What about this one then?

This time I'm going to ask the question before I get into trouble.

So, I have the turbo output flange (70mm i.d.) and need to join this to the silencer. Presently silencer is 2inch i.d. but I will probably clamp around the outside, just to save losing couple of mm in diameter. I want to keep the length as short as possible (minimise weight and heat exchange to engine-bay) and have the cross sectional area as large as possible, and also minimise the cost.


I'm not sure how to do this. My thinking was to get 2 45degree bends, one 70mm (2.75inch) diameter one 57mm (2.25inch) diameter, and then remove a couple of wedges and add a wedge. Like in this diagram.


turbo_outlet_design

Is this one of my classic bad ideas?

I am quite good at cutting, very good at filing, and poor at welding. Plan would be to tack it and then get it TIG welded.


All thoughts appreciated.

Matt

[Edited on 3/1/11 by matt_gsxr]

Thats not good, dropping down in size on a turbo exhaust is never good and will rob power

What turbo are you using & what is the diameter of the turbine outlet not the flange?

pipe needs to sit inside the next pipe otherwise you will have constant problems with the pipe leaking. Probably more effective if you get another silencer or modify your current one

I agree that 3inch all the way to the back might have ultimate power advantages, but I quite like my existing silencer and hole in bodywork. Also silencers are expensive and bigger bore might not help with noise limits. So, I'd prefer to give up a couple of bhp and retain my existing silencer.

The drawing isn't to scale. Outlet of volvo T5R (td04-16T) is about 2.5inch, and the silencer bore is just over 2inch i.d. it is short (much shorter than in a tin-top) and has no baffles, so it shouldn't be too bad.

From what I have read, as the gases cool the exhaust diameter can be reduced a bit, which is why downpipe diameter is important.

One alternative would be to stay at 70mm past both bends and then reduce down just before the silencer. That would increase the downpipe volume a bit.



Any thoughts on which would be best in terms of fabrication?

Matt

I would say that you would be robbing the engine of a few horses that way. A turbo doesn't really want much (if any) back pressure so that it can spin up quickly, so it might be a bit more laggy than usual.
Can you mod the silencer and stick a 2.5"- 3" core inside?

From what I have seen and read on turbo cars the exhaust diameter being large is more important the closer you are to the turbo. So I wouldn't worry too much.

Yes in an ideal world you'd have a large bore system from beginning to end but its not always practical. WRC cars don't have massive exhausts at the end and they seem to do alright! (ok so some of that is for ground clearance but huge diam exhausts can be heavy - unless they are titanium - I quite miss my old 200SX!)

As the gases cool the exhaust diameter can reduce .

i can swage a bit of pipe up to the outlet size of the turbo if you so wish , i have a bit of experience with volvo turbos !!!!

Ryan,

From what I have read the stock 850 T5R exhaust is 2.25inch but includes a couple of silencers, a catalyst, has lots of bends and is pretty long. Does that agree with what you know about these.

It if does then I will run some calculations on back-pressures.

I could modify the silencer but it would make this "upgrade" irreversible, and the silencer is one of the parts of the car that hasn't given me any trouble so far!


Thanks, for the offer on the piping, is it best to swage the pipe and then use the clamp to force it onto the turbo with the flange, or to weld the pipe to the flange and use a gasket? The idea of not having to weld is very appealing.


Matt

for some reason , ryans website is pointed at my domain !!
im dave.....

youll have to tell me what youve got before i can offer any more advice as im confused how oure fitting the piipe to the turbo ?

its a flat flange which i can make for you then weld the pipe to it ?

Sorry Dave,

Although I am relieved that you understood my mistake.

I presently have a 12mm thick stainless flange with 3 holes that mounts onto the 16T.
The i.d. of this is 70mm, which matches the o.d. of the raised lip on the 16T.

My intention was to buy a 70mm tube into this flange, and weld that up, then clamp it with a gasket.


I miss understood, I thought you were suggesting to swage it larger and then clamp it with the flange. You were actually suggesting that I could take a 3inch pipe and swage that down to 70mm (seems a popular volvo trick).

I guess if I do that, so 3inch 90 deg swaged to fit the flange, then 3inch 90 pointing backwards, and then a cone reducer going from 3 down to 2inch and then a short section of 2inch.
Does that make sense?

If this doesn't work so well (or when I get itchy feet again) I can cut the cone back to 2.5inch and modify the silencer.

Matt

Just to add the nissan 200sx sr20det engine rins 2.25" dia exhaust pipe plus it has 2 cats and a big silencer

so if i use it my 2" silencer would be ok to use

I've been researching whether a 2inch silencer is too restrictive and found an article comparing 12 different exhausts for a subaru WRX.

This has a TD04 turbo (13T I think, although not certain, which is slightly smaller than the 16T).

http://www.turbomagazine.com/tech/0212tur_subaru_wrx_exhaust_dyno_results/index.html

Basically going from the stock exhaust 2inch, up to 3inch gives a power increase (from 192bhp) between 4 and 11bhp.


Manuf Pipe bhp
Stock____52___191.8
Cobb____63.5___198
5Z______70_____198.7
Tanabe__70____197.7
HKS_____75______202.9
Skunk2__75_____199.3
MRT_____75____198.8
M2______76.2__195.9
Thermal__76.2___198.3
Blitz_____80_____200.2
Greddy___80_____200.9
Apexi____80_____201.1

So going from 2 to 3inch is worth at best 5% if done really well.
This will be for a proper front to back exhaust, so much longer than my little silencer.

So I will plan to go 70mm for the first bit (18inch) and then 52mm through the silencer, with the option to replace the silencer later if I don't have enough power.

Matt

If you are set on using your existing silencer then I suppose 10 bhp or so will not be too bad - saves splashing out on a new / modded can too

quote:

---

Originally posted by matt_gsxr
I've been researching whether a 2inch silencer is too restrictive and found an article comparing 12 different exhausts for a subaru WRX.

This has a TD04 turbo (13T I think, although not certain, which is slightly smaller than the 16T).

http://www.turbomagazine.com/tech/0212tur_subaru_wrx_exhaust_dyno_results/index.html

Basically going from the stock exhaust 2inch, up to 3inch gives a power increase (from 192bhp) between 4 and 11bhp.


Manuf Pipe bhp
Stock____52___191.8
Cobb____63.5___198
5Z______70_____198.7
Tanabe__70____197.7
HKS_____75______202.9
Skunk2__75_____199.3
MRT_____75____198.8
M2______76.2__195.9
Thermal__76.2___198.3
Blitz_____80_____200.2
Greddy___80_____200.9
Apexi____80_____201.1

So going from 2 to 3inch is worth at best 5% if done really well.
This will be for a proper front to back exhaust, so much longer than my little silencer.

So I will plan to go 70mm for the first bit (18inch) and then 52mm through the silencer, with the option to replace the silencer later if I don't have enough power.

Matt

---

"when everyone tells you that you are drunk, its time to sit down"

In my case you have all told me that I need a larger bore silencer.

So, what do you recommend?

Here is my specification:
must be quiet enough so I don't get kicked off track days (gsxr1100 with volvo T5 turbo)
2.5 or 2.75inch bore
about 18inch long
6inch diameter or smaller
efficient flow design
doesn't need to be pretty because its in my sidepod
light-weight (because I am a weight tart)



Possibles are Jetex, although its not repackable its cheap.


A cherry bomb (mostly because I like the name)
18inch long 4inch diameter

Go to the exhaust place around the corner and see what they have kicking around.


I am hoping that the turbo will act to muffle the engine, my current NA silencer 30inch long 6inch diameter MK stainless job, got me through SVA (to IVA standards in fact) and was embarassingly quiet at the track day where they tested.


So, what do you think?

Matt

On my 2.3l turbo ford I ran reduced right after the turbo 2.5 inch into a offset magnaflow (oval) then to a 5 or six inch-cant remember- magnaflow . Both mufflers are straight through but it is quite quiet at tickover but a good heavy growl as the rpms come up. It should have been 3 inch all the way through but then they sound too much like a tractor.
Dale

U2U sent Matt

if the cars going to be trailered a lot, and has a l;areg bore side exit exhaust, its worth putting a shower cap over the exh outlet whilst being towed, or as the air flows past the outlet it can cause the turbo compressor wheel to freewheel and wear the seals (you can sometimes hear the turbo whistling whilst being towed!). Its only really a problem on short run exhausts. Same theory as the flap on the exh stack on digger exhs

[Edited on 13/1/11 by CNHSS1]

Trailered, me. I don't think so.
Very good point though. Very impressive.


I ended up getting a Jetex one, simply because it should be delivered before the weekend, as this warmer weather makes me realise that I want to get back on the road. 2.5inch diameter, and 420mm long. According to the turbo guy on oldskoolsuzuki forum this should keep it quiet enough.

Matt