Twins!
Twins!
04-06-2010, 12:09 AM
#1
(03-30-2010, 03:43 AM)winmutt Im thinking you need more cold air and faster.
I agree. Time to start thinking about air. Also seemed like a good time for a new thread.
My current plan is to attempt compound turbos on my 617a.
A few months ago, I got the “Turbochargers” book by Hugh MacInnes. I think its great. It explains just about everything about turbocharging. It even talks a bit about how to size compound turbos. Seems to be as one would expect. You size the high pressure compressor for the volume demanded by the engine at the desired rpm. Then you calculate the volume demanded by the high pressure compressor, and pick a low pressure compressor to provide that.
Anyway, made a little spreadsheet to calculate stuff so that picking turbos would be a bit easier. I have attached it here. Feel free to use it for whatever purpose. If you like math, feel even free-er to check it for errors and report back to the forum!
or better yet, post your own, more-correct, easier to use spreadsheet. Im sure plenty of you have them. Fyi, it was exported from open office, so it may not look quite right in excel. The forum wouldnt allow me to attach the .ods file.Of course its pretty easy to follow when I look at it, but its probably a convoluted clusterfuck to everyone else. So if there is confusion on how to use (or troubleshoot) it, ask away and I will do my best to explain it. Basically, the top part calculates the demand from the engine, given the size, displacement, and ve. Then the colored rows calculate the various temperatures and pressures of the gas as it goes thru the system, given pressure ratios, assumed pressure losses, and efficiencies. The stuff in the middle uses the values calced in the colored rows to get the overall density ratios per compressor-intercooler 'stage', and then the volume/time thru each stage, then the stuff on the right is just unit conversions for map-plotting purposes.
I should say that I am not really sure about the unit conversions from volume/time to mass/time on the right side. I just got those conversions from google, and they were probably for STP which Im not sure is right. So that may make the whole thing worthless right there.
In my playing around with it, I came up with a configuration which uses an he351ve blowing into a gt2056v with intercooling and aftercooling. it seems to work out pretty well, which is lucky, cause both of those turbos are dirt cheap. At 5000 rpm, the 2056 looks to me like it is about at its limit. Not sure how efficient most intercoolers are, or how much pressure is lost thru them. Pulled those numbers outta my ass.
Of course I still have no Idea if the turbines will be appropriately sized, and I dont know how to do any useful calculations to find out. Just looking at the turbine housing for the 2056 makes me think its going to be too restrictive even with the vanes fully open. May just have to find out thru trial and error.
Then there's the problem of how to actually mount the things. That took some thought. Last week I was sick. So laying in bed, I decided to play around with Google Sketchup. Once I resigned to relocating the alternator to where the AC compressor used to be, I was able to make things work pretty well, if I do say so myself, with the Garrett where the alternator used to be, and the Holset up above it. It looks like I can even get the header primaries to be equal-length, which I hear is supposed to be good. Below are some pics. Yeah the 3d model is pretty rough. please forgive my half-assedness.
Whaddya think?
Attached Files
From the '10mm element thread':
(03-30-2010, 03:43 AM)winmutt Im thinking you need more cold air and faster.
I agree. Time to start thinking about air. Also seemed like a good time for a new thread.
My current plan is to attempt compound turbos on my 617a.
A few months ago, I got the “Turbochargers” book by Hugh MacInnes. I think its great. It explains just about everything about turbocharging. It even talks a bit about how to size compound turbos. Seems to be as one would expect. You size the high pressure compressor for the volume demanded by the engine at the desired rpm. Then you calculate the volume demanded by the high pressure compressor, and pick a low pressure compressor to provide that.
Anyway, made a little spreadsheet to calculate stuff so that picking turbos would be a bit easier. I have attached it here. Feel free to use it for whatever purpose. If you like math, feel even free-er to check it for errors and report back to the forum!
or better yet, post your own, more-correct, easier to use spreadsheet. Im sure plenty of you have them. Fyi, it was exported from open office, so it may not look quite right in excel. The forum wouldnt allow me to attach the .ods file.Of course its pretty easy to follow when I look at it, but its probably a convoluted clusterfuck to everyone else. So if there is confusion on how to use (or troubleshoot) it, ask away and I will do my best to explain it. Basically, the top part calculates the demand from the engine, given the size, displacement, and ve. Then the colored rows calculate the various temperatures and pressures of the gas as it goes thru the system, given pressure ratios, assumed pressure losses, and efficiencies. The stuff in the middle uses the values calced in the colored rows to get the overall density ratios per compressor-intercooler 'stage', and then the volume/time thru each stage, then the stuff on the right is just unit conversions for map-plotting purposes.
I should say that I am not really sure about the unit conversions from volume/time to mass/time on the right side. I just got those conversions from google, and they were probably for STP which Im not sure is right. So that may make the whole thing worthless right there.
In my playing around with it, I came up with a configuration which uses an he351ve blowing into a gt2056v with intercooling and aftercooling. it seems to work out pretty well, which is lucky, cause both of those turbos are dirt cheap. At 5000 rpm, the 2056 looks to me like it is about at its limit. Not sure how efficient most intercoolers are, or how much pressure is lost thru them. Pulled those numbers outta my ass.
Of course I still have no Idea if the turbines will be appropriately sized, and I dont know how to do any useful calculations to find out. Just looking at the turbine housing for the 2056 makes me think its going to be too restrictive even with the vanes fully open. May just have to find out thru trial and error.
Then there's the problem of how to actually mount the things. That took some thought. Last week I was sick. So laying in bed, I decided to play around with Google Sketchup. Once I resigned to relocating the alternator to where the AC compressor used to be, I was able to make things work pretty well, if I do say so myself, with the Garrett where the alternator used to be, and the Holset up above it. It looks like I can even get the header primaries to be equal-length, which I hear is supposed to be good. Below are some pics. Yeah the 3d model is pretty rough. please forgive my half-assedness.
Whaddya think?
Attached Files
04-06-2010, 01:36 AM
#2
(04-06-2010, 12:09 AM)shredator Whaddya think?
If cold air is your goal, compounds definitely aren't it. Compounds are for applications higher than 35psi and under that a single will be more efficient.
Its been well proven that a single turbo will supply more than 500hp on a 606 so compounds really aren't needed on MB diesels unless you're working in high altitudes (8,000+).
This post was last modified: 04-06-2010, 01:37 AM by ForcedInduction.
ForcedInduction
04-06-2010, 01:36 AM
#2
(04-06-2010, 12:09 AM)shredator Whaddya think?
If cold air is your goal, compounds definitely aren't it. Compounds are for applications higher than 35psi and under that a single will be more efficient.
Its been well proven that a single turbo will supply more than 500hp on a 606 so compounds really aren't needed on MB diesels unless you're working in high altitudes (8,000+).
04-06-2010, 01:42 AM
#3
I know it is fun discussing ifs and whats but wouldn't be more constructive working on something really achievable
.For the heck of the discussion, where is the second turbo
?
1992 Mercedes 190D 2.5 turbo 5sp manual. EGT+boost gauges. Boost controller set to ~14.5 psi. 1 1/4 turns on full load adjustment. LPG injection.
![[Image: 3803751914_8fdca63138_o.jpg]](http://farm4.static.flickr.com/3543/3803751914_8fdca63138_o.jpg)
I think there will be more educated posts, but do you really need all that air?
I know it is fun discussing ifs and whats but wouldn't be more constructive working on something really achievable .
For the heck of the discussion, where is the second turbo?
1992 Mercedes 190D 2.5 turbo 5sp manual. EGT+boost gauges. Boost controller set to ~14.5 psi. 1 1/4 turns on full load adjustment. LPG injection.
04-06-2010, 08:52 AM
#4
(04-06-2010, 01:42 AM)Deni I think there will be more educated posts, but do you really need all that air?
I know it is fun discussing ifs and whats but wouldn't be more constructive working on something really achievable
For the heck of the discussion, where is the second turbo
If someone was building a 603/606 with custom internals for 600hp+, drives like I do, spends time at sea level and 8,000+ feet. I could see the reasoning for a compound system. But personally I think Eaton M90 + HX40 with a by-pass valve would be a better choice for anything up to 400/500hp and still require custom rods. Where as you might just want to use a HX30 instead for stock internals 300HP.
(04-06-2010, 01:42 AM)Deni I think there will be more educated posts, but do you really need all that air?
I know it is fun discussing ifs and whats but wouldn't be more constructive working on something really achievable
For the heck of the discussion, where is the second turbo
If someone was building a 603/606 with custom internals for 600hp+, drives like I do, spends time at sea level and 8,000+ feet. I could see the reasoning for a compound system. But personally I think Eaton M90 + HX40 with a by-pass valve would be a better choice for anything up to 400/500hp and still require custom rods. Where as you might just want to use a HX30 instead for stock internals 300HP.
04-06-2010, 04:50 PM
#5
You're going to lose your engine under all that plumbing.
Honestly an idi mercedes is not going to hold together with 65psi boost up it. Your calcs seem on track, but I work in metric and I can't be arsed converting the answers to metric to check them with my spreadsheets.
Sure a single turbo can produce big hp numbers, but it becomes a dyno queen that does nothing but belch smoke until the turbo finally spools in the last top bit of the rev range.
Compounds offer flexibility that single stage compressors can't.
Two turbos with two intercoolers?
You're going to lose your engine under all that plumbing.
Honestly an idi mercedes is not going to hold together with 65psi boost up it. Your calcs seem on track, but I work in metric and I can't be arsed converting the answers to metric to check them with my spreadsheets.
Sure a single turbo can produce big hp numbers, but it becomes a dyno queen that does nothing but belch smoke until the turbo finally spools in the last top bit of the rev range.
Compounds offer flexibility that single stage compressors can't.
04-06-2010, 05:05 PM
#6
(04-06-2010, 04:50 PM)Kiwibacon Compounds offer flexibility that single stage compressors can't.
As do VNT/VGT turbos.
ForcedInduction
04-06-2010, 05:05 PM
#6
(04-06-2010, 04:50 PM)Kiwibacon Compounds offer flexibility that single stage compressors can't.
As do VNT/VGT turbos.
04-06-2010, 05:14 PM
#7
(04-06-2010, 05:05 PM)ForcedInduction(04-06-2010, 04:50 PM)Kiwibacon Compounds offer flexibility that single stage compressors can't.
As do VNT/VGT turbos.
At the risk of stating the blatantly obvious.
VNT/VGT turbos are single stage compressors. The above statement still applies.
04-07-2010, 05:30 AM
#8
(04-06-2010, 05:14 PM)Kiwibacon VNT/VGT turbos are single stage compressors. The above statement still applies.
No it doesn't, you're missing the point.
There is no reason to use a ridiculously large turbo such as the Super HX40 for only 300-550hp. Using an HY35, HE341 or T3/T4 hybrid will spool up nearly as fast as the stock T3 yet support everything the engine can flow.
A highly modded 606 at 6500rpm and 30psi of boost still flows less air than a factory stock 5.9L Cummins at 30psi and its natural 3200rpm redline. That means there is no reason an HX35/HY35/HE341 can't support "big power" with daily drivable manners.
Even BMW's "big" turbo is just a K26, the factory turbo on many of our engines.
This post was last modified: 04-07-2010, 05:31 AM by ForcedInduction.
ForcedInduction
04-07-2010, 05:30 AM
#8
(04-06-2010, 05:14 PM)Kiwibacon VNT/VGT turbos are single stage compressors. The above statement still applies.
No it doesn't, you're missing the point.
There is no reason to use a ridiculously large turbo such as the Super HX40 for only 300-550hp. Using an HY35, HE341 or T3/T4 hybrid will spool up nearly as fast as the stock T3 yet support everything the engine can flow.
A highly modded 606 at 6500rpm and 30psi of boost still flows less air than a factory stock 5.9L Cummins at 30psi and its natural 3200rpm redline. That means there is no reason an HX35/HY35/HE341 can't support "big power" with daily drivable manners.
Even BMW's "big" turbo is just a K26, the factory turbo on many of our engines.
04-08-2010, 12:53 AM
#9
(04-07-2010, 05:30 AM)ForcedInduction No it doesn't, you're missing the point.
No I'm not. I'm making the point.
A single stage compressor cannot extract peak performance from a passenger diesel engine. The engines airflow requirements have a wider range than a single stage compressor can acheive.
This is why we have staged turbos. They can provide boost over a wider range at better efficiency than any single stage compressor no matter how it is driven.
Doesn't matter if it's driven by a non-wastegated turbine, a wastegated turbine, a variable geometry turbine or even an electric motor. It can't change the fact that a single stage compressor has a limited performance envelope.
The rest of your post is irrelevant.
(04-07-2010, 05:30 AM)ForcedInduction No it doesn't, you're missing the point.
No I'm not. I'm making the point.
A single stage compressor cannot extract peak performance from a passenger diesel engine. The engines airflow requirements have a wider range than a single stage compressor can acheive.
This is why we have staged turbos. They can provide boost over a wider range at better efficiency than any single stage compressor no matter how it is driven.
Doesn't matter if it's driven by a non-wastegated turbine, a wastegated turbine, a variable geometry turbine or even an electric motor. It can't change the fact that a single stage compressor has a limited performance envelope.
The rest of your post is irrelevant.
04-08-2010, 08:36 AM
#10
(04-08-2010, 12:53 AM)Kiwibacon The rest of your post is irrelevant.
Far from it, it invalidates the argument for compounds. Proper matching of the turbo is required instead of just tossing on a BFT and "hoo wee, I've got 500hp at 7000rpm but 100hp below 5000rpm!"
As stated before, BMW's "big" turbo is simply a K26. If they can make 265hp using the same outdated and inefficient turbo found on many of our engines, there is no reason you can't make 300hp with a single turbo that will spool up as fast as the stock turbo.
Compound turbos aren't staged, they are for multiplying the pressure ratio to get high pressures. Low end performance is still limited by what HP turbo is used and the LP turbo won't spool until the second half of the RPM range anyways. PSI for PSI under 35 you'll be making LESS power than with a single because of the efficiency drop across multiple turbines and much higher compressed air temperature.
This post was last modified: 04-08-2010, 08:38 AM by ForcedInduction.
ForcedInduction
04-08-2010, 08:36 AM
#10
(04-08-2010, 12:53 AM)Kiwibacon The rest of your post is irrelevant.
Far from it, it invalidates the argument for compounds. Proper matching of the turbo is required instead of just tossing on a BFT and "hoo wee, I've got 500hp at 7000rpm but 100hp below 5000rpm!"
As stated before, BMW's "big" turbo is simply a K26. If they can make 265hp using the same outdated and inefficient turbo found on many of our engines, there is no reason you can't make 300hp with a single turbo that will spool up as fast as the stock turbo.
Compound turbos aren't staged, they are for multiplying the pressure ratio to get high pressures. Low end performance is still limited by what HP turbo is used and the LP turbo won't spool until the second half of the RPM range anyways. PSI for PSI under 35 you'll be making LESS power than with a single because of the efficiency drop across multiple turbines and much higher compressed air temperature.
04-11-2010, 12:44 AM
#11
(04-08-2010, 08:36 AM)ForcedInduction Far from it, it invalidates the argument for compounds. Proper matching of the turbo is required instead of just tossing on a BFT and "hoo wee, I've got 500hp at 7000rpm but 100hp below 5000rpm!"
That is exactly why they use compound turbos. Your arguments are switching around a great deal.
(04-08-2010, 08:36 AM)ForcedInduction As stated before, BMW's "big" turbo is simply a K26. If they can make 265hp using the same outdated and inefficient turbo found on many of our engines, there is no reason you can't make 300hp with a single turbo that will spool up as fast as the stock turbo.
Please post proof that BMW's current 535D engine is using the same K26 as your old mercs.
Please also post proof that this turbo compressor is inefficient.
(04-08-2010, 08:36 AM)ForcedInduction Compound turbos aren't staged, they are for multiplying the pressure ratio to get high pressures.
Semantics. Compound turbos with a wastegate are staged.
(04-08-2010, 08:36 AM)ForcedInduction Low end performance is still limited by what HP turbo is used and the LP turbo won't spool until the second half of the RPM range anyways. PSI for PSI under 35 you'll be making LESS power than with a single because of the efficiency drop across multiple turbines and much higher compressed air temperature.
You keep repeating this, yet it isn't true. I'm convinced you don't understand this topic.
Compounding lets you use a much smaller HP turbo, result is fast spoolup, high torque at low rpm and higher average power.
The HP turbo increases the engines airflow which spools the LP turbo much earlier than it would as a single turbo.
The boost combinations of the two turbos with naturally staged operation results in a combined compressor map which is wider, taller and more efficient than any single stage compressor.
This results in more power, not less. Do the maths.
Basically, the worlds diesel engine makers disagree with you on this topic. I do too.
(04-08-2010, 08:36 AM)ForcedInduction Far from it, it invalidates the argument for compounds. Proper matching of the turbo is required instead of just tossing on a BFT and "hoo wee, I've got 500hp at 7000rpm but 100hp below 5000rpm!"
That is exactly why they use compound turbos. Your arguments are switching around a great deal.
(04-08-2010, 08:36 AM)ForcedInduction As stated before, BMW's "big" turbo is simply a K26. If they can make 265hp using the same outdated and inefficient turbo found on many of our engines, there is no reason you can't make 300hp with a single turbo that will spool up as fast as the stock turbo.
Please post proof that BMW's current 535D engine is using the same K26 as your old mercs.
Please also post proof that this turbo compressor is inefficient.
(04-08-2010, 08:36 AM)ForcedInduction Compound turbos aren't staged, they are for multiplying the pressure ratio to get high pressures.
Semantics. Compound turbos with a wastegate are staged.
(04-08-2010, 08:36 AM)ForcedInduction Low end performance is still limited by what HP turbo is used and the LP turbo won't spool until the second half of the RPM range anyways. PSI for PSI under 35 you'll be making LESS power than with a single because of the efficiency drop across multiple turbines and much higher compressed air temperature.
You keep repeating this, yet it isn't true. I'm convinced you don't understand this topic.
Compounding lets you use a much smaller HP turbo, result is fast spoolup, high torque at low rpm and higher average power.
The HP turbo increases the engines airflow which spools the LP turbo much earlier than it would as a single turbo.
The boost combinations of the two turbos with naturally staged operation results in a combined compressor map which is wider, taller and more efficient than any single stage compressor.
This results in more power, not less. Do the maths.
Basically, the worlds diesel engine makers disagree with you on this topic. I do too.
04-11-2010, 09:20 PM
#12
Here's a good argument for combination turbos. I especially like how he set it up. It took me a while to figure out the piping but once I understood what he was doing I really felt he was on to something.
Check it out.
Derek
http://www.youtube.com/watch?v=y-Me6yWAp...re=related
Here's a good argument for combination turbos. I especially like how he set it up. It took me a while to figure out the piping but once I understood what he was doing I really felt he was on to something.
Check it out.
Derek
04-12-2010, 07:23 AM
#13
ForcedInduction
04-12-2010, 07:23 AM
#13
Jettmar, thats not a compound system. Its called a modulated 2-stage. Same thing BMW uses on the BMW 335d.
04-12-2010, 07:15 PM
#15
(04-12-2010, 07:02 PM)GREASY_BEAST Forced, why is that not a compound setup? It is two turbos, LP feeding HP, each with its own wastegate.. How is that different from compounds? Edit: basically, you just tweak the wastegates to keep the turbos in their maps and give you the airflow you want... Is a regular compound setup different somehow (i.e. no wastegates?)
It is a compound setup, they're just limiting boost to a very low level for a compound setup (22psi).
That video nicely sums up all the reasons that compound setups have benefits even at boost pressures that single turbos have no problems with.
(04-12-2010, 07:02 PM)GREASY_BEAST Forced, why is that not a compound setup? It is two turbos, LP feeding HP, each with its own wastegate.. How is that different from compounds? Edit: basically, you just tweak the wastegates to keep the turbos in their maps and give you the airflow you want... Is a regular compound setup different somehow (i.e. no wastegates?)
It is a compound setup, they're just limiting boost to a very low level for a compound setup (22psi).
That video nicely sums up all the reasons that compound setups have benefits even at boost pressures that single turbos have no problems with.
04-12-2010, 07:50 PM
#16
If you stop the video at 17 seconds have a look at the piping. After the ex manifold collector it 'y's to the small turbo (st) and to a wastegate dumping to the big turbo (BT). Before EMP reaches 22psi all exhaust is going through the st into the BT prespooling it. Once EMP reaches 22psi the wastegate opens and sends ALL exhaust to the BT so that removes and pressure from the st which therefore means the charge after 22psi is only flowing through the st, not being compressed by it. for it to be a true compound setup there is no wastegate 'between' the two turbos, there is wastegate protection for overboost but not in this manner.
'Jurgen' - 1982 300sd cream paint with palimino MB tex interior. Now running with new cooling system
.......discovered oil cooler has pinhole @#$%@
Nitrile gloves back on......'Otto' - 1985 300sd anthracite? grey/silver? with grey leather interior. (heated front seats!!!!
) Euro headlightsMods are in the works...
Telecommbrkr
04-12-2010, 07:50 PM #16Actually I think FI is correct it is staged. Listen to Marc explain the details, he mentions the external wastegate between the two turbos that dumps all exhaust to bigger turbo after 22psi.
If you stop the video at 17 seconds have a look at the piping. After the ex manifold collector it 'y's to the small turbo (st) and to a wastegate dumping to the big turbo (BT). Before EMP reaches 22psi all exhaust is going through the st into the BT prespooling it. Once EMP reaches 22psi the wastegate opens and sends ALL exhaust to the BT so that removes and pressure from the st which therefore means the charge after 22psi is only flowing through the st, not being compressed by it. for it to be a true compound setup there is no wastegate 'between' the two turbos, there is wastegate protection for overboost but not in this manner.
'Jurgen' - 1982 300sd cream paint with palimino MB tex interior. Now running with new cooling system
.......discovered oil cooler has pinhole @#$%@ Nitrile gloves back on......'Otto' - 1985 300sd anthracite? grey/silver? with grey leather interior. (heated front seats!!!!
) Euro headlightsMods are in the works...
04-12-2010, 07:58 PM
#17
(04-12-2010, 07:50 PM)Telecommbrkr Actually I think FI is correct it is staged. Listen to Marc explain the details, he mentions the external wastegate between the two turbos that dumps all exhaust to bigger turbo after 22psi.
The smaller turbo is always in the loop compressing air. Hence compound.
The wastegates are there for boost regulation. They don't send all the exhaust around the small turbo, that would require shutting off exhaust which doesn't happen. They just bypass enough to keep the boost under control. A wastegate for the small turbo and another for the large.
(04-12-2010, 07:50 PM)Telecommbrkr Actually I think FI is correct it is staged. Listen to Marc explain the details, he mentions the external wastegate between the two turbos that dumps all exhaust to bigger turbo after 22psi.
The smaller turbo is always in the loop compressing air. Hence compound.
The wastegates are there for boost regulation. They don't send all the exhaust around the small turbo, that would require shutting off exhaust which doesn't happen. They just bypass enough to keep the boost under control. A wastegate for the small turbo and another for the large.
04-12-2010, 08:04 PM
#18
(04-12-2010, 07:15 PM)Kiwibacon(04-12-2010, 07:02 PM)GREASY_BEAST Forced, why is that not a compound setup? It is two turbos, LP feeding HP, each with its own wastegate.. How is that different from compounds? Edit: basically, you just tweak the wastegates to keep the turbos in their maps and give you the airflow you want... Is a regular compound setup different somehow (i.e. no wastegates?)
It is a compound setup, they're just limiting boost to a very low level for a compound setup (22psi).
That video nicely sums up all the reasons that compound setups have benefits even at boost pressures that single turbos have no problems with.
I do agree that Marc does say some things that tell of the benefits to be gained from compounding. I do believe I will be trying this .............someday, when the usual time and money allow. The main idea of compounding that has stuck with me in some of the reasearching that I have done on the subject, is the fact that the 20 or 30+ psi of boost that I am looking for from such a set up can be achieved early in the powerband and maintained throughout the entire rev range consistenly, and neither turbo has to 'break a sweat' so to speak. When compared to variable turbos, yes they accomplish nearly the same effect, and are a little easier to set up, but I believe that they lack a possible robustness of tunability in regards to the combined turbo map potential of the two turbos.
Just my semi-informed opinion.....
'Jurgen' - 1982 300sd cream paint with palimino MB tex interior. Now running with new cooling system
.......discovered oil cooler has pinhole @#$%@ Nitrile gloves back on......'Otto' - 1985 300sd anthracite? grey/silver? with grey leather interior. (heated front seats!!!!
) Euro headlightsMods are in the works...
Telecommbrkr
04-12-2010, 08:04 PM #18(04-12-2010, 07:15 PM)Kiwibacon(04-12-2010, 07:02 PM)GREASY_BEAST Forced, why is that not a compound setup? It is two turbos, LP feeding HP, each with its own wastegate.. How is that different from compounds? Edit: basically, you just tweak the wastegates to keep the turbos in their maps and give you the airflow you want... Is a regular compound setup different somehow (i.e. no wastegates?)
It is a compound setup, they're just limiting boost to a very low level for a compound setup (22psi).
That video nicely sums up all the reasons that compound setups have benefits even at boost pressures that single turbos have no problems with.
I do agree that Marc does say some things that tell of the benefits to be gained from compounding. I do believe I will be trying this .............someday, when the usual time and money allow. The main idea of compounding that has stuck with me in some of the reasearching that I have done on the subject, is the fact that the 20 or 30+ psi of boost that I am looking for from such a set up can be achieved early in the powerband and maintained throughout the entire rev range consistenly, and neither turbo has to 'break a sweat' so to speak. When compared to variable turbos, yes they accomplish nearly the same effect, and are a little easier to set up, but I believe that they lack a possible robustness of tunability in regards to the combined turbo map potential of the two turbos.
Just my semi-informed opinion.....
'Jurgen' - 1982 300sd cream paint with palimino MB tex interior. Now running with new cooling system
.......discovered oil cooler has pinhole @#$%@ Nitrile gloves back on......'Otto' - 1985 300sd anthracite? grey/silver? with grey leather interior. (heated front seats!!!!
) Euro headlightsMods are in the works...
04-12-2010, 09:22 PM
#19
(04-12-2010, 08:04 PM)Telecommbrkr I do agree that Marc does say some things that tell of the benefits to be gained from compounding. I do believe I will be trying this .............someday, when the usual time and money allow. The main idea of compounding that has stuck with me in some of the reasearching that I have done on the subject, is the fact that the 20 or 30+ psi of boost that I am looking for from such a set up can be achieved early in the powerband and maintained throughout the entire rev range consistenly, and neither turbo has to 'break a sweat' so to speak. When compared to variable turbos, yes they accomplish nearly the same effect, and are a little easier to set up, but I believe that they lack a possible robustness of tunability in regards to the combined turbo map potential of the two turbos.
Just my semi-informed opinion.....
Very true and you've outlined the exact reasons why I've been scheming to run compounded turbos for about two years now.
I just go through times when I have the spare time to do it but no access to the gear needed. Then times when I have access to all the gear needed but no time.
(04-12-2010, 08:04 PM)Telecommbrkr I do agree that Marc does say some things that tell of the benefits to be gained from compounding. I do believe I will be trying this .............someday, when the usual time and money allow. The main idea of compounding that has stuck with me in some of the reasearching that I have done on the subject, is the fact that the 20 or 30+ psi of boost that I am looking for from such a set up can be achieved early in the powerband and maintained throughout the entire rev range consistenly, and neither turbo has to 'break a sweat' so to speak. When compared to variable turbos, yes they accomplish nearly the same effect, and are a little easier to set up, but I believe that they lack a possible robustness of tunability in regards to the combined turbo map potential of the two turbos.
Just my semi-informed opinion.....
Very true and you've outlined the exact reasons why I've been scheming to run compounded turbos for about two years now.
I just go through times when I have the spare time to do it but no access to the gear needed. Then times when I have access to all the gear needed but no time.
04-12-2010, 11:02 PM
#20
(04-12-2010, 07:02 PM)GREASY_BEAST Forced, why is that not a compound setup? It is two turbos, LP feeding HP, each with its own wastegate.
Quote:Listen to Marc explain the details, he mentions the external wastegate between the two turbos that dumps all exhaust to bigger turbo after 22psi.Exactly. He says right in the video the small turbo puts out 20psi and at 22psi "that wastegate goes wide open and it flows as much exhaust around the small turbo as it can".
If you stop the video at 17 seconds have a look at the piping. After the ex manifold collector it 'y's to the small turbo (st) and to a wastegate dumping to the big turbo (BT). Before EMP reaches 22psi all exhaust is going through the st into the BT prespooling it. Once EMP reaches 22psi the wastegate opens and sends ALL exhaust to the BT so that removes and pressure from the st which therefore means the charge after 22psi is only flowing through the st, not being compressed by it. for it to be a true compound setup there is no wastegate 'between' the two turbos, there is wastegate protection for overboost but not in this manner.
The HP turbo is bypassed out of the loop, allowing the LP turbo to take over the work. They are only compound in low rpm range to get the big turbo spinning without a dead spot in performance like with normal sequential turbos as exhaust flow flips over. Since there is only 2psi difference when the big turbo spools up, that means his setup is almost entirely a sequential system.
Quote:That video nicely sums up all the reasons that compound setups have benefits even at boost pressures that single turbos have no problems with.Except the exhaust efficiency loss, added weight and added intake air heat.
(04-12-2010, 07:58 PM)Kiwibacon They don't send all the exhaust around the small turbo, that would require shutting off exhaust which doesn't happen.They don't have to, BMW doesn't do it either. All they need to do is flow enough exhaust around the turbine for the pressures on the inlet and outlet of the turbine to equalize and there will be little flow (work done) across it. That functionally takes it out of the loop.
...
That wastegate doesn't block flow to the HP turbo, it merely dumps the "wasted" exhaust into the LP turbo.
As you can see, the small turbo still spins but its airflow drops and the pressure ratio goes to back to 1 (no compression).
This post was last modified: 04-12-2010, 11:05 PM by ForcedInduction.
ForcedInduction
04-12-2010, 11:02 PM
#20
(04-12-2010, 07:02 PM)GREASY_BEAST Forced, why is that not a compound setup? It is two turbos, LP feeding HP, each with its own wastegate.
Quote:Listen to Marc explain the details, he mentions the external wastegate between the two turbos that dumps all exhaust to bigger turbo after 22psi.Exactly. He says right in the video the small turbo puts out 20psi and at 22psi "that wastegate goes wide open and it flows as much exhaust around the small turbo as it can".
If you stop the video at 17 seconds have a look at the piping. After the ex manifold collector it 'y's to the small turbo (st) and to a wastegate dumping to the big turbo (BT). Before EMP reaches 22psi all exhaust is going through the st into the BT prespooling it. Once EMP reaches 22psi the wastegate opens and sends ALL exhaust to the BT so that removes and pressure from the st which therefore means the charge after 22psi is only flowing through the st, not being compressed by it. for it to be a true compound setup there is no wastegate 'between' the two turbos, there is wastegate protection for overboost but not in this manner.
The HP turbo is bypassed out of the loop, allowing the LP turbo to take over the work. They are only compound in low rpm range to get the big turbo spinning without a dead spot in performance like with normal sequential turbos as exhaust flow flips over. Since there is only 2psi difference when the big turbo spools up, that means his setup is almost entirely a sequential system.
Quote:That video nicely sums up all the reasons that compound setups have benefits even at boost pressures that single turbos have no problems with.Except the exhaust efficiency loss, added weight and added intake air heat.
(04-12-2010, 07:58 PM)Kiwibacon They don't send all the exhaust around the small turbo, that would require shutting off exhaust which doesn't happen.They don't have to, BMW doesn't do it either. All they need to do is flow enough exhaust around the turbine for the pressures on the inlet and outlet of the turbine to equalize and there will be little flow (work done) across it. That functionally takes it out of the loop.
...
That wastegate doesn't block flow to the HP turbo, it merely dumps the "wasted" exhaust into the LP turbo.
As you can see, the small turbo still spins but its airflow drops and the pressure ratio goes to back to 1 (no compression).
04-12-2010, 11:43 PM
#21
(04-12-2010, 11:02 PM)ForcedInduction Except the exhaust efficiency loss, added weight and added intake air heat.
You keep repeating this, but have offered no proof or explanation to backup these claims.
The weight is certainly valid, but given the lead panzer's that most here are driving around in, it's not exactly top priority.
The efficiency loss and added intake heat you keep claiming need proof.
The graph you keep trotting out is just one example of how a compound system can run. Attempting to apply it to all systems is a little foolhardy.
BTW, BMW's compound system is in at least it's third iteration. Their current system (I was at BMW Welt in Munich this February) externally bears little relation to the system they were using several years ago.
The BMW system is different in many aspects to the system in the video which we are currently discussing.
(04-12-2010, 11:02 PM)ForcedInduction Except the exhaust efficiency loss, added weight and added intake air heat.
You keep repeating this, but have offered no proof or explanation to backup these claims.
The weight is certainly valid, but given the lead panzer's that most here are driving around in, it's not exactly top priority.
The efficiency loss and added intake heat you keep claiming need proof.
The graph you keep trotting out is just one example of how a compound system can run. Attempting to apply it to all systems is a little foolhardy.
BTW, BMW's compound system is in at least it's third iteration. Their current system (I was at BMW Welt in Munich this February) externally bears little relation to the system they were using several years ago.
The BMW system is different in many aspects to the system in the video which we are currently discussing.
04-13-2010, 02:40 AM
#22
(04-12-2010, 11:43 PM)Kiwibacon You keep repeating this, but have offered no proof or explanation to backup these claims.Thats because you keep not reading my posts.
PSI for PSI, compounds are less efficient. They have many times more exhaust surface area (heat energy lost to the atmosphere), two pressure drops, two masses to overcome inertia, two stages of compression adding their own heat to the air and the added vehicle weight.
Compounds at sea level, each working at a 1.7 pressure ratio.
LP turbo
10psi@65% efficiency
Temp out at 85*f ambient: 221*f
HP turbo
16psi out
197*f gain, 386*f outlet temperature
----
A single turbo @16psi will be 280*f.
So to get the same boost you're adding an extra 100*f to the intake air. To get the same airflow as the single you'll have to make even more boost which means even higher energy losses.
Quote:The graph you keep trotting out is just one example of how a compound system can run. Attempting to apply it to all systems is a little foolhardy.I'm not attempting to apply them to anything, its what people keep building!
Quote:Their current system (I was at BMW Welt in Munich this February) externally bears little relation to the system they were using several years ago.Which is the one being discussed.
Quote:The BMW system is different in many aspects to the system in the video which we are currently discussing.Right, BMW actually has a compound mode that makes 42psi of boost for a brief period. Functionally, they are identical. The difference is in timing of the exhaust bypass.
This post was last modified: 04-13-2010, 02:43 AM by ForcedInduction.
ForcedInduction
04-13-2010, 02:40 AM
#22
(04-12-2010, 11:43 PM)Kiwibacon You keep repeating this, but have offered no proof or explanation to backup these claims.Thats because you keep not reading my posts.
PSI for PSI, compounds are less efficient. They have many times more exhaust surface area (heat energy lost to the atmosphere), two pressure drops, two masses to overcome inertia, two stages of compression adding their own heat to the air and the added vehicle weight.
Compounds at sea level, each working at a 1.7 pressure ratio.
LP turbo
10psi@65% efficiency
Temp out at 85*f ambient: 221*f
HP turbo
16psi out
197*f gain, 386*f outlet temperature
----
A single turbo @16psi will be 280*f.
So to get the same boost you're adding an extra 100*f to the intake air. To get the same airflow as the single you'll have to make even more boost which means even higher energy losses.
Quote:The graph you keep trotting out is just one example of how a compound system can run. Attempting to apply it to all systems is a little foolhardy.I'm not attempting to apply them to anything, its what people keep building!
Quote:Their current system (I was at BMW Welt in Munich this February) externally bears little relation to the system they were using several years ago.Which is the one being discussed.
Quote:The BMW system is different in many aspects to the system in the video which we are currently discussing.Right, BMW actually has a compound mode that makes 42psi of boost for a brief period. Functionally, they are identical. The difference is in timing of the exhaust bypass.
04-13-2010, 03:01 AM
#23
(04-13-2010, 02:40 AM)ForcedInduction Thats because you keep not reading my posts.
PSI for PSI, compounds are less efficient. They have many times more exhaust surface area (heat energy lost to the atmosphere), two pressure drops, two masses to overcome inertia, two stages of compression adding their own heat to the air and the added vehicle weight.
Compounds at sea level, each working at a 1.7 pressure ratio.
LP turbo
10psi@65% efficiency
Temp out at 85*f ambient: 221*f
HP turbo
16psi out
197*f gain, 386*f outlet temperature
----
A single turbo @16psi will be 280*f.
Your maths is wrong.
A single compressor at 65% sucking on 29C air produces 137C (278F) output air. You got that bit right.
Total temp rise is 108C
A LP turbo pushing 10psi on the same intake would produce air at 103C, the HP turbo sucking on that produces air at 140C (284F). Not the 386F which you are claiming.
The difference is a whole 3 DEGREES CELSIUS
Far more than that whole 3C gain from the mathematical model will be radiated away from the piping between the two.
So yeah. Time to find the error in your calcs and rethink your turbo theory.
This post was last modified: 04-13-2010, 03:03 AM by Kiwibacon.
(04-13-2010, 02:40 AM)ForcedInduction Thats because you keep not reading my posts.
PSI for PSI, compounds are less efficient. They have many times more exhaust surface area (heat energy lost to the atmosphere), two pressure drops, two masses to overcome inertia, two stages of compression adding their own heat to the air and the added vehicle weight.
Compounds at sea level, each working at a 1.7 pressure ratio.
LP turbo
10psi@65% efficiency
Temp out at 85*f ambient: 221*f
HP turbo
16psi out
197*f gain, 386*f outlet temperature
----
A single turbo @16psi will be 280*f.
Your maths is wrong.
A single compressor at 65% sucking on 29C air produces 137C (278F) output air. You got that bit right.
Total temp rise is 108C
A LP turbo pushing 10psi on the same intake would produce air at 103C, the HP turbo sucking on that produces air at 140C (284F). Not the 386F which you are claiming.
The difference is a whole 3 DEGREES CELSIUS
Far more than that whole 3C gain from the mathematical model will be radiated away from the piping between the two.
So yeah. Time to find the error in your calcs and rethink your turbo theory.
04-13-2010, 03:43 AM
#24
(04-13-2010, 03:01 AM)Kiwibacon A LP turbo pushing 10psi on the same intake would produce air at 103C, the HP turbo sucking on that produces air at 140C (284F).Your math is wrong.
You're not taking into account the HP turbo's inlet temperature and still calculating with ambient.
Doing as you did with a 30c inlet temperature and 24psi absolute pressure, I come up with 103*c as well.
Doing it correctly with a 108*c inlet temperature, surprise, 200*c.
So you're right, I had an error in my math, I listed the HP turbo's outlet temperature to be too cool!
This post was last modified: 04-13-2010, 03:49 AM by ForcedInduction.
ForcedInduction
04-13-2010, 03:43 AM
#24
(04-13-2010, 03:01 AM)Kiwibacon A LP turbo pushing 10psi on the same intake would produce air at 103C, the HP turbo sucking on that produces air at 140C (284F).Your math is wrong.
You're not taking into account the HP turbo's inlet temperature and still calculating with ambient.
Doing as you did with a 30c inlet temperature and 24psi absolute pressure, I come up with 103*c as well.
Doing it correctly with a 108*c inlet temperature, surprise, 200*c.
So you're right, I had an error in my math, I listed the HP turbo's outlet temperature to be too cool!
04-13-2010, 04:48 AM
#25
(04-13-2010, 03:43 AM)ForcedInduction Your math is wrong.
You're not taking into account the HP turbo's inlet temperature and still calculating with ambient.
Doing as you did with a 30c inlet temperature and 24psi absolute pressure, I come up with 103*c as well.
Doing it correctly with a 108*c inlet temperature, surprise, 200*c.
So you're right, I had an error in my math, I listed the HP turbo's outlet temperature to be too cool!
Nope. There's a serious error in your calcs and you still haven't found it. Keep looking. Start with pressure ratios and go from there.
My calculation sets are correct, they've been verified by others.
The HP turbo is only working at PR of 1.24 (equivalent to 3.5psi), which is why it's adding such a small amount of heat (37C).
Expecting a turbo doing such little work to add 97C is truely ridiculous. I suggest checking not only your calculations but reality as well.
(04-13-2010, 03:43 AM)ForcedInduction Your math is wrong.
You're not taking into account the HP turbo's inlet temperature and still calculating with ambient.
Doing as you did with a 30c inlet temperature and 24psi absolute pressure, I come up with 103*c as well.
Doing it correctly with a 108*c inlet temperature, surprise, 200*c.
So you're right, I had an error in my math, I listed the HP turbo's outlet temperature to be too cool!
Nope. There's a serious error in your calcs and you still haven't found it. Keep looking. Start with pressure ratios and go from there.
My calculation sets are correct, they've been verified by others.
The HP turbo is only working at PR of 1.24 (equivalent to 3.5psi), which is why it's adding such a small amount of heat (37C).
Expecting a turbo doing such little work to add 97C is truely ridiculous. I suggest checking not only your calculations but reality as well.
04-13-2010, 05:27 AM
#26
(04-13-2010, 04:48 AM)Kiwibacon There's a serious error in your calcs and you still haven't found it.Sorry bud, bad math on your part doesn't mean an error on mine.
Quote:My calculation sets are correct, they've been verified by others.I have yet to see any "others" post their math. In fact, I haven't even seen you post YOUR math.
Quote:The HP turbo is only working at PR of 1.24 (equivalent to 3.5psi), which is why it's adding such a small amount of heat (37C).3.5psi makes compounds even more of a waste! At such a low ratio you'll just be running the turbo in its choke range, reducing its compression efficiency even more.
The entire basis of compounding is to split the compression load. Running such a low pressure in the primary turbo won't even compensate for the added parasitic and heat losses.
ForcedInduction
04-13-2010, 05:27 AM
#26
(04-13-2010, 04:48 AM)Kiwibacon There's a serious error in your calcs and you still haven't found it.Sorry bud, bad math on your part doesn't mean an error on mine.
Quote:My calculation sets are correct, they've been verified by others.I have yet to see any "others" post their math. In fact, I haven't even seen you post YOUR math.
Quote:The HP turbo is only working at PR of 1.24 (equivalent to 3.5psi), which is why it's adding such a small amount of heat (37C).3.5psi makes compounds even more of a waste! At such a low ratio you'll just be running the turbo in its choke range, reducing its compression efficiency even more.
The entire basis of compounding is to split the compression load. Running such a low pressure in the primary turbo won't even compensate for the added parasitic and heat losses.
04-13-2010, 03:23 PM
#27
If you guys have spreadsheets, you should post em! that way if there are mistakes folks can find them. It would be alot more constructive than this "you're wrong", "no you're wrong", "no you're wrong!" nonsense.
btw, has anyone found errors in mine?
It seems to me that turbos plumbed in this manner could be operated either as "compounds" or "modulated twins" pretty easily, and that the two modes of operation are not exclusive of each other, so the system could be somewhere in between and possibly get some of the benefits of each.
fuck it. Im building the damn thing. Then at least we can argue over actual results.
has anyone welded stainless headers with 75/25 argon/co2? If so, how did it turn out? Did/do you have any corrosion/brittleness at your joints?
lol, I get different numbers than both of you.
If you guys have spreadsheets, you should post em! that way if there are mistakes folks can find them. It would be alot more constructive than this "you're wrong", "no you're wrong", "no you're wrong!" nonsense.
btw, has anyone found errors in mine?
It seems to me that turbos plumbed in this manner could be operated either as "compounds" or "modulated twins" pretty easily, and that the two modes of operation are not exclusive of each other, so the system could be somewhere in between and possibly get some of the benefits of each.
fuck it. Im building the damn thing. Then at least we can argue over actual results.
has anyone welded stainless headers with 75/25 argon/co2? If so, how did it turn out? Did/do you have any corrosion/brittleness at your joints?
04-13-2010, 05:28 PM
#28
(04-13-2010, 05:27 AM)ForcedInduction 3.5psi makes compounds even more of a waste! At such a low ratio you'll just be running the turbo in its choke range, reducing its compression efficiency even more.
Um Lance, this is the example you provided.
You were comparing 16psi on a single to 16psi on compounds with 10psi across the LP compressor.
To provide such an example, then say it was a waste is the dumbest thing I have read today.
Unfortunately I read some really dumb stuff on Pirate4x4 yesterday so it doesn't take this weeks prize.
And no, the people I used to verify my calcs are not on this forum. Nor am I giving away my calculation sheets.
(04-13-2010, 03:23 PM)shredator lol, I get different numbers than both of you.
If you guys have spreadsheets, you should post em! that way if there are mistakes folks can find them. It would be alot more constructive than this "you're wrong", "no you're wrong", "no you're wrong!" nonsense.
btw, has anyone found errors in mine?
Where are your figures? I didn't see them but I'm more than happy to check them through.
Depending of course if toys get thrown and I get banned. Because I'm honestly past caring.
(04-13-2010, 03:23 PM)shredator It seems to me that turbos plumbed in this manner could be operated either as "compounds" or "modulated twins" pretty easily, and that the two modes of operation are not exclusive of each other, so the system could be somewhere in between and possibly get some of the benefits of each.
Exactly. But you need bypass valves on the compressor side as well to run them as true parrallel turbos.
(04-13-2010, 03:23 PM)shredator has anyone welded stainless headers with 75/25 argon/co2? If so, how did it turn out? Did/do you have any corrosion/brittleness at your joints?
Honestly, stainless isn't a good material for headers. IMO it's for show cars. Make them out of steam pipe with weld in bends and ceramic coat them.
This post was last modified: 04-13-2010, 05:32 PM by Kiwibacon.
(04-13-2010, 05:27 AM)ForcedInduction 3.5psi makes compounds even more of a waste! At such a low ratio you'll just be running the turbo in its choke range, reducing its compression efficiency even more.
Um Lance, this is the example you provided.
You were comparing 16psi on a single to 16psi on compounds with 10psi across the LP compressor.
To provide such an example, then say it was a waste is the dumbest thing I have read today.
Unfortunately I read some really dumb stuff on Pirate4x4 yesterday so it doesn't take this weeks prize.
And no, the people I used to verify my calcs are not on this forum. Nor am I giving away my calculation sheets.
(04-13-2010, 03:23 PM)shredator lol, I get different numbers than both of you.
If you guys have spreadsheets, you should post em! that way if there are mistakes folks can find them. It would be alot more constructive than this "you're wrong", "no you're wrong", "no you're wrong!" nonsense.
btw, has anyone found errors in mine?
Where are your figures? I didn't see them but I'm more than happy to check them through.
Depending of course if toys get thrown and I get banned. Because I'm honestly past caring.
(04-13-2010, 03:23 PM)shredator It seems to me that turbos plumbed in this manner could be operated either as "compounds" or "modulated twins" pretty easily, and that the two modes of operation are not exclusive of each other, so the system could be somewhere in between and possibly get some of the benefits of each.
Exactly. But you need bypass valves on the compressor side as well to run them as true parrallel turbos.
(04-13-2010, 03:23 PM)shredator has anyone welded stainless headers with 75/25 argon/co2? If so, how did it turn out? Did/do you have any corrosion/brittleness at your joints?
Honestly, stainless isn't a good material for headers. IMO it's for show cars. Make them out of steam pipe with weld in bends and ceramic coat them.
04-13-2010, 10:17 PM
#29
(04-13-2010, 02:40 AM)ForcedInduction Compounds at sea level, each working at a 1.7 pressure ratio.
LP turbo
10psi@65% efficiency
Temp out at 85*f ambient: 221*f
HP turbo
16psi out
197*f gain, 386*f outlet temperature
----
A single turbo @16psi will be 280*f.
If you're still looking for those maths errors, we can start with the numbers posted above.
16psi is a PR of 2.1 at sea-level.
For some unknown reason you're trying to compare that to compounds running at PR of 1.7 each.
That would produce a PR of 2.9, which is 28psi boost at sealevel.
So 28psi does not equal 16psi.
1.7x1.7 does not equal 2.1
Only when you can get pressure ratios right can you migrate onto trickier things.
(04-13-2010, 02:40 AM)ForcedInduction Compounds at sea level, each working at a 1.7 pressure ratio.
LP turbo
10psi@65% efficiency
Temp out at 85*f ambient: 221*f
HP turbo
16psi out
197*f gain, 386*f outlet temperature
----
A single turbo @16psi will be 280*f.
If you're still looking for those maths errors, we can start with the numbers posted above.
16psi is a PR of 2.1 at sea-level.
For some unknown reason you're trying to compare that to compounds running at PR of 1.7 each.
That would produce a PR of 2.9, which is 28psi boost at sealevel.
So 28psi does not equal 16psi.
1.7x1.7 does not equal 2.1
Only when you can get pressure ratios right can you migrate onto trickier things.
04-15-2010, 04:44 PM
#30
(04-13-2010, 05:28 PM)Kiwibacon Where are your figures? I didn't see them but I'm more than happy to check them through.not sure what you mean by 'figures'... you can download my spreadsheet at the bottom of the first post. the columns on the right show the volume flow rates and mass flow rates at the various locations in the system. So, pick the column for the units that you want, and go to the row for the location in the system that you want. some of the colums display metric units, so hopefully you wont have to convert those. There are also maps for the gt2056v and the he351ve pasted into the spreadsheet, but nothing gets plotted on them automatically.
(04-13-2010, 05:28 PM)Kiwibacon Honestly, stainless isn't a good material for headers. IMO it's for show cars.Can you elaborate? What are the drawbacks, other than cost, and the fact that you cant use 75/25? It wasnt really that much more expensive, and slight additional cost seemed to be worth the corrosion protection to me. Now I realize that I will probably have to TIG it. That makes me wish that I just went with mild steel, cause I suck at TIG.
(04-13-2010, 05:28 PM)Kiwibacon Where are your figures? I didn't see them but I'm more than happy to check them through.not sure what you mean by 'figures'... you can download my spreadsheet at the bottom of the first post. the columns on the right show the volume flow rates and mass flow rates at the various locations in the system. So, pick the column for the units that you want, and go to the row for the location in the system that you want. some of the colums display metric units, so hopefully you wont have to convert those. There are also maps for the gt2056v and the he351ve pasted into the spreadsheet, but nothing gets plotted on them automatically.
(04-13-2010, 05:28 PM)Kiwibacon Honestly, stainless isn't a good material for headers. IMO it's for show cars.Can you elaborate? What are the drawbacks, other than cost, and the fact that you cant use 75/25? It wasnt really that much more expensive, and slight additional cost seemed to be worth the corrosion protection to me. Now I realize that I will probably have to TIG it. That makes me wish that I just went with mild steel, cause I suck at TIG.
04-15-2010, 05:13 PM
#31
(04-15-2010, 04:44 PM)shredator(04-13-2010, 05:28 PM)Kiwibacon Where are your figures? I didn't see them but I'm more than happy to check them through.not sure what you mean by 'figures'... you can download my spreadsheet at the bottom of the first post. the columns on the right show the volume flow rates and mass flow rates at the various locations in the system. So, pick the column for the units that you want, and go to the row for the location in the system that you want. some of the colums display metric units, so hopefully you wont have to convert those. There are also maps for the gt2056v and the he351ve pasted into the spreadsheet, but nothing gets plotted on them automatically.
(04-13-2010, 05:28 PM)Kiwibacon Honestly, stainless isn't a good material for headers. IMO it's for show cars.Can you elaborate? What are the drawbacks, other than cost, and the fact that you cant use 75/25? It wasnt really that much more expensive, and slight additional cost seemed to be worth the corrosion protection to me. Now I realize that I will probably have to TIG it. That makes me wish that I just went with mild steel, cause I suck at TIG.
Oh yeah sorry. I downloaded that spreadsheet a while back and your figures looked good. To check them properly I'd have to convert them all to metric and I didn't feel like doing that for all of it.
I did run through the figures and for column D on yours (PR2 for LP and PR 1.9 for HP with 70% effective cooling before and after).
My numbers matched within about 2 degrees everywhere, which is just rounding and conversion errors.
Keep in mind that the variable vane turbos use different compressors to the wastegated turbos which garrett supply maps for. They're still good for planning but don't take them as gospel. If indeed you believe in gospel.
For stainless:
It's not good for high temps because it grows 50% more than carbon steel in expansion and doesn't have the ductility needed. I think you'll have cracking problems.
For the exhaust after the turbo stainless will do fine. It's not constrained so expansion won't cause it to thermal cycle itself to death and the temps there are lower.
(04-15-2010, 04:44 PM)shredator(04-13-2010, 05:28 PM)Kiwibacon Where are your figures? I didn't see them but I'm more than happy to check them through.not sure what you mean by 'figures'... you can download my spreadsheet at the bottom of the first post. the columns on the right show the volume flow rates and mass flow rates at the various locations in the system. So, pick the column for the units that you want, and go to the row for the location in the system that you want. some of the colums display metric units, so hopefully you wont have to convert those. There are also maps for the gt2056v and the he351ve pasted into the spreadsheet, but nothing gets plotted on them automatically.
(04-13-2010, 05:28 PM)Kiwibacon Honestly, stainless isn't a good material for headers. IMO it's for show cars.Can you elaborate? What are the drawbacks, other than cost, and the fact that you cant use 75/25? It wasnt really that much more expensive, and slight additional cost seemed to be worth the corrosion protection to me. Now I realize that I will probably have to TIG it. That makes me wish that I just went with mild steel, cause I suck at TIG.
Oh yeah sorry. I downloaded that spreadsheet a while back and your figures looked good. To check them properly I'd have to convert them all to metric and I didn't feel like doing that for all of it.
I did run through the figures and for column D on yours (PR2 for LP and PR 1.9 for HP with 70% effective cooling before and after).
My numbers matched within about 2 degrees everywhere, which is just rounding and conversion errors.
Keep in mind that the variable vane turbos use different compressors to the wastegated turbos which garrett supply maps for. They're still good for planning but don't take them as gospel. If indeed you believe in gospel.
For stainless:
It's not good for high temps because it grows 50% more than carbon steel in expansion and doesn't have the ductility needed. I think you'll have cracking problems.
For the exhaust after the turbo stainless will do fine. It's not constrained so expansion won't cause it to thermal cycle itself to death and the temps there are lower.
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