Engine/Transmission (1994 - 1998) Building my twins

[mschoenheider]

I live In Denver, and drive my truck 95% of the time between 5000 and 8500 feet. As my truck sits, empty it runs great, and does not get too hot. Don't get me wrong, it will peg my EGT gauge, but without a trailer, this usually only happens after I am up to triple digits. With a trailer, it is a whole different story. I can hit 1600 degrees, and can't use the full power the truck has without worrying about melting it down. So.....



I decided to build my own set of twins. It would be easier, and probably in the long run cheaper to buy a set of twins, but I like to build stuff, and so I am building a set myself. I decided I want a small set of twins that spool extremely fast. I will be happy if I am able to use all of the 400 hp I currently have while towing, and I don't think that a single will do that at the elevations I drive at. I figured I would share my experience, so here goes... .



This will not be a quick build because I am working and going to school. I will probably only be able to work on this about a day every two weeks, but I think I can get it done in a couple of months. I chose a stock turbo from a 2004 Cummins for the secondary because it will spool very fast, and has a (in my opinion) superior wastegate design to the hx-35/40 I currently have. For the primary turbo, I chose an HX-50w which I picked up off of EBAY. The 50 has a 17 cm wastegated housing which should spool well, and flow enough on the top end.



I started by planning everything out, and ordering building the hot pipe between the turbos. I started with a 3" 90 degree schedule 40 steel weld L which I ordered from McMaster Carr. I cut a circular flange out of 1/8" plate to clamp to the exhaust flange of the secondary. For the Primary exhaust inlet, I went with 1/2"x 4" bar stock. I drilled the mounting holes, and cut the 2" x 3" opening to mate up to the hx-50 inlet. I need to heat and squeeze the end of the 3" diameter elbow to match the 2x3 "rectangular" inlet for the 50.



Let me know what you think! (I know my torch skills leave something to be desired)



#ad




#ad




#ad




#ad




#ad

 

[pwerwagn]

Not to shabby. You will be happy once you get them done, its always more pleasing to say "I built them myself".



--Jeff

 

[EBansberg]

I've been looking around at twins too. From what I've found, most people have said the hx50 is a little small as a primary. I'm not sure you'll be able to breathe at the upper rpms, should spool and compound pretty low though. I haven't seen it done personally though so keep up the good work and let us know how they work.



Also, you will probably want to enlarge the wastegate hole as large as possible to avoid overspeeding the hy-9.

 

[mschoenheider]

I think small is the key to getting the high pressure ratios I need at altitude. We'll see how they work out.



Does anyone know where I can get a stock exhaust outlet flange clamp for the 2004 turbo? I actually need two of them, one for the 2004 outlet and one for the 50 outlet.



Mark

 

[mschoenheider]

I had a chance to do a little more work this weekend. I am almost done with the fabrication of the hot pipe between the two turbos. I ended up making the transition from the round 90 degree elbow to the HX-50 inlet flange out of a piece of 2 1/2" x 3 1/2" 0. 188 inch box tubing about 3 inches long. I sliced it open, and bent the flaps out to meet the outside of the circular tubing. Once I tacked the flaps to the tube, I heated the ends of the flaps up and pounded them into a circle. I filled the gaps in with the mig, and ground down some of the welds. I still need to do a little bit of cleanup on the joints on the inside of the transition.



#ad


https://webfiles.colorado.edu/schoenhe/cummins twins/adapter.jpg?uniq=-v10bij



#ad


https://webfiles.colorado.edu/schoenhe/cummins twins/welded adapter.JPG?uniq=-v10bai



#ad


https://webfiles.colorado.edu/schoenhe/cummins twins/squareend.JPG?uniq=-v10bfr



#ad


https://webfiles.colorado.edu/schoenhe/cummins twins/roundend.JPG?uniq=-v10bfw



#ad


https://webfiles.colorado.edu/schoenhe/cummins twins/hotpipe.JPG?uniq=-v10bg1

 

[JAmos]

Keep up the good work. Someday I would like to build a set of twins. Have the mentality that I would rather build them than buy them-even though it means more work.



Jordan