I am wanting to make up my own twin setup and i need a hot pipe. I found them already made up for like 400 or i can get the stuff to make up my own for 100 or so. I just need to know what size to run and what the radius lenght needs to be. I am going to upload some pics of what i found and if any of you guys could tell me which one i need it would be alot of help.

These are with 4in pipe they also have 3 and 3.5
This is one with a 4in radius




This is the one with the 6in radius




Thanks for the help

 

4" pipe is too big for the hotpipe IMO. What are you using for your top turbo?

 

3.5" is better for towing twins... ought to be good up through S480 - long-radius is better if there's room, and hot-coating is always a good idea.

 

Best to match, as close as possible, size of exhaust on top turbo....and inlet on bottom, Hopefully the same size??
Ditto on wrap, or hot coating.

RJ

 

I run a 3" with divorced wastegate. 3" worked out well I transitioned from round to rectangle at the bottom where the pipe meets the lower turbo flange so that the pipe made a slow transition into the same size as the HT3B ex inlet.

 

I'm going to be using a super b top and s400 on the bottom. Outlet on the top is i think 4in and don't know what the bottom one is as i don't have it yet. I was going to use a 3in but didn't know what you did going into the top turbo? how would you make that work ? Diesel doc how did you do the transition from round to rectangle?

 

with a persuasive vice and hammer

 

Use a 3" short, gives more room

 

Here's some pics of when I built mine... It's 3" tubing into a 3 to 3.5" reducer that I "persuaded" into fitting with a vice, hammer, and blunt chisel like DD said. The hx outlet flange is slightly less than 3" anyway, so there is no reason to go any larger until the WG dump at least.
It didn't take long at all for this part, but I've done it a couple times now.

 

Braxton, have you dynoed your home built twin setup yet?

 

End of next week if everything goes well and I can still get diesel fuel.

 

I went with 3" on mine. The outlet on the top is a 4" flange, but the actual ID of the outlet is right around 3". I got the 3" as close to the housing as possible with out contact, and welded the 4" flange to it to mate up. Then added some extra pipe and hacked and sliced until it transitioned half decently from 4" to 3".

 

What top turbo are you using? I've always used 3.5 or 4" exhaust tube. I never had a problem with my setups. The longer radius is nice and would flow better, but in reality once you start fabbing everything up it is easier to use a shorter radius. if you wanted to do a little extra work you could use to 45's. Just my experience

 

Braxton, can you take more pics of where your wastegate mounts to the turbine housing? It looks like you have built a spacer between the manifold and the turbine housing for the wastegate. I'm building my next twin set-up and I plan to do something like that as well. What size of wastegate you planning on running?

I used a 3in exhaust tubing. Just abit of hammer got it into the right shape. The garrett has only a 3in exit in the turbine housing and the flange for the 3b is the same area as a 3in so, there was almost no value to going larger. It works well. My PDR kit used 3 1/2in, but they machine the 3b flange to tapper the 3 1/2in into.

 

braxton, i like that wastegate spacer, i was going to build something just like that but with the limited room under the ford hood it just wouldnt work so i had to put the wastegate in the exhaust manifold. For a hot pipe there are places that sell oval exhaust pipe and round to oval transitions which work great for getting into your bottom turbo without too much hammering.