Mandic 0 Posted June 28, 2006 Hi guys, Help me out, I'm choosing a DP for my turbo and just can decide what to buy. At first I wanted to make it by myself, but then I realised that material, laser cutting and that stuff involved would bring me very close to the costs of a DP which can be bought off the shelf. Now, after reading A.G Bell's book I encountered on issue regarding downpipes and he suggests that when having internal wastegate for optimal flow DP should look something like this: twin port: After searching web up and down and knowing what I want, I finally found this one, which to my taste looks perfect as it destributes the flow right at the begining and connects them cca 5" after, where turbulences are no longer present: The only problem is, that is produced by some chinese guys and their min. order is 100 DP So I went on a search again and since I couldn't find DP of similar design, I found this, which is pretty comon design for most performance DP on the market. This particular DP is form (as the title says) Cobb tuning and after reading their "tech stuff" about it they recon it's pretty good, but they could also say this for any stuff. Now to the point, does anyone know, are these DP (so called bellmouth design) any good, it this Cobb DP any good or even which DP should I go for? Brand, bellmouth, split, ...? Thanks! Ziga Share this post Link to post Share on other sites
tom_m 0 Posted June 29, 2006 hopefully i'm using one of these: with one of these: welded to one of these: all held together with one of these: hopefully if all goes to plan this should give a nice 3in downpipe, all I have to do now is work out how to attach the rest of the exhaust! Share this post Link to post Share on other sites
Mandic 0 Posted June 29, 2006 No offence mate but that outlet is not a very good design, I'm going for 300ZX downpipe (dual port design), which I'll mod later on. Cheers Ziga Share this post Link to post Share on other sites
Mandic 0 Posted June 29, 2006 This one looks exactly like the one I drew in autocad and wanted to make it: Cheers Ziga Share this post Link to post Share on other sites
tom_m 0 Posted June 29, 2006 No offence mate but that outlet is not a very good design, I'm going for 300ZX downpipe (dual port design), which I'll mod later on. Cheers Ziga thats true, but its just as good as the cast elbow TT made for the 205, and theres not a whole lot of space to get your exhaust out of the turbo. this is a solution that isn't going to cost the earth and can be tailor made for the 205. i know divorced waste gates and bell mouths are good for those last few ponies, but at the end of the day mines not going to be about balls to the wall out power. Share this post Link to post Share on other sites
TEKNOPUG 3 Posted June 29, 2006 There always gonna be a compromise between, performance, practicality and cost. Share this post Link to post Share on other sites
Mandic 0 Posted June 29, 2006 Agree with both of You, that's why I'm looking for a DP which is shared by many cars and is thereofre cheap, and which can be modded with ease to fit on my car. Cheers Ziga Share this post Link to post Share on other sites
tom_m 0 Posted June 29, 2006 i do like the idea of divorced wastegate flow; i read somewhere it can reduce wastegate duty cycle by upto 30%, so keep us posted of your progess Ziga Share this post Link to post Share on other sites
Mandic 0 Posted June 29, 2006 Well I've emailed a company which deals with this divorced DP and asked them if they can make custom ones and not just bolt on ones, in my case 300ZX DP. I'll let You know what they say, if they don't do custom jobs I'll just buy one, cut it to fit and weld it back together. Cheers Ziga Share this post Link to post Share on other sites
