to go for 3.0 and 3.5l engines for a car with say, CAI, exhaust, headers and a dyno tune. :)


For a dual exhaust to work effectively (ie. performance), pretty much what Whitemagna said, you'll want twin piping one coming out from each header, which means you will need two of everything.
Dude, the problem with this is that one banks pulses doesn't help the other bank scavange exhaust gases.

We had two 3.0l manuals on a dyno withing half an hour at dyno day once. The main difference was exhaust and filter. The dual, (from the rear axle back), had a pod and the single with factory piping had a panel. The dual scored around 148HP and the single 159HP. I'd suspect that a total dual could actually pull less than this duel. Obviously still depends on the engine to an extent as they vary a little.

Look at drag cars. Straight into the atmosphere, no mufflers, nuthin. Reason - get the bad air out as quick as possible. Mufflers are used to stop pensioners and little kiddies gettin a fright when you floor it.
Basic concept of a go-fast car. Force air/fuel in as quick and much as possible and then get it out quick.

Look at drag cars. Straight into the atmosphere, no mufflers, nuthin. Reason - get the bad air out as quick as possible. Mufflers are used to stop pensioners and little kiddies gettin a fright when you floor it.
Basic concept of a go-fast car. Force air/fuel in as quick and much as possible and then get it out quick.

I've seen tests where cars performed worse with the exhaust manifold venting directly to the atmosphere than they did with a full exhaust system. I think it really depends on how the engine is set up as to what works best.

Look at drag cars. Straight into the atmosphere, no mufflers, nuthin. Reason - get the bad air out as quick as possible. Mufflers are used to stop pensioners and little kiddies gettin a fright when you floor it.
Basic concept of a go-fast car. Force air/fuel in as quick and much as possible and then get it out quick.

ok daft question - theres forced induction, has anyone got forced extraction? would it help or hinder?

There's a theory about a particular exhaust design but it seems pretty crazy. I can't remember if it's negative displacement or not. Theoretically whatever it is works and the guy who markets the stuff makes it come across like it's a scam so he always gets pasted for it. Can't remember where it is.

I have twin exhaust which is split before the muffler. I noticed no performance decrease, but rather an increase in high revs. It accelerates harder now after 4500rpm.


Exactly the same here, i have the a K&N panel filter, pacie extractors and the original piping until the last flange. Just after the last Flange I have a Y split that goes into 2 x 2.25 pipes. I noticed no power loss but definatly more pull in the higher revs.

Thanks for all the replies guys....lots of good info there, especially TM_SE_RED's article, that really clarified the whole thing. :thumbsup:

After evalutating all the responses, I have decided not to go for the dual option. Reason I have chosen not to do this, is that according to the responses, there will be more power at high revs which is great, but according to the theory that TM-SE-RED posted, I would make better power gains in the mid range with just a single straight through exhaust. Afterall, most of my driving is done in the mid rev range, not high revs. The other factor is cost and I am not going to spend a heap of money on something which is really not going to deliver the performance that I would expect from a single straight through.

So a single Lukey LR2779 is going on Saturday morning. Should be good....I hope :D

:cool: im glad i helped. maybe we should possibly get the whole theory i posted stickied, so ppl can come and read that and decide straight away about their exhaust

Good Choice not to go Dual Mark H, it's too risky and if done incorrectly, your car will run slower than a Barina :D

had a similair idea of somehow creating a vacuum or constant fan / turbine to constantly suck the exaust fumes out.

Keep in mind im not extremely mechanically minded so be nice.

Also a system to cool the fuel, as ive heard colder fuel is more dense and detonates better
either running the fuel lines through an intercooler radiator type thing or some kinda AC condenser heatsink. im just babbling now.

BE NICE

Cheers, Luke

Okay here 'tis.... I'm not far off being ready to get my first performance mod (3 grand later & my car still doesn't go any faster than the day I got it :nuts: ) and I've decided that the trusty Magna exhaust is a great first place to start.

What I'm reading here leads me to believe there is a fairly fine line between "removing restrictions of the stock exhaust" and compounding the notorious "low RPM flat spot". Here's my dilemma:-
- I wanna get the most out of my car performance wise,
- I'm stuck with a 4spd Auto - so my ultimate goal is to improve low down torque without compromising peak power (I realise this will require more than an exhaust upgrade, but the exhaust has to fit the requirements).
- I'm not ruling out going 'forced induction' at a later date - but there's a good chance it won't happen soon

In an attempt to remove as much "restriction" as possible from the exhaust, I intend to replace the following components:-
- Cast Factory Headers (Pacemakers will probably fit the bill nicely)
- Stock Catalytic Converter (Exhaust is only gonna flow as well as the most restrictive part, and surely the stock cat could be better)
- ALL piping (here's where I have a problem, see below)
- Stock Muffler(s)

My dilemma:-
The issue I'm having is deciding on diameter of exhaust piping. The options I'm tossing up between are 2.5" mendrel bent piping, or 3" mendrel bent piping. My concern is that going for the later option may actually degrade my mid/low RPM performace/efficiency. Last night I was reading up on the subject on RPW's website and the following passage was of obvious interest to me:

The fourth and final option is that RPW has found that upgrading the whole system to a complete 3" system ie 3" cat converter, resonator, muffler and piping mandrel bent whilst does not on a fairly stock motor increase horsepower over the above 2 1/2" system, nor did it lose horsepower or torque. We have found the vehicle to be non - responsive in this size meaning that either sizing works well. The 2 1/2" system tends to be slightly quieter. But if you are planning on doing more work later being camshafts, twin throttle bodies, internal engine work etc then the 3" system is definitly the way to go to bring it in line with future mods. And since there is no loss of power over a 2 1/2" system its the perfect way to go.

I couldn't help but feel this was contradictory to the following quote of Anthony from Phillcom Rally in a recent thread on these forums:

mufflers comes in 2.25 or 2.5" inlet. so it will match up flush with whatever pipe you choose. usually 2.25" on a 3L car will give you good torque and improved top end. 2.5" on a 3.5L car is similar. But a 2.5" on a 3L car may induce slight lag down low but very good up top. So it all depends on what style of driving you like. DO NOT go with 3" unless you are turboed.

So I'm sure you can appreciate my dilemma - I want the exhaust which will best accentuate(sp?) my planned future mods (if not forced induction - cams, heads and piggyback ECU are definetly on the cards), but as explained above, I feel I would get most benefit from increasing low/mid range RPM pulling power, rather than just getting the highest peak output I can.

Thoughts please.
*just thought I should point out that I'm not considering a dual exhaust system*

both anthony and EZ boy know what their on about, and both say 3" is too big unless your going forced induction..................2 against 1 ner ner lol

Here's my take on it. [preface = I do not claim to be an expert]

1. Don't bother changing the cat (at least not yet) as it won't make that much difference.
2. Install the extractors and muffler, with 2.5" piping. For your current setup, 3" is too much and you'll lose midrange power (which is where you need it most of the time.)
3. Down the track, if/when you decide to add a turbo, then you can factor in a high-flow cat and 3" piping to suit.

I don't think Anthony and RPW contradict each other - they are both saying basically that you need some serious mods and be producing *way* over stock power before you want 3" piping - whether that be via turbo or wild n/a setup.

Well thanks for confirming what I'd already thought guys. I guess I kinda had my heart set on going 3" all the way thru for the w@nk factor more than anything else.

Last thing I want to do is reduce performance at any stage in the RPM range. So full 2.5" system here I come.

FYI - I intend to do get a before and after dyno to demonstrate how successful (or unsuccessful) the exhaust upgrade is. There's a good chance I may even replace just the stock muffler initially - in which case I will have a Stock Dyno, a Muffler only Dyno, and finally a full exhaust Dyno. All of this data will be filtered back thru these forums so that other members can use it as reference.

both anthony and EZ boy know what their on about, and both say 3" is too big unless your going forced induction..................2 against 1 ner ner lol
I'd be re-reading EZ boy's posts. I'm pretty sure he has a car with 3' piping.

http://www.aussiemagna.com/forums/showpost.php?p=218952&postcount=8

At least 3 cars I know of with 3' piping have shown on the dyno to not loose anything anywhere. My only concern about the dyno though is that it doesn't typically show what 1000 - 1500 rpm is doing and if it is, it's probably not at WOT.

I'd be re-reading EZ boy's posts. I'm pretty sure he has a car with 3' piping.

http://www.aussiemagna.com/forums/showpost.php?p=218952&postcount=8

At least 3 cars I know of with 3' piping have shown on the dyno to not loose anything anywhere. My only concern about the dyno though is that it doesn't typically show what 1000 - 1500 rpm is doing and if it is, it's probably not at WOT.

I was sure I'd read that EZ boy had 3" piping too - in fact I'm pretty sure there's a post from him somewhere with reference to it making alot more torque.

Geez thanks Redav...... I thought I'd made my mind up... now I'm confused again.

Oh well - off I go to PM EZ Boy and Monjunior for their expert advice.

By the sounds of it what you should get a after-header dual system with the piping to the second muffler only opening above a certain RPM... somehow...

By the sounds of it what you should get a after-header dual system with the piping to the second muffler only opening above a certain RPM... somehow...

Funny you should mention that..... I chanced upon this autospeed article over the weekend while attempting to research the science of performance exhaust:

http://www.autospeed.com/cms/article.html?&A=0883

Very interesting concept - and I believe there are a few variations of it getting around.

I'd be re-reading EZ boy's posts. I'm pretty sure he has a car with 3' piping.
http://www.aussiemagna.com/forums/showpost.php?p=218952&postcount=8

At least 3 cars I know of with 3' piping have shown on the dyno to not loose anything anywhere. My only concern about the dyno though is that it doesn't typically show what 1000 - 1500 rpm is doing and if it is, it's probably not at WOT.

he's going forced induction very soon..........

both anthony and EZ boy know what their on about, and both say 3" is too big unless your going forced induction..................2 against 1 ner ner lol

Damn straight :D

When you force feed you have to allow for normal intake volume under n/a PLUS forced air volume. To keep port and valve velocities up you need the extra exhaust volume to accomodate. A 3-3.5L n/a engine will not be able to generate the most efficient velocity for exhaust gases thru 3" pipe. You'll get an increase in torque for free across the rev range simply from after cat gas expansion into larger pipe creating a little vacuum and extraction but you can do much better at 2.5" and good long headers with a long slender collector and high flow cat.

A true twin system would need to be viewed as installing two exhausts to suit two 1.75L engines in your car. Think 2" max.

Best to run 2.5" from the cat or dump pipe (check your wallet first) and split near the fuel tank into 2 mufflers with pretty tips.

ok fellas if you want to go twin exhaust for the best power you would branch it after the back wheels or befor it doesent really matter but when you branch it use twin 2 inch piping cuase twin 2.25 is still too big think about it thats 4.50 inch exhaust if you put them together so twin 2 inch is fine any thing under that is ok as well but your getting a bit small for a nice looking rear muffler to go with it

the exhaust im getting im branching it after the rear wheels with twin 2 inch pipes and 2 suppercat cannon mufflers.

Ps or if you can afford it go duel 2 inch pipes all that way from the headers with duel cats duel every thing thats were you get some very nice gains cause you dont have two sides fighting for one pipe you have both independent pipes and not to mention you have a very nice sound this way cause one pipe puleses different then the other and they sound sweet :D


I'm thinking of going for a duel setup and this thread has lost me in some parts. Would I be best spending the extra money and going from the headers? What size piping would you use if doing this. What items would I need exactly. I was just going to go duel 2 inch over the rear axel.

Also, Ego could you please tell me what 2 mufflers are you using

I'm thinking of going for a duel setup and this thread has lost me in some parts. Would I be best spending the extra money and going from the headers? What size piping would you use if doing this. What items would I need exactly. I was just going to go duel 2 inch over the rear axel.

Also, Ego could you please tell me what 2 mufflers are you using

2" is tops. Re-read my post 5inches up the screen. You then have to run twin cats if you can find the room :doubt: A split after fuel tank near the axle(?) would make more sense. Run 2.5" from the dump pipe or cat back if you wish, and split into 2 x 2" or 2.25" or 2.5" mufflers. Make sure you keep 2 resonators in or you will go deaf - and get defected :(

cool looks like that's the best option then. Go 2 inch after the axel. I would love to have two lukey mufflers but everyone I talk to seems to think I would be better using two more restricted mufflers. Two lukey's would be to noisy someone alse told me.
I love the sound of my lukey and don't really want to go to much louder.

Hey EZY thanks for your help, when can I get one of your custom made pod boxes. My pod is just sitting in the engine bay sucking in all that hot air, your set up is the only set up I have seen which I have really liked

cool looks like that's the best option then. Go 2 inch after the axel. I would love to have two lukey mufflers but everyone I talk to seems to think I would be better using two more restricted mufflers

who told you that :nuts:

As Ezy Boy mentioned, go 2.5" cat-back, get new muffled performance resonator, then split just after axle/before first muffler and run 2.5" pipe to the other side around the spare tyre compartment into another muffler. Here are a few pics of my setup.

here is where my degree is handy (about the only time lol)

2 inch is 12.556sq inch
2.5 inch is 19.634sq inch
3 inch is 28.273sq inch

2x 2 inch is 25.12sq inch


id go with 3 inch personaly.

head loss equation is given as hl=[(128.u.l.p)/(pi.gamma.d^4)]Q

given a q of 1, gamma 1, u 1, l 1, roe 1, we get a headloss thru a pipe being 128(1)1(1)1/3.1415(1)d^4 where d is diameter in MM < 2x(128(1)1(1)1/3.1415(1)d^4) where d is 2.diameter/3 in MM

now ide definatly go with the 3 inch single :) :badgrin:

here is where my degree is handy (about the only time lol)

2 inch is 12.556sq inch
2.5 inch is 19.634sq inch
3 inch is 28.273sq inch

2x 2 inch is 25.12sq inch


You should get your money back on that degree ;) :P

Area = Pi * r^2

2" pipe area =~ 3.14159 * 1^2 = 3.14159 in^2
2.5" pipe area =~ 3.14159 * 1.25^2 = 4.9087 in^2
3" pipe area =~ 3.14159 * 7.0685 in^2

and 2 x 2" pipe area =~ 2 * (3.14159 * 1^2) = 6.2831 in^2

So your conclusion is right, but your working is wrong. 3" flows better. :D

Hah, u beat me to it. Wonder what kinda degree is it - 180 deg after a flaggan of Bourbon?

Noo, no offence meant, just joking, we all make the odd mistake. What did your calculation mean?

You should get your money back on that degree ;) :P

Area = Pi * r^2

2" pipe area =~ 3.14159 * 1^2 = 3.14159 in^2
2.5" pipe area =~ 3.14159 * 1.25^2 = 4.9087 in^2
3" pipe area =~ 3.14159 * 7.0685 in^2

and 2 x 2" pipe area =~ 2 * (3.14159 * 1^2) = 6.2831 in^2

So your conclusion is right, but your working is wrong. 3" flows better. :D
that'll teach me to use 3.1415*2*2 in windows calculator..
:bowrofl:

that'll teach me to use 3.1415*2*2 in windows calculator..
:bowrofl:

Heheheh - c'mon, don't bag the good old Billy Boy's products.... :bowrofl:

I have duel lukeys at the rear, split before the axle, I made sure they flowed evenly to the two mufflers, that was a must, I had them take out the front resonator and put straight pipe through instead, also my stock headers have been modified before I bought it, looks weird, but the exhuast guy looked at pics of stock units and then mine and said someone wanted a bit more power from it, I dont have the typical curve from the rear bank like others I have seen, and the pipe looks fatter, It goes damn hard to redline though, pulls like tonka truck.

I paid $500 for mine, the tips where worth $150 for the two, so take that off for the exhuast setup alone.

All up, there is no way I have a power loss, it is a definate gain over stock for sure, you can often tell by the amount of tyre smoke left behind. :badgrin:

i got a twin setup on mine and it is pretty good.

mine is 2.5 up to the rear axle where it splits into 2inch then into the supercat triple flow glass packed mufflers. it sounds awesome and looks great

all up it cost me $450 and half a days wait

frig me i learnt alot about exaust gases form that aritcle. so now for the V6 3.0L, whats the best system, dual pipes from the headers, or a single pipe, also, those pipes you were talking about with the ferraris, are they commercialy availbale?

Okies, the way I see it is this: the only reason you would need to increase your exhaust out-put (efficiency) is when your engine is producing so much (increased) power that the standard system can't cope with it.

In the case of increased power, a properly designed dual exhaust system IS beneficial because (obviously) you have twice the number of outlets for the gases to be expelled.

This is the case with my Sprintex Supercharged Magna. Because of the tremendous increase in Kw, it needs to be able to expel the exhaust gases ASAP. I was thinking of a dual exhaust solution because to me, it would look cool but didn't know if it would actually benefit the car's performance. So, I consulted with Sprintex's Chief Technician and he came back to me with the answer that yes, it would. So, as we speak, Sprintex, together with Genie, are developing a custom, dual exhaust, high-flow, stainless-steel system for me.

Both Sprintex and Genie are leaders in their own fields of Magna performance solutions. So, to me, it makes sense to trust the experts and not some 'cowboy' operators out to make some quick bucks at YOUR expense.

You may have heard it before but...you really do get what you pay for (providing you're dealing with experts), IMHO.

Personally, I'm not interested in ANY mod to my car that doesn't increase its performance (legally) and I leave it to the experts to guide me as to what those mods should be. I'd much rather spend my bucks on genuine car performance mods than window shattering audio gear, eye-catching but non-performance increasing big wheels or half-as*ed interior and/or suspension mods.

With all due respect, mate, what you need to consider first is some serious engine mods to justify a new exhaust system.

As for myself, my personal goal is to be able to run in the 13s and blow-off 5.7 litre 300Kw V8 Clubsports (low 14s). Hopefully, that goal will be realised at the end of the week :thumbsup:

VR-X II

As for myself, my personal goal is to be able to run in the 13s and blow-off 5.7 litre 300Kw V8 Clubsports (low 14s). Hopefully, that goal will be realised at the end of the week :thumbsup:
Most of those sit in the mid 13's but good luck. It's been an interesting evolution to watch :thumbsup:

Most of those sit in the mid 13's but good luck. It's been an interesting evolution to watch :thumbsup:

The newer 6.0 HSVs have run as low as 13.2 in auto form (apperenttly quicker than the manual by around 0.2 sec) :shock:

The newer 6.0 HSVs have run as low as 13.2 in auto form (apperenttly quicker than the manual by around 0.2 sec) :shock:
Ouch. That's it, I'm buying one.

Okies, the way I see it is this: the only reason you would need to increase your exhaust out-put (efficiency) is when your engine is producing so much (increased) power that the standard system can't cope with it.

In the case of increased power, a properly designed dual exhaust system IS beneficial because (obviously) you have twice the number of outlets for the gases to be expelled.

The major flaw in that reasoning is that no matter what you do your exhaust is only as free-flowing as the most restrictive part. If you run 2.5" pipe from the cat back to before the fuel tank then split in to two pipes, it doesn't matter if you split into 2 x 5" runs of pipe, your exhaust won't flow more than if you continued with a single 2.5" pipe all the way to the back of the car. But I'll let you off because you said "properly designed" :D

The ultimate system is of course to run seperate pipes from the collectors into two cats and all the way back through two independant mufflers to the back of the car, but I don't think there's room under the car for this is there?

Short of some funky fluid dynamics stuff, I can't see that splitting a single pipe into two pipes of the same or larger diameter is ever going to improve flow unless your muffler on the single pipe system was imposing a restriction.

I'm not saying it can't and doesn't perform better.. just that I don't understand why it would.

The ultimate system is of course to run seperate pipes from the collectors into two cats and all the way back through two independant mufflers to the back of the car, but I don't think there's room under the car for this is there?
Actually, the ultimate setup is to have the pipes all of a tuned length designed and in an arrangement that takes into account firing order. On 6's and higher it's quite hard, expecially when the engine's of a tansverse layout. Subaru's Liberty GT does this quite well. It's obviously a boxer engine but the pipes aren't arranged in a a layout dictated by a bank of cylinders. They extracted some more power and torque through their matched arrangement.

I have a sneaking suspision that on a V6 if you seperate the banks, you'll actually loose a little especially when it's a quick attempt.

Most exhaust upgrades see a gain because they are simple and are a proven method. Once one starts getting tricky, exhaust theory needs to be used to determine what works and what doesn't and exhaust theory is actually quite tricky. I tried reading a book on it once and it blew me away. I couldn't follow most of it. I'm sure Genie will be on the ball.

Okies, just got off the phone to Genie. First off, the system they were going to design WAS a Split one. After talking with them, I've now knocked that idea on the head.

I had thought that I was going to get a true dual system but apparently it's not feasible to do so, mainly because of the way the header pipes come off the engine and meet in the middle of the car (no room for separates I was told).

I was also told that there would be absolutely no advantage, performance-wise, by going to a Split system other than for cosmetic reasons (in other words, it would just be a wa*k).

So, it looks like a single 2.5 inch system for me!

Thanks for your posts, cthulhu and Redav, they got me thinking and spurred me on to enquire. I owe you guys a drink or three with the money I'll save! :D

VR-X II

EDIT: Hmmmm, but because the car is going to be featured on the Drive Time show, maybe I should reconsider...afterall, it WOULD look hotter. :bowrofl:

Reckon you should go for at least a 2.75-inch mandrel bent system, 3-inches would be even better. Your engine will be generating significantly more exhaust gases than standard, so all the comments made in other threads about the 'sweet spot' for magna exhaust diameter are relevant. Some twin-turbo cars needed to go to 3.5-inches because 3-inches was not enough.

Thanks for your posts, cthulhu and Redav, they got me thinking and spurred me on to enquire. I owe you guys a drink or three with the money I'll save! :D
Forget the drinks, just let us go for a spin when we're nearby :badgrin:

Yeah, I think I'm with Meansolara on this one. I mean, a few 3.5l cars have not shown 3' to be too much on an NA 3.5. Bounce the ideas off the Genie dudes, they should have a better idea.

The car I just bought has a full dual exhaust system, compared to other magna's I have test driven, it seemed quite quick after a few thousand revs, more so than other 3L Manuals.

But the car has also been lowered, so I might have "felt" the pickup moreso than standard 3L Manuals.

Here's mine

LOL. barely can see the exhaust. make the pic brighter :)

On the topic of 'forced extraction', I'd just like to bring up dirtbikes and 2-stroke bikes in particular. To enhance a bike's performance, you add an expansion chamber as the first part of the exhaust manifold. The theory is that at they are engineered to a desired rev range so that each 'wave' of expelled exhaust gas hits the end of the chamber, reflects back toward the cylinder and reflects back again so the low pressure behind the wave 'sucks' the next wave of exhaust gas out. Obviously not all the energy is reflected and some exhaust escapes, but expansion chambers can be manufactured for this purpose.

They're also used in miniature 2-stroke engines and the high performance chambers look almost rectangle and have the exit at the top. Obviously these would have a very small rev renge but they would be very effective and as a result, they would have a highly defined power band.

Before you all start telling me how different 4-stroke engines are to 2-stroke engines, and that 6 cylinders would complicate things, has anyone heard or read about the development of this sort of thing in cars? Could we make our headers form 3 into 1 each at an optimum distance from the cylinder head so at 3-4000 revs the waves of exhaust exiting each cylinder could compliment each other and result in a nett constant exit flow? Could we introduce valves into the exhaust manifold at the cylinder so air can be sucked in behind each wave and better the flow of the system?

I think Philcom, being an engineer, could help me answer some of these Qs.

P.S. If this is a new idea, its mine... lol

Here's mine

i fixed up the image for him

http://i7.photobucket.com/albums/y285/Skando1/Clipboard01.jpg

How did u do that.... :confused:

with my magic wand called Photoshop
and a spell called Shadow / Highlight

that's great :)

yeah its awsome for rescuing underexposed photos not that id ever take any haha,

Photoshop CS only

Image / Adjust / Shadow / Highlight

heres mine...... :bowrofl: :bowrofl:

heres mine...... :bowrofl: :bowrofl:

bugger me mine is droney, I'd hate to hear that :bowrofl:

Look at drag cars. Straight into the atmosphere, no mufflers, nuthin. Reason - get the bad air out as quick as possible. Mufflers are used to stop pensioners and little kiddies gettin a fright when you floor it.
Basic concept of a go-fast car. Force air/fuel in as quick and much as possible and then get it out quick.

Look at Formula 1 engines. They have convoluted headers to get scavenging effects. Top fuel engines are just too nuts to bother. Their headers would be gigantic.

Look at Formula 1 engines. They have convoluted headers to get scavenging effects. Top fuel engines are just too nuts to bother. Their headers would be gigantic.

they are also convoluted because they dont have much room and have to be very compact, yet all the headers must also be equal length for max performance, so thats why they have to go everywhere

hey if anyone wants to get a muffler or new exhaust
i strongly suggest going to bottany mufflers

hey if anyone wants to get a muffler or new exhaust
i strongly suggest going to bottany mufflers


why? back it up

why? back it up

beeeeeeeecause hes my uncle :doubt: hahaha lol

my dual zorsts :D

broom broom

$250 fitted for just the muffler, and 2 hours wait from when i walked in..to when i walked out.

then another 2 hours to get a fine for it :( bahaha...dammit

http://i2.photobucket.com/albums/y1/sirboost/My%20Car/DSC00186.jpg

http://i2.photobucket.com/albums/y1/sirboost/My%20Car/DSC00184.jpg

http://i2.photobucket.com/albums/y1/sirboost/My%20Car/DSC00194.jpg

http://i2.photobucket.com/albums/y1/sirboost/My%20Car/DSC00193.jpg

dam that looks sweet,

u for real about the fine?? that'd have to suck, lol

I'm looking to get the exhaust done on my Ralliart some time soon and was wondering what some of you think would be the best option... Straight through 2.5", straight through 3" or a straight through 3" to the rear axles then split into 2 x 3" pipes? Any of them or your own suggestion. It's gonna have pacemaker extractors and a high flow cat.

3" is excessive. Not needed in a NA car. 2.5" is good enough. However, if you are going extractors, high flow cat and straight through system, that is gonne get loud. :)

I would say, go 2.5" all the way with 2 x 2.5" split at the rear with muffled muffler and a straight through hotdog resonator after the cat. :)

Good luck

dam that looks sweet,

u for real about the fine?? that'd have to suck, lol

yeh bro no ****.. driving a car in a way that creates un-nessesary noise = $240.

ive learned my lesson

I'm looking to get the exhaust done on my Ralliart some time soon and was wondering what some of you think would be the best option... Straight through 2.5", straight through 3" or a straight through 3" to the rear axles then split into 2 x 3" pipes? Any of them or your own suggestion. It's gonna have pacemaker extractors and a high flow cat.
I've got a full 3" system on mine, including a high flow cat, a resonator after the cat, and a large cylindrical lukey muffler on the end. It's loud! Well, no louder than half the other cars around the place, but too loud for my tastes.

Unless you're going to do big performance mods, stay 2.5".. 2.75" if you want to push it.

Remember that if you split in to two pipes you needn't stay the same diameter after the split if you don't want to. A 3" splitting into two 2.5" sections won't lose you any flow as two 2.5" sections flow around the same as a 3.5" pipe.

I've got a full 3" system on mine, including a high flow cat, a resonator after the cat, and a large cylindrical lukey muffler on the end. It's loud! Well, no louder than half the other cars around the place, but too loud for my tastes.

Unless you're going to do big performance mods, stay 2.5".. 2.75" if you want to push it.

Remember that if you split in to two pipes you needn't stay the same diameter after the split if you don't want to. A 3" splitting into two 2.5" sections won't lose you any flow as two 2.5" sections flow around the same as a 3.5" pipe.


2.5 + 2.5 = 5 :bowrofl:

2.5 + 2.5 = 5 :bowrofl:

I hope your joking man, or your gonna look like a big fool who never studied area at school :nuts: Cthulhu is 100% correct.

Matthius

I hope your joking man, or your gonna look like a big fool who never studied area at school :nuts: Cthulhu is 100% correct.

Matthius


im offened!!! :bowrofl: ya man im joking, dont mind me... im just :nuts:

im offened!!! :bowrofl: ya man im joking, dont mind me... im just :nuts:


lol , you had me going
I'll shut up now.

Matthius

lol , you had me going
I'll shut up now.

Matthius

Don't worry - I nearly had a bite earlier today. Decided I'd better get back to what they pay me for lol

yeh bro no ****.. driving a car in a way that creates un-nessesary noise = $240.

ive learned my lesson


hehe i got a loud exhaust but still no silencer...guess ill regret it one day :rant:

Im not going to read the whole thread, so im not sure if someone has pointed this out.

If a car has decient headers than back pressure isn't needed! (its actualy a load of rubbish the concept but its easier to call it back pressure than frequency resonance of fluids)

If you have a set of extractors then your best option (power and torque wise) is to have the exhaust end right at the end of the primary pipes, because they are tuned length and diamter.

Twin 2 inch pipes from each bank would be good, 2.5 would be overkill and too loud.

Well today i got quoted 350 buck for a rear dualies, I spoke to a guy who has these on an auto 3.0, 2.5 inch hiflow cat and 3 inch piping after the rear wheels into 2 big cannons with custom made headers no power lostbut he gain power in the low rpm range and he said it expolds in the higher rev range, no other mods done to the motor, So i thought i take the chance and do what he did but just from the rear but was told to do it with the 2.25 inch piping which is standard on a 3.5 v6 magna so im doing it.

$350??? ****. i hope they change the hole piping from cat back to 2.5" for that... otherwise you get ripped off mate

$350??? ****. i hope they change the hole piping from cat back to 2.5" for that... otherwise you get ripped off mate

It includes piping 2 lukey muffler and 2, 3inch dumpers, fitted

So i thought i take the chance and do what he did but just from the rear but was told to do it with the 2.25 inch piping which is standard on a 3.5 v6 magna so im doing it.
3.5l piping is 60.5mm i.e. ~2.4 inch.

3.5l piping is 60.5mm i.e. ~2.4 inch.
thought so, is 350 to much

3.5l piping is 60.5mm i.e. ~2.4 inch.

thats external, ive measured it.

thats external, ive measured it.
Yeah, that's right. I measured it after MMAL told me what it was. After Killbilly being told that the DOHC won't fit, I figured I'd better test it.

I have twin exhaust which is split before the muffler. I noticed no performance decrease, but rather an increase in high revs. It accelerates harder now after 4500rpm.
yeh i have a dual exhaust 2.5" split into to 2"x2 and its an increase in power no loss at all so i dnt no wat you guys are talking bout

i want to run the twin pipe set up from extractors,but what size piping have u other guys used in that case???

i want to run the twin pipe set up from extractors,but what size piping have u other guys used in that case???
2.5" is da way to go

i want to run the twin pipe set up from extractors,but what size piping have u other guys used in that case???
2.5" is da way to go
but note you shouldn't try to run two pipes the whole length of your car its a fire risk and itll almost always bottom out plus there isnt much room for it

2.5" is da way to go
but note you shouldn't try to run two pipes the whole length of your car its a fire risk and itll almost always bottom out plus there isnt much room for it

so what full system would u recommend??extractors,hiflow cat then split the pipes??

so what full system would u recommend??extractors,hiflow cat then split the pipes??that is correct that is exactly wat ive done minus the cat and extractors for now

that is correct that is exactly wat ive done minus the cat and extractors for now

and you have noticed a significant increase in power??
but would u not gain more power by keeping them completly separate??

and you have noticed a significant increase in power??
but would u not gain more power by keeping them completly separate??
not saying that just it will be to much modifying toi keep it safe and abbove the lowest point under the car
trust me was already looking into this

not saying that just it will be to much modifying toi keep it safe and abbove the lowest point under the car
trust me was already looking into this

thats originally what i wanted to do but staying safe is more important.are u urself planning to put extractors??
ive got the car booked in for the exhaust in a week,ill tell u how it performs with the whole kit and caboodle

thats originally what i wanted to do but staying safe is more important.are u urself planning to put extractors??
ive got the car booked in for the exhaust in a week,ill tell u how it performs with the whole kit and caboodle
yeh i am just got other things worth puttin my muny into atm so im holdin it off for now yeh leme no please

yeh i am just got other things worth puttin my muny into atm so im holdin it off for now yeh leme no please

cheers for the help mate.
wot type of mitsi u got??

cheers for the help mate.
wot type of mitsi u got??
verada kh xi u

Got headers (28" primaries), into 3" High Flow Metalcat, split into 2 x 2", all the way (no reso's) into 2 x 2" triflow muffs with twin tips (1 x XR8 and 1 x SS). Fluttering at the 3" to 2x2" atm, will be fixing that with some knife edging, bit of rasp in system so I placed a funnel silencer (1.5") into the muffler outlet and sounds SMICKO :D . Just need to kill the fluttering and maybe some resonator pipes along the 2" pipe to cancel out some droning and I'm all smiles.

Power? Power comes on HARD from 3300rpm. If I still had my manifold I reckon it would be an insane combination. Probably come on at 2500.

Looks? I'm getting lots :cool:

Will post pics when I can find my bl0ody camera.

ok fellas if you want to go twin exhaust for the best power you would branch it after the back wheels or befor it doesent really matter but when you branch it use twin 2 inch piping cuase twin 2.25 is still too big think about it thats 4.50 inch exhaust if you put them together so twin 2 inch is fine any thing under that is ok as well but your getting a bit small for a nice looking rear muffler to go with it

the exhaust im getting im branching it after the rear wheels with twin 2 inch pipes and 2 suppercat cannon mufflers.

Ps or if you can afford it go duel 2 inch pipes all that way from the headers with duel cats duel every thing thats were you get some very nice gains cause you dont have two sides fighting for one pipe you have both independent pipes and not to mention you have a very nice sound this way cause one pipe puleses different then the other and they sound sweet :D

Or you could run Wildcat extractors as these run a shorter rear bank and Ego Jase Mysti K.B can all vouch that i definately have quite a distinguishable bark from my exhaust (3" marine grade stainless mandrel bend high flow res high flow cat 3ARace muffler and it's all stainless so plenty of nice bark)

These Berklee mufflers sound like the way to go! Im thinking of just doing the muffler and tip, and a few people seem to have good results with them.
Is there a part number, or do I just ask for a Berklee PEX straight through muffler? Who sells them in SA?
Pete

See Nigel at Streamline exhausts ph 8337 0066 he will be able to hook you up with a pex muffler he just fitted one to my car

See Nigel at Streamline exhausts ph 8337 0066 he will be able to hook you up with a pex muffler he just fitted one to my car
Ive got a twin set up of these with a 4 inch s/s dumper on the ends... sounds hell wicked!! i got the chamber ones set up!