V-Ref
Active member
JD
JD-Great contribution to this thread, and get it off to the right start. :rockon:
JD-Great contribution to this thread, and get it off to the right start. :rockon:
Twins for dumbies
- Thread starter juniort444e
- Start date
jdgleason
Active member
You can do either. As a general rule its much easier to plumb it back into the exhaust. You get pressure to deal with dumping into a hot pipe.
jdgleason
Active member
Lol Thanks brotha
swamp_ratt
New member
See the " between quote and q-reply. Click that then click quote on the other person you want to quote. If you want to multi quote more than 2 people just keep hitting " on each persons reply you want to quote. On the last person hit quote
They only hold so much pressure. The diaphram inside the gate will open at a preset value. The gate is a pressure relief valve that allows you to run a pump or series of pumps at their efficient points yet not have to use all of the available output. Its easier on the pumps(compressors) to be running along at a low point in their map.
Lets say you have a s5xx for a low pressure turbo, to prevent blowing the heads off the motor you decide that you want to gate it for only 12psi(this is just an example) and then that 12psi/____cfm will be further compressed in the high pressure stage. So you set the gate to open at 12psi(you can pre-set it by hooking it up to an air compressor that is regulated to 12psi) and anything that is produced in excess of that 12psi will be emitted from the outlet of the wastegate. In diesels its usually dumped into the exhaust to keep the smoke contained.
This is really the difficult part, deciding which pressures are to be allowed in each stage. Egt, total manifold pressure, driveability, and power are all interconnected and changing pressure at one gate can TOTALLY affect what the other charger does. For instance, lowering the allowable boost of the high pressure by lowering the pressure that the wastegate will open at, will lower the pressure at the low pressure charger too.
Id say tuning them is the hardest part. Although using a proven setup, you could mimic what someone else already tested and used.
V-Ref
Active member
Like Tycorr 'splained above. Read the link below, it'll be crystal clear how a gate works.
http://www.precisionturbo.net/tech/instruction-manuals/PTE-PW46-Wastegate-Instructions.pdf
juniort444e
New member
Anyone thinking this would be close. Im thinking wastegate primary into hotpipe going to atmosphere, wastegate the atmosphere into downpipe. What psi would be good. Here's the maps.
Attachments
jdgleason
Active member
So, using Charles' example here, say we wanted to run 25psi out of the atmosphere charger. We multiply the 25 psi by 1.8163 (representing the primary charger compressing the air further) and we get a grand total of 45.4075 psi. Again this is using that example which will vary from turbo to turbo.
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juniort444e
New member
Ya you posted that one already. Im just having issues reading the maps and understanding it then translating it to what charles said in that post. Thats all.
:doh:
:doh:
jdgleason
Active member
Youre right, i did :doh: i am tired lol.
Here is a good post explaining how pressure ratios work and are incorporated into a map. Thank Dustin for this one.
Here is a good post explaining how pressure ratios work and are incorporated into a map. Thank Dustin for this one.
Your thinking about it wrong i think.
As a single turbo trying to make 50psi of boost.
14.7 absolute + 50 psi of boost = 64.7/14.7= a pressure ratio of 4.40
look at this compressor map, note that 4.40 puts the pressure ratio very high on the map, if not out of the map completely
I used this map for an example because its a similar compressor map to a stock low pressure turbo
Now high altitude people... it only gets worse
11.7 absolute ( 6000ft) + 50 psi of boost = 61.7/11.7= 5.27 pressure ratio!!! thats way out of the map
Now if you take that same truck making 50 psi of boost, and say make the low pressure make 30 psi of the total boost you have now made the pressure ratio much better
14.7+30psi of boost= 44.7/14.7= 3.04 PR alot better in the map, and you are still able to make 50 psi of total boost which is needed to make x amount of hp,
The high pressure is now being fed 44.7 absolute pressure into the inlet of the turbo, outlet pressure is say 50 psi total
44.7+20=66.7 since the pressure going in is 44.7 you divide it by that number so your pressure ratio is 1.44 which is way low, in most cases low pressure boost is probably half of total boost so the numbers will actually be closer to each other, say 2.5pr each turbo, i know this is gunna get confusing, charles is much better at explaining it
DO the same with tripple compounds, and it only gets better because the required amount of boost from each turbo goes down, say even at 50 psi of boost
samoht517
New member
This thread helps a ton. I was pretty much all backwards on how the pressures added up and matching turbos
jdgleason
Active member
I was the same way. Ive learned a lot from some of the big boys around here. Its cool to have access to such a wealth of knowledge.
If you are gonna look at a gt40 for a manifold a cheap choice would be to do a pull off of a gt4288. It will give you the same 65/88 comp but with a 42 frame and turbine wheel @ 88mm Might allow you to play with a tighter turbine housing with the larger wheel.
Then run a gt47/55 or s400 of some sort as an atmosphere.
Then run a gt47/55 or s400 of some sort as an atmosphere.
juniort444e
New member
Explain that again tarm. Your saying use a gt4288. Whats cheaper about it, not BB.
Since i have a 4202, would it hurt to put a 1.01 on it followed by a 47xx.
Since i have a 4202, would it hurt to put a 1.01 on it followed by a 47xx.
Cobra 19 & 54
New member
Sub'd, I need to read this sober, tonight it only ALMOST made sense.
Dieselboy.
New member
Your in the same boat as me, I think our chargers are on the large side for the high pressure charger.
Unless you have a huge atmoshere charger like what Brian has done.
I think Charles pretty much nailed an ideal setup with the 38r/4788. I already have a T4 mount so my high pressure would be a 62-66mm size. Then maybe an S484 or bigger ?
I just get lost on the wastegate portion.
Vader's Fury
Active member
First of just to clarify, the type of turbo set-up you guys are talking about is a compound turbo set-up. "Twins" is when you are running 2 turbo's that are the same, one off each manifold, like chris did on his build I believe was called WTF.
Most of the DD set-ups that I have seen for the 7.3 use a 66mm primary and a 88+ for the atmosphere. The types of turbo's can be mixed and matched however you would like but the size is the important part.
For example I will use the set-up I am currently putting together. I have a set of 250/100 injectors in my 450. I am currently installing a S466 with a .90 housing. I know that the housing is tight but I have a wastegate going on as well to limit backpressure. Basically my goal with this set-up is to get good spool-up and low end power as I regularly tow heavy with this truck. I also have a 1.00 and a 1.10 housing that I plan to swap onto the turbo to see how much of a difference in spool-up and backpressure the different housings make.
You could use a larger turbo such as a 68 or a 71 for your primary turbo, or even a 75, but unless you are building a set-up like brians for all a racing or pulling only truck, You have to remember that the primary is what gives you your low end responce. So you don't wanna go to big as that will cause it to be laggy and completely defeat the purpose of compound turbo's.
I am pretty sure that the 66 will not move enough air in the higher rpm's for me to use all 250 cc's that my inj are capable of so I have a plan to go with compound turbo's later on down the road.(maybe as early as this winter, depending on funds) From all of the research I have done, I would not use anything smaller than an 88mm for the atmosphere charger. While you could use say an s483 and it would work, the 88 would be more efficient and most likely live a longer life.
As for how to set it up. My plan is basically the same as I have seen for charles set-up or for brian's new set-up. Hang the atmosphere charger where the pass battery resides. The charged air would route from the outlet of the primary, down and into the stock intercooler. (you would be reverse flowing throught the intercooler) On the driver side it would exit from the intercooler and flow up and into the intake of your primary charger. From the primary it would go directly into the intake plenums on the motor.
For the exhaust flow, the flow leaves the manifolds and goes up the up-pipes and into the primary turbo. You will want to run a wastegate around the primary turbo and back into the intermediate pipe. I am using a 46mm. From there the exhaust gases flow through the intermediate pipe and into the exhaust housing on the atmosphere turbo. Once again you are going to want to use a wastegate to bypass around this turbo to the dp. From the atmosphere turbo you would go into the dp and out the exhaust.
For exhaust housings you want a exhaust housing on your primary that is tight enough to give you good spool-up, but not so tight that your wastegate is not large enough to keep it from overspeeding. For the Atmosphere turbo you want a larger exhaust housing as this turbo does not need to light as fast but will be seeing alot of exhaust flow. Remember anything that you gate around the atmosphere turbo is wasted energy. I plan to use either the 1.00 or 1.10 on my S466 as a primary and a T-6 1.32 on a S488 or S491 as the secondary.
Most of the DD set-ups that I have seen for the 7.3 use a 66mm primary and a 88+ for the atmosphere. The types of turbo's can be mixed and matched however you would like but the size is the important part.
For example I will use the set-up I am currently putting together. I have a set of 250/100 injectors in my 450. I am currently installing a S466 with a .90 housing. I know that the housing is tight but I have a wastegate going on as well to limit backpressure. Basically my goal with this set-up is to get good spool-up and low end power as I regularly tow heavy with this truck. I also have a 1.00 and a 1.10 housing that I plan to swap onto the turbo to see how much of a difference in spool-up and backpressure the different housings make.
You could use a larger turbo such as a 68 or a 71 for your primary turbo, or even a 75, but unless you are building a set-up like brians for all a racing or pulling only truck, You have to remember that the primary is what gives you your low end responce. So you don't wanna go to big as that will cause it to be laggy and completely defeat the purpose of compound turbo's.
I am pretty sure that the 66 will not move enough air in the higher rpm's for me to use all 250 cc's that my inj are capable of so I have a plan to go with compound turbo's later on down the road.(maybe as early as this winter, depending on funds) From all of the research I have done, I would not use anything smaller than an 88mm for the atmosphere charger. While you could use say an s483 and it would work, the 88 would be more efficient and most likely live a longer life.
As for how to set it up. My plan is basically the same as I have seen for charles set-up or for brian's new set-up. Hang the atmosphere charger where the pass battery resides. The charged air would route from the outlet of the primary, down and into the stock intercooler. (you would be reverse flowing throught the intercooler) On the driver side it would exit from the intercooler and flow up and into the intake of your primary charger. From the primary it would go directly into the intake plenums on the motor.
For the exhaust flow, the flow leaves the manifolds and goes up the up-pipes and into the primary turbo. You will want to run a wastegate around the primary turbo and back into the intermediate pipe. I am using a 46mm. From there the exhaust gases flow through the intermediate pipe and into the exhaust housing on the atmosphere turbo. Once again you are going to want to use a wastegate to bypass around this turbo to the dp. From the atmosphere turbo you would go into the dp and out the exhaust.
For exhaust housings you want a exhaust housing on your primary that is tight enough to give you good spool-up, but not so tight that your wastegate is not large enough to keep it from overspeeding. For the Atmosphere turbo you want a larger exhaust housing as this turbo does not need to light as fast but will be seeing alot of exhaust flow. Remember anything that you gate around the atmosphere turbo is wasted energy. I plan to use either the 1.00 or 1.10 on my S466 as a primary and a T-6 1.32 on a S488 or S491 as the secondary.
Big Bore
New member
Can you clarify inducer or exducer and what the differences and possible affects are? This is the part where I get a little lost. I'm planning a setup with 38r (88mm) primary with 1.15 drive side and a 102mm atmo with a 1.44 A/R drive side. I also noticed you have a very large wastegate, I was planning a 38mm in the 38r, is that potentially too small?
jdgleason
Active member
38mm wastegate will be too small. You will need a 44mm or a 46mm and at that maybe even 2 depending on housings.
samoht517
New member
The size vader mentioned is inducer side and the size you mentioned would be exducer. Most people use inducer number to size turbos.
