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6.0 compound turbos

45K views 72 replies 18 participants last post by  Nickjames525 
#1 ·
im thinking of a compound turbo set up on my 03 6.0. ive seens lots of pictures and im sure theres a bunch of threads on here but i hate searching though them. i just wanna know what all it takes to make a good reliable daily driver out of a compounded 6.0. im thinking of a Borg Warner S-475 or S-366 to feed the stock VGT. i just want a good daily driver that still makes the power to be a decent weekend sled puller or drag truck. any advice or good pics of how people have theirs set up would be awesome!!

my truck currenty has ARP studs, 5" turbo back exhaust, SCT X4 tuner, S&B intake, blue spring upgrade, and a few other things like lift and 35's.
 
#2 ·
Unless you really want compounds maybe you should look at the KC stage 1.5. @peixinho
 
#3 ·
I know you said you hate searching through them, but you'll really find the best information from a lot of different guys and builders that way. The trick to compounds is knowing your end goal.....how much power do you want to make? That'll determine injector size, which will help determine air needs, which will help determine turbo sizing.
 
#14 ·
That's what I'm trying to get out of this feed. It's more of a concept right now. I'm just trying to see what others have done. The searching sucks because I'm deployed and Internet is crappy enough. So the research I've done took forever as is.


2003 F-250 Crew Cab 6.0L. SCT X4,S&B intake, 5" turbo back exhaust, running 35x12.50s and 6" of lift
 
#4 ·
You have a lot of homework to do on this.

If you aren't willing to search I imagine most won't be willing to search on your behalf. If you do your research you will find that people will be more willing to jump in and help.
 
#6 ·
Yeah I spend weeks searching through forums before I finally make a decision on what I want. Plus not sure any one will want to try and tune a compound setup with stock vgt.
 
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#7 ·
IIRC, MPD had built and tuned a pretty successful VGT compound setup, but it quickly went away due to "other" reasons :lol: 6.4s use a VGT compound setup......it can be done....

FWIW, if I ever can find a donor engine/truck to mock up the parts on and build my setup, my plan for the next stage of my build is to do a compound VGT setup. Using my S2 as a HP, and maybe an S400 series LP to feed it, but I want to put both in the engine valley and I don't know if I could make the 475 fit.....which is why I need the donor truck......but on the other hand, going through the math and how much air I need, I don't think I need something as big as an S475. I've been studying compressor maps and trying to figure out what the required lbs/min air is going to be for the power level I'd estimate myself at, and then the science/art on splitting the PR between the two turbos to find out where the required airflow would land on the efficiency maps. An S475 would more than support my peak air needs by itself, so with the help of the 2nd charger being able to help share the PR load, I shouldn't need all that turbo right? Well, it's not that easy......cue the endless hours of reading.

With the VGT aspect in our 6.0 world, now you also have to think about tuning and how in the heck you're going to control the vanes for optimal setup when your EBP numbers are going to be higher, driving now 2 turbines instead of 1. IMO this is why most folks stray away from the VGT compound setup, because there are a few caveats with the tuning, EBP probably being the biggest. In the tuning tables, we don't have a "commanded/required boost", we have "commanded/required EBP," which then uses the VGT% to adjust to the commanded EBP, spinning your turbo faster or slower and giving your more/less boost. With a non-VGT single or compound setup, that challenge goes away since there's no VGT% to worry about.....but with a VGT compound setup on a 6.0 (or even a big single VGT), the stock EBP sensor gets maxxed out and vane control is lost above 40psi EBP....so that is an issue that needs addressed.

With enough thinking and fabricating, the right hardware can be stuffed in, but getting the software right and making it driveable like you want it is the tricky part. It would most likely be outside of what most tuners could do via email and would require a live tuning session, and possibly require some better, higher reading EBP sensors to still be able to control the vanes *cough cough* :sly:.
 
#12 ·
I thought that you would :)

If this is something I'll get to do (baby#2 on the each now :hyper:) I was figuring on making a drive to AZ to spend some time with you and the guys on the dyno.
That would be awesome!
 
#15 · (Edited)
An s366 will never be a lp turbo in a 6.0, 6.4, 6.7, or 7.3 Superduty.
 
#16 ·
Sure it would......for a Honda :sofa:

OP, unfortunately because we have trucks that are 9-13 years old, a lot of this was discussed when they were "in their prime" so to speak. A lot of the active members that had compounds have since moved on to bigger/better 6.4 and 6.7 things....so that's why I suggested searching through the old threads
 
#17 ·
@nighthawk285,

If you swap to a full BPD setup with the remote oil filter option, and a reg return that doesn't require the OEM fuel regulator mounting location, you can ditch the pedestals in favour of the BPD custom oil distribution block. Should open up a fair amount of space in that area.
 
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#18 · (Edited)
I knew someone was going to go there.
 
#19 ·
Yep, everything in stages my friend. I don't have enough time and money to do it all at once. All part of the plan......I'll need the space for the piping to connect the HP to the LP.

Another tricky thought that I've had in this mix of goodies.....traditionally, the exhaust routes through the HP turbo first, then to the LP,and usually gated around the HP once EBP reaches a higher number....my thought is to run the exhaust to the LP first, really focusing the drive pressure, and the VGT HP could be driven secondly, using the vanes to keep the A/R down and still be able to spool close to stock, and then opening them as needed to relieve EBP and keep the turbo speed high in order to compound the incoming boost .....but then ALL of the exhaust energy is used since you don't dump it out of the gate. The EBP sensor then would need to be moved to the intermediate exhaust pipe instead of the drivers side manifold.
 
#29 ·
That is definitely an interesting thought... and has even crossed my mind. But it does not work like that. You would get a bottle neck affect. I am no expert on the compound subject, but I will explain my understanding.

First off it is important to understand the turbine wheel/turbine housing does not really care about EBP. It only cares about the pressure ratio or pressure differential across the turbine wheel. Power/boost is derived from expanding gases and the release of energy through the turbine housing which drives the turbo.

Essentially you need a "pressure drop" across the turbine wheel. If PSI was the exact same on both side the the wheel would not spin... like when the truck is off. Even when the truck is off the turbine wheel is being hit with "barometric pressure" which is about 14-15psi. But it is seeing the same pressure on both sides. The turbine wheel spins when the pressure inside the turbine housing is higher that the pressure going out... there is a pressure drop across the turbine wheel. As the gases pass along the wheel they expand and energy is released, that is why the outlet of the turbine housing is bigger than the inlet. Maybe numbers will make more sense.

30psi of EBP with 15psi of barometrice pressure means that you have a pressure ratio of 2:1. You can plot that on a turbine map and calculate the flow.


So now how do compound turbos work...

Lets assume the turbine housing of the HP turbo chokes out at 60psi

60psi goes in the HP turbine housing and 30psi comes out. HP turbo is at a 2:1 pressure ratio
The air expands through the intermidiate pipe and into the bigger LP turbine housing
30psi goes into the LP turbine housing and meets 15psi of barometric pressure so it is also at a 2:1 pressure ratio


It is the "drop in pressure" through the turbine housing that spins the turbine wheel as the gas expands into the turbine outlet.


If you have the LP turbo first then the HP turbo will become a big restriction at some point when the HP turbine housing chokes out and backs up into the intermediate pipe. This will cause the Pressure ratio for the LP to dwindle down to nothing.
 
#21 ·
Easiest way to make space for compounds......A/C delete! LOL! Lemme see if I can find a pic of mine
 
#33 ·
I have had the idea pop into my head a bunch of times... because it would be easier to just add an smaller turbo. But it just does not work right. I made up a picture that explains my thought process. This might help anyone else that is still confused.

Take this as general theory explanation... not actually data. It shows how a compound turbo system is essentially more efficient and how plumbing it backwards does not work.

 
#38 ·
Are you kidding me... I am the turbo guy. That is never going to be set in stone :hehe:

I am only looking for a 650-750hp setup. I am not sure these 205/30s are going to get me above 700hp. I have some 250/100s on order also. I am going to see if I can get 250/100s to run clean with a compound setup... if not then I will stick with the 205/30s.

I am going to start with a small vgt. Maybe even a stock 2007 turbo with a billet wheel. I think I am going to pair it with an s475. I have even thought about pairing it with an s369 or s468 for a super fast spooling setup. I am not looking to break HP records. I just want an awesome quick spooling, clean running, towable 700hp truck.
 
#44 ·
The size of the LP isn't the deciding factor in how fast compounds spool up. I'm running a 62.5 and 88 and they spool stupid fast. They're both dual ball bearing cartridges as well which helps a lot. But again size of the LP isn't the deciding factor.

Charlie,

Oliver had the best results on vgt compounds running a 61mm compressor vgt with a 72mm turbine in the stage 3 turbos from Barder. Iirc he ran it behind a S475. @ODAWG714
 
#42 ·
Who did you have make the pipes?
 
#46 ·
Ive been thinking about doing this for a while, but don't know if I should add a turbo to what Im already running or start with two new turbos. Currently have a RCD 68mm powermax but it is a little laggy and runs out of air pretty quickly. I live at about 8k ft in elevation and the air is a little thin for the single vgt to clean up my 205 injectors. I want to be able to use my truck for towing and this setup limits that.
 
#49 ·
Not to open up an older post, but it was only a few months ago. I've recently finished doing a compound setup. I will start by saying before we even get into turbos, fuel, etc.. I will say you NEED oringed heads. I did my gaskets and installed my injectors and an s366. I kept that setup for 4,000 miles. Then I did the compounds and it only lasted another 2,000 miles before the heads had to come back off, and that was on my reduced fuel tune.
At first my setup was fairly simple. Fass 200 with a beans sump, stock fuel system for the rest, other than I had larger lines made to go from the fuel bowl to the heads. I also had a -4 line to connect heads together at the rear. I used 225/100 injectors from Warren. Beyond that, that was it. I got tired of the horrible lagg at 55 with the converter locked.. and wanted compounds. My duramax has compounds and so obviously, the two didn't compare in spool time.
I put the truck down and ordered a windrunner stage 3 intake, a thumper stage 2 hpop, MPD oil cooler relocate kit, BPD water pump, Flex a lite fans, Mishimoto radiator, and of course the turbos. I went for the box 475 as my atmo turbo. It's the same one on my duramax and works great and it is a cheap turbo.. for the high pressure i was torn between a 60mm turbo and upgrade the internals or an sxe362, but went with the 62sxe. After a few weeks of an hour or two here or there it was finished. The only thing I touched for the fuel was I ran the 1/2 inch fass hose clear up to my 3/8 lines and Y'd them. I do not run a return.... though I have 50 psi at WOT at the back of the heads on that -4 line. I really don't see the need for a return since the fass does that already, and it also regulates. One can argue the return gets rid of the air, but my truck runs twice as quiet as a stock truck even with the modified solenoids.
Spool up is like stock. I have not yet gotten new tunes, so it is still running the 366 tuning. The smoke is nearly non existent. No gauges yet so I can only read up to 29 psi. (06-07 truck). I did tow about 6-7,000 lbs with it on that reduced fuel tune, which is slipping my trans and popped the gaskets with studs and brand new gaskets, so it is at least that big of a tune.. and it did great. 1150 was the hottest I saw, and it spools perfect even lugging it. Getting up on the interstate it'll shift into 5th and TC locked at about 55 mph (wasn't using tow haul) and as soon as it dropped into 5th it pegged the gauge and just cruised on up to 75 mph. Cruising 60 mph and rolling into it yields no smoke and immediate spool up. About 1600=1650 rpm to start off. Putting the truck up for winter as it takes several minutes to make oil pressure on cold start because that dumb high pressure pump sucks faster than the poor low pressure pump can move the thick oil. But, if anyone has any questions or concerns I'm open to answering anything and/or trying other things on it! Before winter is over I'll have oil pressure, high pressure oil, fuel psi gauge to monitor 100% of the time, and a 100 psi boost gauge for it. I will put a temporary gauge on the intermediate pipe after all gauges installed just to see what each one does. I have two boost gauges in my dmax, 75/stock setup and the big turbo puts out 22-25 psi for a total boost of 42-45 psi depending on where i punch it. I have a feeling it's going to make over 60 psi though. I also have a triple disc converter to install into it that I acquired for nothing. So far I've gotten no slippage codes, but can see the torque converter is slipping and not holding.
I am done with adding power to this truck, in the future it will get a fully built trans, and I will pull the motor out just to rebuild it. It has 215k on the clock right now. I will be doing oringed heads and 625 studs and a stage 2 cam. Nothing major to the bottom end. I did just slap my heads back on with new gaskets (machine shop had to take off another .006) and hoping that'll get me by until I can fund the mild motor build/trans build. I'm uncertain why the heads needing that much taken off since they were just machined 6,000 miles prior. Motor never saw over 190 ECT or 1150 EGTs during those 6,000 miles.. definitely not enough to warp them. I think the last machine shop didn't do their job properly. The gasket let go in just one small corner by the stud on cylinder 5.
Anyway, I welcome any input!
 
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#51 ·
Man that sounds like a pretty nice setup. If its keeping those injectors cool even on reduced fuel tune it is moving some serious air (while towing). I hate to ask almost but how does it seem to fair compared to your tt dmax power wise?
 
#52 ·
Not to start an argument but you need to fix your fuel line situation. Post-injector regulation is what's needed to keep equal fuel pressure at all 8 injectors. In your situation you still have the potential to starve 7 and 8 of fuel
 
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