Turbo Terminology Explained...
04-06-2003, 08:55 PM
#22
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Join Date: Sep 2002
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Q: What is the difference between an "on-center" turbine housing and a "tangential" turbine housing?
A: The difference is the way that they mount in the engine compartment and the manner in which the exhaust is evacuated from the housing. The "on-center" uses a standard T4 inlet flange, as well as a four-bolt discharge flange. The reason that it is called on-center is just that, the housing sits right on top of the inlet flange.
The "tangential" turbine housing differs both in form and function. The housing sits off to one side, similar to that of a snail shell. The other difference is that to connect an exhaust down-pipe, a V-Band flange-and-clamp assembly must be used. This setup sometimes proves to be more convenient for race applications. The "tang" housings are 4 to 5 percent more efficient in flow. Neither the "on-center" nor "tangential" perform better than the other. The decision to use one over the other should depend completely upon the installation of the turbos in the engine compartment.
A: The difference is the way that they mount in the engine compartment and the manner in which the exhaust is evacuated from the housing. The "on-center" uses a standard T4 inlet flange, as well as a four-bolt discharge flange. The reason that it is called on-center is just that, the housing sits right on top of the inlet flange.
The "tangential" turbine housing differs both in form and function. The housing sits off to one side, similar to that of a snail shell. The other difference is that to connect an exhaust down-pipe, a V-Band flange-and-clamp assembly must be used. This setup sometimes proves to be more convenient for race applications. The "tang" housings are 4 to 5 percent more efficient in flow. Neither the "on-center" nor "tangential" perform better than the other. The decision to use one over the other should depend completely upon the installation of the turbos in the engine compartment.
04-06-2003, 09:13 PM
#23
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Join Date: Sep 2002
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Some good turbo info from a NISSAN site NOT ROTARY SPECIFIC
The "BIG" turbochargers
Here are the big dogs of the turbo community, the biggest turbos, that are mostly used for drag strip use only.
HKS T-51R
This is the crown jewel of HKS single turbos (although the GT3245 in the HKS drag celica is probably bigger, i've NEVER seen it in the US) This turbo in size, is slightly bigger than a T66, but has an exhaust housing that is quite a bit bigger, it ships with 0.96 stock, and makes TONS of power. Bryce Danna made his ~830 rwhp with 75 shot of nitrous with this turbo, that looks like ~760+ rwhp without bottle most likely, which is plenty. Its probably possible to make 800 rwhp on turbo alone with this turbo, which is very impressive. You will want upgraded internals most likely, along with cams, Gforce computer to raise rev limiter, a BIG fuel system, and either a high-stall torque converter, or a stick, with a very nice clutch. This turbo is BIG and has significant lag. You are waiting for it quite a bit, probably 800 rpm if not more of noticable lag. I would say its POSSIBLE to have this turbo on a "street" car, but I wouldn't do so personally because i'd want nitrous to spool this big boy up, its pretty laggy makes full boost around 5k. No one has really made any passes with this turbo yet that have been very fast, but maybe this year someone will.
HKS GT2835
This is probably the most common twin turbo setup, these are pretty big twin turbos, about the size of a TS04 0.58 for each turbo, but most often they come with 0.70 exhaust housings... I would switch these with 0.63s personally, unless you are a glutton for lag, with the stock housings they make full boost in the early 5k range with cams. You do have quite a bit of potential here, I believe you can make 800 rwhp on the HKS GT2835s with the proper setup, which is PLENTY of power. With the smaller housings, you can probably have 700 rwhp with lag in the mid 4k range, which is quite a bit too. Very nice setup, but insanely expensive for what you get, almost twice as expensive as the RPS kits.
Turbonetics T70, T72, and T76
These turbos are similar to the T66, but bigger. Most of the T70s are pretty similar to the T66, although they have a slightly bigger turbine wheel. This allows them to make somewhat more power, but at the cost of somewhat more lag. A T70 is good for probably 30-50 rwhp more than a comparable T66, but has about 2-300 rpm more lag. T72 is correspondingly bigger, it uses a different compressor and turbine wheel setup, and allows for significantly more power, but quite a bit more lag. Supposedly capable of 800-900 rwhp, the T72 makes full boost in the low/mid 5k range. I haven't heard of anyone using the T76 as this is simply too big a turbocharger, it would make TONS of power, but probably not make full boost till ~6k rpm. RPS sells kits with all of these turbos, although I believe that the T72 and T76 have to be special ordered.
Greddy T78 and T88
These turbos are made by mitsubishi and modified by Greddy, the T78 uses a TD07 exhaust housing with a TD08 compressor, T88 has TD08 on both sides. T78 is capable of an insane amount of power, at the cost of monumental lag, although with a stock motor, the T78 may make full boost in the mid 4k range with proper tuning. T78 can make ~750 rwhp on the turbo alone if tuned right, you do need electronics, a higher rev limiter, cams, probably headwork... T88 is good for maybe 20% more power... this is one of the few turbos that is theoretically capable of flowing enough air to approach 900 rwhp, although you would need a SERIOUS engine build up to do this. Ara from NJ has run 141 mph traps with a T78 w/o bottle, Humberto has run 9.8@14x with T78 with nitrous, and a number of other people use the T78 as well, mainly because its quite inexepensive today, selling for under $4k. The downside to the T78 and T88 is that they need ALOT of work to get them working to their potential, and they lag into the low/mid 5k range for the T78 and even more with the T88, a car with this turbo is almost non-streetable in my opinion.
HKS GT3037
These are the biggest twin turbos available from HKS as far as I know. Craig Paisley uses this setup, as does the UPRD car. This is one of those turbos that should have a tag on it that says "DO NOT USE WITHOUT NITROUS" in my opinion. You will probably see lag in the ~6500 rpm range, which is fine for the strip, with nitrous, but for a streetable car? remember the supra's stock rev limiter is 6800 rpm, although obviously you would raise it if you had these turbos... These turbos are probably capable of 1000-1100 rwhp w/o nitrous, but you need headwork, internals, fuel system, and probably lots of other custom stuff to use these turbos, don't do it unless you have nearly infinite money.
The "BIG" turbochargers
Here are the big dogs of the turbo community, the biggest turbos, that are mostly used for drag strip use only.
HKS T-51R
This is the crown jewel of HKS single turbos (although the GT3245 in the HKS drag celica is probably bigger, i've NEVER seen it in the US) This turbo in size, is slightly bigger than a T66, but has an exhaust housing that is quite a bit bigger, it ships with 0.96 stock, and makes TONS of power. Bryce Danna made his ~830 rwhp with 75 shot of nitrous with this turbo, that looks like ~760+ rwhp without bottle most likely, which is plenty. Its probably possible to make 800 rwhp on turbo alone with this turbo, which is very impressive. You will want upgraded internals most likely, along with cams, Gforce computer to raise rev limiter, a BIG fuel system, and either a high-stall torque converter, or a stick, with a very nice clutch. This turbo is BIG and has significant lag. You are waiting for it quite a bit, probably 800 rpm if not more of noticable lag. I would say its POSSIBLE to have this turbo on a "street" car, but I wouldn't do so personally because i'd want nitrous to spool this big boy up, its pretty laggy makes full boost around 5k. No one has really made any passes with this turbo yet that have been very fast, but maybe this year someone will.
HKS GT2835
This is probably the most common twin turbo setup, these are pretty big twin turbos, about the size of a TS04 0.58 for each turbo, but most often they come with 0.70 exhaust housings... I would switch these with 0.63s personally, unless you are a glutton for lag, with the stock housings they make full boost in the early 5k range with cams. You do have quite a bit of potential here, I believe you can make 800 rwhp on the HKS GT2835s with the proper setup, which is PLENTY of power. With the smaller housings, you can probably have 700 rwhp with lag in the mid 4k range, which is quite a bit too. Very nice setup, but insanely expensive for what you get, almost twice as expensive as the RPS kits.
Turbonetics T70, T72, and T76
These turbos are similar to the T66, but bigger. Most of the T70s are pretty similar to the T66, although they have a slightly bigger turbine wheel. This allows them to make somewhat more power, but at the cost of somewhat more lag. A T70 is good for probably 30-50 rwhp more than a comparable T66, but has about 2-300 rpm more lag. T72 is correspondingly bigger, it uses a different compressor and turbine wheel setup, and allows for significantly more power, but quite a bit more lag. Supposedly capable of 800-900 rwhp, the T72 makes full boost in the low/mid 5k range. I haven't heard of anyone using the T76 as this is simply too big a turbocharger, it would make TONS of power, but probably not make full boost till ~6k rpm. RPS sells kits with all of these turbos, although I believe that the T72 and T76 have to be special ordered.
Greddy T78 and T88
These turbos are made by mitsubishi and modified by Greddy, the T78 uses a TD07 exhaust housing with a TD08 compressor, T88 has TD08 on both sides. T78 is capable of an insane amount of power, at the cost of monumental lag, although with a stock motor, the T78 may make full boost in the mid 4k range with proper tuning. T78 can make ~750 rwhp on the turbo alone if tuned right, you do need electronics, a higher rev limiter, cams, probably headwork... T88 is good for maybe 20% more power... this is one of the few turbos that is theoretically capable of flowing enough air to approach 900 rwhp, although you would need a SERIOUS engine build up to do this. Ara from NJ has run 141 mph traps with a T78 w/o bottle, Humberto has run 9.8@14x with T78 with nitrous, and a number of other people use the T78 as well, mainly because its quite inexepensive today, selling for under $4k. The downside to the T78 and T88 is that they need ALOT of work to get them working to their potential, and they lag into the low/mid 5k range for the T78 and even more with the T88, a car with this turbo is almost non-streetable in my opinion.
HKS GT3037
These are the biggest twin turbos available from HKS as far as I know. Craig Paisley uses this setup, as does the UPRD car. This is one of those turbos that should have a tag on it that says "DO NOT USE WITHOUT NITROUS" in my opinion. You will probably see lag in the ~6500 rpm range, which is fine for the strip, with nitrous, but for a streetable car? remember the supra's stock rev limiter is 6800 rpm, although obviously you would raise it if you had these turbos... These turbos are probably capable of 1000-1100 rwhp w/o nitrous, but you need headwork, internals, fuel system, and probably lots of other custom stuff to use these turbos, don't do it unless you have nearly infinite money.
04-06-2003, 09:28 PM
#25
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Join Date: Sep 2002
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-TD05, GT2530, T78, T72... What do those terms mean?
There're two commonly used types of turbos, Mitsubishi and Garrett turbos. There are others but as not common...
Mitsu and Garrett turbos have totally different designations.
-Mitsu turbos:
Mitsubishi uses TD04, TD05, TD06, TD07, TD08...to designates turbo housing.
For example, TD05H-16G 7cm^2 is a turbo with,
TD05 turbine housing with 'H' style turbine housing/wheel. There are S, SH, H... style of turbine wheel/housing.
16G compressor wheel. 16 is the size of the wheel, 1.83 inducer, 2.37 exducer. G is the style of wheel (alternating height of blades). C, B, T style wheel's blades have the same height. Blades are always evenly spaced, but the number of and pitch of the blades can change between models.
8cm^2 is referring to exhaust discharge area in the turbine housing. More specifically, it is the cross-sectional area of the smallest intake passage in the turbine housing before the passage spreads around the circumferential volute that leads to the turbine wheel. Very similar to Garrett turbo's A/R. The smaller number means faster spool-up but more back pressure at higher rpm. Bigger number means longer spool up but less back pressure, thus more top end power.
Greddy modifies Mitsu turbos. Bisides, TD04, TD05, TD06, TD07 turbos, Greddy also makes hybrid turbo, T67 is TD07 compressor and TD06 turbine, same turbo as TD06SH-25G. T78 is the compressor of TD08 and turbine of TD07, T88 uses compressor and turbine from TD08.
-Garrett Turbos:
Garrett basically has two lines of turbos. The older T series turbos and new ball bearing GT series turbos.
T family has T22, T25, T28, T3, T350, T370, T4, To4B, To4E, TS04, To4R ...
The new line of GT turbos are ball bearing, GT20, GT22, GT25, GT30, GT35, GT40, GT45, GT50... GT turbos produce slightly more hp then older T series turbos with the same number. Turbonetics and many domestic makers use T series turbos. A T3/To4E 60 T .63A/R is a hybrid turbo with T3 turbine, To4E compressor, 60 Trim compressor wheel and .63 A/R. Wheel "trim" refers to the squared ratio of the smaller diameter divided by the larger diameter times 100. Generally, the larger the trim number the more flow the wheel has. For compressor wheels , larger trim tends to mean slightly lower efficiency. For "families" of turbine wheels (those with the same inducer diameter), larger trim usually means better flow with less backpressure but longer spool time. A/R is a ratio of the exhaust discharge area vs the distance from the center of turbine wheel to the center of the discharge area. The so called "T-series': T60, T61, T66, T70, T72, T76... are T4 turbos as well. The number means the compressor inducer size. ie: T76 means it has 76mm compressor inducer.
HKS uses Garrett turbos. HKS GT series turbos use Garrett GT's turbine with T's compressor. For example, HKS GT 2530 is GT25 .64A/R turbine with T3 63 trim compressor.
There're two commonly used types of turbos, Mitsubishi and Garrett turbos. There are others but as not common...
Mitsu and Garrett turbos have totally different designations.
-Mitsu turbos:
Mitsubishi uses TD04, TD05, TD06, TD07, TD08...to designates turbo housing.
For example, TD05H-16G 7cm^2 is a turbo with,
TD05 turbine housing with 'H' style turbine housing/wheel. There are S, SH, H... style of turbine wheel/housing.
16G compressor wheel. 16 is the size of the wheel, 1.83 inducer, 2.37 exducer. G is the style of wheel (alternating height of blades). C, B, T style wheel's blades have the same height. Blades are always evenly spaced, but the number of and pitch of the blades can change between models.
8cm^2 is referring to exhaust discharge area in the turbine housing. More specifically, it is the cross-sectional area of the smallest intake passage in the turbine housing before the passage spreads around the circumferential volute that leads to the turbine wheel. Very similar to Garrett turbo's A/R. The smaller number means faster spool-up but more back pressure at higher rpm. Bigger number means longer spool up but less back pressure, thus more top end power.
Greddy modifies Mitsu turbos. Bisides, TD04, TD05, TD06, TD07 turbos, Greddy also makes hybrid turbo, T67 is TD07 compressor and TD06 turbine, same turbo as TD06SH-25G. T78 is the compressor of TD08 and turbine of TD07, T88 uses compressor and turbine from TD08.
-Garrett Turbos:
Garrett basically has two lines of turbos. The older T series turbos and new ball bearing GT series turbos.
T family has T22, T25, T28, T3, T350, T370, T4, To4B, To4E, TS04, To4R ...
The new line of GT turbos are ball bearing, GT20, GT22, GT25, GT30, GT35, GT40, GT45, GT50... GT turbos produce slightly more hp then older T series turbos with the same number. Turbonetics and many domestic makers use T series turbos. A T3/To4E 60 T .63A/R is a hybrid turbo with T3 turbine, To4E compressor, 60 Trim compressor wheel and .63 A/R. Wheel "trim" refers to the squared ratio of the smaller diameter divided by the larger diameter times 100. Generally, the larger the trim number the more flow the wheel has. For compressor wheels , larger trim tends to mean slightly lower efficiency. For "families" of turbine wheels (those with the same inducer diameter), larger trim usually means better flow with less backpressure but longer spool time. A/R is a ratio of the exhaust discharge area vs the distance from the center of turbine wheel to the center of the discharge area. The so called "T-series': T60, T61, T66, T70, T72, T76... are T4 turbos as well. The number means the compressor inducer size. ie: T76 means it has 76mm compressor inducer.
HKS uses Garrett turbos. HKS GT series turbos use Garrett GT's turbine with T's compressor. For example, HKS GT 2530 is GT25 .64A/R turbine with T3 63 trim compressor.
05-08-2003, 03:09 AM
#27
Junior Member
Join Date: May 2003
Posts: 2
http://320i.com/turbocharging.htm
The above website has very good general information about turbo sizing even though thery are installing a system on an older BMW. It also gives a more involved "primer" on reading compressor flow maps. A few things it lacks is a more detailed explanation of Volumetric Efficiency (VE), any explanation on wheel sizing, and a graphic description of A/R numbers.
http://www.dune-buggy.com/turbo/turbo.htm
...gives a VERY general explanation of a turbo system, but has an excellent explanation of what an A/R actually is; the area of the outlet divided by the radius to the center of the area,... i.e., the center of the compressor or turbine wheel to the largest radius of the housing (see pic on website)
http://www.turbonation.com/turbo.htm
Has alot of text info, but gives a fair description of housings and other general info.
Inducer and Exducer refer to the major and minor diameters of a compressor or turbine wheel and function of each part of the wheel. (I think)
see below
The term "wheel trim" is proprietary for the actual diameter of the compressor and turbine wheels.
[QUOTE] Clipping [QUOTE]
Could be argued that clipping removes enough material from the edge of the ends of a compressor wheel so that the critical speed of the tips of the wheel "blades" is reduced, so that there increased compressor efficiency at higher wheel speeds, albeit at the expense of low speed effectiveness.
No idea
Umm,... I've been muddling though the math on these for 'ahem,' fun? for the past year or so,... and would love to try and explain these but my best advice is to check out the BMW site listed above. It gives a good idea of what numbers go where. One thing of importance about compressor maps are that most turbo companies consider that information a "trade secret" or that the average 'Joe Tuner' isn't smart enough to understand them. And, that turbine maps are very extra special, Area51 top-secret, gaurded information.
Hope that helps a little.
*****quotes aren't working for me, sorry*****
The above website has very good general information about turbo sizing even though thery are installing a system on an older BMW. It also gives a more involved "primer" on reading compressor flow maps. A few things it lacks is a more detailed explanation of Volumetric Efficiency (VE), any explanation on wheel sizing, and a graphic description of A/R numbers.
http://www.dune-buggy.com/turbo/turbo.htm
...gives a VERY general explanation of a turbo system, but has an excellent explanation of what an A/R actually is; the area of the outlet divided by the radius to the center of the area,... i.e., the center of the compressor or turbine wheel to the largest radius of the housing (see pic on website)
http://www.turbonation.com/turbo.htm
Has alot of text info, but gives a fair description of housings and other general info.
O.K. who wants to do it? I've heard alot of people asking questions about this and I'm curious myself.
What do these things mean?
Inducer
Exducer
Inducer
Exducer
Inducer and Exducer refer to the major and minor diameters of a compressor or turbine wheel and function of each part of the wheel. (I think)
A/R
see below
Wheel trims (P,Q,R...)
The term "wheel trim" is proprietary for the actual diameter of the compressor and turbine wheels.
[QUOTE] Clipping [QUOTE]
Could be argued that clipping removes enough material from the edge of the ends of a compressor wheel so that the critical speed of the tips of the wheel "blades" is reduced, so that there increased compressor efficiency at higher wheel speeds, albeit at the expense of low speed effectiveness.
Dynamic, carbon seals
No idea
And who wants to explain how to read compressor maps?
Umm,... I've been muddling though the math on these for 'ahem,' fun? for the past year or so,... and would love to try and explain these but my best advice is to check out the BMW site listed above. It gives a good idea of what numbers go where. One thing of importance about compressor maps are that most turbo companies consider that information a "trade secret" or that the average 'Joe Tuner' isn't smart enough to understand them. And, that turbine maps are very extra special, Area51 top-secret, gaurded information.
Hope that helps a little.
*****quotes aren't working for me, sorry*****
05-08-2003, 03:30 AM
#28
Junior Member
Join Date: May 2003
Posts: 2
Originally Posted by 93 R1' date='Apr 6 2003, 05:55 PM
Q: What is the difference between an "on-center" turbine housing and a "tangential" turbine housing?
A: The difference is the way that they mount in the engine compartment and the manner in which the exhaust is evacuated from the housing. The "on-center" uses a standard T4 inlet flange, as well as a four-bolt discharge flange. The reason that it is called on-center is just that, the housing sits right on top of the inlet flange.
The "tangential" turbine housing differs both in form and function. The housing sits off to one side, similar to that of a snail shell. The other difference is that to connect an exhaust down-pipe, a V-Band flange-and-clamp assembly must be used. This setup sometimes proves to be more convenient for race applications. The "tang" housings are 4 to 5 percent more efficient in flow. Neither the "on-center" nor "tangential" perform better than the other. The decision to use one over the other should depend completely upon the installation of the turbos in the engine compartment.
A: The difference is the way that they mount in the engine compartment and the manner in which the exhaust is evacuated from the housing. The "on-center" uses a standard T4 inlet flange, as well as a four-bolt discharge flange. The reason that it is called on-center is just that, the housing sits right on top of the inlet flange.
The "tangential" turbine housing differs both in form and function. The housing sits off to one side, similar to that of a snail shell. The other difference is that to connect an exhaust down-pipe, a V-Band flange-and-clamp assembly must be used. This setup sometimes proves to be more convenient for race applications. The "tang" housings are 4 to 5 percent more efficient in flow. Neither the "on-center" nor "tangential" perform better than the other. The decision to use one over the other should depend completely upon the installation of the turbos in the engine compartment.
O_ resembles a tangential housing.
O- on-center housing.
Flange type or design has nothing to due with the properties of the housing.
One thing that was'nt mentioned about housing design is the divided outlet design which apparently increases the quality of exhaust flow from the housing under very specific circumstances (some bigger housings?) I don't really understand the aerodynamics of a divided housing and would think that it is similarily related to the reason why 2 pipes flow more than 1 pipe given an equal cross sectional area.
05-30-2003, 07:35 AM
#30
Senior Member
Join Date: May 2003
Location: Pensacola, FL
Posts: 124
Originally Posted by 93 R1' date='Apr 3 2003, 06:04 PM
Is the pressure on the vertical axis measured in BAR?
Pressure Ratio = P1/P2
P1 = Boost pressure + Atmospheric pressure
P2 = Atmospheric pressure (approx 1Bar or 15psi at sea level)
So with no boost P1 = P2 and the Pressure Ratio = 1
With 1Bar of boost P1 = 2Bar so PR = 2
2 Bar of boost gives PR = 3
you get the picture.
_____________________________
To the original question, it's technically unitless. But little rotor got the applied meaning. Multiply bar * 14.7 to get psi.