This is quite a simple idea/question/theory that I'm just going to throw out there.

It comes about after fitting HM Headers to my AWD. The exhaust shops I've used have all said the stock cast headers flow quite well - its just the Y-Pipe that chokes the cars.

So... why dont we just make a better Y-Pipe over buying a set of headers?

Not wanting anything like "logic" to stand in my way I measured up a Standard Y-Pipe and the HM Headers Y-Pipe. I then created my own Y-Pipe that would bolt to standard cast headers.

I present to you - My Custom AWD Y-Pipe (http://imgur.com/nFTuA)

Now, I'm a purest, nothing beats a full set of proper headers. They just look good and they reduce weight and just maybe you get a few extra horses. But, why reinvent the wheel? Why not just jimmy up a new - better - Y-Pipe? Sure, the old Magna's are a limited market and for the idea to be commercially viable you'd have to market something like this for between a third and half the price of a full set of headers.

I dont know, maybe I was just looking for something to kill time with.

The model would fit, be it with some final tweaks. The tuning wouldn't be much better than stock other than to reduce that restriction... maybe my secondaries are as close to identical as possible. And, I did relocate the oxygen sensor port... Not quite sure how I'd get to my rear banks header flange. But, its just an idea.

Thoughts?

None of the headers available for magna are that great fot power anyway so youre probably right.

I just got a VR muffler fitted and asked the exhaust guy that same question about making a better y pipe and he reckoned around the $250 ish, gotta be cheaper this way

The exhaust shops I've used have all said the stock cast headers flow quite well - its just the Y-Pipe that chokes the cars

Huh? I thought a better header was a recommened and simple mod for these cars, resulting in slightly better performance? Is that not the experience?

But headers are very expensive.

for example

$700 for new headers = 3kw

$250 for modified Y pipe = 3kw

Cheap power

But headers are very expensive.

$700 for new headers = 3kw

$250 for modified Y pipe = 3kw

Cheap power

So you

A/ know that on an AWD that the improvement is 3kw
B/ Know that an engine pipe redesigned and NOT tested would also be 3KW

Wow, can you please send me a link to where you got your crystal ball from, I want one. While there can you also please tell me the lotto numbers for this weekend

If anyone would have an idea it would be someone who has acutally got an AWD, has done a change from std to AWD headers.

IF what Skapper has shown would fit and clear the K frame and Transfer case then this would be something that may be worthwhile. Yes the manifold set on a Std Magna is very good for a std set up, the engine pipe on a FWD is also very good however the AWD (after all this is what we are talking about here) is very poor deign and there is more than just a couple of KW to be gained, there is also torque as well to be gain which Skapper and most who have actually owned an AWD and done this will testify to. Also the HM's do take a lot of the AWD droan out of the car as well which is an added advantage.

Skapper, have you made these at all or just a design on the puter, I would be interested in looking into this further for those who dont want to touch the upper manifolds either for originality or for cost factor, may be on a winner here for the AWD. For the FWD owners, no use as the engine pipe is already well designed.

I can tell you that Skaper's design y-pipe section won't fit an AWD as it is the same shape as the FWD one. The AWD is a circular design.
See my post here (http://www.aussiemagna.com/forums/showthread.php?p=980227&highlight=awd+header#post980227). All the points Mal made are correct. Less drone, more low to mid torque. Give back the stolen power plus a bit more. Was designed for the Ralliart Magnas and looks OEM as it still allows the OEM heat shields to be attached.

So you

A/ know that on an AWD that the improvement is 3kw
B/ Know that an engine pipe redesigned and NOT tested would also be 3KW

Wow, can you please send me a link to where you got your crystal ball from, I want one. While there can you also please tell me the lotto numbers for this weekend

If anyone would have an idea it would be someone who has acutally got an AWD, has done a change from std to AWD headers.

IF what Skapper has shown would fit and clear the K frame and Transfer case then this would be something that may be worthwhile. Yes the manifold set on a Std Magna is very good for a std set up, the engine pipe on a FWD is also very good however the AWD (after all this is what we are talking about here) is very poor deign and there is more than just a couple of KW to be gained, there is also torque as well to be gain which Skapper and most who have actually owned an AWD and done this will testify to. Also the HM's do take a lot of the AWD droan out of the car as well which is an added advantage.

Skapper, have you made these at all or just a design on the puter, I would be interested in looking into this further for those who dont want to touch the upper manifolds either for originality or for cost factor, may be on a winner here for the AWD. For the FWD owners, no use as the engine pipe is already well designed.

Are you serious? I was making a damn example. You just launch on me for no reason like I have offended you so much. You call everyone else keyboard warriors, have a look at yourself.

dreggzy, I know exactly what you mean and are saying - I'm sure mad magna is just living up to his name - but you didn't put "example" or even EG: in your post, so that makes it a statement and that's what Mal is jumping on . remember, search engines may quote that and someone down the line will read that headers give 3kW - personally I think it would be much higher - 5% for FWD and 10% for AWDs is my guess. that's about 8 and 15kW.

Back on topic - I'd be interested in this - I know the FWD has a Y pipe and the AWD has a T connection and would like to improve this.

Thanks oggy for pointing that error out. I addressed it. When I am writing in my phone sometimes small errors slip through.

Mal, the way you worded your post was incredibly aggressive and offensive. A decent person would apologise.

Op, I would be interested to see more of how your theory works. If you can achieve a power increase, this would he a mod that I would do.

dreggzy, I know exactly what you mean and are saying - I'm sure mad magna is just living up to his name - but you didn't put "example" or even EG: in your post, so that makes it a statement and that's what Mal is jumping on . remember, search engines may quote that and someone down the line will read that headers give 3kW - personally I think it would be much higher - 5% for FWD and 10% for AWDs is my guess. that's about 8 and 15kW.

Back on topic - I'd be interested in this - I know the FWD has a Y pipe and the AWD has a T connection and would like to improve this.
The stock awd y pipe rear bank folds back on itself.

Skapper, have you made these at all or just a design on the puter, I would be interested in looking into this further for those who dont want to touch the upper manifolds either for originality or for cost factor, may be on a winner here for the AWD. For the FWD owners, no use as the engine pipe is already well designed.

I was just pissing into the wind to see what it felt like Mal - (I'm happy with the HM's) - But, I'll at least knock up a drawing to use for dimension checking/budget quoting.

As for fabricating them... it would take skill and patience. The model I've created is something you could work from, but I wouldn't go building straight off the plan. My concerns were the rear flange and access to it. Both the stock Y-Pipe and the HM Y-Pipe have great access... mine, does not. Needs tweaking. The other thing that has me concerned is that there's a slight angle in the flanges to the headers on both Y-Pipes and its not something I could easily measure.

My experience with exhaust systems is pretty primitive, though I have made my own expansion chamber for a two stroke motorbike I owned long, long, ago. I'm pretty confident that the process I went with when creating the model would allow for easy fabrication.

Let me tweak the model, then do some drawings. Enough for some of you to get a budget quote with at least.

I can tell you that Skaper's design y-pipe section won't fit an AWD as it is the same shape as the FWD one. The AWD is a circular design.
See my post here (http://www.aussiemagna.com/forums/showthread.php?p=980227&highlight=awd+header#post980227). All the points Mal made are correct. Less drone, more low to mid torque. Give back the stolen power plus a bit more. Was designed for the Ralliart Magnas and looks OEM as it still allows the OEM heat shields to be attached.


Vlad, the model was created using the dimensions from a stock AWD Y-Pipe and a HM Headers Y-Pipe - it would fit.... easily as I've kept it within the dimensions of the HM's wide radius turn from the rear bank. I'l upload a better image, top down, so you can see how I've routed it.

I do this kind of thing for a living - square peg into a round hole type mechanical engineering. Measure twice... maybe three times then cut once. Even then I get paranoid right up until I see what I've designed fit together and work.

* Disclaimer; I don't draw/design exhausts for a living, nor do I do any real "car related" stuff in my job. Mostly heavy mining equipment and the like. But, there is a lot of "we've got this thing and we want it to attach to that thing" going on. Its fun.

Okay,

Here we go (http://imgur.com/a/vTfSz). Some better images to clear up any confusion. Plus a comparison image of all three Y-Pipes; Stock, HM and this custom job.

Edit;
Looking at them now I can see a few ways to make this easier/cheaper to construct....

Are you serious? I was making a damn example. You just launch on me for no reason like I have offended you so much. You call everyone else keyboard warriors, have a look at yourself.

Yes I am serious, I did not "launch" on you what ever that even means

This is a tech section, you have made a statement which is clearly incorrect, you were at best using an example of the effect of a fitment to a FWD car, this thread was about an AWD and clearly your facts were not facts. In a tech section we want facts here only, guesses are no good to anyone given that some may come in and read 2 or 3 comments and come to an incorrect conclusion on something.

As for having a go, seriously??? you need to harden up mate, anyone who makes a comment on a forum needs to be prepared to be criticised for those comments, if they can take the criticism then perhaps time to rethink about making posts. Also, care to point out where I call "everyone" keyboard warriors, best to reply in a PM so I do not need to then infract you for placing even more spam in a tech section :)

As for apologising, I have nothing to apologise for, I made a tongue in cheek comment, if you cant take these comments dont make posts, simple really??

Skapper, now back on topic, That looks like it would work, the access is not much on an issue, there are a few ways to get up in there with the correct tools anyway. I have on occasion considered fitting a modded HM lower section to a Magna, is simply a matter of extending the HM pipes to make them longer as th HM headers come down lower than the std manifold but at the end of the day the cost difference between the HM set and the pipe on its own as you know is not that great thus by the time it was modded there would be little to gain financially.

For those wondering, the main issue with the AWD set up is the engine pipe, the ones in Skappers pics show the AWD std engine pipe, it is pretty much a dump in with little to show for smooth gas merging at that point. Even just a decent engine pipe set up will make a world of difference. The HM do this by simply moving the whole set up over a little to give the room for the rear curve around. The FWD engine pipe comes no where near to fitting the AWD as the pipe is simply too far over. I have seen one FWD pipe modded to fit an AWD but was very messy, it did what it was supposed to do but the time, effort and expense of the job a new one could have been made in my opinion. The FWD and AWD manifolds are the same as each other, they are decent in relation to design and flow and while extending those primary pipes like HM and others do does assist in the torque the power gain is not much at all.

On a FWD there are many modded ones around running std engine pipe and manifolds with no issues. AWD it is a must to do something for this

I'll re-hash the pipes a little later. Mostly to remove/reduce the harsher bends. And... Maybe reposition the collector. Double check my dims and see if I can match the flange angles seen in the stock and HM pipes.

The construction of the stock y-pipe must just be two stampings welded together? Or a casting? I mean, I'm just thinking of construction methods that are easy to mass produce. That is why they went that way, budget constraints - an easy construction that gave the most durable result.

Deleted.

Okay. I've chalked up a set of drawings of a revised custom Y-Pipe. Its not a set of fabrication drawings as yet. This is to check dimensions and iron out the bugs.

Check and let me know what I've missed or what I've gotten wrong (http://imgur.com/a/WeYst#0) - Thanks

What about details such as N&V, ground clearance and mountings and such; any issues or impacts there?
Would the design obstruct access to components at maintenance time?

What about details such as N&V, ground clearance and mountings and such; any issues or impacts there?
Would the design obstruct access to components at maintenance time?

Noise and vibration outside of the quality of construction and materials used wouldn't (shouldn't?) be any worse than any other set of headers. Sound quality? I'm not an expert so I couldn't comment on how this might change exhaust note.

Tuning is something else that has not be factored in at all either. The general idea was to produce a "direct fit" Y-Pipe. Tuning could be a factor. I might research this.

The dimensions used are within the physical limits of a standard y-Pipe. The clearance would be slightly more generous as there are no heat shields. That's not saying this would be a perfect fit, there would be adjustments I imagine. Mostly in the bend radiuses used, as I'm not sure if A) they're physically possible, and, B) how the larger radiuses affect clearance.

To check clearances I'd essentially have to model the whole underside of the car. And (if this was a commercial venture) the costs of that would outweigh the costs of a physical prototype.

Please remember this is just me wasting time, I'm not submitting this as a legitimate idea per se. Just throwing out an idea. If somebody wants to take it and run with it then sure, the bugs need ironing out. Currently it's just a toy to provoke thought and ideas.

As for mounting you've brought one thing to light - AWD y-pipes have a mounting bracket toward the rear of the outlet. Mine does not! Best be fixing that....

While this addresses the flow problem you have with standard fitment, it doesnt address the two other advantages of fitting aftermarket headers, i.e. quicker heat dissapation and lighter weight, both of which, IIRC, lead to better efficiency, which is why I usually fit headers (early) in the first place...Good Idea though..

Great work Skapper, your replacement Y piece should give the AWD an easy 5kw atw gain.

While this addresses the flow problem you have with standard fitment, it doesnt address the two other advantages of fitting aftermarket headers, i.e. quicker heat dissapation and lighter weight, both of which, IIRC, lead to better efficiency, which is why I usually fit headers (early) in the first place...Good Idea though..

I couldn't agree more - a full set of headers will always be the better option. Provided they're good quality headers of course.

As for efficiency, the debate is still on going on the flow capacity of the stock cast headers. Heat dissipation is of course not so debatable.

This all started out of boredom one Sunday afternoon. I had one if those (extremely) rare moments when I found some free time. I also had a stock Y-Pipe and a HM Headers Y-Pipe layout around.

It struck me that the biggest failing of the AWD - the chokey chicken Y-Pipe - wasn't just "upgraded" at some point by somebody. Obvious answers came up; cost effectiveness compared to a full set of headers, limited commercial market and costs of prototyping and manufacturing.

At the same time I wanted to create an accessible "idea" for those AWD owners on a budget? Not that I want anything to do with making and/or marketing something like this. This idea is "open source" and something any AWD owner can use and improve one. Hopefully at a budget that's less than a full set of headers.

My next step is to create the model using only "off the shelf" mandrel bend sections as seen on eBay and the like. So it could be "kitted" together by an exhaust shop or an adventurous welder.

It's an idea. Take it and run with it! I'll be updating it as find errors or improvements - with the help of those who want to check dimensions or have suggestions. Eventually producing a bill of materials and a set of fabrication drawings that can be dragged down to your local exhaust shop for a quote.

Great work Skapper, your replacement Y piece should give the AWD an easy 5kw atw gain.

Five Kw would be a bonus. But I'm hoping the biggest bonus will be saving some AWD owners some money.

A side bonus would be to kick off ideas in other Magna owners. Get the cogs whirring.

I wonder what gains our cars would see if someone got custom extractors that have tuned length pipes?

I wonder what gains our cars would see if someone got custom extractors that have tuned length pipes?

You know, that's the one thing that would interest me the most. To tune the headers to a stock Magna engine. To see what the maximum gains could be achieved with a fully tuned exhaust system.

That and just exhaust tuning in itself. I could probably dig up the reams of notes and the load of books I have for making custom expansion chambers... but, two stroke stuff won't be of much help :P

I have done some "light" reading on the subject and considered making a set of stepped headers when I started this Y-Pipe. But figured that my lack of knowledge on the subject dictated I focus on just creating a "practical" idea. I did however crank out the outlet if the headers from 2.25" to 2.5".

Measuring and modeling the headers wouldn't be difficult, but it exposes the idea to a greater room for error and would drag out the timeline in producing a working prototype...

I'll model up some headers after I have the Y-Pipe broken down to kit parts. I might dig around for books on exhaust tuning in the meantime. To give me a starting point at least.

It would be difficult to know how far the pipes need to be stepped in order for max gains without numerous sets and dyno testing, might just wait until i get a new car that has these available off the shelf :P Good headers like we are talking also lets you go to larger exhaust diamaters without having to push air out of the pipe as flow would be more constant.

It would be difficult to know how far the pipes need to be stepped in order for max gains without numerous sets and dyno testing, might just wait until i get a new car that has these available off the shelf :P Good headers like we are talking also lets you go to larger exhaust diamaters without having to push air out of the pipe as flow would be more constant.

Computer modeling software for exhaust tuning could be used to get a good starting point as far as tuning goes. I've got some basic engine tuning software but it doesn't tackle things at depth. Not exhaust system tuning anyway. There is a package available though. The point being dyno time and the end number of prototypes can be reduced with a software determined starting point.

If a tune could be determined the problem then becomes getting that mass of tuned pipes to fit into the tight space that it the rear bank on these cars. And, or course, matching the tune in both banks.

I do like a challenge though... :P

For fun I might jimmy up a full set of "balls out" dirty great headers for the AWD. I mean, in 3D land ANYTHING is possible.

I couldn't agree more - a full set of headers will always be the better option. Provided they're good quality headers of course.

As for efficiency, the debate is still on going on the flow capacity of the stock cast headers. Heat dissipation is of course not so debatable.

This all started out of boredom one Sunday afternoon. I had one if those (extremely) rare moments when I found some free time. I also had a stock Y-Pipe and a HM Headers Y-Pipe layout around.

It struck me that the biggest failing of the AWD - the chokey chicken Y-Pipe - wasn't just "upgraded" at some point by somebody. Obvious answers came up; cost effectiveness compared to a full set of headers, limited commercial market and costs of prototyping and manufacturing.

At the same time I wanted to create an accessible "idea" for those AWD owners on a budget? Not that I want anything to do with making and/or marketing something like this. This idea is "open source" and something any AWD owner can use and improve one. Hopefully at a budget that's less than a full set of headers.

My next step is to create the model using only "off the shelf" mandrel bend sections as seen on eBay and the like. So it could be "kitted" together by an exhaust shop or an adventurous welder.

It's an idea. Take it and run with it! I'll be updating it as find errors or improvements - with the help of those who want to check dimensions or have suggestions. Eventually producing a bill of materials and a set of fabrication drawings that can be dragged down to your local exhaust shop for a quote.

Great idea, ive been thinking of trying to make my own y-pipe for a couple of weeks now and was also checking out the mandrel bends availiable on ebay as i have made a stainless steel cat back dual system for my corolla seca because i was bored at work so wanted something to do also have access to a s/s tig and mig so a set of drawings and list of parts is an awesome idea, ill be up for a set of those

Great idea, ive been thinking of trying to make my own y-pipe for a couple of weeks now and was also checking out the mandrel bends availiable on ebay as i have made a stainless steel cat back dual system for my corolla seca because i was bored at work so wanted something to do also have access to a s/s tig and mig so a set of drawings and list of parts is an awesome idea, ill be up for a set of those

I'll try get something sorted over the weekend.

I'll try get something sorted over the weekend.

Sweet, cheers for that :woot:

Sweet, cheers for that :woot:

Well, while I did get around to doing some of this I dont have anything tangible to show you. Yet.

I've been using the parts listed here (http://www.spdexhaust.com/) for my technical specs. I'm having some issues getting the rear bank to do its loop and remain within the bounds set by the sump, K-frame and transfer case. But, I should have something soon.

In my search for AWD headers, options and searching for advice with this custom pipe I got talking with a guy from Advanced Headers. While they market AWD headers they do not actually make a Y-pipe - you buy their headers then have your own Y-Pipe made. :nuts: My initial reaction was "WTF?" but I'm looking at their headers, especially the rear bank, and thinking a Y-Pipe to suit could be easy to make. Possibly easier than making a Y-Pipe to suit the cast headers?

Mind you Advance headers look like pipe bent headers and I know nothing of their quality. Mind you the headers section on my HM's are pipe bend, the Y-Pipe appears mandrel bent.

Moving on. I'll focus on creating a Y-pipe to suit the cast headers. Should have something very soon, I'd show you my progress but its not that pretty. After that I might focus on a Y-Pipe to suit the Advance Headers, and, after that focus on designing my own complete set of headers - hopefully with some form of tuning included in the design.

Well, while I did get around to doing some of this I dont have anything tangible to show you. Yet.

I've been using the parts listed here (http://www.spdexhaust.com/) for my technical specs. I'm having some issues getting the rear bank to do its loop and remain within the bounds set by the sump, K-frame and transfer case. But, I should have something soon.

In my search for AWD headers, options and searching for advice with this custom pipe I got talking with a guy from Advanced Headers. While they market AWD headers they do not actually make a Y-pipe - you buy their headers then have your own Y-Pipe made. :nuts: My initial reaction was "WTF?" but I'm looking at their headers, especially the rear bank, and thinking a Y-Pipe to suit could be easy to make. Possibly easier than making a Y-Pipe to suit the cast headers?

Mind you Advance headers look like pipe bent headers and I know nothing of their quality. Mind you the headers section on my HM's are pipe bend, the Y-Pipe appears mandrel bent.

Moving on. I'll focus on creating a Y-pipe to suit the cast headers. Should have something very soon, I'd show you my progress but its not that pretty. After that I might focus on a Y-Pipe to suit the Advance Headers, and, after that focus on designing my own complete set of headers - hopefully with some form of tuning included in the design.
Yep, no probs, sounds like yourve got it sorted, initially i thought of buying another Y-Pipe and fabricating a jig so as to get the rear bank within the sump/k-frame/trans case boundries seeing as thats the tricky bit, also what OD is the piping used in the HM's

Good idea and im no expert either but would the tighter bend before the y-pipe be more restrictive than the larger bend on the hm headers?

Yep, no probs, sounds like yourve got it sorted, initially i thought of buying another Y-Pipe and fabricating a jig so as to get the rear bank within the sump/k-frame/trans case boundries seeing as thats the tricky bit, also what OD is the piping used in the HM's


HM Header dimensions;
Primaries - ID 38mm, OD 41mm
Outlet Dia. of Collector on headers - ID 51mm, OD 53mm

I'm not sure I have this figured out. :S

Good idea and im no expert either but would the tighter bend before the y-pipe be more restrictive than the larger bend on the hm headers?

There could be a restriction in the tighter bends for sure. The trick is to avoid the tighter radius where possible, and that will change as things progress. Must off the shelf mandrel bends aren't as savage as what I've drawn in my initial models.

The stock Y-Pipe essentially has the exhaust gases running into each other. I'm no expert either, but having gases exiting into a T-junction, or, exiting so they flow in the opposing direction of other gases is not efficient. Less efficient than a tight radius maybe?

Excuse me for interrupting, but this is an interesting topic, i wish i understood the technical issues better.
If anyone has a few minutes free could they take the time to explain it via PM or post here? Just for those of us who dont understand but are interested to follow the thread? I dont understand why we have this complex OEM design in the first place. As a non-technical person i get the concept that bends in the pipe restrict flow, but dont understand why the bends are there then?

here's a dumb question from me . is there anyway to run twin pipe's back to the cat .
would save doing having a loop in the pipe

Excuse me for interrupting, but this is an interesting topic, i wish i understood the technical issues better.
If anyone has a few minutes free could they take the time to explain it via PM or post here? Just for those of us who dont understand but are interested to follow the thread? I dont understand why we have this complex OEM design in the first place. As a non-technical person i get the concept that bends in the pipe restrict flow, but dont understand why the bends are there then?

Its not that the stock Y-Pipe is complex, its more that its simple, cost effective and gets the job done. Its inefficient in its design if you were to mark it on efficiency at channelling exhaust gases. But, bean counters will tell you its super efficient as it improved Mitsubishi's bottom line by reducing manufacturing costs.

The will have gotten a quote to manufacture a proper Y-Pipe and compared that to costs to manufacture the Y-pipe we see today. Add to that they would've factored in failure rates based on the complexity of a "proper" Y-Pipe; more joins/welds = increase failure possibility especially in mass produced items. The design we see today is the result of dollars controlling the "square peg - round hole" problem the engineers were faced with.

As for where the pipes inefficiency lays, its in where the exhaust gases exit the rear bank and meet with the Y-Pipe; its like traffic attempting to merge onto a free-way without the benefit of an acceleration or merging lane - the result is collision/turbulence and disruption of the exhaust gases on the journey out of the cylinder, affecting the volumetric efficiency of the rear banks cylinders predominately but also the front bank as its exhaust gases get caught up in traffic so-to-speak.

I hope that helps. If anybody has any corrections feel free to let me know?



here's a dumb question from me . is there anyway to run twin pipe's back to the cat .
would save doing having a loop in the pipe

Once again you would be limited by room.. maybe moving the 2-1 collector further back, increasing the length of the secondaries? Or, if you wanted to run say two 2" pipes back - right back - I'd have to wonder how performance would be affected? Its an idea though, one of those simple but complex ideas - Its solves one problem but introduces another.

As for where the pipes inefficiency lays, its in where the exhaust gases exit the rear bank and meet with the Y-Pipe; its like traffic attempting to merge onto a free-way without the benefit of an acceleration or merging lane - the result is collision/turbulence and disruption of the exhaust gases on the journey out of the cylinder, affecting the volumetric efficiency of the rear banks cylinders predominately but also the front bank as its exhaust gases get caught up in traffic so-to-speak..
Yes that helps thankyou. Someone said something about a loop? Is that to navigate the components and structures around it? Why not just route it further below the structures, to clear them, plenty of clearance there?

Yes that helps thankyou. Someone said something about a loop? Is that to navigate the components and structures around it? Why not just route it further below the structures, to clear them, plenty of clearance there?

The loop is used in an attempt to achieve equal lengths in the secondary pipes (correction anybody?).

Plenty of clearance might apply to one or two cars, in ideal conditions. But, when you're attempting to design something that's to fit multiple vehicles in a multitude of different situations and conditions... it quickly reduces any clearance, especially from the underside of the car. This is something Mitsubishi would have considered at one point I'd imagine. Failure rates are an important consideration in large commercial ventures, if it were a one off, built for purpose, item you'd fudge a little on costs and almost disregard "costs to repair/replace".

Yes that helps thankyou. Someone said something about a loop? Is that to navigate the components and structures around it? Why not just route it further below the structures, to clear them, plenty of clearance there?

Not a lot of clearance height wise. Also, if you lengthen the rear bank pipe then you will have to lengthen the front one as well. Also, the inefficiency of the stock y pipe robbed the Sports/VR/VRX/GTVi AWD versions 4kW at the fly and 1kW at the fly for the non-sports AWD versions.

Just for some useless information, I've been discussing AWD Headers with everybody who admits to making them. Mostly to find out materials used, but also to discuss failures (if they were willing to).

So far I've had talks with Advanced headers, X-Force and RPW. Yes, yes, I said the naughty word - RPW. But, this is for research, put the flamethrowers away please. The more information collected now leads to fewer errors in the future.

Advance headers and X-Force have been pretty helpful overall. X-Force admit their flex pipes need replacing from the get go due to whistling. The X-Force system uses what appears to be two large flex joints in the headers. But the front banks flex is quite a ways back from the outlet - might crack at the front banks flange? The three-to-one collectors look to be similar in design to HM's - 25 degrees roughly. X-Force use 1.8mm wall 304 stainless tubing. That's about all I can get from them at this point, though they're being prompt with answers to my questions. They no longer manufacture these headers unfortunately (fortunately?).

Advance headers don't do the Y-Pipe, but supply all of the parts required to attach your custom made Y-Pipe. Mild steel, no mention of ceramic coating, or wall thickness. The three-to-one collectors they use have a very shallow angle to them - 7 degrees maybe, not sure how this affects tuning. Very helpful staff though. Price for the headers (no Y-Pipe) was $310 + freight.

RPW headers are all mild steel, with an option to ceramic coat them. No mention of failures, though there was some suggestion that LPG fuelled cars may affect durability. Price was $620 landed, no ceramic coating. No mention of diameters, wall thicknesses are ohter data, but so far RPW are helpful and prompt in answering my questions so far

I called Hurricane but they wont admit to making AWD headers despite me being sure they did. Liverpool = Hurricane now. Genie don't do AWD Headers (or Magna headers?), Nothing back from Redback/Lukey and nothing back from Wildcat as yet.

The HM's I have a set of already and have listed the diamters, wall thickness already. I bleieve they are constructed from 409 stainless steel with a light coating of some kind. All of HM's collectors, 3-to-1's and 2-to-1 are steeper angles 20/25 degrees.

It would be interesting to know what style collectors are used. If they are similar to HM's 3-to- where the header pipes are molded to the collector (I'll upload a pic) or if the more "fancy" style I've seen is used on any of these other products.

Tuning "style" for all three are quite different. Long primaries on the RPW set, shorter primaries on the X-Force and Advance headers are some where in the middle.

Prices are listed so a cost cut-off point can be established for the construction of a custom Y-Pipe.

From the suppliers that have replied I see advantages in all systems. Advance headers design could lead to easier fittment, and maybe an easier Y-Pipe design. X-Force headers sure do look pretty, and the RPW design being similar in principal to Pacemakers could be a good thing to.

Note: I'm commenting on exhaust DESIGN, not the QUALITY of any of these systems.

RPW use Hurricane, used to use Pacemaker but then apparently "got told" to not do this anymore :)

RPW use Hurricane, used to use Pacemaker but then apparently "got told" to not do this anymore :)

Whoa... THAT is confusing? Hurricane just said "no, we dont make headers for the AWD". Then I figured the RPW's were Liverpool headers... turns out Liverpool IS Hurricane.

It was a research bent I went on. Still waiting to hear back from a few places. So far its been okay, I'm getting materials and general information at least.

Moving right along

I've modelled a Y-Pipe using readily available mandrel bends, created a drawing and a bill of materials. Heres the catch - I've used a mandrel "donut" - cha-ching! They can be expensive. I've also avoided detailing the joins/welds to the donut, as I figure somebody with better experience would know what was best there.

Y-Pipe V3.0 using "off the shelf" parts (http://imgur.com/a/MZtwk#0)

Can somebody check for errors, both in fit to an AWD and just for other general errors? Check, check, double check. If I've missed a dimension you need, let me know and I'll update. If I get time I might attempt a basic model of the underside of the car - just sump, k-frame and transfer case, to check with.

I'm going to do a Y-Pipe to suit the Advanced Headers as well... later. just because I said I would. Before that though, I might just make my own set of headers.

The loop is used in an attempt to achieve equal lengths in the secondary pipes (correction anybody?).
Is that to ensure equal pressure at the collector (and hence equal flow)? Couldnt we increase the diameter of the pipe in order to achieve the same result, without the loop? Or alternatively, couldnt we construct a pipe within a pipe, and route the gases through both to achieve the same length as the other pipe? Alternatively, what if we split the pipe into two or three pipes of equal but smaller diameter, thereby providing the same throughput at a shorter length?

Is that to ensure equal pressure at the collector (and hence equal flow)? Couldnt we increase the diameter of the pipe in order to achieve the same result, without the loop? Or alternatively, couldnt we construct a pipe within a pipe, and route the gases through both to achieve the same length as the other pipe? Alternatively, what if we split the pipe into two or three pipes of equal but smaller diameter, thereby providing the same throughput at a shorter length?


I think the emphasis is on the speed/timing and behaviour of the exhaust pulses? With two strokes the different tapers in the expansion chamber affect the speed of the exiting exhaust gases as well as the return pulse. I imagine a similar principal applies to four stroke engines. I've ordered a couple of books to read, so I'm making "educated guesses", not just plain guesses.

With my "pre-fab" pipe set the goal was simply to take out the restriction in the rear bank - there's no tuning in it. Advantages it might have over a stock Y-Pipe? Just eliminating that restriction is my guess.

As for pipes in a pipe, or different approaches to how the rear bank exhausts into the Y-Pipe, the danger is developing an idea that's overly complicated to construct. Defeating any advantage in costs of just fabricating a Y-Pipe over just buying a proper set of headers.

Modifying the stock Y-Pipe directly wouldn't produce a very attractive result I dont think. One idea though I was kicking around was to do away with the collector and do something similar to what I see X-Force have done with thier FWD Y-Pipe - just splice it into the front banks secondary. But, I'm not sure this is the right way to do things.

X-Force;
http://imgur.com/qcOCh

I'll develop the idea more and more as dimensions are checked, and as I get more feedback from you guys, and as I get more advice/ideas from guys in the know. Right now, my goal is to produce a "kit" that's a cost effective option compared to a set of headers. which is tough going considering how affordable headers can be - keeping in mind "you get what you pay for". If something like this could be fabricated for a total of say $300 including labour it could be an alternative for those of us on a budget.

NOTE
I thought I'd take the time just to clarify once again; this is an "open source" idea, its not a commercial venture. Its the start of an idea, it can be developed in different ways by others and improved over time (hopefully without fabricating too many prototypes). I'm happy to update the drawings until they reach a stage where the Y-Pipe can be build directly from the plan.

Another Update

Okay, so I wasnt happy with using the expensive "donut" in the system. The idea being to keep costs down. I've just ditched the whole loop in the rear bank for a single, rear facing, 90 degree bend. This should take a large chunk out of the budget.

I've also used a different 2-to-1 collector, but its still an "off the shelf" part - a "formed, weld-on collector".

Haven't done any drawings for it as yet, still trying to make my own "from scratch" headers.

Link to this update (http://imgur.com/a/F6Tvg#0)

http://imgur.com/2Fj0S

Last design looks clean, but uses unequal length pipes. That would affect the scavenging effect between the two banks, surely? I don't know how important that is in real life, but the loop in the factory one is there to make the two pipes equal length before they join, so it must matter?

i did somthing similar on my TR v6, had a horrible "T" intersection....but must say very impressed with ur efforts so far...


http://www.aussiemagna.com/forums/showthread.php?t=51451&highlight=

i did somthing similar on my TR v6, had a horrible "T" intersection....

http://www.aussiemagna.com/forums/showthread.php?t=51451&highlight=


THAT looks pretty damn good! What were the costs involved? Any issues with fit, or issues with the pipe/welds etc on the road?

Last design looks clean, but uses unequal length pipes. That would affect the scavenging effect between the two banks, surely? I don't know how important that is in real life, but the loop in the factory one is there to make the two pipes equal length before they join, so it must matter?

Unfortunately tuning is still a little way out of my league. The main aim of this Y-Pipe project is to simple create a cost effective replacement... a set of drawings that anybody can take to an exhaust shop for quotes on fabrication.

I'm looking into tuning, but I'm not that confident I could answer your question reliably. To maintain equal length secondaries is a bit of a challenge considering the space restrictions. The idea at this stage, as far as tuning goes, is to just remove the restriction in the stock Y-Pipe.

If you have some scope on tuning that could be useful, feel free to share. I'm looking far as much feedback and ideas as possible. Bare in mind though, this end pipe should be at least half the cost of a set of good headers, and something the average exhaust should could fabricate.

so far i havent had a problem with the pipes ive made... they are on about 6 cars i think... used 304 s/s madrel bends and s/s double wall flex joint... i think from memory costs were about $200-250 ish.... but did per order and on my back with cars on stands....

As far as I know, secondaries are of equal length so that a high pressure wave from one bank sucks out exhaust gases from the other bank when the high pressure gets to the "Y" junction. Seeing the V6 has a firing order of 1 2 3 4 5 6 , ie alternate banks fire, scavenging is important surely? Scavenging of exhaust gas should also happen at each 3 pipe header, if the header has been designed with tuned length in mind. There is a lot of maths involved in that, and with some (huge) brain power you could come up with optimal primary and secondary lengths, but that is way beyond me. I looked at this when I was into 2 stroke dirt bikes wondering why the exhaust was shaped as it was, but the maths scared me right off. lol
I'd like to think Mitsu have done the maths and got the best performance/cost/fit combination for the FWD. The AWD secondary setup has me scratching my head though, doesn't look good at all.

so far I havent had a problem with the pipes I've made... they are on about 6 cars i think... used 304 s/s mandrel bends and s/s double wall flex joint... i think from memory costs were about $200-250 ish.... but did per order and on my back with cars on stands....

That's the price range we're after. I've attempted to use as many mandrel bends as possible, but there are some odd angles to cover in the pipe between each banks, and the pipe between the 2-to-1 collector and the outlet flange. In that last idea I did I used "custom bent" pipe.

As far as I know, secondaries are of equal length so that a high pressure wave from one bank sucks out exhaust gases from the other bank when the high pressure gets to the "Y" junction. Seeing the V6 has a firing order of 1 2 3 4 5 6 , ie alternate banks fire, scavenging is important surely? Scavenging of exhaust gas should also happen at each 3 pipe header, if the header has been designed with tuned length in mind. There is a lot of maths involved in that, and with some (huge) brain power you could come up with optimal primary and secondary lengths, but that is way beyond me. I looked at this when I was into 2 stroke dirt bikes wondering why the exhaust was shaped as it was, but the maths scared me right off. lol
I'd like to think Mitsu have done the maths and got the best performance/cost/fit combination for the FWD. The AWD secondary setup has me scratching my head though, doesn't look good at all.

I'm trying to apply my basic theory that equal lengths are the key. But, there's no room left to increase the rear banks secondary. There's talk of increasing the rear banks secondary to 2.25" over 2"... but then I run into problems with the collector. Just remember the idea is to retain the stock cast headers.

Compared to the stock Y-Pipe its got to be just that little bit better... right? Tuning is a possible next step, though I'd rather focus the tuning aspect in a complete set of headers.

Just so we all know - I'm still working on this. Too busy during my holidays to get a good look at it. The image HERE (http://imgur.com/PSWHy) shows me trying to use "tuned lengths" in the system, notably the rear bank. Which was going well until I realised it wouldnt fit. Still working on modelling the complete underside of the car to ensure a better fit with tuned lengths.

Also, in my end design I'm trying to incorporate a "spring retaining" system for the headers. My aim here is to allow easier access to the manifold bolts.

Just for comparison sake, these are pics of the standard 'Y', you can see how you may potentially achieve more flow.
http://i1192.photobucket.com/albums/aa339/magnaforce/IMG_0911_zpsf09140b1.jpg
http://i1192.photobucket.com/albums/aa339/magnaforce/IMG_0909_zps6f56c590.jpg

Just for comparison sake, these are pics of the standard 'Y', you can see how you may potentially achieve more flow.

That's some nice work there.

Just for comparison sake, these are pics of the standard 'Y', you can see how you may potentially achieve more flow.

That is fwd y pipe which already flows well. Skapper is trying to design an awd y pipe as stock awd one is a mess.

Can that be modified in any way to fit awd????

Can that be modified in any way to fit awd????
No, otherwise Mitsubishi would've done it themselves.

Can that be modified in any way to fit awd????

yes, but that's what Mitsubishi did and created a restricted T junction.

Where the main exhaust pipe runs to the back of the car in that photo, the AWD has a drive shaft, so that space isn't available. So the AWD T pipe is a bit to the left of the Y in that photo.

Can that be modified in any way to fit awd????

yes, but that's what Mitsubishi did and created a restricted T junction.

Where the main exhaust pipe runs to the back of the car in that photo, the AWD has a drive shaft, so that space isn't available. So the AWD T pipe is a bit to the left of the Y in that photo.

Cheers Skapper, yeah sorry vlad I forgot to mention mines fwd. Would definitely be nice to see a custom job for awd though, hope it pans out.
That's some nice work there.

See, I've been reading again. Header design sure is tricky stuff. In the meantime I figure I'd reverse engineer the headers based on the equations I've found.


Primary cross sectional area vs RPM. This is obviously not hard and fast, but its a good starting point. To determine the RPM for which the headers primaries are tuned;
1. Peak torque rpm = Primary pipe area x 88,200 / displacement of one cylinder

Using this I compared the HM's vs the Xforce headers;

HM tuned for peak torque @ 3500rpm
Xforce tuned for peak torque @ 4800rpm

There's more science to this, so don't rip into me yet (corrections and hard facts appreciated though). If anything I believe this could be a clearer indicator of the "characteristic" of the headers; the HM giving more low down vs the Xforce being a higher RPM tune - this statement is based on crude sums and some experience with both brands of headers on the same car (no dyno runs, no hard facts).
--------------------------------------------------

There's an equation I've found that determines primary lengths, but it must be dated or I'm missing something as using this equation suggests that the HM and Xforce headers are tuned for peak power somewhere past 10000rpm.

The Xforce primaries are longer than the HM's, but not by much. The stock cast headers are very short....

The math suggests the HM headers do have some tuning designed into them - probably a no brainer for some. The Xforce headers seem to be designed using the other method of header design where the aim is purely to reduce restriction - this is not always the best idea, but is used when space/budgets are restricted.

--------------------------------------------------
Next interesting one is the collector. There's information out there that suggests the collector design is the real key successful header design... aside from how many you use and how you use them. There is however a suggested ratio you should use - ratio between total primary pipe cross sectional area versus collector outlet cross sectional area. Ratio's between 1.4:1 and 1.7:1 are deemed optimal.

Ratios between Primaries and collector outlets;
HM = 1.39:1
Xforce = 1.33:1 suggesting that the collector outlet is slightly undersized compared to the size of the primaries used.

--------------------------------------------------
Other stuff that seems to be consistent information;

Long equal length primaries are (from what I've read) the best way to go. But this arrangement yields best results on open open exhaust - adding cat's and mufflers reduces its advantage over shortie headers. As you shorten the primaries you spread the torque curve out past its peak. Longer primaries to the reverse - spreading torque back below peak torque RPM. THIS confuses me as the mantra here on AMC is that pacemakers are the high RPM headers.

Exhaust tuning isn't about "back pressure", its about resonance, pressure waves and timing.... which is hurting my old brain, but is loads of fun to learn about.

Any and all constructive input is much appreciated - dyno charts and/or hands on "real world" experience is even better.

i have been doin exhausts for a few yrs now, it hurts my head too... not to mention we have to work in cooling and density changes from the fired cylinder....
the 1 thing that i will give ya.... they say that if you make the header pipes run the car with just the primaries and get em hot at the rev range you want the power, where they stop glowing red is the flame cutoff point. This is where you put the collector as this point scavenges the most as the flames dies and cools creating vacuum in the other primaries

and all this works on the inlet side of things aswell...

this is why i like forced induction. haha

where they stop glowing red is the flame cutoff point

Man, that sounds like fun o.O Now to see if my neighbours would appreciate my "primaries only" car running at 5000rpm....

Thanks for the input Trotty. You used to fabricate exhausts/headers from scratch?

ive done a few..... this was my last set i made

http://i1306.photobucket.com/albums/s577/Daniel_Trotman/581D3924-8648-471D-9069-31AC73982E22-1029-000003CDE729A2F1_zpsd2a9623b.jpg (http://s1306.photobucket.com/user/Daniel_Trotman/media/581D3924-8648-471D-9069-31AC73982E22-1029-000003CDE729A2F1_zpsd2a9623b.jpg.html)


http://i1306.photobucket.com/albums/s577/Daniel_Trotman/18F75252-8F5A-4219-BB59-14E9ED293C45-1029-000003CE2AC85202_zpsb295bfe6.jpg (http://s1306.photobucket.com/user/Daniel_Trotman/media/18F75252-8F5A-4219-BB59-14E9ED293C45-1029-000003CE2AC85202_zpsb295bfe6.jpg.html)

http://i1306.photobucket.com/albums/s577/Daniel_Trotman/A940CF30-7693-4BCD-9D49-8906F8D8EF39-1029-000003CE4EF6B27D_zpsc65d510d.jpg (http://s1306.photobucket.com/user/Daniel_Trotman/media/A940CF30-7693-4BCD-9D49-8906F8D8EF39-1029-000003CE4EF6B27D_zpsc65d510d.jpg.html)

ive done a few..... this was my last set i made

[/URL]

(http://s1306.photobucket.com/user/Daniel_Trotman/media/581D3924-8648-471D-9069-31AC73982E22-1029-000003CDE729A2F1_zpsd2a9623b.jpg.html)

[URL="http://s1306.photobucket.com/user/Daniel_Trotman/media/A940CF30-7693-4BCD-9D49-8906F8D8EF39-1029-000003CE4EF6B27D_zpsc65d510d.jpg.html"]

Now THAT is the sort of work I truly admire. Mostly the welds, and getting it all together and working. I do like shiny things to, but the skill is something I'm envious of especially.

I did see this Lego type exhaust modeling stuff you can get - a series of bend segments that you assemble into the shape you're after.... I'd have the skill for that, but that's about it.

Keep up the good work Trotty!