New BW EFR Turbo Thread
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From: Redmond Washington
So what I think happened was, BW said we want to only go as big as 2.5" to help packaging and we therefore need the big trim wheel to get more flow. So I bet all the 70-83mm EFR wheels have ported shrouds in their compressor housings and therefore they could trim the wheels down to 56 trim. So it shows how dramatic the effect on compressor performance the ported shroud has.
What the ported inlet does do that is great is move the surge line further to the left. In some cases much further to the left.
This is an area where I think the GTX turbos are a little weak - that is, even though they have ported inlets for surge control, they still have a surge line that is quite far to the right, making for a map that is a little narrow left-to-right.
For example, in the dyno post made a few weeks ago by 240Z Twin Turbo using a GTX, 240 states that there was surge at the top of the spoolup region, and you can see it in the dyno plot. I'm sure that if you plotted a point from that region on the compressor map for the turbo he was using, you would see that the point is way left of the surge line. Whereas, the same operating point on an EFR7670 would probably be ok - within the map.
Last edited by Talonboost; May 17, 2013 at 11:47 AM.
Check them out a 3.0 PR. The housing with the ported shroud has a range of ~35-67 lbs/min. The non-ported shroud housing is only 40-59 lbs/min. So the ported shroud improved both surge and choke giving much wider map width at 3.0 PR. The ported shroud location, slot width, and angle all affect the map. You can adjust those parameters to tweak the compressor performance.
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From: Redmond Washington
Actually, go back and look at the ported shroud and non-ported shroud compressor maps for the GT3582R I posted
Check them out a 3.0 PR. The housing with the ported shroud has a range of ~35-67 lbs/min. The non-ported shroud housing is only 40-59 lbs/min. So the ported shroud improved both surge and choke giving much wider map width at 3.0 PR. The ported shroud location, slot width, and angle all affect the map. You can adjust those parameters to tweak the compressor performance.
Check them out a 3.0 PR. The housing with the ported shroud has a range of ~35-67 lbs/min. The non-ported shroud housing is only 40-59 lbs/min. So the ported shroud improved both surge and choke giving much wider map width at 3.0 PR. The ported shroud location, slot width, and angle all affect the map. You can adjust those parameters to tweak the compressor performance.
However, I don't know what to make of it really. This is something new.
If you read Garrett Turbo Tech 103, in the section where it discusses ported shroud, it says this: "The presence of the ported shroud usually has a minor negative impact on compressor efficiency."
Then they show a picture of 2 compressor maps laid over each other for comparison, 1 ported, the other not, the ported lines are red, the non-ported lines are black. They are radically different on the left side of the map, but on the right side of the map they go to almost exactly the same right-hand extreme. You can't read any of the numbers in this fuzzy picture unfortunately.
http://www.turbobygarrett.com/turbob...Tech%20103.pdf
I also have a comparison of ported vs non-ported inlet from Borg Warner, based on the Airwerks S200sx-7670. This shows the non-ported going further to the right at high pressure ratios and having better efficiency numbers at every point on the right side of the map. Then of course the ported one is much more favorable on the left side of the map and goes much further to the left. This map is not labeled completely. I was told what it meant by email, then got confirmation of the description from Kurt Henderson at Borg Warner. I'll post the map here.
The black lines are the ported, blue lines are the non-ported. Near the right edge of the map you can (barely) make out that the non-ported lines are about 2% more efficient than the ported lines in the same location.
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Last edited by Talonboost; Jun 22, 2013 at 01:35 PM. Reason: .70 a/r compressor housing, not turbine housing, silly.
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From: Redmond Washington
Going back to the GT3582 maps, I haven't seen the ones you posted, but the ones I see on the Garrett web site - they are a mess - Garrett makes the lines nice and then just splatters numbers all over the page good luck! But what you can see is a little suspicious.
The one for the ported shroud has an extra speed line at the top of the map that the non-ported map doesn't have. 136,046 rpm vs 116,891 rpm. Wow.
Also with the efficiency isolines, the farthest one to the right for the ported shroud looks like 60%, vs 65% for the farthest right one for the non-ported.
Doesn't look like apples to apples.
The one for the ported shroud has an extra speed line at the top of the map that the non-ported map doesn't have. 136,046 rpm vs 116,891 rpm. Wow.
Also with the efficiency isolines, the farthest one to the right for the ported shroud looks like 60%, vs 65% for the farthest right one for the non-ported.
Doesn't look like apples to apples.
The maps I linked are off of turbobygarrett.com. Go to 'products' > turbochargers> and go through the different variations of the GT3582. And under the 'performance maps' tab, you can bring up the maps.
On the non-ported shroud, good eye on it not having the 135k speed line like the ported shroud map has. Both maps have 111k speed lines, and the ported shroud looks to be at around 63lbs/min vs. ~60 for the non. If you do a rough extrapolation on the non-ported map to 135k, it would probably be around 64-65lbs/min, still less than the ported shroud map.
But like I said, depending on how far down the wheel axially the slot is located, the width of the slot, and the angle of the slot, it tweaks the map. You can design the slot to give better surge, or bias it towards more choke, or compromise for some type of middle ground.
On the BW maps you have overlaid, it appears they went only for improved surge and were content with the choke flow.
These are all good examples of just what a ported shroud can do. They are like a sway bar for suspension tuning; depending on the design (diameter) of the sway bar and then whatever adjustable mounting hole options, you can tweak the handling of the car. Just saying a car has a sway bar doesn't tell much. Is it bigger? Smaller? Does it tune for more understeer or oversteer? And just like sway bars, just saying there is a ported shroud doesn't automatically mean only surge is improved. They can be tuned for more choke too.
On the non-ported shroud, good eye on it not having the 135k speed line like the ported shroud map has. Both maps have 111k speed lines, and the ported shroud looks to be at around 63lbs/min vs. ~60 for the non. If you do a rough extrapolation on the non-ported map to 135k, it would probably be around 64-65lbs/min, still less than the ported shroud map.
But like I said, depending on how far down the wheel axially the slot is located, the width of the slot, and the angle of the slot, it tweaks the map. You can design the slot to give better surge, or bias it towards more choke, or compromise for some type of middle ground.
On the BW maps you have overlaid, it appears they went only for improved surge and were content with the choke flow.
These are all good examples of just what a ported shroud can do. They are like a sway bar for suspension tuning; depending on the design (diameter) of the sway bar and then whatever adjustable mounting hole options, you can tweak the handling of the car. Just saying a car has a sway bar doesn't tell much. Is it bigger? Smaller? Does it tune for more understeer or oversteer? And just like sway bars, just saying there is a ported shroud doesn't automatically mean only surge is improved. They can be tuned for more choke too.
Last edited by spdracerut; May 18, 2013 at 03:38 PM.
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From: Redmond Washington
Yeah, they both have speed lines at about 116,900 rpm also, and the difference there looks to be 2 or 3 lbs per min in favor of the ported version.
These maps though, my god, for one thing on the ported version I can't read any of the efficiency labels that are immediately left of the 60% line. Even in the pdf catalog it's no better quality picture.
I do have a copy of the non-ported one from 2006 that appears to be a non-dumbed-down copy - you can actually read it.
The other thing about these maps, they were made how many years apart? Quite a few. I have some old Garrett pdf catalogs saved on my computer. As recently as 2008 the ported 3582 didn't exist. At that time the -1, -2, -3 were all using the non-ported inlet.
Maybe Garrett should re-evaluate whether their statement in turbo-tech 103 is still correct - that "The presence of the ported shroud usually has a minor negative impact on compressor efficiency." If they have learned a few new tricks about this they might want to let us know! Or maybe the statement is still true, and there are some other things going on here that we don't know about.
These maps though, my god, for one thing on the ported version I can't read any of the efficiency labels that are immediately left of the 60% line. Even in the pdf catalog it's no better quality picture.
I do have a copy of the non-ported one from 2006 that appears to be a non-dumbed-down copy - you can actually read it.
The other thing about these maps, they were made how many years apart? Quite a few. I have some old Garrett pdf catalogs saved on my computer. As recently as 2008 the ported 3582 didn't exist. At that time the -1, -2, -3 were all using the non-ported inlet.
Maybe Garrett should re-evaluate whether their statement in turbo-tech 103 is still correct - that "The presence of the ported shroud usually has a minor negative impact on compressor efficiency." If they have learned a few new tricks about this they might want to let us know! Or maybe the statement is still true, and there are some other things going on here that we don't know about.
What can I say, if you want to talk about the finer details of a compressor flow map, you need to include all the finer details.
Garrett corrects to a CONSIDERABLY less dense inlet condition which has an appreciable impact on rated airflow. Seems like it was 5-6% or so just on inlet conditions alone. Then add in WHERE they take “choke flow” at and some turbochargers seem comparable at first glance of the marketing material, but are not even close when compared evenly with hard numbers.
Comparing hard numbers, the GTX wheels out flow the EFR wheels (inducer for inducer) at a given maxium flow @ efficency limit.
I'd compare by exducers, but with the extended tips, it's kind of misleading anyway as sure, the back plate might be 71mm, but tip diameter might be 71mm or 75mm and there is no real way to know by the marketing data. I think my GTX3071R measured out at like 73.5mm exducer but they still call it a 71mm wheel, for example. It's smart engineering though, the flow of the larger wheel, the inertia of the smaller wheel.
Last edited by 03whitegsr; May 21, 2013 at 04:14 PM.
Nice, thank you.
If it came across as insinuating they are trying intentionally to mislead, I apologize. I meant it more like "hey, something ****y is going on here" in more of a skeptical sense. Garrett and BW are using very different conditions and limits to suggest airflow capability though and that is what I was pointing out. And really, let's be realistic, the max airflow is listed clearly on the compressor flow map in an effort to provide a number that people are use to hearing and that number sways the judgement in favor of the BW due to an uneven playing field to the uninformed, intentional or not. I also stated why I believe Garrett uses 13.9 PSI, I imagine it is based on the idea that a typical OEM turbo inlet system is going to have about that range of inlet pressure under service conditions.
But let's get to the rest of the statement where I supposedly don't understand what's going on.
I can admit when I'm wrong, and actually, I did make a mistake here. I pulled those numbers straight out of the matchbot program. Where I made the actual mistake was I had forgotten to zero out the air filter pressure drop setting. My numbers are off, as I basically corrected for 13.75 psia. I apologize for the mistake and will update that chart (taking it down until I get around to it as well) accordingly, however, I understand far better then most how this works, the fact I even mention these subtleties should clue you in to that.
I still disagree with the 2.7% number you posted though. It's actually closer to 4.1% using the matchbot program. Put the numbers in and try it for your self. Either their program is wrong...or hey, I guess I'm still missing a setting in there. This time I was pretty careful to double check it though. Now, I did toss in some numbers really quick to good old PV=mRT to find density as-> P/T = mR/V and interestingly enough, it's a 5.8% difference between the two conditions still...weird.
85F - 13.95 PSIA = 1.1075 kg/m^3
75F - 14.5 PSIA = 1.1727 kg/m^3
1.1727 / 1.1075 = 1.058 or 5.8%
Or (1.1727 - 1.1075)/1.1727 = 5.6%
Or (1.1075 - 1.1727)/1.1075 = -5.9%
I mean, I don't get 2.7% no matter how I look at it. Maybe they can explain where I'm wrong here.
Beyond that though, I never once said either of the turbos reached a true choke flow limit. I simply pointed out the airflow rating you are use to hearing from Garrett are based on the maximum airflow that can be pumped out at 60% efficiency...regardless of pressure ratio and the number printed on the BW charts is not based on the same standards.
Do you dispute that claim?
Also, I don't disagree, Garrett's standard seems arbitrary and 100kPa and 25C is much more standard...but that's not really the point. The point is putting the comparison on a level field, regardless of why it is not level to start with. Also, frankly, I'm surprised I haven't seen this mentioned yet as, really, all we have at this point is compressor flow maps and a few random cars to look at for data. I would think these peculiarities would have been talked about and carefully explained to properly inform potential customers.
If it came across as insinuating they are trying intentionally to mislead, I apologize. I meant it more like "hey, something ****y is going on here" in more of a skeptical sense. Garrett and BW are using very different conditions and limits to suggest airflow capability though and that is what I was pointing out. And really, let's be realistic, the max airflow is listed clearly on the compressor flow map in an effort to provide a number that people are use to hearing and that number sways the judgement in favor of the BW due to an uneven playing field to the uninformed, intentional or not. I also stated why I believe Garrett uses 13.9 PSI, I imagine it is based on the idea that a typical OEM turbo inlet system is going to have about that range of inlet pressure under service conditions.
But let's get to the rest of the statement where I supposedly don't understand what's going on.
I can admit when I'm wrong, and actually, I did make a mistake here. I pulled those numbers straight out of the matchbot program. Where I made the actual mistake was I had forgotten to zero out the air filter pressure drop setting. My numbers are off, as I basically corrected for 13.75 psia. I apologize for the mistake and will update that chart (taking it down until I get around to it as well) accordingly, however, I understand far better then most how this works, the fact I even mention these subtleties should clue you in to that.
I still disagree with the 2.7% number you posted though. It's actually closer to 4.1% using the matchbot program. Put the numbers in and try it for your self. Either their program is wrong...or hey, I guess I'm still missing a setting in there. This time I was pretty careful to double check it though. Now, I did toss in some numbers really quick to good old PV=mRT to find density as-> P/T = mR/V and interestingly enough, it's a 5.8% difference between the two conditions still...weird.
85F - 13.95 PSIA = 1.1075 kg/m^3
75F - 14.5 PSIA = 1.1727 kg/m^3
1.1727 / 1.1075 = 1.058 or 5.8%
Or (1.1727 - 1.1075)/1.1727 = 5.6%
Or (1.1075 - 1.1727)/1.1075 = -5.9%
I mean, I don't get 2.7% no matter how I look at it. Maybe they can explain where I'm wrong here.
Beyond that though, I never once said either of the turbos reached a true choke flow limit. I simply pointed out the airflow rating you are use to hearing from Garrett are based on the maximum airflow that can be pumped out at 60% efficiency...regardless of pressure ratio and the number printed on the BW charts is not based on the same standards.
Do you dispute that claim?
Also, I don't disagree, Garrett's standard seems arbitrary and 100kPa and 25C is much more standard...but that's not really the point. The point is putting the comparison on a level field, regardless of why it is not level to start with. Also, frankly, I'm surprised I haven't seen this mentioned yet as, really, all we have at this point is compressor flow maps and a few random cars to look at for data. I would think these peculiarities would have been talked about and carefully explained to properly inform potential customers.
Spdracerut pointed out I was wrong here and provided some info on what the correct correction is.
I had to do some more investigating to put my mind at ease. While the numbers I provided are correct, they appear to be from dated material. I can't locate any reference where Garrett (Allied Signal at the time) chose the 13.95psi/85F correction from originally. I do have a couple engineering compressor flow maps showing those values though so I believe at one point in time, it was a correct statement.SAE J922 and SAE J1826 however seem to determine 100kPa and 298K are standard inlet test conditions for turbochargers. Assuming Garrett complies with these standards, the BW and Garrett numbers are directly comparable...Just like Geoff stated. Sorry, Geoff. You tried, and I didn't listen as I don't take much at face value even when I should at times.
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From: Welly NZ
Most excellent, that clarification is worth a lot as I have been a bit unsure of how to compare those maps due to the pretty credible looking rant you had on the topic - so thanks for updating the thread, and full credit for coming back and setting it straight Makes life a bit easier too.
Makes life a bit easier too.
Ha, would have been credible if it was 1992... That's the newest map I have anyway and it's for a GT42...
I know I had a newer paper (2004ish) on a GT42 with an 11-blade compressor used for garbage trucks. I'm curious what conditions it has listed on it. I'll have to dig through my archives and see what I turn up.
I know I had a newer paper (2004ish) on a GT42 with an 11-blade compressor used for garbage trucks. I'm curious what conditions it has listed on it. I'll have to dig through my archives and see what I turn up.
