Twins for dumbies

[juniort444e]

TT has it right. But im not sure if i completely understand how the exhaust flow is going to slow down or make the little one more laggy, the exhaust still has to flow through the big one some way, its not like the atmosphere is blocking all the flow. So i am having a hard time believeing that the atmosphere is going to suck up that much flow. The intake side of things will stil flow the same as before moving the chargers. As i put in the picture with arrows and some labels.

 

[Big Bore]

TT has it right. But im not sure if i completely understand how the exhaust flow is going to slow down or make the little one more laggy,.

Its not that the exhaust will slow down, it wont spool the turbo without the little one spooling it. Its the exhaust that drives the turbo, not the compressor side. If you put the atmo first in line on the exhaust side, it is not going to spool, anymore than it would spool by itself.

 

[psduser1]

Heat energy, not just airflow, also plays a part, in addition to what big bore said.

 

[juniort444e]

I understand the whole atmosphere being first isnt going to help spool it and the little turbo is the one that does make the bigger one go. So im still not seeing why it wont work this way then. If exhaust gases are going to still flow through them, and the little turbo still has heat and gases going to it, why wont it work.

 

[juniort444e]

Also, if i wrap the piping and put a turbo sock on the housings, that should help keep all the heat inside. So im guessing that it should be just fine.

 

[Cat_rebel]

I think it would be like trying to spool a 88mm+ alone which isn't a fun idea.

 

[psduser1]

Heat energy, I.e. the expansion of the hot exhaust is what's driving the turbo. Wrapping pipe, housing etc. can limit parasitic loss, but you'll still spend the bulk of your energy trying to turn the big turbine with limited success. Somebody here (in this thread?) talked about the turbo lighting at 2200-2400 rpm. That's great for a pulling truck, not so much for a dd.
Now you've reduced available energy to drive your hp turbine as an added bonus, exaggerating your spoolup problems. Just my opinion.

 

[Big Bore]

I understand the whole atmosphere being first isnt going to help spool it and the little turbo is the one that does make the bigger one go. So im still not seeing why it wont work this way then.

It's not going to work for the exact reason you stated.

If exhaust gases are going to still flow through them, and the little turbo still has heat and gases going to it, why wont it work.

Basically what you are trying to do is drive the smaller turbo, but throwing a big turbo in the way. You might as well not even put the bigger turbo on.

 

[juniort444e]

Do you honestly think it could hurt that much. Im still not understanding how it will loose that much energy.

Psduser1 thanks for clarifing for me. The single that i have on now wont light till then so anything before that is a step up in my book.

So from what your saying, is im going to lose all this heat energy from the exhaust going into the big charger first, then into the hp.

 

[juniort444e]

Ok. Its starting to make some sense. Just hard to grasp the concept right now.

 

[psduser1]

Yes your HP turbine will have less available heat energy after going through the atmospheric turbine. I mean it will work, as in everything will go 'round, but your bottom end, lightup if you will, still won't happen as low as you think it should.y (stock) turbo lights at 1500, that's still to high in my book! The trade off, with single turbos, for quick spoolup is topend, although thats getting better all the time.

 

[Tree Trimmer]

ya know, i wonder how many ppl that are really "in the know" about compounds, read this daily, and just smile the whole time? they dont offer assistance, just sit and smile as they read.

 

[TARM]

It will work not much if any better than running that big atmosphere turbo as a single, likely worse. You can play this thing out if you want; as you know, I am all for working things out from the ground up to learn new things but they need to have good bases in mech and science and this is where its a no go.

You loose most all the benefits of the compound as you are dumping the majority of the early heat (and do not think for a second that heat is not the primary thing that makes things go round and round) That early (low rpm heat in that HUGE turbos turbine will be of little use to the HP once it gets there and the small amount the engine is creating at those rpms will not be but a drop in the bucket of what is needed to spool that big atmo turbo turbine. In fact it may very well never get on top. If it does at best you will have a top end in a extremely small rpm band width with no bottom end. With every shift you will likely end up under the turbo again. This is if it spools fully at all depending on what you were to chose for it. Just look how you properly size a turbo, specifically the turbine, for good bottom end response and boost.


If someone with Compounds has egt sensors at both the manifold and the intermediate pipe before the atmo turbine you could see the dif in egts.


Do some reading on turbine maps and how to read them. You basically need that flow ( they show in lbs of air) where the map curve flattens out to lite the turbo. Until then you are in the spooling up phase. You need to be there with the manifold turbo before you can ever hope to build enough flow achieving enough of a PR in the turbine to spool up that big turbine of the atmo turbo. This if course is depending on size of the systems parts etc.. But in general you need to energy or ci created by the manifold turbo to get the atmosphere turbo spun up and then have its addition feeding into the system (becoming self sustaining) and driving the whole thing creating more energy

 

[V-Ref]

ya know, i wonder how many ppl that are really "in the know" about compounds, read this daily, and just smile the whole time? they dont offer assistance, just sit and smile as they read.

I've often pondered the same thing....not just on this thread/topic, but others as well.

I've concluded it's combination of the following:

1. The topic has been previously covered, and folks don't want to weigh in yet again, on something that's already out there for the reading...if a fella wanted to do some leg work to dig it up.

2. Limited audience. How many compound turbo 7.3's are actually running....and how many of those have made proven power with a track time/dyno/pulling accomplishment? This thread is looking for knowledge that just a few have actual working experience on. This thread was started a little over a week ago...crap...some 7.3 brains have jobs that might take 'em away from the forums for a month or two.

3. Proprietary knowledge protection. Our 7.3 community is pretty secretive. WOP doesn't publish specs (other than CFM) on their turbos for a reason. Injector builders protect their methods with Area51 like secrecy. Most tuners keep their approaches/philosophies pretty darn close hold. Trying to get cam specs for a aftermarket 7.3 camshaft is a challenge. Folks/shops that have made the investment in time/energy/thought into the proven power solutions for our motors aren't going to give that away by posting on a public internet thread. I wouldn't either.

*IMHO it's refreshing to see Powersmoker and Thuglike post up their recipe for their successes. That will certainly ensure a bunch of folks reach for the next rung on the 7.3 power ladder, and move things forward yet again for our old dinosaur motors.

4. Unqualified audience. As an example...When you have the majority of folks in the thread using incorrect nomenclature for the turbos in a compound turbo system....when the discussion/question comes up of motor exhaust gas routing needs to go through the HP turbo, then the LP turbo....well folks with the knowledge and expertise, are going to shy away from engaging in those discussions, as they just don't care to take the time to square away a topic that is consider basic for the subject.

That said...the name of this thread is Twins for Dumbies, which is why I can post here So those questions/issue need to be asked and resolved. Nobody was born know that stuff (except maybe Charles). That and the OP has PMRs, so a lot of folks probably didn't take the thread seriously to start....probably why you haven't seen the participation from the sages on this issue.

Treetrimmer/Junior444-If I may...maybe a PM to the smart fellas on compounds asking what stuff should a fella know regarding a "base knowledge" level, to qualify the participants in a Compounds for Pros thread...maybe with a link or two, or maybe a reference (a book) or two to read. You don't post in that thread unless you've got compounds/experience building them, or you have a question, and you've read/accomplished the "base knowledge" stuff....so as to prevent Joe Blow from asking if his 38R could be used as an Atmosphere because he's got a 5" exhaust and done the Hutch mod...

Call it a new sticky if you will, like HRT (the builder of the finest sounding 7.3s known to man :rockon started for the turbo setup thread, but make it for twin-charged and compound charged setups instead.

Just to be clear...because a forum post misses inflection/intent/the human element, and my point come across like I'm intending...I'm a newbie too. ointlaugh:

I post the above, because I genuinely think it's the only way to get the smart guys to post to help us goobers out.

My 2 cents. The next 7.3 compound guy I run into gets to have one on me the next time we meet. int:

 

[juniort444e]

I will be running a 38r with a s475. The 38r has a 1.0 housing and the s475 has a 1.32. I'm hoping to be driving it by next week :ford:

You driving this yet. And can you post up any pictures or videos.

 

[juniort444e]

Tarm thanks for the info man. Helping me out alot.

V-ref those are very good points. I figure brain storming this would help, but secrecy is a hard egg to crack on most of these topics. Im a doit myself kind of person anyway so reguardless noone was going to get my business unless they helped me out, thats why i went with jake in the first place.

So my hopes and dreams of saving on piping and saving space on flopping the turbos seems to be a hard pill to swallow but i can except it. I have two ways of mounting the turbos and connecting them from pictures of what others have done. Now its time to go back and reread some of this on wastegating and oil lines so i can get a whole image in my head to make things smoother later on.

 

[TARM]

Junior,

Take it in steps.

As an example take oil feeds for the turbos:

first thing on a engine diagram draw in all the locations you can get a pressurize oil feed from and all the places you can access a return from. Then go look at them on a installed engine to see what can route where.

Look at as many pictures of compounds as you can. Not only of 7.3 but all different engines as well. Something you see might spawn an idea.

Make yourself a list of pros and cons of different configurations such as waste gate setup specs etc. Then you can look at it and hopefully more effectively weight whats going to be best for your setup. What you are and are not willing to live with etc...

I think first you need to decide on what you are looking for it to do and whats the priority and then what turbos you plan to use. Then what specifc specs of those you will go with. Then go to figuring out mounting etc.

 

[silverpsd_06]

I would personally in an ideal world and just thinking out loud here use my 4094r as high pressure with a 1.15 housing, then run a 91mm inducer atmosphere with a 1.15-1.23 housing. Then gate prior to the 4094 to the intermediate, gate the atmo to dump to exhaust. That would be my feeling for an ideal setup for towing heavy/ hot street with some pretty large sticks say 300/300 and up and clean them up nicely.

Now as for mounting options obviously your manifold charger will be in stock or t4 type arrangement with all the normal bells and whistles associated for each..

Atmosphere charger on the other hand is kinda tricky depending on what you use and what can stay in the bay or has to go..

No a/c is the most simple straight forward approach and clears up a lot of room on the passenger side of the motor where the compressor is mounted at now is gone fabricate yourself a bracket to go on top of the idle pulley now in place of the compressor to attach to the turbine flange and support the turbo off that. With all that extra room you now have assuming your turbo is a 4" outlet you can just squeeze that in between the oil fill and the plastic box for your heater then out the stock down pipe location..

With a/c.. Build your intermediate pipe almost the same as what you would without a/c, your still gonna hang it off the compressor only the topside of it with the back bolts and make sure you put all the weight of it down on the compressor not hanging off the side or anything unintelligent like that, it will act like a cradle that you can tack weld to it. Now as for exhaust you can still use the 4" option assuming you didn't bring your intermediate pipe too far to the passenger side. 5" outlet is too big you will have to z around the shock tower and into the fender well then split the frame and tranny to bring you back to your stock location. All the while you will have to remove a little sheet metal but not too much.

Oil feed the way i look at it there are a few options:
There is a port on the drivers side that swamp's uses to feed extra oil to the gen 3 system.
Off the top of the hpop cover it may not be as quick to get oil to the turbo but a few seconds w/o oil never hurt too much.
There is another pressurized port at the back passenger side of the motor that you can utilize. I'd tell you more specific but i don't know that much about where exactly its at and what you will need to get into it.

Draining oil from that point leaves you only one option to the top of the pan a bitch to deal with but its the best option in my opinion.

Between my other posts thats all the good info i can throw out there for anyone to start with and deduct what you want to do from there...

 

[TyCorr]

I think that picture of Elites setup that someone posted is a pretty good, straightforward layout and execution of a set of compounds.

 

[Tree Trimmer]

is about the only useful contribution i can make. i can speculate with the best of them.