torqmonster

I'm going to start building a set of twins. I'm just looking for any helpful information from anyone who has done it or has them. What size pipe to use? What kind of pipe? Is it just exhaust pipe? How thick walled? Just wondering if you could give me any information to help out. Thanks

sgreen3

I just put them on my first gen and i just used exhaust pipe from my local exhaust shop1

8UPRACIN

I used the 3.5" Exhaust tubing and supported it really well. My first setup I used 3" with the HX35/S400 and my new setup is a S362/S400 which I like a lot better. Guess it depends on your mods and turbos to see how much fuel your going to put to it. Here is a picture of my side by side setup. Chris
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BigErksG2

I used 3" sch 40 weldable sprinkler pipe for the hotpipe with a 2" pipe integrated on the inside of the radius for the wastegate on my 35. It works great and is solid. I used some 3" pipe from summit for the coldpipe. I also did a 3b under my 35, didnt want too much distance to the primary on the exhaust side, didnt want too much heat in the engine bay, and it leaves room for my 2nd battery.

Mike Holmen

Which turbos you gonna run and what size exhaust you planning on using? I've run both 3in, 3 1/2in and 4in air tubes for my air tubes and a 3 1/2in air tube to the intercooler. How much power you think you'll run?

torqmonster

I was thinking an HX40 and either an HT3B or S400. I'd like to run 4" or 5" exhaust out. As far as power, whatever 150 hp injectors gets me.

BigErksG2

You will have to run 5" exhaust from a s400 or a 3b. From what I hear, the 3b has a little more on the top end but the s475 will spool a smidge quicker. Twins will be plenty to clear up 150hp injectors.

Mike Holmen

Torquemonster, whats you power level for your 12v? You done any mods to the injection pump? From my experience, 12V seem to run hotter at the same power level that a 24v will, of course there are lots of variables that come from using a P7100 pump.

The HX-40 will work, I've used that turbo in a HX40/3b combo. IMO, the 40 is a laggy secondary and I found that it doesn't really lite-up as decently. How is the 40 set-up? Housing, and compressor/turbine wheel arrangement.

You have any other secondary turbo available? If your going to use that turbo, you should put in a larger wastegate flapper. Mine used a 38mm and to me it wasn't big enough and the primary didn't lite up as well. I had my HX-40 gate set-up to open at 24psi of boost. I've found that the garrett 3782R or 3788R work very well in twins, and in my mind they are the best secondary turbo available.

I had used the 3782R over a BTH-3B and the GT3788R over a S475 set-ups. I've used both set-up for towing as well. Super responsive twins.