Custom back box

[DickiJ]

Bigger is not always better. My understanding is that you want the gas to exit as quickly as possible. The important thing here is that the flow of gas needs to be laminar. If the bore is too big the gas flow becomes turbulent and the speed that it exit effectively drops. As seen below:

[Chris_Blue]

Interesting Dickij- but the Bastuck is made specifically for DS3 and is 63mm so it would have been tested
Now I am trying to see how much a sports cat is
CBLUE

[Fabian]

Chris, yes you can get to 215hp without any modifications to your exhaust, but this will "stress" the Turbo very much and think you need more boost presure.
When placing an good flowing exhaust you'll get to 215hp without much problems and without stressing the turbo and with lower boost levels.

And what Cyclone says, with turbo engines, you want as less backpressure as possible.

The picture from DickJ is especially for NA engines, so without Turbo!
With NA engines you need a certain kind of "backpressure" to keep a good flow in the exhaust!

[chiefnerd]

Now when it comes to a turbo and the exhaust you can basically go as big as you want, no back pressure wanted on the turbo since the gases leave the turbo with minimal pressure but at the end of the day- this is a 1.6l engine with a twin scroll turbo so do you need a massive exhaust manifold to cope with the gases? No you don't- these aren't massive twin turbo engines.

It's all about compromise of available space vs diameter of pipe and this is where the acoustic effect of exhausts come in on turbo engines- they can actually tune the exhaust to different notes using different diameter pipes at different points, turn circumferences and tail pipes. Just listen to the Cooper S compared to the DS3 Sports- same engine, different exhaust design and a totally different exhaust noise.

Is 63mm better once you're exhaust volume is increased because of the increased power- yes, of course it is but if a 57mm if designed correctly should also be enough as long as it the flow nice and smooth with no back pressure at all on the turbo. The last thing you want is some ridiculous Scooby sized exhaust on a ds3- it won't make a damned bit of difference and will more than likely sound god awful.

Glad Fabian mentioned NA's needing backpressure- that's one of the things that makes chuckle alot when I see a Micra with an exhaust the size of the channel tunnel- they don't even realise they've dropped their engine's efficiency and thus it's power as a result.

If you do your homework you can always work out the gas volume and pressure leaving the turbo at certain power ratings- from their you can do the maths yourself and work out the diameter of pipe you actually need to cope with the exhaust gas.

l also seriously doubt laminar flow and other things will really make much difference on the volumes and pressures we're talking about but you never know.

[Chris_Blue]

Thanks for the contributions- decisions are being made, cash is ready

I AM NOW considering the best performance "Turbo back" install where the BASTUCK system is used, then
a turbo downpipe and cat assembly is fabricated and installed locally by the BASTUCK agents.

That sound good? (Does me) - as usual cost kicks in, so gonna have some interesting conversations on the day in question

Oh- and DYNO run too
CBLUE

[ds3r]

HI fabian said that the racing exhaust is 60mm the straight part of the exhaust that runs the lenth of the car on mine is 50mm is that the part you mean.

[Chris_Blue]

DS3R If you have 50mm (Which is what i was told my THP 150 has) and you have remapped, you may not be getting best performance as the 63mm Bastuck is for the DS3 (Sorry for repeating meself)
CBLUE

[ds3r]

hi chris thanks for that it makes sense about the size . that exhaust is one i have been looking at then sort sports cat out.

[Chris_Blue]

ds3r- left a visitor message for you (By mistake) on your profile
Will hopefully get my new exhaust fitted in Southampton mid/early September (Subject to change)
Always come along if you like- have a chat with them bout yours- see mine put in and working.
Dyno run too
CBLUE

[chiefnerd]

Just remember to keep us posted as to what you finally go for. I still would have mapped it first but that's me

[Chris_Blue]

Am aware there are lots of people on here who dont detail what mods they do
Exhaust wise I have no problem at the moment
But am temperemental- my mind changes when it likes
Understand what you say and will hopefully comply
Will see you at WRC anyways Nerdy
CBLUE

[chiefnerd]

I'll probably hear you before I see you if you get it sorted by then

[Chris_Blue]

Nerdy- Ha- Mebes
Not gonna be that loud is it?
Most exhausts that put out a sound, dont usually put out sound till the foots pressed on the floor
Wont be too loud toodling round town will it?
Sounds good on utube (DS3 Bastuck)
CBLUE

[chiefnerd]

Winding you up mate- should sound nice

[ZACK]

Never mind the exhaust, Map it !