Replacing full exhaust line, make me wise!

[SketS47]

Goodday Gents,

Without getting to much into detail, I've been searching the forums quite a bit on this subject but came out more dizzy then I entered. So please correct and add on the below as that will help me for sure Keep in mind I am a newb regarding any mechanical tuning.....

1. Manifold, all tubes of the manifold should be around the same lenght, this to increase a better flow.
- Is that correct?
- Does the manifold already increase in width from lets say 2" to 2,25" at the end? Or does the manifold always stay the same width. And why?

2. Downpipe, this bit also sends the flow to the turbo right?
- So again, about the width, do you increase it from start to finish?
- Do you increase the pipe towards the turbo? Or is that a nono?

3. Centre pipe, this has the cat in there.
- A sports centre pipe/cat has less airflow restriction and therefor increasing power correct?
- Again same question about the width

4. End pipe/muffler So this is the last bit correct? I understand you need a sports muffler as that has less restriction in airflow and thus improving performance.
- Also does this also still become wider?


So yeah, a lot to do with the width as I do not understand that properly on how that works or starts. And are there good brands which have full lines I can purchase right away, or do you buy each part from a different manufacturer? Or do I let a garage... produce one? I hope a few of you will take the time to teach me a thing or two about this. Thank you very much in advance!

 

[Rev]

Velocity results in flow ( HP ) for a given width. Initially velocity is high so pipes can be a little smaller but increase to avoid restriction as velocity drops. Width is usually sized for max torque.
Too wide early compared to turbo exhaust port equals turbulance. Too wide in the exhaust pipe equals temperature drop and can slow velocity.
Starlet is very short car plus back boxes get larger at the muffler to help the rear portion have no resistance so it can act like an even shorter pipe. The result is you can get more horse power with a smaller diameter for two reasons . 1 The pipe is much shorter and 2 if the diameter is not over sized it will have the optimum velocity to move more gas through its whole length with optimum back pressure.
Back pressure, turbo flow doesn't like back pressure but it does effect suction on turbo seals , off boost ve and spool.

 

[dark_knight]

what he said ^^

 

[weeJohn]

Exhaust technology is an art all by itself, good to know a little about it but it will melt your brain if you try to go to deep into it.

Have a look at the products supplied by our traders on here, they are all tried and tested and of the best quality so worth looking at. But before you decide what to buy, its best to know where you want to end up or you will end up buying more than once.

 

[SketS47]

Thank you guys for the advise so far, will certainly check out the on forum traders.

So if I understand it correctly you want to keep the fumes as hot as possible as this keeps the velocity up. So in terms of the glanza does that mean its not really needed to put on a bigger exhaust but its better to get a less bendy/restricted exhaust with a slightly larger width on the end so the airflow stays as quick as possible? Or do you advise to widen the centre pipe as well? Keep in mind the end goal is to run around 250 ponies, with either the stock turbo at higher boost or one that can handle a little more if needed.

 

[weeJohn]

You wont get 250 out of a CT9, you will need to go to a bigger unit than that and have other supporting mods. Straight exhausts give good results on an EP as other factors hold them back. Like I said before, dont get caught up in exhaust technology. I did all the equations once for the best exhaust manifold, they came back saying the 4 primaries should be 500mm long and the 2 secondaries 300mm long. Try fitting that in the front of an EP lol.

 

[SketS47]

Hehe gotcha, it is indeed mindboggling. So a bigger turbo will be needed at some point then.... But thats still far off! So I have time to learn about that.

And I asked around a bit and this fella told me the following is a good way to go and he could do it for EUR 500,-
A Catback system, with a 2,25"downpipe, 3"centrepipe and 4,15" end dampener.

That just sounds really big on the end? Will that truly work? He was talking about approx 15 pony gain with just this and a much better gasresponse.

Could use a little wisdom because it sounds rather cheap for a stainless system incl. being fitted. Thanks for the feedback in advance!

 

[weeJohn]

I got 250 bhp with a 2" exhaust straight from turbo out to back box. Some people go to 2.5 when building a high horsepower set up with a big turbo, but for 250 I dont think I would go above 2.5". Just my opinion on this, there will be other views and people may have different experiences, but these are mine.

I would send a pm to Sacha through Wicked EP racing, one of our traders on here, he can give you a world wide views worth of advice as he supplies world wide.

 

[SketS47]

Thanks , I have send Sascha a PM.

 

[bongskag]

if your having it made up from scratch , get V-band join fittings instead of the bolts and gaskets. it makes it a whole lot easier to fit and take apart if you need to .