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After having tons of bad experience with old smoking s5 t2 turbos, hybrids etc, I almost went with a full on turbo upgrade, but decided to get a BNR when Bryan said he was having new turbos made. The only part I reused was my exhaust housing. I should have went with the full turbo upgrade, but anyways.
I wanted to reduce boost spikes as much as possible , so I ported my wastegate and decided to make this smoother flowing bell mouthed downpipe. I decided to do 304 stainless tig welded mainly so I could practice and improve my fab skills. back purging would have been nice, but I didn't, so you will see some sugaring here and there. Sorry, no step by step but ill try to add a description to the picture
check 1st picture on the third post
1/2" thick stainless flange I made. The outlet out of the turbo is 2.5" cut with a hole saw on the mil. The wastegate side was a 2" holke saw cut on the mill, then I cut across so the 2 holes would meet. It looked like a male private part , and my buddies would call it the ***** flange. The s5 turbo isn't that exact shape, so I used the 1/2" thickness to port out the outline of the actual footprint of the shape. I made the bell mouthed section first and used the belt sander to flatten it as much as possible. I ordered some thin stainless sheet to make a multilayer gasket, thanks to BlueT2. Oh yeah, I left it kinda like a block hoping the extra material in it will help keep it from warping. I had to grind a little more on one side so it would clear the factory heat shield that goes between the turbo and intake manifold. I also have some reflective tape on my lower intake manifold
check 2nd pic on the third post
I didn't like how my rb downpipe was a 3" pipe over the 2.5" hole, so I was able to take a 2.5" pipe and have a cone shaped piece on the press to flare it out to 3" perfectly. This way the pipe was not in the way of the bolts, and there was a smoother transition. I did the 3" pipe first. Then I took a 2" pipe and merged it into the 3". I figured where I was going to need to hollow out both pipes so my 16 gauge stainless sheet could be welded over it to connect the 2. From the first picture you can see inside it wasn't a perfect cut, but I didn't mind. Spending more time than I already did on this bell mouth would be ridiculous.
3rd picture
The other side of the bell mouth. I got mad at this side and hammered it quite a bit as you can see.
4th picture
Finished product. I welded a lot of it on the car under it using jack stands. I did it hoping it would move less when welding vs just tacking it on the car and welding it on the bench. My racing beat exhaust needed a lot of adjustment, I used this opportunity to make this downpipe to help match my exhaust tips better. It's not perfect, but better than before, sorry, no pics of my exuast tips before and after
Like I said in the beginning, I should have done a full on turbo upgrade, but my bnr and doing this downpipe vs a new turbo, lines, fittings, and even more on fabrication material, and more time, this downpipe was a pain in the *** but still half the price . Sorry guys, my car is not running yet, so no dyno or boost numbers to compare before and after. This is just a small project of mine and practice http://s307.photobucket.com/user/two...p%203.jpg.html
Last edited by GrossPolluter; 05-16-15 at 12:31 AM.
that looks really decent, i think it will work really well, especially with an S5. I doubt you even need to port the wastegate now that the flapper can open up all the way
that looks really decent, i think it will work really well, especially with an S5. I doubt you even need to port the wastegate now that the flapper can open up all the way
I actually pumped up the actuator and the flapper valve does not pen much. If you were to remove the factory cast plate, it only goes a tad further.
Does anyone know hour fat other IWG turbos open up?
This could be a mistake, but I changed the length on the pivot for my flapper valve, and now it opens completely. I will find out when my car is tuned
Borg Warner thinks this is optimal opening on their very gone over EFR line.
With the S5 design (out of turbine exhaust stream) it can only help to open it further, but opening beyond a certain point will have rapidly diminishing returns.
I think you did well to have it open more, but if you are getting any weird problems with boost control you can always try to put it back in the stock hole (unless you had to trim that so it didn't hit the backplate you made).
What kind of boost control are you using? Right off the turbo? Manual Boost Controller? Electronic Boost Controller?
I found playing with the bleed orifice size (making a little bigger, then a little bigger) on my Hallman Pro I could get boost onset to peak boost without a spike. It would be like messing with the Gain setting on an EBC.
It probably would have been easier and better to have the 2 pipes divided and then just merge them... but it looks good, it should work great.
I have a semi-similar downpipe and it cured most of my boost creep issues.
it doesn't let the wastegate open as much as yours, but I didn't change the wastegate flapper arm like you did so it's way more than the stock wastegate can open it anyway.
let me know how the gasket works for you, currently I'm just using copper sheet, it's worked pretty well, but per bluetii, the layers of stainless sheet should work better.
It probably would have been easier and better to have the 2 pipes divided and then just merge them... but it looks good, it should work great.
I have a semi-similar downpipe and it cured most of my boost creep issues.
it doesn't let the wastegate open as much as yours, but I didn't change the wastegate flapper arm like you did so it's way more than the stock wastegate can open it anyway.
let me know how the gasket works for you, currently I'm just using copper sheet, it's worked pretty well, but per bluetii, the layers of stainless sheet should work better.
bluet2 suggested using the stainless steel, and said the copper ones were blowing out on him.
Eage8, does your downpipe have a separator in the middle of it? I was thinking of doing a similar design as yours. Oh well, im going to run with this. My next plan would be a complete turbo upgrade
yeah, you can see in this picture that the main downpipe track has an extension on the pipe that extends into the turbine. The plate is also recessed quite a bit to let the wastegate open more.
Mine doesnt have the response that yours has, but another option is a clipped turbine with external wastegate on the S4 manifold. The twin scroll flapper has to be removed, and I get 15psi at 3800ish RPM, but there is 0 spike with a MBC and holds 15 all the way to redline! Oh, and best of all...the noise. oh that sweet sweet noise.
05-15-15, 10:46 PM
