Turbo Efficiency Range for RX-8
01-17-2009, 12:05 AM
#26
well first i think 55lb/min is a bit of a stretch for the typical street car. Thats around 490 at the flywheel
I think 40-45lb/min is a bit more realistic. 44lb/min is closer to 400 at the fly
^^this assumes AFRs of 11.2-11.5
that puts the 3071R at an almost perfect match. I dont think you'll find a turbo that will spool like everyone wants and still play nice at 55lb/min.
I think 40-45lb/min is a bit more realistic. 44lb/min is closer to 400 at the fly
^^this assumes AFRs of 11.2-11.5
that puts the 3071R at an almost perfect match. I dont think you'll find a turbo that will spool like everyone wants and still play nice at 55lb/min.
the thing is : at 45lb the 3071 is only pulling 10psi ish (according to MM) so it is way off its map at that point .
From my little experiments I can see a mod that may rectify this situation - 10 points if you can guess what that might be .....
01-17-2009, 12:31 AM
#29
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true, i think 75%+ of the people that say they want that bigger numbers dont even realize what thats gonna be like or everything involved in getting there though...
so why dont we? we have enough data floating around here to plug it all in right?
ok, i think i'm understanding what you're implying, just not how you're implying it... if you'd like to fill me in i'd gladly try and keep up, here or PM
ok, i think i'm understanding what you're implying, just not how you're implying it... if you'd like to fill me in i'd gladly try and keep up, here or PM
01-17-2009, 01:23 AM
#31
5x trim? You realize that trim is just an aspect ratio right? The GT42 is a 53 trim. Does that mean it should be used for most applications? Remember too that rotaries tend to make less hp per lb/min than piston engines.
trim: inducer^2 / exducer ^2 .
The inducer of the compressor wheel is what's sucking the air in and the exducer is what's hurling the air out of the compressor housing. Typically a larger inducer is going to mean more total airflow and a larger exducer is going to have more efficiency at higher pressure ratios.
Generally speaking, lower trim = more efficiency at lower boost, higher trim = more efficiency at lower boost. Why do you think diesel turbos (Holset HX35 etc) are usually like a 42 trim? They are meant to run at high pressure ratios.
Here is a good example to illustrate this point:
Garrett GT3582 wheel, 61mm inducer 82 mm exducer, ~56 trim
Turbonetics/Garrett 60-1 wheel, 59.5mm inducer 76 mm exducer, 60 trim . This is among the most popular wheel for rotary applications. The upgraded 2nd gen Rx-7 stock turbos use this wheel. The T04S (popular single turbo for FD) uses this compressor wheel.
in sheer airflow, they are pretty close. But the GT35 is more efficient at higher boost--hence the lower trim value. Does that make it 'better' ? Well that depends on the application. And we are not even including other factors like manifold design, hotside A/R, and wastegate design.
The GT30 is a great turbo, but there are a lot of other options...
http://www.turbocharged.com/catalog/comp_wheels.html
look at the T04E family of wheels, which are used in most medium sized turbos available that are not Mitsubishi (20G for example) or Garrett GT series. They all have the same exducer and just the inducer changes. The result is higher total airflow on the high trim turbos and a little less efficiency up top.
T04E 50 trim (54mm inducer 75mm exducer):
T04E 60 trim (58mm inducer 75 mm exducer)
and once again, the GT3071, 53mm inducer 71mm exducer
Notice that the T04E 60 trim is more efficient at 1 bar of boost than the 3071? it flows 40 lbs/min at a higher efficiency. The 3071 is really designed for higher boosting 4 cylinders, like Evos. It is a smaller wheel in both dimensions yet is more efficient at higher boost--that is what the concept of trim is all about. And yes, the T04E's are available with T3 inlets and ball bearings as well as internal wastegates (how well the internal wastegate on that turbo will control boost on a rotary is another matter).
I currently have a T04R for my 2nd gen, 67mm inducer 84 mm exducer , ~64 trim. The larger GT40 is a 68mm inducer, 94mm exducer, 52 trim. It is more efficient at a higher pressure ratio than the T04R, but I suspect it does not significantly outflow it at lower boost (I haven't seen a T04R compressor map anywhere).
trim: inducer^2 / exducer ^2 .
The inducer of the compressor wheel is what's sucking the air in and the exducer is what's hurling the air out of the compressor housing. Typically a larger inducer is going to mean more total airflow and a larger exducer is going to have more efficiency at higher pressure ratios.
Generally speaking, lower trim = more efficiency at lower boost, higher trim = more efficiency at lower boost. Why do you think diesel turbos (Holset HX35 etc) are usually like a 42 trim? They are meant to run at high pressure ratios.
Here is a good example to illustrate this point:
Garrett GT3582 wheel, 61mm inducer 82 mm exducer, ~56 trim
Turbonetics/Garrett 60-1 wheel, 59.5mm inducer 76 mm exducer, 60 trim . This is among the most popular wheel for rotary applications. The upgraded 2nd gen Rx-7 stock turbos use this wheel. The T04S (popular single turbo for FD) uses this compressor wheel.
in sheer airflow, they are pretty close. But the GT35 is more efficient at higher boost--hence the lower trim value. Does that make it 'better' ? Well that depends on the application. And we are not even including other factors like manifold design, hotside A/R, and wastegate design.
The GT30 is a great turbo, but there are a lot of other options...
http://www.turbocharged.com/catalog/comp_wheels.html
look at the T04E family of wheels, which are used in most medium sized turbos available that are not Mitsubishi (20G for example) or Garrett GT series. They all have the same exducer and just the inducer changes. The result is higher total airflow on the high trim turbos and a little less efficiency up top.
T04E 50 trim (54mm inducer 75mm exducer):
T04E 60 trim (58mm inducer 75 mm exducer)
and once again, the GT3071, 53mm inducer 71mm exducer
Notice that the T04E 60 trim is more efficient at 1 bar of boost than the 3071? it flows 40 lbs/min at a higher efficiency. The 3071 is really designed for higher boosting 4 cylinders, like Evos. It is a smaller wheel in both dimensions yet is more efficient at higher boost--that is what the concept of trim is all about. And yes, the T04E's are available with T3 inlets and ball bearings as well as internal wastegates (how well the internal wastegate on that turbo will control boost on a rotary is another matter).
I currently have a T04R for my 2nd gen, 67mm inducer 84 mm exducer , ~64 trim. The larger GT40 is a 68mm inducer, 94mm exducer, 52 trim. It is more efficient at a higher pressure ratio than the T04R, but I suspect it does not significantly outflow it at lower boost (I haven't seen a T04R compressor map anywhere).
Last edited by arghx7; 01-17-2009 at 01:46 AM.
01-17-2009, 01:24 AM
#32
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thank you Kane - i was sitting here thinking the only way to keep 40lb/min on that turbo but raise PR was to change displacement but i couldnt really grasp it till you said that 
01-17-2009, 01:38 AM
#34
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deleted some stuff in the middle there.
the goal is to put all the compressor maps of the available turbo kits in one thread and the n show which is the best match so far for the RX-8 .
then for that T-Rex-8 feller to post up what he says is his choice and then to compare that with what we already have
the goal is to put all the compressor maps of the available turbo kits in one thread and the n show which is the best match so far for the RX-8 .
then for that T-Rex-8 feller to post up what he says is his choice and then to compare that with what we already have
01-17-2009, 02:34 AM
#39
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yeah kane's point is important. thats why we need the maps in one place
for spool you could plot the flow at 2k on the x axis, then plot it at 3k then plot it at 50 ilbs /min and you get something like this
disclaimer: no actual math used to plot line. holding a 6month old at midnight dark 30 who wont sleep and typing with one hand
for spool you could plot the flow at 2k on the x axis, then plot it at 3k then plot it at 50 ilbs /min and you get something like this
disclaimer: no actual math used to plot line. holding a 6month old at midnight dark 30 who wont sleep and typing with one hand
01-17-2009, 02:46 AM
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^^was about to ask what you were smoking, just saw the disclaimer
spool and turbine maps are apparently a black art of sorts. i spent a couple weeks searching the web for info on how to read turbine maps and found nothing but people guessing and asking the same question...
spool and turbine maps are apparently a black art of sorts. i spent a couple weeks searching the web for info on how to read turbine maps and found nothing but people guessing and asking the same question...
01-17-2009, 08:04 AM
#41
Finally Boosted!!!!!!!
Notice that the T04E 60 trim is more efficient at 1 bar of boost than the 3071? it flows 40 lbs/min at a higher efficiency. The 3071 is really designed for higher boosting 4 cylinders, like Evos. It is a smaller wheel in both dimensions yet is more efficient at higher boost--that is what the concept of trim is all about. And yes, the T04E's are available with T3 inlets and ball bearings as well as internal wastegates (how well the internal wastegate on that turbo will control boost on a rotary is another matter).
Last edited by tdiddy; 01-20-2009 at 08:18 PM.
01-17-2009, 09:25 AM
#42
these higher trim turbos are better suited for low boost, high compression engines. What does a stock Renesis motor need with a turbo that is efficient to 25-30psi like the 3071? Like I said, it was designed for relatively low displacement piston engines like Evos, Mazda 3's, etc, which are already running in the 1+ bar range from the factory. Everybody is always saying "well it's capable of this airflow but nobody/few have really pushed it." The GT30 is not that great of a match to the Renesis because it is designed for boost levels that hardly anyone will ever run. It gets the job done, but there are plenty of other good options. Piston and rotary cars running low boost never run those things.
It is obviously losing efficiency FAST. If this were a topographic map instead of a flow map, I would you were falling off the side of the mountain at the highlighted pressure ratio. I know you can sit there and do some calculations that might show you are still in its efficiency range, but rotary engines make closer .7ish hp per lb/min than 1 hp per lb/min . You need to flow more air on a rotary than on a piston engine to make the same power. The 3071 is not designed to flow a lot of air at the range everybody is running them. But once again it still gets the job done, but it's not 'ideal' since we are talking theory here.
see the much more gradual loss of efficiency in the useable range of pressure ratios?
and I am not convinced that the GT30 is the only thing that will fit the Greddy manifold given the space constraints. I've made that clear in other threads. The GT30 has basically off-the-shelf housings.
It is obviously losing efficiency FAST. If this were a topographic map instead of a flow map, I would you were falling off the side of the mountain at the highlighted pressure ratio. I know you can sit there and do some calculations that might show you are still in its efficiency range, but rotary engines make closer .7ish hp per lb/min than 1 hp per lb/min . You need to flow more air on a rotary than on a piston engine to make the same power. The 3071 is not designed to flow a lot of air at the range everybody is running them. But once again it still gets the job done, but it's not 'ideal' since we are talking theory here.
see the much more gradual loss of efficiency in the useable range of pressure ratios?
and I am not convinced that the GT30 is the only thing that will fit the Greddy manifold given the space constraints. I've made that clear in other threads. The GT30 has basically off-the-shelf housings.
Last edited by arghx7; 01-17-2009 at 09:45 AM.
01-17-2009, 09:52 AM
#43
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which 60-1 trim is that?-- seems it would stay in its efficiency island much longer. i havent looked at every 5x trim but so far i havent seen one that looks as good as the t04 60-1
01-17-2009, 10:17 AM
#44
the 60 series (60-1 and 62-1) is a different series of wheels than the T04E. real 60-1 wheels are all 60 trim.
http://www.turbocharged.com/catalog/comp_wheels.html
the 62-1 is also a good wheel, although the two aren't all that different: 62mm inducer, 76mm exducer, ~67 trim.
the key here though is that you would want a 60-1 HiFi. That comes with the 2.75" inlet, but it is the same wheel. Otherwise you have to get the 4" inlet which has some packaging problems. I ran a T04S 60-1 (4" inlet, larger P trim turbine wheel) and I was pretty happy with it. It still pulled hard up to 21psi.
Has anyone here considered contacting Bryan at BNR Supercars to put an upgraded wheel in the 18G hotside? He may also be able to modify the turbo to fix some of the reliability problems. He does all the upgraded bolt-on hybrids for 2nd and 3rd gens. He puts a 60-1 wheel in the stock 2nd gen turbine housing and ports the wastegate and turbine housings. For a bolt-on turbo it's pretty good. I think he charges 900 dollars for that car.
this is what his 2nd gen hybrid turbo looks like:.JPG)
his site is http://www.bnrturbos.com/Mazda.htm
http://www.turbocharged.com/catalog/comp_wheels.html
the 62-1 is also a good wheel, although the two aren't all that different: 62mm inducer, 76mm exducer, ~67 trim.
the key here though is that you would want a 60-1 HiFi. That comes with the 2.75" inlet, but it is the same wheel. Otherwise you have to get the 4" inlet which has some packaging problems. I ran a T04S 60-1 (4" inlet, larger P trim turbine wheel) and I was pretty happy with it. It still pulled hard up to 21psi.
Has anyone here considered contacting Bryan at BNR Supercars to put an upgraded wheel in the 18G hotside? He may also be able to modify the turbo to fix some of the reliability problems. He does all the upgraded bolt-on hybrids for 2nd and 3rd gens. He puts a 60-1 wheel in the stock 2nd gen turbine housing and ports the wastegate and turbine housings. For a bolt-on turbo it's pretty good. I think he charges 900 dollars for that car.
this is what his 2nd gen hybrid turbo looks like:
his site is http://www.bnrturbos.com/Mazda.htm
Last edited by arghx7; 01-17-2009 at 10:24 AM.
01-17-2009, 01:56 PM
#46
^ if you really want that kind of flow at such ridiculously low boost, you are going to need something close to the "enormous" range in terms of size. like a GT42 (75mm inducer, 102mm exducer, 53 trim)
or probably better, the Turbonetics T-76 (76 mm inducer , 102mm exducer , 55 trim
or probably better, the Turbonetics T-76 (76 mm inducer , 102mm exducer , 55 trim
Last edited by arghx7; 01-17-2009 at 01:59 PM.
01-17-2009, 02:29 PM
#49
can you find one that will do 50lbs/min at 1.8 PR right on the edge of its efficiency island
10-11psi is rediculously low boost for the amount of air you are trying to flow, if you are looking to do it at peak efficiency (the innermost island). You realize the GT42 and T-76 have a four inch compressor wheel?? not just the compressor housing inlet, the whole wheel. And you're not going to be able to go much smaller than that. You'll have a lot of trouble fitting that turbo in there, and you will probably need a 60mm wastegate to keep it under control.
Last edited by arghx7; 01-17-2009 at 02:37 PM.
01-17-2009, 02:31 PM
#50
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I completely washed over this post I apologize. It'll be a nice discussion if useless commentators such as 05rex8 are left out of the loop ad it is closely moderated.
I appreciate zoom44s ability to recognize I wasn't trying to bash anyone or start an argument I simply felt that there are better options for these cars.
To explain myself, I understand a majority of my knowledge stems from the earlier 13 wankels and piston engines but in general some aspects.. actually MOST aspects can be applied juxtaposed to which ever engine. With that being said I'll be pulling some maps later and posting them up on some of the turbos from my experience would be better suited for our cars.
The problem with the MM upgrade and Esmerill were both mentioned. Both turbos are operating out of their efficiency range. This stems from the Greddy being so small it blows hot air in the upper rpms. The solution was to get a turbo that runs in the higher rpms yet what was forgotten is that in most cases mid range power >low and top. To achieve this one must find a turbo who has an efficiency range lower in the spectrum and can pull the car fast enough that you wont lose out on the upper yet wont be bogged down trying to spool.
I appreciate zoom44s ability to recognize I wasn't trying to bash anyone or start an argument I simply felt that there are better options for these cars.
To explain myself, I understand a majority of my knowledge stems from the earlier 13 wankels and piston engines but in general some aspects.. actually MOST aspects can be applied juxtaposed to which ever engine. With that being said I'll be pulling some maps later and posting them up on some of the turbos from my experience would be better suited for our cars.
The problem with the MM upgrade and Esmerill were both mentioned. Both turbos are operating out of their efficiency range. This stems from the Greddy being so small it blows hot air in the upper rpms. The solution was to get a turbo that runs in the higher rpms yet what was forgotten is that in most cases mid range power >low and top. To achieve this one must find a turbo who has an efficiency range lower in the spectrum and can pull the car fast enough that you wont lose out on the upper yet wont be bogged down trying to spool.