| [ Total Views: 1337 | Total Replies: 13 | Thread Id: 57246 ] |
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 Turbo54
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| posted on October 9th, 2006 at 03:06 PM |
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Turbo Exhaust Dump (Boostn, Dangerous, Iswinkles)
Hi Everyone,
As I am limited to room under the back of my car and dont want a big muffler poking out the back like a cal looker I have some questions to ask you
turbo guru's (Boostn) out there.
Question 1: Pipe Size
I was thinking a very short 3" pipe. I understand that you have got to get the gasses out and that it will be slower moving in a larger pipe but it
is less than 2 foot long. Would it be better with a 2.5"?
Question 2: Exhaust dump design
Anyone know if there are any benefits keeping the wastegate and the exhaust seperated ie: a pipe for each opening or should it just be one big pipe
that merges into a 3"?
Question 3: Muffler design
This is the muffler design that I was thinking of using. I know a 180 bend proberly isn't the best for flow but this is a little compromise. It is a
street car after all I dont dont want to wear ear plugs while driving it. What I really wanted was the exhaust to come out of the turbo and bend 90
towards the front of the car, head up on a 45 towards the underneath of behind the back seat and then down in between the IRS arm and the back end of
the pan and exit in front of the passenger back wheel. I think it would fit but not sure where to sqeeze the muffler in. I would like a cannon style
to fit inbetween the IRS arm and the pan but not sure it would go. Do I need a muffler? could it dump straight out of the turbo onto the ground?
Thanks for your help and if you haven't yet seen the build or need more pics for what I am on about look here:
http://forums.aussieveedubbers.com/viewtopic.php?tid=31777
[ Edited on 10-10-2006 by Turbo54 ]
C'mon kids gather round,
there's a new sensation hitting town,
It's moving straight, low to the ground,
it'll pick you up when your feeling down.
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tassupervee
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| posted on October 9th, 2006 at 06:32 PM |
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Righto, 2.5" is more than adequate for the dump.
No, the dump does not necessarily need to be seperated. seperating them was an easy way to create a "screamer" pipe which was a smaller bore pipe
just for the wastegate outlet which merges back into the main system passt the muffler. Gives the charachteristic "scream" when the wastegate
opens....wank!
Yer you will need a muffler. The turbo will remove some sound energy but it will still be pretty noisy thru shorter length pipe.
Dont get too bothered by a tortuous pipe path. So long as you construct it from mandrel bends and maintain the innder diameter, the gas will make its
way out with limited fuss..
That single ended muffler looks the goods but i find the picture a little disturbing given in that setup, the oil filter is the lowest point on the
car....eeeyew!
Good luck widdit.
l8tr
E
Im not a complete idiot, quite a few parts are missing....
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boof2332
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| posted on October 12th, 2006 at 12:12 AM |
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With the dump pipe design...most stock turbo cars such as wrx's have a round dump pipe with a plate directly in front of the wastegate. My exhaust
guy said he did dyno tests on the split pipe and the open mounth(oval shape), with a splitter type, and there was no difference. Must have the
splitter which stops the immediate disruption of the turbine exhaust gas. I have made all my dump pipes(mounth/splitter type), and they work really
well and they were not $200+ each.
Matt
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boof2332
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| posted on October 12th, 2006 at 12:18 AM |
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Also...my exhaust makes a C shape bend off the turbo, out and down under the cv joint amd then through a massive tri-flow(awesome muffler, just big
and heavy), next to the heads, then a 90 bend and out in 2x3inch pipes at the normal spots. What you are proposing is my muffler just running
backwards. It would be easy....I;m pulling mine off in the morning..I'll take a pic.
matt
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Turbo54
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| posted on October 12th, 2006 at 09:39 AM |
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Thanks Matt,
Would love to see it, looking forward to the pics.
T54
C'mon kids gather round,
there's a new sensation hitting town,
It's moving straight, low to the ground,
it'll pick you up when your feeling down.
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dangerous
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| posted on October 12th, 2006 at 10:28 AM |
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I honestly don't know a lot, first hand, about this subject,
but except for space constraints and added costs with 3",
that is what I would do myself.
My friends, with high boost T04 combos(nissan FJ20), in the past found a boost increase
(thus indicating turbine efficiency increase?), when increasing dump pipe size from 3" to 5".
Also, accurate wastegate control is dependant on good flow,
so minimal back pressure in that area is important.
So, either a separate high flowing pipe or large dump pipe and muff size may be required.
Space will be your limiting factor.
On another note, it appears that your pipes are as yet not fully welded.
It will take someone who is quite experienced to weld the system fully,
without causing you grief as the welds pull.
I have had a similar problem in the past when the collector was welded.
It caused a huge misalignment.
Not sure how it could be tackled other than completing the collector welding first,
in small welds, bit by bit.
| Quote: | Originally
posted by westi
That's mad Alan.
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Boostn
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| posted on October 12th, 2006 at 11:48 AM |
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Hi Heath,
This is the reason why I don't like kits that mount low down. It seems that you always run out of room. At this stage you should see what size pipe
fits, beggers can't be chooses. Try to get the bends flowing because you will restrict the flow, loose power, create heat and might even find it hard
to control the boost properly. A turbo creates a lot of back pressure so a good flowing exhaust is a must and always pics up with a dumper. If you
can't get it shortish you might have to dump the wastegate on it's own so you don't have boost control problems. But that also depends on how well
the turbo flows. You might just have to try it because sometimes what works for one kit doesn't work on another one.
I have done a kit for a customer, 180kw at the wheels with an internal wastegate.
It had a T3 with a 2.5'' pipe with a straight through muffler. It works well but not the quietest car around. I have not tried a muffler like the
one in the pic, it might work well, I am not sure. Let me know if it works well and how quiet it is.
Just get it finished and try different systems if you like. You can always make improvements later.
VOLLKOMMEN ART
nick@vollkommenart.com
Speed and Style
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Turbo54
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| posted on October 12th, 2006 at 01:41 PM |
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Thanks for the input, I have spoke to some turbo experts and they seem to think the 2.5" will be borderline and that 3" would be better. I have also
heard that with the turbo going straight into the muffler and then out again it will get good velocity and suck the gasses out rather than them
lingering around in a large 3" pipe so I am a little confused. I understand that bends mean heat and backpressure and this is my problem, like a
watermelon in a sandwich bag. As for boost control I am running elec boost controller. The turbo will flow very well.
Dangerous, I am going to do all the final welds with it bolted up to the motor to limit distortion.
T54
C'mon kids gather round,
there's a new sensation hitting town,
It's moving straight, low to the ground,
it'll pick you up when your feeling down.
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dangerous
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| posted on October 12th, 2006 at 01:58 PM |
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| Quote: | Originally
posted by Turbo54
I have also heard that with the turbo going straight into the muffler and then out again it will get good velocity and suck the gasses out rather
than them lingering around in a large 3" pipe so I am a little confused.
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Heath, as I said i am not a guru with this stuff, but this comment sounds like it is from someone who will miss out on a muffler sale.
| Quote: | Originally
posted by westi
That's mad Alan.
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Turbo54
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| posted on October 12th, 2006 at 02:50 PM |
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It was actually from someone on here who runs a really really fast VW!
C'mon kids gather round,
there's a new sensation hitting town,
It's moving straight, low to the ground,
it'll pick you up when your feeling down.
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dangerous
A.k.a.: Dave Butler Muffin Man
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| posted on October 12th, 2006 at 04:01 PM |
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Oh well, as I said I am no Guru.
| Quote: | Originally
posted by westi
That's mad Alan.
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Boostn
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| posted on October 12th, 2006 at 11:26 PM |
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| Quote: | Originally
posted by Turbo54
As for boost control I am running elec boost controller. The turbo will flow very well.
Dangerous, I am going to do all the final welds with it bolted up to the motor to limit distortion.
T54
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Heath,
if the wategate gasses get choked at the pipe, the elec boost controller is a band aid fix, heat is still the problem.
Even bolted up you will surprised how it will still distort to the point where you won't be able to bolt it up again, especially stainless.
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westi
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| posted on October 12th, 2006 at 11:44 PM |
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hi,
i have made a few differnt styles of dump pipes in my time and the main reasoning behind a split dump is to greate a greater amount of volume for the
exhaust gases to fill before going through a cat which in turn helps the turbo to spool up quicker.
in your case with no cat,2 1/2 inch will be more than ample for that size huffer.
3 inch is only going to be louder and make it harder to make your pipes due to the increased radius.
not a bad set of pipes . it's nice to see other people creations.
if you have your heart set on 3 inch i would recomend using metal spun donuts as they have a range of smaller radiuses that you can buy.it will help
you out heaps .
also another sugestion for when you are welding up your pipes, if you are useing a tig that is.purge weld it.
i look forward to seeing it finished.
down sharon.
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2443TT
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| posted on October 14th, 2006 at 10:14 AM |
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So many things here to comment on  . Here's my opinions...
3" turbo back will make perhaps 5-10hp at best extra top end power, so if 2.5" is easier to fit make a 2.5" system. The average 400kw twin turbo
GTR will have 2.5" turbo back dump pipes, as will most 200kw+ SR20 engines. They only go to 3" and larger after their catalitic convertors mostly.
3" is definatly better, but keep in mind the length of the pipe off the back of the turbo is 1/2 that which it would be if it were an SR20 or any
other front engined car. A 2.5" pipe will be more than adequite for well in excess of 300hp at the wheels.
Seperate wastegate dump pipes like the one in your picture were originally developed by companies like HKS for the SR20DET's and GTR RB26's. Like
Dangerous suggested, reducing back pressure behind the wastegate valve helps flow which results in better perforamce. Turbo's spin because of heat
and gas expansion, but also keep in mind the pressure drop from inside the turbine, to the outside of the turbine wheel as gas enters the exhaust.
That pressure drop is also a key part in how turbo's work. Thus why reducing turbulance around that area can only help things. At best you'd
probably see a 1-2hp gain i'm thinking. If you look at some of the HKS branded turbochargers like the GT2530's, the turbine housings often have a
seperation between the wastegate and the turbine exhaust port cast into the housing. HKS have go to do this for a reason.
Screamer pipes... normally associated with an external wategate and yes definatly wank factor on a car thats equipped with an internally gated turbo.
My recommendation is to not vent it externally. You will find you attract enough police attention when you floor it, without having to worry about
having them defect you for noise. I got away with my external gated system for a few years though and never had issues with the police with it. I
suspect I was just lucky though...
Yes welding stainless does suck too. Distorts all over the place (mine did a little), but your piping wall thickness will reduce that a lot, so I
don't think you will have too much drama's there. Having a fabricator that is a welding guru will help for sure as well.
About the muffler, i've tried a couple of diferent kinds and the current one is a 2.5" straight through stainless one. Its weighs a ton as well.
For the upgrades that I am going to be starting on soon i'm definatly taking a page out of Reub's book and i'll be fabricating my own mufflers from
alloy to try and keep the weight down.
Keep up the good work!
Ian
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