liftem95

I've decided to give twins a try. I tow a lot and daily drive my truck, no sled pulling or racing. What would be the best option. I'm not looking for major horsepower, just usable, clean horsepower and torque. Would the stock HX35/HT3B be a good choice or S300/400 be better. I'm open to suggestions. I want reliability out of this. Also what are all of the misc. hidden costs that can make twins seem good but add up (i.e. headstuds, external wastgates, blow off valves, manifold, downpipe, etc.)

BigErksG2

Depends on your budget. You already have an hx35, so putting a s475 or ht3b under it wouldnt be difficult or expensive. The 35/ 3b combo works very well for me DD and towing. I am upgrading my top turbo to an s360 in the spring and selling the combo that I dont use since I have an extra 3b laying around. You dont need an external wastegate or pop-off valves for your application. Studs would be a good idea, possibly o-rings down the road but you wont have dependability issues with studs and twins as long as you keep it under 50psi.

liftem95

Would it be easier to upgrade in the future by going with a s400 on bottom due to the diiference in piping with the 3B. Also will my stock injectors be O.K. or should i look at, say some SDX 5X12's. I found a s300g 57/65/12 and a s480, I can get them both for $1600. Would this be a good towing combo or not? Who has a good deal on piping because I can't tig weld. Would that 57/65/12 be a good charger to get right now and I would be able to use it down the road for a twins setup.

8UPRACIN

Look at Source Automotive.biz. Rip has all the parts for putting one together or you can buy his 2/3rds kit and use your HX35-S400 setup. I ran a HX35-HT3B combo then bought a S475 and liked it better. My current setup is a HTB2(62/65-12)-S475 and I really like it

BigErksG2

The S300g would work very well as a top turbo in a set of twins. You can get a brand new S475 for less than $600. I would do the 475 instead of the 480 and go with 5x.014 injectors.

RowJ

If your HX-35 is in good shape.... hard to beat Source Automotive's add on kit with an S400 and all the piping and parts.you will need. Cheapest way to go ...unless your a master metal fabricator.

I have driven a 6 sp with this combo and felt it performed as well as my BD twins.

RJ

pgdsm

Dieselautopower.com has some good prices and is a real good guy to deal with.

Mike Holmen

How much power you want to run or have? If your over 500rwhp, you might need to tweak the wastegate on the 35. An external gate 38mm work also work nice. The HX-35 will work good, it just will limit top end power and have high egt's similar to a single. I would also put in pressure gauges on the primary and secondary and one on the exhaust manifold, to determine if the wastegate is sized right. Basically, you could run a 3in hot pipe off the 35, and put a T-06 flange for the S475. The BTH-3b, is a different flange, and the turbine housing is flipped from the S475. I think for a lower HP, tow rig, the S475 is a nicer turbo, than the BTH-3b. I think that the 3B, just finishes harder than the S475. Abit sluggish, but still drivable. Which size air pipes you going with?

liftem95

So the s300 57/65/12 over a s474 would be a better setup than a HX35 over the s474 for a fast spooling towing rig.

RowJ

Both would spool about the same....and very quickly!
With the 57/65/12.... you get more air and lower EGT's. But with either set of twins, towing egt's will not be a problem so it's your choice.
If strictly for towing, the 12 cm2 turbine housing will work. Adding any fueling (hp) at all and I would go with a 14 on the secondary. Especially if keeping your HX-35.

RJ

Mike Holmen

liftem, hows the pump set-up and what timing you running at? How fast does the pyro get pegged. P-pump are harder to put a turbo size on cause there are so many varables. Have you done anything with the AFC? I'm just trying to figure out how much fuel you have available. I find that a worked 12v run hotter than 24v.

liftem95

The pump is pretty much a virgin. I have the 10 plate pretty close to 3/4 forward, and the afc slid 3/4 forward, turned the starwheel so it don't smoke except for a small puff. Timing is stock as far as I know. I can hold her to the floor as long as I want and not see over 1300. Towing is different, I just need more power, and I know if I put anymore fuel to it and tow heavy, the only way to manage it would be twins. I haul heavy, round bales and tractors, so I need all the help I can get. I'm still new to this so help me out.

Mike Holmen

liftem, if you get the right twins, you can add more fuel at the off idle spool-up. This will offset the increased in lag from the second turbo. This just will improve intial spool-up. You going to be able to tow, regardless of which primary you select. Which help to get things up to speed faster when you tow. If it takes awhile to get the egt's I would so smaller on the primary, so you can spool-up faster. So tighter on the primary turbine disk size/A/R ratio, just so it can be spooled. A K-31 works well with the HX-35, lots of room to grow down the road. I would massage/enlarge the wastegate flapper on the HX. I think stock is 32mm. Going to the 14cm over the 12cm, a good way to drop drive pressure/egt's. Which wastegate actuvator you going with? Whats your static pressure openning pressure on the wastegate. I find 22-26psi is a good starting point to open the gate. An external gate, you'll spool the primary easier and drop egt's/drive pressure. Good luck, lots of good choices. I myself, I just try and adjust, until its a perfect set-up. I'm looking for the perfect combo for twins. Fast spooling and lots of room for making decent power.

1320

I ran the hx35 12 with the ht3b26. The 12 cm housing was to small. I then ran the non gated 14 housing with the 35 for years. Towed great, made good power.

Now after a engine rebuild, I switched it to a hx40. At first it as a divided 19 with a quick spool valve. Then I switched to a 16 cm t3 housing. (I didnt know I had a boost leak when the 19 was on it)
Doesnt matter now, it currently has a hx40 16 (t3) and the ht3b 26 with a quick spool valve on the ht3b, and NO gate anywhere. It has never made power like it does now. Its absolutely retarded. It did collapse two different airfilters, and now runs the napa bhaf. I pull pretty heavy , and now worry about bearings and tires alot more then anythng.

Currently as for egts....I pulled 32k lbs and saw 1200 degrees when I lugged it pretty hard in 6th gear. Most of the time, 1080.....

liftem95

Wow, the more I read the more options and confused I get. It seems like the only way to get exactly what you want is to try different combos. I don't have the time or funds so I need a bolt on and forget it setup. Would the S472 with the 1.32 AR or 1.10 AR be better with the HX35? I need to be able to keep the bottom turbo spinning while cruising at lower highway speeds, say 55-60. You guys are being very helpful.