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Old 06-11-2021, 03:51 AM   #26
hk 40
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Originally Posted by DurableSwedish View Post
why not just get a modern twin scroll turbo instead of messing around with such an outdated and complex setup? Both of those turbos have designs that are over 30 years old...
How old and dated is the idea? If Im not mistaken new volvos run a compound setup almost like a supercharger and turbo. Its pretty neat.


Welcome to today...D13TC with enhanced turbo compound technology.




https://www.bing.com/videos/search?q...tail&FORM=VIRE

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Old 06-11-2021, 11:44 AM   #27
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To the untrained eye, a compound turbo setup looks a lot like a twin turbo setup on a car. But, once you trace the piping from the intake and exhaust manifolds to the turbos you begin to identify the major differences between the two. In compound turbo systems, the turbochargers are different sizes and operate in series, meaning the first turbo feeds the second turbo boosted air and the effect is compounded whereas a twin turbo configuration, identical sized turbos operate independently. Compound turbo systems are most common in OEM diesel applications to provide vehicle owners with response, power, and fuel economy. This is accomplished by a small turbo providing low RPM response with a larger turbo producing power at high RPMs and simultaneously the two turbos operate as one throughout the RPM range.

The charge air flow path highlighted in the image shows the air entering the low-pressure turbo first. At low engine RPMs, the low-pressure turbo does not spin very fast and is producing little to no boost, but the air still flows through it into the second/ high-pressure turbo. At low engine RPMs, the smaller, high-pressure turbo produces the initial boost for the engine. As engine RPMs rise, the larger low-pressure turbo spins faster and creates boost which is fed into the high-pressure turbo to be compressed a second time, compounding the boost pressure that the turbos make. After the air leaves the high pressure turbo it is routed through an intercooler to reduce its temperature before going into the engine intake.

Calculating pressure ratios for compound turbo systems can be achieved with the formulas below. This is important for understanding compressor efficiency and potential power for your selected turbochargers. Pressure ratio is a variable equation that combines ambient pressure with gauge pressure divided by ambient pressure. This identifies where the compressor will perform its max duty cycle. Knowing pressure ratio is a key component to selecting the correct turbo for your application. PR is identified on the Y (vertical) axis of the compressor map. Additionally, pressure ratio is not an indicator of horsepower.

P2c Absolute outlet pressure
P1c Absolute inlet pressure

P2c= (PSIg + PSIa) Boost Gauge Pressure (PSIg) + Absolute Atmospheric Pressure (PSIa)
P1c = (PSIa) Absolute Atmospheric Pressure (PSIa)

PSIg refers to gauge pressure and measures the pressure above atmospheric. A boost gauge pressure reading of 12 means the pressure in the manifold is 12 psi above atmospheric pressure. Depending on the build of the engine, your gauge pressure limits will vary. Stock engines usually have lower ability to handle boost, while highly modified engines can handle much more. Having a boost target is necessary for determining pressure ratio. PSIa refers to absolute atmospheric pressure. This is standard atmospheric pressure at standard conditions. If you are not at sea level you can substitute a value from the chart below for PSIa.
~Garrett Turbos~

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Old 06-11-2021, 11:51 AM   #28
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Hi Marcus,
Dont know if you had a look yet but this should help you set it up. https://www.garrettmotion.com/news/n...0independently.

"Collin Wilshire with Jett Racing in Australia has worked years on mastering the science behind compound setups for his race car which is the world’s fastest 4-cylinder compound turbo car with a 6.2 second ¼ mile at 229 MPH. This Mitsubishi Eclipse has a 2.2L 4G63 engine with a compound turbo setup using two Garrett turbochargers and makes about 1900 horsepower. Follow Jett Racing on social media.

The desire to squeeze more boost from a turbo system would have taken a single turbo out of its efficiency zone and turned it into a heat pump. A compound turbo system makes big boost and keeps both turbos in an efficient zone on the compressor map eliminating the use of intercoolers in this setup. Remember, efficient air is cooler air. The high-pressure turbo is a GTX4202R and the low-pressure turbo is a GTX5533R Gen II. Collin says keeping the turbos operating at a lower RPM provides better boost ratios, cooler intake temps, better clutch control and still produces up to 100 lbs of boost to the engine and close to 1900 horsepower."

~Garrett Turbos~


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Old 06-12-2021, 02:11 AM   #29
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yeah, sequential turbos are fine to help a giant turbo spool up at lower RPMS, but the turbos you are choosing are old 70s junk and can easily be supposed by a modern twin scroll turbo in both quick spool and high RPM boost. The 2 examples you posted was a huge semi-truck diesel engine and a 2000+ hp drag car. your car is neither of those. Why would you specifically choose to create a sequential turbo setup with old turbos instead of one modern one? you could put a GTX3076R on a stock b230ft exhaust manifold and make more top end and power under the curve than the sequential setup with a T3 and 13c. Less weight, less complexity, less oil and coolant lines.

I see your wiki copy-paste, but those setups are not appropriate for your low horsepower small engine. My billet 20T made 20psi by 3200RPM, is that not fast enough spool or power for you? even that's a cheap 90s turbo on a 2.1L...
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Old 06-12-2021, 06:23 AM   #30
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yeah, sequential turbos are fine to help a giant turbo spool up at lower RPMS, but the turbos you are choosing are old 70s junk and can easily be supposed by a modern twin scroll turbo in both quick spool and high RPM boost. The 2 examples you posted was a huge semi-truck diesel engine and a 2000+ hp drag car. your car is neither of those. Why would you specifically choose to create a sequential turbo setup with old turbos instead of one modern one? you could put a GTX3076R on a stock b230ft exhaust manifold and make more top end and power under the curve than the sequential setup with a T3 and 13c. Less weight, less complexity, less oil and coolant lines.

I see your wiki copy-paste, but those setups are not appropriate for your low horsepower small engine. My billet 20T made 20psi by 3200RPM, is that not fast enough spool or power for you? even that's a cheap 90s turbo on a 2.1L...
Thats cool but I don't who you're talking to though Im not the op. So you don't know anything about my car if its me your asking. No 20psi is not enuf. Anyway Tell me though how much boost are the two old turbos he's running going to produce mapped correctly? You've compared your compressor maps to his that quickly? Those are also not wiki pasted pages they are from the official Garrett website. They know quite a bit about Turbos. It explains clearly for people that ask why he'd do it. I cant speak for the op but another dudes car is never enuf for me. I can tell you those turbos aren't from the 70's coz I am. Also no need to call what he has junk. Would you like it if he said what you had and are proud of was junk? It makes perfectly good sense anyway as there no need to mock it up with brand new turbos. Nailing down plumbing and control shouldn't cause anyone not tasked with the labor too much trouble.

Regards,
Hubert

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Old 06-12-2021, 07:07 PM   #31
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all RWD Volvos are junk, I know mine definitely is a $40k pile of smoking garbage...
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Old 06-13-2021, 04:46 AM   #32
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why not just get a modern twin scroll turbo instead of messing around with such an outdated and complex setup? Both of those turbos have designs that are over 30 years old...
Well i don't now of a turbo that can produce 2 bar(30 psi) boost at 3000 rpm on a 2.3 liter engine and hold it to 7500 rpm. Without producing a lot of back pressure at higher rpm. The plane from the start was to use a supercharger at lower rpm but I don't have the machinery to make all the parts to make it work. So a took a smallish turbo to make it spool up fast. So the small turbo is to small to make any real power at higher rpm so the big turbo makes all the power at higher rpm. The t3/t4 turbo will be change to a holset hx35 turbo later. I don't only want high end power but also a lot of down low torque.
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Old 06-13-2021, 07:59 AM   #33
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Well i don't now of a turbo that can produce 2 bar(30 psi) boost at 3000 rpm on a 2.3 liter engine and hold it to 7500 rpm. Without producing a lot of back pressure at higher rpm. The plane from the start was to use a supercharger at lower rpm but I don't have the machinery to make all the parts to make it work. So a took a smallish turbo to make it spool up fast. So the small turbo is to small to make any real power at higher rpm so the big turbo makes all the power at higher rpm. The t3/t4 turbo will be change to a holset hx35 turbo later. I don't only want high end power but also a lot of down low torque.
To get around 30psi at 300rpm you need a pressure ratio of more than 3.18 (assuming volume efficiency of 84%), assuming you are aiming at 190HP (~275CFM/20.9lb/min/570Kg/h of air) at that RPM (the spreadsheet I made starts at HP and then I enter the RPM to figure out the pressure ratio I need). I know you are thinking boost pressure but I suggest to think airflow instead.

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all RWD Volvos are junk, I know mine definitely is a $40k pile of smoking garbage...
I will give you $1 for it.
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Old 06-13-2021, 09:46 AM   #34
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all RWD Volvos are junk, I know mine definitely is a $40k pile of smoking garbage...
Thats all you have in it.... Do you suggest that because you have sunk that much in your vehicle Marcus should just stop having fun with his turbos and welder? Not trying to be funny but 40k is alot if you are only in the 300 hp range. They probably dont have that much sunk in the 1400 hp t6 Jussi sent us a view of. 40k for that level of performance Im not sure is so outstanding. Im only going by your sticker beneath your name.

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Old 06-13-2021, 06:10 PM   #35
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It's been through a few versions and I've had it for almost 20 years. My dyno chart is in my build thread shows the boost versus torque and afr.
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Old 06-13-2021, 09:00 PM   #36
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I was only kidding, Im sure you have a very nice volvo if you have spent 20 years loving it. I was only suggesting that he should still be able to experiment despite it. If you have a volvo no matter what I like it.... You seem very knowledgeable so why not take a serious look at what hes trying to do versus just saying he has junk and the idea is worthless. His reasoning seems sound and merits at least a more serious discussion.

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Old 06-14-2021, 04:02 PM   #37
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Some progress on the exhaust manifold and turbos placement and charge pipe routing and placement.

I only have 0.6 bar(9 psi) set as the base spring pressure for the two turbos. To see what happens to the boost pressure and spool of the small and big turbo. The small turbo will make the engine seems bigger to the big turbo so hopefully it will spool faster.

ignore the mess in the background




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Old 06-14-2021, 04:43 PM   #38
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I do like your angled compression turbine clamp; where did you get it?

BMW has some little air-water intercoolers. They may fit between the compressor outlet of one turbo and the inlet for the other.
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Old 06-14-2021, 07:01 PM   #39
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https://www.youtube.com/watch?v=1pV_tLbZY0A

I think there are some bits and pieces missing from the conversation of compounds here. Watch the video. Shane T knows his **** and breaks it down a bit into some easier to understand concepts.
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Old 06-15-2021, 03:38 PM   #40
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I do like your angled compression turbine clamp; where did you get it?

BMW has some little air-water intercoolers. They may fit between the compressor outlet of one turbo and the inlet for the other.
Do you mean that on the small turbo? If so the flange is from klracing and then there is a bit of a 3 inch pipe then there is a 3 to 2.5 inch adapter. Then it will be a bend down to the big turbo

Thanks for the information about bmw water to air intercooler, looks like it may work
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Old 06-15-2021, 04:29 PM   #41
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Some progress on the exhaust manifold and turbos placement and charge pipe routing and placement.

I only have 0.6 bar(9 psi) set as the base spring pressure for the two turbos. To see what happens to the boost pressure and spool of the small and big turbo. The small turbo will make the engine seems bigger to the big turbo so hopefully it will spool faster.

ignore the mess in the background





Damn you've been busy keep going and thanks for picking me up.......

Regards
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Old 06-15-2021, 05:11 PM   #42
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Damn you've been busy keep going and thanks for picking me up.......

Regards
Hubert


Yea a some progress but I'm out of welding sticks to my welder so no progress today sadly. Will resume tomorrow evening.

Thanks for posting the theory behind this and some of the reason why I'm doing this
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Old 06-22-2021, 01:39 PM   #43
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Hello. Have got some progress now. Almost everything on the exhaust side is done now. Have also test fitted it in the car to and it fits no problem.






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Old 06-22-2021, 01:46 PM   #44
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Tig/mig/arc?
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Old 06-22-2021, 01:58 PM   #45
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Tig/mig/arc?
Arc welder. Will see if a can get hold of a cheap mig welder but arc welder for now. It’s not optimal but it work
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Old 06-22-2021, 04:15 PM   #46
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If you want to learn tig, find a used torch that has a gas valve on it. Hook it up to your arc welder, and practice with scratch start.

What thickness pipe/tubing are you using?
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Old 06-23-2021, 01:54 AM   #47
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because he can? Why buy something expensive when you can build something instead? remember where you are logged in...
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Old 06-23-2021, 02:51 AM   #48
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If you want to learn tig, find a used torch that has a gas valve on it. Hook it up to your arc welder, and practice with scratch start.

What thickness pipe/tubing are you using?
I have look in to doing something like that to my arc welder to make it a tig welder but that is for the future.

Pipe diameter of the small pipe is 2.6 mm and for all other pips it’s 1.5 mm thick. So I will need to add bracing so it doesn’t move when it gets hot.
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Old 06-23-2021, 04:31 AM   #49
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How old are your rods? Have they been sitting out collecting moisture?
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Old 06-23-2021, 06:20 AM   #50
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How old are your rods? Have they been sitting out collecting moisture?
They are brand new but my welding skills are not the best but it’s not that easiest to weld thin tubing with a stick welder so. But it’s holding together and hopefully not leaking.
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