12VBLacKCLouD

I've been looking into compounds for awhile, what do yall reccomend if runnin #2 only? ATS, Industrial Injection, BD, Piers?

logskidder

I dont think you can go wrong with any of those^^^ if you can do some welding and fab work you may want to build your own.

Mattl

Or you can call Rip @ Source Automotive. Use your top turbo and his piping/ turbo below it. Saves you a little money. Am very happy with mine. Great customer service.

12VBLacKCLouD

Thanks fer Responding, Been welding for a couple years, not much experience on pipe welds, i guess i better get going on that, it would certainly save some $$$ doin it myself.. My next question, how hard is it to find turbos that will match if im doin it myself? I dont want to get stuck with two turbos that dont work togther while ATS and other companies engineer their turbos to match

Mike Holmen

If you want a decent set-up. Pick-up a Bth-3b or S400 turbo and use your existing turbo for the secondary. You will have to play with your wastegate on the secondary to get the exhaust to flow right. You could put together a decent set-up for $1000 to $1500. If you want more air put a HX-40 or S300 on top. The only thing you might have to research on what turbine housing you want to use or compressor impeller. I like the HX40's as they are cheap and work pretty sweet in twins. Good luck.

Big Blue24

Mike meant BHT3B or HT3B when he said Bth-3b. Just want to make sure you search for the right turbo.


FYI Piers uses a HT3B for their bottom turbo, Rip @ Sourceautomotive.biz uses an S-400= little bigger, 76mm usually for his bottom turbo. ATS uses Aurora 5000 for their bottom turbo little smaller 71mm, and BD uses the smallest, S300 with 66mm.

The BD towing twins spool the fastest, but run out of air the soonest, 550-575 HP.

S-400 is the cheapest turbo to purchase new, anywhere from 650 to 800, and seems to be the new trend for bottom turbos since it can support more HP and spools almost the same as the HT3B.

12VBLacKCLouD

Thanks fer the correction, Im lookin for low end torque, pull otta the hole, and i guess i gotta sacrafice top end HP gains from the looks of it and what little reaserch ive done. in that case, ill look more closely at the BD and ATS setups.

Big Blue24

The first out of the hole hit comes mainly from the smaller top turbo so it's size greatly affects initial hit. Then, as the smaller top turbo starts pushing air into the engine, the engine starts to exhale a lot more exhaust which really gets the top turbo singing and starts to spool the larger bottom turbo. The size of the bottom turbo greatly affects HP in the 1800-2200 rpm range. Once bottom turbo starts to push 4-5psi boost, the top turbo explodes in air production because it no longer has to suck air but actually is being force fed, thus it can really explode in air production. Of course this big hit of air equates to even more exhaust exhaled energy. At this point, the wastegate on the top turbo or external gate should be fully open. At this point, the top turbo is at full speed. Once the waste gate opens, the bottom turbo is experiencing plenty of exhaust flow to get up to full speed and then you are making some serious HP!

So, what I'm saying is that the size of both turbos will independently and collectively affect spoolup. I've heard, and others may post as well, that the source automotive twins have great bottom end when used with the stock HX-35 because the stock turbo spools faster than anything out there in the aftermarket (except similarly sized Ball Bearing turbos). So the stock HX will give you the most stock like right off idle HP. But, the stock turbo is limited in it's flow potential so it needs a bigger bottom turbo in order to have decent top end airflow.

The reason the BD twins are so slick is they use the smallest bottom turbo. That means their setup gets into the air flow game quickly. To help out their top end, they have a bigger top turbo than the stock HX 35 so it can do it's fair share of the air compressing.

*Disclaimer, I do not own a twin turbocharged, compound setup truck. This is what I have gleaned and think I have gleaned from reading, research, and of course, other member's posts.

Have Fun

12VBLacKCLouD

Well thought out, that makes me wanna keep my Holset for torque and look at Auto Bros for the bottom turbo. I thought I needed to spend 4 or 5k to get a good set of twins, until i found this forum!

olddodgetruck

i have a tial 38mm wastegate aroung my stock hx35 to a ht3b with a 26cm housing on the bottom. this setup works great. the external gate realy helps to free the top turbo up.

HOHN

+1 on Rip. Great price and service.

His twins kits that use your stock turbo might be the best bang/buck you can get in twins. MUCH cheaper than many other sets.

jmo

12VBLacKCLouD

sounds like a 3B would be better, but might lag more? Is Rips bottom turbo quick to make boost compared to the 3B? I dont want to wait 5mins while the bigger one spools up.

Big Blue24

Alot of guys say the spoolup difference between the 3B and S-400 is only 100 rpm. The S400 has extended tip technology so it will definitely outflow the 3B. The 3B is old, but still good technology, been around for 20 or more years. If you want a setup more like the BD ones, source yourself a K-31, or a GT4294. They are wastegated so it gives you two wastegates to play/tune with. They flow a little less than the 3b but spool up a lot faster and have a waste gate that opens to lower drivepressure and prevent high end exhaust choke. The down side, they cost 850-1000 bucks. The K-31 is probably the best match for a stock turbo but their expense has limited their use.

Mike Holmen

most of the turbo we use are of old design. The s400 is at least 10 to 15 years old, they been on hiway trucks and we just found that they work sweet on a over fueled pickup. I've heard S400 are better than 3b before too, but they lots of different combantions to the 3b or S400. A/R ratio for the compressor and turbine also effect spool-up and your ablity of egt control. The harder you can get the primary to lite, the more air gets into the engine. Depending on how you set-up your wastegate on your truck. At a point the secondary starts to limits your air flow and start to choke off the primary. The turbine housing is smaller on the K-31 turbo vs the 3b. The s400 typically uses a different a/r ratio's than the 3b for the turbine and compressor, so its difficult to compare them. From what I seen the K-31 is just a garrett 4294 with a wastegate which is used on the detroit tractor engines. My next setup will be a GT3582R over a largest S300 impeller and turbine housing I can find. Wicked spoolup and still have air to support 450-500rwhp. No smoke and decent egt's. I haven't landed on the exact turbine housing size but there are a few different turbine housing for some fine tuning of egt's for the GT35.

Mattl

The HX-35/S400 will impress you on spool-up speed. When you get your pump adjusted correctly for your fuel and the twins, you'll have a good daily driving set-up which is not much slower to spool than the single HX-35. Plus, if your HP goals change to 500+, Rip's twins are engineered so that you can order a new hot pipe that will bolt-up to a new different turbo. In other words, very well thought out and cheaper than having to order all new piping/connections. I just replaced my 35 with a 62/14 above the S400 with no problems.