Big Bore
Active member
That is what I suspected, thanks for clarifying.
Twins for dumbies
- Thread starter juniort444e
- Start date
That is what I suspected, thanks for clarifying.
Vader's Fury
Active member
Sorry, all the numbers that I mentioned are compressor inducer side numbers. I would have to look up the exducer numbers. Also another thing to keep in mind is that the turbine wheel comes in different sizes as well and will affect the spool-up of the turbo and also the backpressure.
I agree. I believe that charles is having issues with his 44mm being to small now that he has stepped up to a gt55 as his atmosphere charger.
See pic as this changes from the compressor side to the turbine side. Compressor side uses inducer while turbine side uses exducer.
Id buy the biggest gate I could!! With the 38r making around 20psi, in a 'common' 7.3 setup one would be venting much gas.
Is everybody of the thought that the dump on the high press turbo needs to go to the drive side of the atmosphere? I thought just using exhaust manifold flow would be sufficient.
Im not sure I want to throw everything at the induction system and then just have to vent most of it anyway!! Its not like its gonna take tons of pressure to make a set of compounds work especially with a big block diesel.
Im all ears if Im overlooking something.
Big Bore
Active member
My atmo is going to be significantly smaller than the gt55. I don't talk about it much because most people will naysay the charger I'm going to use, but it has a 102mm exducer/74.3 inducer compressor wheel and a 84mm turbine with 1.44 A/R. Most of the reason I get flak is because very few people, even those who know turbos, know what towing at 9,000ft to 11,000ft is like. My compounds are being sized for performance but still be ableuse my truck to tow heavy without the high altitude penalties of a larger turbo i.e. lag, smoke and heat.
Using the above specs would a 38mm WG on the 38R with 1.15 A/R exh housing still be too small? Is there a formula to help calculate the WG size needed?
See pic as this changes from the compressor side to the turbine side. Compressor side uses inducer while turbine side uses exducer.
Good picture. I was aware of what the terms meant in regards to direction of flow etc, my confusion was when numbers were being thrown around which one were they. Thanks for clearing that up.
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juniort444e
New member
Im wondering how a gt4088/gt5533 setup would work. This obviously not going to be DD much but seem s like if the housings and wg's are setup right that it would be an awesome setup. Im not up on all the s-series turbos thats why i always use gt's.
Tycorr--i was always under the impression that if you could use all the exhaust possible to help spool the atmosphere that it wouldnt hurt too. I understand what you are saying, but no matter what, i think it would still be roughly the same pressure to gate the atmosphere with or without the primary routed into the intermediate pipe.
How big of a wg do most use on a bigger atmosphere turbo. Or would you go with two. And how does one setup a twin gate for one charger.
Tycorr--i was always under the impression that if you could use all the exhaust possible to help spool the atmosphere that it wouldnt hurt too. I understand what you are saying, but no matter what, i think it would still be roughly the same pressure to gate the atmosphere with or without the primary routed into the intermediate pipe.
How big of a wg do most use on a bigger atmosphere turbo. Or would you go with two. And how does one setup a twin gate for one charger.
I do NOT think that WG is big enough!!! By the time you get to dumping boost off that hp charger the 38mm wont be enough. A 46mm would be best and leave much more room for tuning. The bigger gates are beefier to boot.
I would venture to guess that most people running compounds that want to tow are going to be looking for lower boost numbers when towing. You dont want 100psi hitting your manifold when you're pulling a trailer. That would be hard on drivetrain parts!!
Lets say you want 65lbs MAX for towing. That'd be about 20lbs at the atmosphere. Then you've got air charged to 34psi going into the 38r. So you are going to run that up that up to about the same boost figure and literally BLOW the rest of that boost out the tailpipe in one shape or form. Thats why Im having trouble wrapping my head around plumbing all the gates into the turbo piping, when we are already dumping quite a bit of our forced air off as excess pressure.
Maybe Im not seeing the point of having the gate opening constantly.
Back to the topic, I think you'll be sorry with a small, entry level WG. Id not go any smaller than the 44. A 46mm Tial would be the standard, imo.
I would venture to guess that most people running compounds that want to tow are going to be looking for lower boost numbers when towing. You dont want 100psi hitting your manifold when you're pulling a trailer. That would be hard on drivetrain parts!!
Lets say you want 65lbs MAX for towing. That'd be about 20lbs at the atmosphere. Then you've got air charged to 34psi going into the 38r. So you are going to run that up that up to about the same boost figure and literally BLOW the rest of that boost out the tailpipe in one shape or form. Thats why Im having trouble wrapping my head around plumbing all the gates into the turbo piping, when we are already dumping quite a bit of our forced air off as excess pressure.
Maybe Im not seeing the point of having the gate opening constantly.
Back to the topic, I think you'll be sorry with a small, entry level WG. Id not go any smaller than the 44. A 46mm Tial would be the standard, imo.
Derek@Vision Diesel
New member
Are the people that actually are running compounds (or know what they are going to run) willing to post up names of turbos/specs/ect.
My biggest dilema seems to be finding two affordable turbos someplace that i can put together. For instance, would me 72mm s300 make for a good primary charger? If it does how do i know how big to go with the atmoshpere charger?
My biggest dilema seems to be finding two affordable turbos someplace that i can put together. For instance, would me 72mm s300 make for a good primary charger? If it does how do i know how big to go with the atmoshpere charger?
While true, Im just wondering if we're just increasing the demand and possibly the necessity for more gating than we really need. If you are using a dual gated setup then you've got excessive boost, imo
You'd have to split(and upsize) the line to the wg's and install one on each leg after the Tee or Y. My point again is if you need two 44's to get rid of what you cant use then you've got too much boost
Im wondering what some useful charger sizes would be to make a nice dd, tow rig for a set of 238/100s or even stage II's? Could a guy get away with a 38r and something smaller in front of it?
Like Charles said in a diff post, in a diff thread, in a diff forum in reply to people suggesting he upsize his HP charger, the 38r isnt a restriction. He was making about 22-28lbs of boost there. In other words, by changing out his atmosphere he actually reduced the demand on the 38r in the pair. So a 38r on a 7.3, even making up to 100psi is plenty big. That is a standard base part, imo, the 38r. It even lends itself to putting the truck back to a point close to stock should the need arise.
My biggest question is what does a guy who wants the wide powerband but doesnt need 700hp use? Would a 38r and 47-88 still be ideal for a smaller set of hybrids? Or maybe Im trying to find a solution in the compounds for a problem that isnt even there when using inj's smaller than 250 and up with 200%+ sized nozzles. That sh!t is over my head at this point.
juniort444e
New member
Makes sense, but im looking at it like this...
You are probably going to need two to begin with, so i dont think it will hurt.
And if you can get the atmosphere spooling just a touch faster with the exhaust from the primarys wg then what could it hurt.
I read somewhere that 250/200 in a compound setup where ideal. Pending on the setup. If i do a compound setup on my dd i want the best of all four, dd, sledpulling, towing and drag racing.
You are probably going to need two to begin with, so i dont think it will hurt.
And if you can get the atmosphere spooling just a touch faster with the exhaust from the primarys wg then what could it hurt.
I read somewhere that 250/200 in a compound setup where ideal. Pending on the setup. If i do a compound setup on my dd i want the best of all four, dd, sledpulling, towing and drag racing.
Big Bore
Active member
Yes, I was thinking an absolute max boost of 75psi under WOT for racing only, so my WG would indeed need to be sized for that. However 65lbs for towing seems like a lot, I wouldn't think I would ever need to be that hard into the throttle with the kind of power I'll be making, maybe I'm wrong. In any event, advice on WG size duly noted.
One thing above confused me a bit.
If the atmo is putting OUT 20psi, how will it be any different going IN to the 38R?
20lbs outta the atmosphere is psig(the g being gauge). Atmospheric pressure is 14.2psi for us flatlanders so I added that to what the atmosphere was compressing additionally. I mean if you drove the truck 1k feet down in a quarry you'd have to change your gating because the pressure would be greater down there!
65lbs of boost IS excessive for towing...but hey thats what compounds are all about right? In all seriousness, that was just an example.
This brings us to another point that people need to consider! Charles tuned his own truck. He ran one tune, for everything. I would want that same level of dynamic control in a compounded truck. I would say a truck built like this isnt for someone who needs eight different tunes. If you find yourself not being able to use the throttle incrementally to tow and such it could be disastrous. Not to mention the number of tuners that would be able to tune that setup isnt as vast as slapping a bb charger on a truck with a hot fuel system. Im kinda warming up to the idea of learning to tune before I do something like this.
Hopefully someone with compounded induction will chime in on how they got tunes established and if any tuners have programs at the ready for such hardware.
juniort444e
New member
Thats a good point Ty. I was thinking about learning and doing my own tuning soon. Was also curious what it would take to tune a dp tuner, and a ts chip. Such as softwares that would be needed if possible.
One tune for everything sounds wonderful. Right now the way my truck is setup i use one tune. So im sure i could live with it like that in a compound setup.
One tune for everything sounds wonderful. Right now the way my truck is setup i use one tune. So im sure i could live with it like that in a compound setup.
Big Bore
Active member
Ahhh, ok I figured I was missing something. I need to research atmo for my altitude here, but knowing what it would be at sea level is good also since there's always the possibility of towing there.
Those exact thoughts went through my head as I read your last post. My current tuner tunes with that exact philosophy in mind. I currently use only the hot tune for DD because the lower portion of the throttle is very stockish and I can drive up the mountains without blowing smoke all over the place, egt's don't threaten to melt my motor, and when I want to pass I can meter how much power I use very easily with my foot. I also get the best mileage my truck has ever gotten with that tune, and I also see the highest boost levels I've ever had under WOT.
There is a lot of travel available in the pedal, I've never understood the need to ramp up the fuel to 50% at 25% throttle input. After using tunes that ramp up instantly and are almost impossible to drive smoothly on slower or bumpy roads, it took a while to get over the dead pedal feeling, but after about a month I began to realize just how much more pleasant it was to drive. It also works a lot smoother with the cruise control. Having a smoother, slower fuel delivery on compounds would seem key to DD driveability.
Vader's Fury
Active member
I agree with the ONE tune for every situation.... This is why I have planned to get live tuning done on the truck once I get the entire set-up installed and running without any issues.
I also agree with a min 44mm wastegate. I look at it as it is always better to be able to bypass more air than needed than to need to bypass more than you are capable of.
I also agree with a min 44mm wastegate. I look at it as it is always better to be able to bypass more air than needed than to need to bypass more than you are capable of.
oldbluef250
Member
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:
That is exactly how it should be!! Bill at PHP is really good about that. His 40-140 tunes are all stock tunes in idle quality and throttle reaction. Until you apply more than 50% throttle, then the fuel comes on hard!
I really have limited firsthand knowledge of other tuners but Id love to try EVERYONES tunes! Ivet gotta say that Matt's tunes will probably be my next selection as far as tuners go...Matt of Gearhead fame that is! Id loooove to try Swamps tuning too. Heck Brian of BTS' tunes.
Ive been thinking more about compounds on my 95 gsx here lately than my truck. Ive got the truck torn apart and the car too. The car is getting worked on more!
11.8 ish i bet maybe lower if your much above 6000 feets
Big Bore
Active member
House is at 9000, drive over 10,000 regularly.
psduser1
Well-known member
Following this thread when I have time, for towing purposes.
When I spoke with Charles a while back about injector sizes, we discussed compounds for q second. He said the one thing he would have done differently was a bigger gate.
As in, don't be shy with the size. He in fact recommended a 60mm gate to me, with a 200% nozzle. The 40 mm was always on the ragged edge and would have a hard time controlling the bp on his 38r. That was happening with a 1.15 housing. I can only imagine the problem would only be more pronounced with a 1.0 housing.
I'm still setting up a 38r on my setup, so I've got time to research gate sizes (thank you to all who are discussing), but I'm leaning towards the 60 mm just for mire flexability on the atmospheric charger.
I'm also thinking gating the primary to the atmospheric will help bring that lovin feeling on lower in the rpms, especially if you can keep exaust temps a little higher at the atmospheric charger, while maintaining a reasonable temp at the primary.
When I spoke with Charles a while back about injector sizes, we discussed compounds for q second. He said the one thing he would have done differently was a bigger gate.
As in, don't be shy with the size. He in fact recommended a 60mm gate to me, with a 200% nozzle. The 40 mm was always on the ragged edge and would have a hard time controlling the bp on his 38r. That was happening with a 1.15 housing. I can only imagine the problem would only be more pronounced with a 1.0 housing.
I'm still setting up a 38r on my setup, so I've got time to research gate sizes (thank you to all who are discussing), but I'm leaning towards the 60 mm just for mire flexability on the atmospheric charger.
I'm also thinking gating the primary to the atmospheric will help bring that lovin feeling on lower in the rpms, especially if you can keep exaust temps a little higher at the atmospheric charger, while maintaining a reasonable temp at the primary.
