HKS manifold with 3" down pipe
 

Hello, my turbo project is getting pretty close to being ready to put in. Ive got everything I need (knock on wood) minus injectors and exhaust. Injectors are easy but since the hks is top mount I have to have a downpipe custom made or make it myself. I know having artech build one for me would be ideal but it would probably cost half as much as my whole build lol. (I'll make a build thread when I start installing with a parts list but I'm still under a grand, diypnp included.) Really for now I just basically need a 3" dump pipe.

Anyways... For the exhaust I'm going to have a local exhaust shop just make me my exhaust. Nothing special just 3" straight back to a magnaflow muffler. The problem I run into is in order to drive with the turbo I need to have exhaust, but in order to have exhaust I have to drive to the exhaust shop. To get around this the plan is to build a down pipe and run it as a dump pipe in order to get me to the exhaust shop and have them build the exhaust onto the down pipe.

Ok so now for the questions on making a downpipe. Since I cant weld I'm going to try to acquire the pieces then have an exhaust shop or a friend weld it for me. Problem is I don't know exactly which pieces to go with. Is it even possible to have a 3" downpipe in an nb with a hks? I've seen others on here do it with 2.5 downpipes I just don't know if i'm going to have room for 3" without having to cut up the engine bay or use like a 100+ degree bend off of the turbo and then bend back out later downstream.

As for the parts this is what I was thinking. T25 flange->oval to round transition -> 3" radius, 3" 90 degree elbow and then another 3" straight pipe to get it down to the bottom of the car. I really wish I had somebody that could mandrel bend the 3" and flare the end for the t25 that I need, would save me a couple inches. Problem is the shops I talked to were hesitant about bending 3" in a tight radius or flaring it. Also, I would really like to put a v-band clamp in there between the transition and the elbow but don't know if that will add more length than I can afford.

Ok so I don't have that many specific questions but anybody have any input, advice or ideas? Any help is greatly appreciated. Oh and my turbos gt2554r if that matters.

This is a video I made when I was selling my HKS setup, it'll give you an idea of how everything will fit. There is absolutely no way a 3" tube is going to fit there. It's just way too tight.
http://www.youtube.com/watch?v=P35L1PhyJm0

In the video the larger pipe is like 2", and the two of them merge into a 2.5" pipe.

Haha thanks, actually I commented on that earlier while I was searching. I did not know it was a 2 inch pipe though. Thought that was 2.5 from the turbo.

Yah it's crazy tight there. There's very little room. Going with the smaller pipes and then merging them was really the best option, but lots of fab.

I just wonder how much it's gonna clog up the system if its a 2 inch pipe to start out with If I create a 2" bottleneck wouldn't it be almost like having a full 2"?

As long as you keep the 2" to a minimum you shouldn't be too bad. Probably the biggest you could go is a 2.5" but I would think you would have to flatten to get past the shelf.

3" with hks mani

Attachment 190733

Cool thank you for the picture, guess it can be done. Did you have to modify the shelf or use a 100 degree bend or anything? Definitely doesn't' look like I'll be able to use the round to oval adapter or vband. I've never worked with piping really, if I just get the elbow how hard would it be to modify the inlet of the elbow to fit onto the t25 flange?

Great job on making that 3" fit. Wouldn't of thought it was possible.