Why would you avoid just whacking a seam back 25mm? It takes 10 minutes and makes a lot of room. A quick squirt with a spray can, and evidence is gone. Looks oe and easily fits. 3" downpipe.

Or I guess you could keep printing inferior designs...

Or

I've got a piggyback question for this since I don't think it deserves its own thread.
My turbo outlet is 2.5 so I have to at least have a 2.5" flange and section of 2.5 downpipe.

I'm debating whether I make a new downpipe which enlarges from 2.5 to 3 within 5 or so inches and requires a dump for the wastegate or I would be generally ok with what I have right now.
My current downpipe begins at 2.5 and continues for about 1.5-2 ft until it gets under the car. It then enlarges to 3". But, the wastegate is kept totally separate until after the downpipe enlarges to 3" where the gate tube rejoins the exhaust.

I don't think I could replicate the existing setup but with 3" since its already very tight as is so I'm thinking the atmospheric dump is my only option.

https://cimg7.ibsrv.net/gimg/www.mia...32729e356c.jpg

I really don't think that's restricting your setup, if at all. I've made near 300hp on a 2.5" downpipe, as long as it flows well (which that does), and it steps up to 3" around the cat (which that does), you should be able to make 300-400, depending on other support mods and turbo size, which is a crazy amount of power for the chassis. I'm fairly certain I made 350hp on that exact setup (internal wastegate though?) a few years ago with Blaen99's car.

On that turbo T3Super60 made 290 wheel at 19-20psi. I have since changed to a gtx3071r and a bp4w head.
Good to hear I don't have to re-develop my setup. If anything the manifold is probably holding me back.

Would you care to elaborate on the 'inferior design'? I have a very small turbo (GT2554R) so the tube size I chose for the first bend is the same as the exit diameter of the turbine wheel. [EDIT] A 60.3 mm bend / tube does not fit between the bolts that fit the flange to the turbo [/EDIT] Besides that, do you have pics of the 'hammer-mod' and what it brings?

Oh, and if you do get 3"down, do you make that smaller towards the end of the exhaust system or do you run a full new 3+" system all the way to the rear of the car?

Cheers,

Hugo

Whoa this seems over complicated, I would just get a v band adapter for the outlet flange and pound the shelf back a bit and be done.

Like this?


is that possible on my nb, too?

Hugo

I'll find a picture. I didnt chop anything. Just a big hammer . Yes to 3 inch all the way out.

so you want to bolt something to the turbo, so you can clamp something to the turbo, so you can have less room for your downpipe, instead of just bolting a downpipe to it? I would not recommend this.

I cut the shelf on mine years ago. I had a top notch welder weld the vband adapter to my exhaust housing and built it from there. But I'm a bit different. And I was having problems with the DP bolts.

Yeah, I found this:
https://ae01.alicdn.com/kf/HTB1Fl7Rm...hq6zGvVXai.jpg
On Aliexpress. It seems nice, but I would need an additional adapter:
https://ae01.alicdn.com/kf/HTB1N7dJL...Xq6xXFXXXA.jpg
To make it work. Which takes up a lot of space. I found stainless ones, too, all without any real room for the nuts or bolt heads:
https://ae01.alicdn.com/kf/HTB1kMg4K...Xq6xXFXXX8.jpg
You could never really fit that, I think. And all, stainless bodged or mild cast, take about 60 - 75 additional milimetres to fit.

I am working on a design with one 3" / 76 mm elbow. Might print one to check fitment, soon.

Cheers,

Hugo

this has got to be the hardest downpipe to build. It cant be done.

No, it cannot be done. But it will. I'm just weird in what I want and do.

Progress, this is a 76mm weld elbow squeezed flat to fit the flange. I designed it yesterday, printed it when I was at work and glued it together just before dinner:
https://www.modelbouwforum.nl/media/...47.249039/full

https://www.modelbouwforum.nl/media/...27.249038/full

But I still don't like the whole 3" deal, as I will only run 200 whp.

Hugo

looks good.

2.5" passed the shelf, and neck it up to 3" if you dont want to cut or smash your shelf in. 3" full is obviously the best but this is a reasonable compromise, i make 220 wheel at 10psi with a 2560 with the necking up to 3". Regardless of how much power you want the exhaust sizing directly affects your spool as well. it's worth the extra work and has been done countless times.

I dunno, I was able to fit a 3" downpipe using one and it was super easy it but seems he figured out a better option for him.

+1 on 3D printing the prototype. Thats the best way to figure out how things are going to fit. I'd love to see what happens if you try running your 3D printed downpipe :)

I used a 45-180, but I just welded a <90* cut off to a blank flange and built the pipe down from there. It was a huge mess, and I wasted a lot of material. Unless you're equipped to make the cuts needed on your exhaust, and have experience welding. I'd print your downpipe and bring it to a shop and ask them to build you it.

If you do DIY build this.
I saw something pretty trick once for helping you line up pipes for tacking them together. It was an exhaust clamp that you drill a couple of 3/4" holes in around the sides. THe idea is that you clamp your pipes together and tack them together through the holes.

FYI, if you ever need a super tight bend, buy a formed exhaust donut instead of a bend and cut it. They will have a CLR equal to the OD of the tubing.

Well, I think hell just froze over :)

https://www.modelbouwforum.nl/media/...09.251758/full

I found the Kraken casting which does not add 100% in freight and taxes, I printed the bends and straighs first and 'welded' them with CA glue. Just cut the stainles version and stitch welded the first section. I need to stitch the rest still. I will only fully weld it when it actually fits in the car, when I swapped the engine.

Cheers,

Hugo