The NEW "GT35R" from Buschur Racing..
Feb 13, 2007, 03:19 PM
#136
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Got me in now , anything that can make these (GT3582R) turbos get up earlier and have more power potential is worth reading .
Cheers David - what Arnie said .
Cheers David - what Arnie said .
Feb 13, 2007, 04:09 PM
#138
Face it, this is not a scientific community that expects the person making the claim to validate and disclose their methods. To us (the purchaser) the validation is in how much power the turbo produces, not how they made it do it. It's good to have them "prove" and "reproduce" said power but naive at best to think they are going to write up a nice "white paper" for everybody to read and then duplicate the new turbo design.
Feb 13, 2007, 04:17 PM
#139
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240Z, I was actually going to answer your question seriously but didn't want to put up my much to basic version of why there is less back pressure. Here is what I was going to tell you:
"When you make the compressor wheel more efficient it will slow the shaft speed down and make the turbine wheel work less, this reduces back pressure."
I didn't feel that was technical enough for a college man like yourself so I asked Robert at FP to give me his version of what I was thinking just for YOU!
Here is what Robert at FP says:
"Compressor efficiency is one of the big parameters that determine both spool up and the amount of actual power required to pump the air. By improving the compressor efficiency you will decrease lag and also decrease the amount of "pressure head" required to drive the compressor. Changing only a compressor wheel and observing both improved spool AND reduced back pressure ("pressure head" is a good indication of a design that is on the right track.)"
I truly hope that this is going to make you happy and not get me some smart *** comment telling me how dumb I am.
"When you make the compressor wheel more efficient it will slow the shaft speed down and make the turbine wheel work less, this reduces back pressure."
I didn't feel that was technical enough for a college man like yourself so I asked Robert at FP to give me his version of what I was thinking just for YOU!
Here is what Robert at FP says:
"Compressor efficiency is one of the big parameters that determine both spool up and the amount of actual power required to pump the air. By improving the compressor efficiency you will decrease lag and also decrease the amount of "pressure head" required to drive the compressor. Changing only a compressor wheel and observing both improved spool AND reduced back pressure ("pressure head" is a good indication of a design that is on the right track.)"
I truly hope that this is going to make you happy and not get me some smart *** comment telling me how dumb I am.
Feb 13, 2007, 04:45 PM
#140
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Hi all , just thought I'd air my thoughts on compressor wheels and how they effect a turbo's boost threshold .
Most people agree that using a larger diametre and or trim compressor wheel makes for a higher capacity pump . So pumping a greater mass or weight of air means that the wheel has higher power demands than the previous lower capacity pump . So this now means for a given exhaust gas speed the rotating assembly spins slower which adds up to extra turbo (turbine) lag . With exhaust gas velocity rising and the turbine speed not rising as fast as it could/should I reckon gasflow throught the turbine housing would have a little more restriction .
I believe its possible to go the other way with some turbos and use a slightly smaller trim version of the same family compressor wheel which basically gives the existing turbine (and available exhaust gas energy) a little less workload so the whole rotating assembly tends to want to accelerate more easily and the transients should improve as well .
Some will have noticed that amongst the Garrett GT BB range there are optional compressor trims of basically the same theme ie 48/52/56 trim GT2871R's and GT3076R/GT3037S's and the GT2835 series also in 48/52/56T .
The GT3582R (AKA GT3540R) I believe has only been sold in two forms ie the HKS spec GT3240R and the Garrett marketed GT3582R .
The GT3240 appears to have a cropped GT35 turbine to get it approximately GT32 turbine dimensions . Its compressor wheel is the 54 trim version of Garretts 82mm GT40 or BCCW-18C . The GT3582R uses the 56 trim version of this compressor family .
As far as I can tell it has been available in 50/52/54 and 56 trim sizes from turbos like Garrett GT4082 and HKS GT3040 (50T) , Garrett GT3782 (52T) , HKS GT3240 (54T) and the GT3582R and GT3782R I believe use the 56T wheel .
If I was trying to get a little better response from a "GT3582R" I would be trying the 52 and possibly 54 trim versions of this same wheel family . To make it really punchy it would be very easy to take a HKS GT3040 and exchange the turbine/heatshield/turbine housing for the GT35BB bits . The compressor bore would need to be reamed because the GT30 turbine shaft is slightly smaller than GT35 (where the compressor fits) so would need to be resized and balanced .
A problem exists if you use the bush bearing 50 and 52 trim wheels because their bore is larger than the GT35 BB turbine shaft so may need to be bushed which is not easy , also backspacing is different so machining required .
Also its just possible that Garrett may be making an 82mm version of the C117 series compressor ie same family as the GT4088R uses but in 82mm instead of 88mm . The Cummins upgrade turbo (GT37R Stage 1) I think uses a C117 series compressor in I think 82mm 50 trim . These wheels are 7/14 blade designs and usually in smaller trims ie 50/52 rather than the GT40's 56 trim . I suspect that the extra pair of blades and smaller trim sizes have a lot of say in the workload/shaft speed/airflow stakes .
Food for thought .
Most people agree that using a larger diametre and or trim compressor wheel makes for a higher capacity pump . So pumping a greater mass or weight of air means that the wheel has higher power demands than the previous lower capacity pump . So this now means for a given exhaust gas speed the rotating assembly spins slower which adds up to extra turbo (turbine) lag . With exhaust gas velocity rising and the turbine speed not rising as fast as it could/should I reckon gasflow throught the turbine housing would have a little more restriction .
I believe its possible to go the other way with some turbos and use a slightly smaller trim version of the same family compressor wheel which basically gives the existing turbine (and available exhaust gas energy) a little less workload so the whole rotating assembly tends to want to accelerate more easily and the transients should improve as well .
Some will have noticed that amongst the Garrett GT BB range there are optional compressor trims of basically the same theme ie 48/52/56 trim GT2871R's and GT3076R/GT3037S's and the GT2835 series also in 48/52/56T .
The GT3582R (AKA GT3540R) I believe has only been sold in two forms ie the HKS spec GT3240R and the Garrett marketed GT3582R .
The GT3240 appears to have a cropped GT35 turbine to get it approximately GT32 turbine dimensions . Its compressor wheel is the 54 trim version of Garretts 82mm GT40 or BCCW-18C . The GT3582R uses the 56 trim version of this compressor family .
As far as I can tell it has been available in 50/52/54 and 56 trim sizes from turbos like Garrett GT4082 and HKS GT3040 (50T) , Garrett GT3782 (52T) , HKS GT3240 (54T) and the GT3582R and GT3782R I believe use the 56T wheel .
If I was trying to get a little better response from a "GT3582R" I would be trying the 52 and possibly 54 trim versions of this same wheel family . To make it really punchy it would be very easy to take a HKS GT3040 and exchange the turbine/heatshield/turbine housing for the GT35BB bits . The compressor bore would need to be reamed because the GT30 turbine shaft is slightly smaller than GT35 (where the compressor fits) so would need to be resized and balanced .
A problem exists if you use the bush bearing 50 and 52 trim wheels because their bore is larger than the GT35 BB turbine shaft so may need to be bushed which is not easy , also backspacing is different so machining required .
Also its just possible that Garrett may be making an 82mm version of the C117 series compressor ie same family as the GT4088R uses but in 82mm instead of 88mm . The Cummins upgrade turbo (GT37R Stage 1) I think uses a C117 series compressor in I think 82mm 50 trim . These wheels are 7/14 blade designs and usually in smaller trims ie 50/52 rather than the GT40's 56 trim . I suspect that the extra pair of blades and smaller trim sizes have a lot of say in the workload/shaft speed/airflow stakes .
Food for thought .
Feb 13, 2007, 08:29 PM
#141
240z, I do understand how it works but thought my explanation might have been over simplified for you. Obviously maybe Robert's was too. It is quite easy to understand actually. It's one of those, "Yeah, makes perfect sense" things to me.
Feb 14, 2007, 01:19 AM
#142
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Robert's explaination was great. I think more and more people get excited by coupling large compressor wheels with small turbine housings because they feel that...I'll make a LOT of power and I'll have no lag. Unfortunately for them turbochargers are quite a bit more dynamic. We've been playing with turbine housing back pressure on 40R and 42R hondas for quite some time now. We've actually seen less than a 1:1 pressure ratio!!! keep up the great work Dave... would you mind sharing your PR with us? If not I understand.
Feb 14, 2007, 12:16 PM
#146
Dave is a trial and error kind of guy, sometimes it takes longer, but it also results in concepts that work, when the engineers will say it shouldn't or won't.
I do a little of both.. I try to engineer an idea on paper, but ultimately it boils down to trying it to see what works.
If he gives every technical detail, it would just confuse people and its not necessary to know every finite piece of data as its only useful to someone who wants to copy his work anyway.
Feb 14, 2007, 12:49 PM
#147
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Sometimes elaborate technical explanations do nothing but confuse people more. Its more important to understand the concept of why it works, than the esoteric language and mental masturbation that isn't required to communicate the details for most people.
Dave is a trial and error kind of guy, sometimes it takes longer, but it also results in concepts that work, when the engineers will say it shouldn't or won't.
I do a little of both.. I try to engineer an idea on paper, but ultimately it boils down to trying it to see what works.
If he gives every technical detail, it would just confuse people and its not necessary to know every finite piece of data as its only useful to someone who wants to copy his work anyway.
Dave is a trial and error kind of guy, sometimes it takes longer, but it also results in concepts that work, when the engineers will say it shouldn't or won't.
I do a little of both.. I try to engineer an idea on paper, but ultimately it boils down to trying it to see what works.
If he gives every technical detail, it would just confuse people and its not necessary to know every finite piece of data as its only useful to someone who wants to copy his work anyway.
Feb 14, 2007, 01:29 PM
#148
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Sometimes elaborate technical explanations do nothing but confuse people more. Its more important to understand the concept of why it works, than the esoteric language and mental masturbation that isn't required to communicate the details for most people.
Dave is a trial and error kind of guy, sometimes it takes longer, but it also results in concepts that work, when the engineers will say it shouldn't or won't.
I do a little of both.. I try to engineer an idea on paper, but ultimately it boils down to trying it to see what works.
If he gives every technical detail, it would just confuse people and its not necessary to know every finite piece of data as its only useful to someone who wants to copy his work anyway.
Dave is a trial and error kind of guy, sometimes it takes longer, but it also results in concepts that work, when the engineers will say it shouldn't or won't.
I do a little of both.. I try to engineer an idea on paper, but ultimately it boils down to trying it to see what works.
If he gives every technical detail, it would just confuse people and its not necessary to know every finite piece of data as its only useful to someone who wants to copy his work anyway.
Feb 14, 2007, 04:34 PM
#150
Compressor efficiency and shaft speed
It is possible to have a more efficient compressor that will increase flow with a reduced shaft speed. This concept was a given for me.
Term "Pressure Head"
There are several formulas/meanings of "pressure head" as it applies to fans, compressors, etc., but in this case it can only be applied to the compressor wheel and "pressure head" does not translate or affect performance on the turbine side as nothing on the turbine side was changed.
You can easily do a google search or pick up your old physics book to better understand this concept as it applies to this scenario.
HP and BackPressure
With all else remaining equal, an increase of hp will generate additional exhaust flow and only have the potential to increase backpressure.
Shaftspeed and backpressure
With all else remaining equal, reduce shaft speed and you reduce the flow. Not a hard concept to understand. Turn a turbine faster it flows more, turn a turbine more slowly and it flows less.
=========================
Based on the scenario and information presented, the reduction in backpressure does not appear to be plausible.
The turbo gods have spoken
It is possible to have a more efficient compressor that will increase flow with a reduced shaft speed. This concept was a given for me.
Term "Pressure Head"
There are several formulas/meanings of "pressure head" as it applies to fans, compressors, etc., but in this case it can only be applied to the compressor wheel and "pressure head" does not translate or affect performance on the turbine side as nothing on the turbine side was changed.
You can easily do a google search or pick up your old physics book to better understand this concept as it applies to this scenario.
HP and BackPressure
With all else remaining equal, an increase of hp will generate additional exhaust flow and only have the potential to increase backpressure.
Shaftspeed and backpressure
With all else remaining equal, reduce shaft speed and you reduce the flow. Not a hard concept to understand. Turn a turbine faster it flows more, turn a turbine more slowly and it flows less.
=========================
Based on the scenario and information presented, the reduction in backpressure does not appear to be plausible.
The turbo gods have spoken