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Motorcycle Exhaust pipes for Subarus ?


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In my own situation, I have decided, one way or the other, thatI am goingtohave 'side-pipes' or 'Lake pipes' for my exhust(s), even if I have to fabricate them myself from scratch.

 

However, in researching the parts to do so, we have the smaller-than-most diameter of Subaru exhuasts vs. other vehicles, and I might have to get perforated muffllertubing - for motorcycles as a result.

 

I wonder... how close would the right motorcycle exhaust come to what would be needed for a Subaru???

There would still be the complication of the needed cross pipe, but otherwise, maybe Motorcycle exhausts would work just fine once attached to such??? Might be a tad louder than a normal exhaust, but then again, would it be such a bad thing for your Subaru to sound alittle like a Harley ?? lol... - a 4WD Harley ?!? lol...

 

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On my ea81 powered trike I had a custom exhaust system. It comprised of- both exhausts 1.75" diameter for about 10"ong then a crossover pipe. both exhausts continued in a u-turn to separate mufflers then another u-turn tp twin exhaust pipes each side. It was a little loud so installed a motorcycle baffle in each pipe. Helped a little but prefer a small muffler . Hope that helps.

 

IMG_0005-17.jpg

 

IMG_0003-22.jpg

 

IMG_0003-10.jpg

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Are you talking about using actual motorcycle mufflers? If you are, they will need to be identical (from or for the same bike) and they will have to come from a 1000cc bike that had only one pipe or you will have unequal flow and a restriction. Subaru 1.8l = 1800cc / 2 = 900cc. It will be far cheaper to go online and buy standard exhaust pipe components to piece together what you want than it will to buy customizeable motorcycle components. Piece together what you need from the standard stuff, then get yourself a couple of Supertrapps to put on the ends. You can tune them for performance and sound, and they sound awesome. I did this back in the 80's on my Buick Skyhawk (Chevy Monza) 231 V-6.

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On my ea81 powered trike I had a custom exhaust system. It comprised of- both exhausts 1.75" diameter for about 10"ong then a crossover pipe. both exhausts continued in a u-turn to separate mufflers then another u-turn tp twin exhaust pipes each side. It was a little loud so installed a motorcycle baffle in each pipe. Helped a little but prefer a small muffler . Hope that helps.

 

IMG_0005-17.jpg

 

In your top picture (above) It appears that you have a sensor in the exhaust pipe - I'm not familiar with such - what is it?

I am suprized that with two separate regular mufflers, and that was still too loud, so you added baffles???

Is is that you wanted a super quiet machine, or is there some other factor, like being a relatively short exhaust system made it louder than normal - I would think that nomatter what, two normal (not glasspack) mufflers would be more than enough...

I like jhow you set it all up- turning the mufflers vertically on each side may have been necessary, but it also looks good.

Thanks for sharing.

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Are you talking about using actual motorcycle mufflers? If you are, they will need to be identical (from or for the same bike) and they will have to come from a 1000cc bike that had only one pipe or you will have unequal flow and a restriction. Subaru 1.8l = 1800cc / 2 = 900cc. It will be far cheaper to go online and buy standard exhaust pipe components to piece together what you want than it will to buy customizeable motorcycle components. Piece together what you need from the standard stuff, then get yourself a couple of Supertrapps to put on the ends. You can tune them for performance and sound, and they sound awesome. I did this back in the 80's on my Buick Skyhawk (Chevy Monza) 231 V-6.

 

Yes and no - Not already existant exhaust from a given motorcycle, but new motorcyle exhaust kit/parts.

( Although I saw a couple of used exhausts from a motorcyle at a thrift shop and was momentarily tempted, lol )

 

 

Here's the deal...

I wanted dual exhausts, bought most of the parts to do so, but the 'bender' pipe I needed was nowhere to be found, and it was complicated by the fact that my Brat was designed/built with space for a muffler on one side in the rear, but not on the other side.

I would have had to pay for custom exhaust pipe for most of the length, and that costs too much for me, I have a lot to do on my Brat, and if I go the traditional way with everything, it would take way too much money and time. I am pretty good with problem solving, conceptual and mechanical design, and improvising, so I decided to do something different.

 

Next idea was to see if I could just attach my small glass packs directly to the ends of the exhaust pipes after the 90 degree turn, and then route them out just behind the front tire. There were potential issues with such a short system, and as I have learned, there needs to be some kind of  'Y', or cross pipe due to "back pressure" issues. There was also the issue of exhuast fumes coming out at the doors.

Next idea I started was to run coaxial pipes - one inside the other, running them under the doors like side pipes on hot rods, but using some kind of perforated pipe on the inside wrapped with fiberglass/muffler packing, with a stainless steel larger pipe on the outside, and essentially turning the entire exhaust into a long glass pack muffler. I'm not sure if that is what side pipes or "lake" pipes do anyway.

 

Whilst lookng for somthing for the perforated inner pipe, I discovered that such can be bought, but that the right, small diameter needed for a Subaru exhaust was not very common, but turns out to be very common with motorcycle exhausts. In that same search, I found multiple websites/source for motorcycle "Exhuast kits" or parts, with virtually eveything I would need to make exactly what I wanted.

 

So in the end, I plan on using motorcycle exhaust kit/parts to build Side pipes or "lake" pipes/exhaust for my Brat. They are the perfect size/scale, and with one on each side, they would not be handling much more than the average large motorcycle, like a Harley.

They may be just a bit on the louder side, but hell, I have an exhaust leak right now, and somehow the idea of my Brat potentially sounding a little like a Harley does not seem too bad, and the look of perfectly scaled hot-rod style side pipes would look pretty cool too.

 

Note the pictures below for examples:

 

IMG_0835_zps9f585d65.jpg

IMG_0832_zps044ef514.jpg

 

These are pics off the net, and show "normal" Automotive side pipes, which are likely not as slim as Motorcyle parts/exhaust would be, and include protective grating to prevent muffler burns, lol.  I would find something to do same, and the end result would probably look vary similar, but again, possibly slimmer, and even possibly more stylish.

Edited by Subaruist
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If you are doing a true dual exhaust on the Brat, you do not need a 'T' or crossover pipe. They are only needed for high RPM, high horse power and high exhaust flow applications. Your EA81 is none of the above. Installing one will do nothing except cost you money. Seems to me, a couple bent sections right to a long glass pack painted with your choice of high temp color and a fabbed expanded steel heat cover should be cheap and easy.

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Subaruist,   sitting just above the ea81 engine in my trike or just ahead of it, with little more than a sheet of fibreglass between you and the exhaust, makes it a little loud. I've just ordered some fibreglass sheet to wrap around the baffles. Should do the job.  Besides, I'm an old fart and like them quiet. :)

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If you are doing a true dual exhaust on the Brat, you do not need a 'T' or crossover pipe. They are only needed for high RPM, high horse power and high exhaust flow applications. Your EA81 is none of the above. Installing one will do nothing except cost you money. Seems to me, a couple bent sections right to a long glass pack painted with your choice of high temp color and a fabbed expanded steel heat cover should be cheap and easy.

 

Subarus fire 1-3, 2-4

 

So if you seperarte the banks.....you make the exhaust in each bank pulse wildly....since there is a full crank rotation where NO exhuast is pushed out the pipe.  You'd be making it run like a joined pair of 2 cylinder engines rather than 1, 4cyl.

 

This is very bad for scavenging......dual exhaust works OK on v6 and v-8 because ussually there are cylinders firing on each bank during each rotation.  Works on motorcycles because of short, narrow pipes with very little restriction or tuned restrictions.

 

Not so good for Subarus.  not that it won't run.....but it will be a novelty not an upgrade.

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What I am wondering about are the side pipes or lake pipes I have seen in google images or on ebay - should I assume that they have some kind of glass pack or baffling built in? Some that I have seen look too narrow to have much of that. I also notice that many have the end outlets covered - does that mean that they are not any form of muffler, have no glass pack or baffles, and are either purely cosmetic or something that is not street legal or something ???

I confused, lol...

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Covered 'Lake pipes' are opened for drag racing -straight pipe = not street legal. Usually when the covers are on, there is a second system with mufflers for street driving. Many cruisers just have lake pipes for 'old scool show' and never open them.

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if you plan for a short exhaust you may be able to get away with a bit larger diameter pipe.  the longer the distance the more velocity you need to clear it, but if you are shortening it then it may clear out quick enough before it looses its oomph.   I don't know the actual math on it, but if you end the exhaust in front of the rear tire (like side pipes usually do) then you are eliminating a few feet of exhaust.  you may be able to get away with a more standard diameter as long as its close.

 

also you may look at a system with 2 sizes.  much like a cat back exhaust will increase the diameter of the rear segment of the exhaust but leave the front half stock.  run stock sizes off of the motor and increase the exhaust diameter behind the muffler, or just before the side pipe, or whatever.  

 

I don't know the actual viability of this, its just a dart board idea, but could you maybe take the original manifold and open it up at the front chamber (resonator I believe).  weld in a baffle to separate the chamber into 2 halves, leaving a small portion open to act like a y pipe, then run 2 separate pipes as outlets to your side pipes in whatever diameter is appropriate.  i don't know if the effect would even be achievable in one piece or if the 2 pulses would interfere with each other instead of running out the proper exit port. again I don't know if this would allow the exhaust to work properly, but if so it would allow you to use free/cheap stock parts for a lot of the system, and even the custom welding isn't difficult so should be moderately cheap.  it also makes it stock parts up front and any standard size out back so you won't have to get too creative with diameters.  you could technically make your own box as well if this is feasible with flanges so you just need to weld a flange on the appropriate pipes and make it very modular and easy to replace segments at a time.

Edited by djellum
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Another idea would be to use an X pipe for the dual exhaust, it would improve the scavenging and would be super loud.

 

NOt sure about the availability about an "x" pipe istself, or what you are specifically referring to, but I had an almost exactsame ide with the motorcycle exhaust partsin the above picures - they show a narrow 2 into 1 piece - if I attach thoseback to back ( 1 to 1 ) then it would form a wide/narrow "X".

I was also thinking, similarly to you, that running the exhausts into each other in that way wouldsend likely more or less equally divide the exhaust gasses/pulses/etc into both exhausts, and in the same vaien of course help the scavenging, etc.

The only technicality I fear is that these parts have set angles, and I hope that I can run the pieces fromthe heads into this "X" with no 'angular' mis-match, as well as for running the pipes into the mufflers without same.

 

I have been in contact with another forum member who has the vital stats and such, and we think the this type of exhaust may be more than adequate, but ideal for a Subaru, and I have a hunch that it might actually be a superior way of doing things, aside from looking WAY cool.

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If you want something louder, try this :

 

'J' Extractors from Willy : http://www.ausubaru.com/forum/showthread.php?t=25070

 

A much cheaper option & you wont lose power like the dual side setup ... :)

 

Cheers, Bantum ...

 

I love the descriptions about the sound in makes! I wish I knew exactly what he meant, and wish I could hear it myself.  My only real reservation is that (#1) It looks like it would likely prevent using the usual rock guard/shield, which I rather like, (#2) That it might add, more or less directly to heating the engin oil up because of its close proximity and essentially surrounding the oil pan, and (#3) That nobody would want to get thier hands in there to change the oil until the engine had cooled, lol.

 

I believe that the actual sound it would produce in the end would be determined by the difference in length of that one pipe, so, theoretically, it might be possible to actually "Tune" the sound of the exhaust by varying or experimenting with the length of that one pipe for the best sound! lol.

- How it would be done, I don't know, would it really be worth it to go to the extra trouble for a perfected exahaust sound, not sure.

 

If we consider what djellum said above, and you wanted to performance tune your exhaust, being able to vary the length of the exhaust(s) while driving could also improve top-end performance - quoted from djellum :

"the longer the distance the more velocity you need to clear it, but if you are shortening it then it may clear out quick enough before it looses its oomph."

-And from "Willy Fisterbottom" at http://www.ausubaru....ead.php?t=25070 , as you mentioned:

"She used to run out of breath at 80kmh in 2nd gear, I can now rev it to 100kmh before shifting"

 

Thus, If you could somehow vary the effective length/diameter of your exhaust(s) somehow, on-the-fly, as you drive, you could make a small but real difference in overall performance. It is beyond my purposes, as I am not building a "Fast" vehicle.

- Maybe something similar to how a slide trombone works? Maybe linked somehowwith the gearshifter or your RPMs or something, as a driver concentrating on racing would not want another thing to mess with while operating the vehicle - but otherwise I think it would make a difference.

- Just over thinking it, as I often do with many things, lol...

Edited by Subaruist
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NOt sure about the availability about an "x" pipe istself, or what you are specifically referring to, but I had an almost exactsame ide with the motorcycle exhaust partsin the above picures - they show a narrow 2 into 1 piece - if I attach thoseback to back ( 1 to 1 ) then it would form a wide/narrow "X".

I was also thinking, similarly to you, that running the exhausts into each other in that way wouldsend likely more or less equally divide the exhaust gasses/pulses/etc into both exhausts, and in the same vaien of course help the scavenging, etc.

The only technicality I fear is that these parts have set angles, and I hope that I can run the pieces fromthe heads into this "X" with no 'angular' mis-match, as well as for running the pipes into the mufflers without same.

 

I have been in contact with another forum member who has the vital stats and such, and we think the this type of exhaust may be more than adequate, but ideal for a Subaru, and I have a hunch that it might actually be a superior way of doing things, aside from looking WAY cool.

 

Mismatched angles could/would change the sound too, if it is required to fit physically. As long as the 2 side merge, at least in the first half length of the exhaust, sounds like a solid idea. You could get a very awesome sounding exhaust if done right.

 

Different angled X pipes can be ordered, just like the typical pre-cut bends and such. The X pipe on a 997 gt3 fits in a very small space, search on google for some image porn.

 

The ej twin turbo (EJ20H/EJ20R/EJ206/EJ208) sounds amazing. I've always wondered what it would sound like with a individual pipe for each bank.

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  • 4 weeks later...

I happenedto be across froma Midas shop, so I stopped in to see if they would dare do the job.

They had half a dozen caveats/conditions that would make my life difficult, did not want to use new parts I could supply for the job, (Not counting the actual motorcycle mufflers I would have to supply) but then admitted that they would need this and that, and wanted a minimum of nearly $300.00 to almost $400.00 for what amounts to half the size, parts and work of the average small car exhaust system, with me supplying some of the parts. Yeah, right... But I expected that. Someone else who is more capable, less demanding, and more cooperative will be getting my money, lol...

Edited by Subaruist
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  • 3 weeks later...

Are you talking about using actual motorcycle mufflers? If you are, they will need to be identical (from or for the same bike) and they will have to come from a 1000cc bike that had only one pipe or you will have unequal flow and a restriction. Subaru 1.8l = 1800cc / 2 = 900cc. It will be far cheaper to go online and buy standard exhaust pipe components to piece together what you want than it will to buy customizeable motorcycle components. Piece together what you need from the standard stuff, then get yourself a couple of Supertrapps to put on the ends. You can tune them for performance and sound, and they sound awesome. I did this back in the 80's on my Buick Skyhawk (Chevy Monza) 231 V-6.

 

( Sent you a PM on this )

 

So far, things appear to be a 'GO' on the Motorcycle exhaust system. I have found an affordable X pipe that has the right angles, and a shop that can do the work as I need it to be done.

 

But I am confused about this "Supertrap" thing. When  search for them, I find mufflers, very expensive ones, but your post may indicate that they might be add-ons,which is what I am hoping. ( "get yourself a couple of Supertrapps to put on the ends" ).

I need some general clarification on this.

 

I have also found these:

 

http://www.ebay.com/itm/271440725186?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

"Voodoo Custom Sportbike Motorcycle Speakeasy Variable Exhaust Silencer Insert"

 

voodoosilencer1_zpsd7e8fcc2.jpg

 

I would also entertain any other ideas or known tunable inserts or ends for a Motorcycle exhaust...

 

I have also decided to add a couple of very short flex pieces:

 

_122_zps17e1b62c.jpg

 

I plan on adding them,  as no matter how you mount everything, under some circumstances the  engine will wobble just a little, and that would make it easier on the exhaust system. I am only wondering if it would be OK to add it right after the OEM cut-off pipes coming from the headers, or if the heat might be too much for it? The pipes out of the headers will be max.possible length, maybe over a foot.

Edited by Subaruist
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Another idea would be to use an X pipe for the dual exhaust, it would improve the scavenging and would be super loud.

 

Yes, that was/is/seems to be the ticket. Thank you for the idea. I had to look long and hard and repeatedly to find a true X pipe that was affordable, but finally did, for about $23.00 and just ordered it. Otherwise, the average was between $60 and $100 for same thing.

 

Are you talking about using actual motorcycle mufflers? If you are, they will need to be identical (from or for the same bike) and they will have to come from a 1000cc bike that had only one pipe or you will have unequal flow and a restriction. Subaru 1.8l = 1800cc / 2 = 900cc. It will be far cheaper to go online and buy standard exhaust pipe components to piece together what you want than it will to buy customizeable motorcycle components. Piece together what you need from the standard stuff, then get yourself a couple of Supertrapps to put on the ends. You can tune them for performance and sound, and they sound awesome. I did this back in the 80's on my Buick Skyhawk (Chevy Monza) 231 V-6.

 

It would be extremely unlikely that I could find matching muflers for an 1800cc Harley, lol, as I don't THINK they make them that big, but I may be wrong. I did find the best possible thing - a good pair of long Harley mufflers for a good price.

One thing I was running into was that most motorcycle mufflers are shorter than I would prefer for this project. The best candidates were averaging 26" - 27" overall. I found a used but good condition pair of Harley mufflers on ebay, that are the best I could hope for, are 29 1/4:"long, for less including shipping than the new, affordable, too short ones not including shipping.

Ideally, the end of the improvised side pipes should be at least just past the end of the door, which is a pretty wide door I know.

 

I fully realise that these pipes are likely meant for a max. 1350cc engine, and that my 1800cc going through them might be uncomfortably loud. I have, almost from the start, considered also getting a couple of "Universal Shorty" Motorcycle mufflers, that average 12". Adding these just before the long Harley pipes may make an interesting look, and further quiet the sound.

The odd thing about these "Universal Shorty" mufflers is that at one end, they are 1 3/4" dia.just like the Harley muflers, but at the other end are 1 1/2" - a potential problem, -or maybe not...

 

My thinking is that with the exhaust first coming through the shorty mufflers through 1 3/4", then out through 1 1/2" outlet may cause the slightest back-up or back-pressure in those shorty mufflers, maximizing what they can do, before it even gets to the harley mufflers.

I am considering expanding that 1 1/2" outlet slightly to accomodate the 1 3/4" harley muffler inlets. This would likely only be a difference of 1/8", but  being that they are chrome, might mess up the finish a little. However, If I do this, I plan on putting a mount there between the pipes anyway, and at worst,there may end up being a heat shield there anyway.

My plan if for very solid mounting at maybe two points for the harley mufflers themselves, possibly one more where the two mufflers meet, (depending) another at the begining of the first muffler, not counting whatever mounts may be necessary for the rest of the exhaust going under the vehicle, and then flex joints just before going to the engine to allow for any shock or wobble that might come from the engine under various circumstances, or hard driving, but not likely much of any off-roading, as this will be primarily a "Street" rod, especially once I paint it.

As another back-upplan, I still have the two 18" glasspacks I originally bought when I wanted to do the basic dual exhaust.

These have 2" inlets and outlets, and could possibly be welded right to the ends of the X pipe,between it and the side of the vehicle, and thus, there would actually be THREE mufflers in a row one ach side.

This is not something I am looking forward to, as even if it worked out measurements and length wise, itt would reduce my actuall clearance by at least 2" more. I have jokingly considered putting them in a big vise and flattening them a bit, ifthat is even possible without ruining them.  If I did add these though, it would be pretty much a guarantee that the vehicle would not only not be too loud, but might actually be quieter than I prefer, as I would prefer a low rumble ideally.

 

What I need to find out now, before ordering the flex joints, is what the diameter of the OEM pipes/tubing coming out of the engine are - are they 1 7/8" ? I can't remember... - Anybody know ???

I did find this on the internet:

"The exhaust system is next. Use 1.75 inch pipe instead of the stock 1.25 inch, (???) which is half the cross section. This is important and accounts for about 10 HP. Run each side back to the exit and couple them together with a cross-over as close as possible to the oil pan to form an ‘H' pattern. This gives two ways out for each pulse and also reduces exhaust noise by a big amount."

 

Is this an error? are the tubes comingout of the engine really only 1.25" diameter ???

 

If I were able to have the exhaust pipe replaced right up to the headers, I would consider putting a plate using 4 bolts rather than the usual 2 bolts, tapping those two potential mounting spots/holes/whatever on those square flanges that attach to the head - I am assuming this right now fromother Subarus I have hadm as my beloved Brat is stil ln the shop until at least tomorrow right nowand unavailable for me to take a quick look under there.

Edited by Subaruist
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