GT2 Turbochargers Explained
#46
03-23-2011 | 07:49 PM
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Remember, 1.6 bar from a factory VTG and 1.6 bar from one of our 68mm VTG's is very different. The actual volume of air being pushed through the intercooler is much greater. They're a great option....and if I was only planning on running a tune/exhaust on my car, I'd be ALL OVER these for the price.
#49
03-23-2011 | 11:28 PM
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Do you have any datalogs of MAF readings you could share so we can actually see the difference in flow you describe?
#50
03-24-2011 | 06:39 AM
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With both the 65's and the 68's we never run more then 23 psi on any car with stock engine internals. The WHP numbers I gave above for the two GT2's we built we both at 23 psi, the only variable being the turbochargers and turbo inlet pipes.
We've never conducted an actual "real-world" comparison between the .2 IC's and ours, because the reality is that's just impossible for us to do. We'd have to take the same car, go find a stretch of highway to do a high speed run, come back, change the IC's, and go do it again. Street testing is just something we don't endorse. We don't have the roads for it here in South Florida, and we just don't take chances on the street like that.
That being said, I can tell you that we recently completed a build on Arone997TT's tiptronic turbo cab. That car safely makes 670 awhp. During our testing runs on the dyno with his car, the ambient temperature was 25ºC. The highest intake temperature we recorded with the GIAC datalogger was 30.8ºC at 6734 rpm's. That's with absolutely NO knock, and full lambda control. The tunes we use are VERY safe. Granted...as I mentioned above, we were not conducting a comparison test of any kind, this is simply the results we got with his car during our final tuning stages.
The fact is that the .2 IC's are good...very good. They are extremely efficient, thermally. The only issue with them becomes flow in applications where a larger turbocharger is used. Remember, 1.6 bar from a factory VTG and 1.6 bar from one of our 68mm VTG's is very different. The actual volume of air being pushed through the intercooler is much greater. They're a great option....and if I was only planning on running a tune/exhaust on my car, I'd be ALL OVER these for the price.
#51
03-24-2011 | 12:14 PM
I do have MAF readings, but to be perfectly honest, I'm not going to post them for a couple reasons. The MAF readings I post won't be comparible to what you may have seen in the past, because each one of our 68mm kits uses a custom MAF, and details about it are something we just won't release. It took quite a bit of time and engineering to develop.
#52
03-24-2011 | 12:30 PM
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Hi TTdude. Excellent question...you've done some homework. I do have MAF readings, but to be perfectly honest, I'm not going to post them for a couple reasons. The MAF readings I post won't be comparible to what you may have seen in the past, because each one of our 68mm kits uses a custom MAF, and details about it are something we just won't release. It took quite a bit of time and engineering to develop.
I do have MAF readings, but to be perfectly honest, I'm not going to post them for a couple reasons. The MAF readings I post won't be comparible to what you may have seen in the past, because each one of our 68mm kits uses a custom MAF, and details about it are something we just won't release. It took quite a bit of time and engineering to develop. It's an interesting project. GL with it.
#53
03-24-2011 | 12:52 PM
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OK. Believe me...I want to do the comparison. So this is what I propose. We have a second 997 GT2 in our shop right now getting the full 68mm billet turbocharger upgrade. What I'm willing to do is strap that car onto the dyno once the engine upgrade is complete and do back to back dyno runs with our intercoolers, and factory 997.2's. My question is....what data would you like to see? And perhaps more importantly...will this data be scrutinized and viewed as biased because it's coming from our dyno within our four walls? To combat that, I'm willing to open the doors to someone who might be willing to come and observe. A neutral third party. Does that sound fair? If so...maybe we can finally do this comparo!
3 pulls in the highest gear (4th minimum) you can safely do with exactly 1 minute between runs
Record via durametric: rpm, MAF, IAT, ignition angle, lambda banks 1 & 2, pressure of sensor (boost)
Note the shop conditions and take a video of everything.
Swap coolers and do the same thing.
The issue you may run into is the ducting for the .2 coolers. I'm not sure what trimming you do for the CMS coolers but hopefully it will work. Just be sure they're both sealed well.
That's the issue Tom, except for a select few, there IS no data coming from anyone's walls! If it's well documented, I don't think it will be scrutinized.
#54
03-24-2011 | 04:21 PM
Tom, thanks for being willing to take this on. While IC evaluations on a dyno are going to be limited, you should be able to quantify how they're performing relative to each other. If I had to do a dyno comparison, I would do the following for each cooler:
3 pulls in the highest gear (4th minimum) you can safely do with exactly 1 minute between runs
Record via durametric: rpm, MAF, IAT, ignition angle, lambda banks 1 & 2, pressure of sensor (boost)
Note the shop conditions and take a video of everything.
Swap coolers and do the same thing.
The issue you may run into is the ducting for the .2 coolers. I'm not sure what trimming you do for the CMS coolers but hopefully it will work. Just be sure they're both sealed well.
3 pulls in the highest gear (4th minimum) you can safely do with exactly 1 minute between runs
Record via durametric: rpm, MAF, IAT, ignition angle, lambda banks 1 & 2, pressure of sensor (boost)
Note the shop conditions and take a video of everything.
Swap coolers and do the same thing.
The issue you may run into is the ducting for the .2 coolers. I'm not sure what trimming you do for the CMS coolers but hopefully it will work. Just be sure they're both sealed well.
I appreciate that. We'll do it. And I'll make sure to document the whole process with video as well.
#55
03-25-2011 | 10:42 PM
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#57
04-24-2015 | 04:45 PM
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So does anyone actually know what the differences are between turbos on following cars i.e. exact differences inc if the housing is made of a different material. Doesn't seem to be an authority on this even 8 years on!
997.1
997.2
GT2
GT2 RS
Also are GT2 or Champion 68mm VTGs better - subjective I know but what's the consensus from the tuners out there themselves? Be good if Todd at Proto might chime in as 9e who have tuned my car use his remaps.
I only ask as I'm running GT2 hybrid turbos with clipped billet wheels, motorsport bearings and a few other tricks.
My tuner can't run them at more than 1.3 bar without the ECU pulling power.
997.1
997.2
GT2
GT2 RS
Also are GT2 or Champion 68mm VTGs better - subjective I know but what's the consensus from the tuners out there themselves? Be good if Todd at Proto might chime in as 9e who have tuned my car use his remaps.
I only ask as I'm running GT2 hybrid turbos with clipped billet wheels, motorsport bearings and a few other tricks.
My tuner can't run them at more than 1.3 bar without the ECU pulling power.
#58
04-24-2015 | 06:53 PM
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Tom, killer post, but we noticed some points that are incorrect.
The standard compressor wheel is different on the 997.1 turbo, the GT2 wheel is larger. It is the same on the 997.2 but the compressor housing is different.
Info on wheel sizes and turbine material from the BW catalogue:
GT2 Borg Warner turbocharger specification:
BV50-2280DCB426.10BVAX0
997.1TT Borg Warner turbocharger specification:
BV50-2277DCB405.10BVAX0
997.2TT Borg Warner turbocharger specification:
BV50-2280DCB426.10BVAX0
The four numbers in RED indicate the compressor wheel size. All have the same size exducer, 56mm. The 997.1 inducer is 43mm and the GT2 and 997.2 inducer is 45mm.
The last letter that is bold and underlined indicates the turbine material. In this case O stands for Austenitic stainless steel, which is specially formulated to withstand high EGTs.
Actually, as I pointed out above, the housings are made of the same material according to Borg Warner spec.
Your cooling statement is inaccurate as well. Heat should be kept in the turbo, turbine housings are never cooled. That is why you see some people wrap their turbos or even coat them. You want to keep the energy inside the turbo and not dissipate it. Please don't confuse this with exhaust gas temperature...that is an entirely different conversation.
This is also technically not correct.
Rotational speed is controlled by the vanes, the blade profile is not a factor. Clipping the wheel is to decrease back pressure and therefore EGTs at steady state operation. This raises the flow limit of the turbine to better match the larger compressor wheel.
The standard compressor wheel is different on the 997.1 turbo, the GT2 wheel is larger. It is the same on the 997.2 but the compressor housing is different.
Info on wheel sizes and turbine material from the BW catalogue:
GT2 Borg Warner turbocharger specification:
BV50-2280DCB426.10BVAX0
997.1TT Borg Warner turbocharger specification:
BV50-2277DCB405.10BVAX0
997.2TT Borg Warner turbocharger specification:
BV50-2280DCB426.10BVAX0
The four numbers in RED indicate the compressor wheel size. All have the same size exducer, 56mm. The 997.1 inducer is 43mm and the GT2 and 997.2 inducer is 45mm.
The last letter that is bold and underlined indicates the turbine material. In this case O stands for Austenitic stainless steel, which is specially formulated to withstand high EGTs.
Actually, as I pointed out above, the housings are made of the same material according to Borg Warner spec.
Your cooling statement is inaccurate as well. Heat should be kept in the turbo, turbine housings are never cooled. That is why you see some people wrap their turbos or even coat them. You want to keep the energy inside the turbo and not dissipate it. Please don't confuse this with exhaust gas temperature...that is an entirely different conversation.
This is also technically not correct.
Rotational speed is controlled by the vanes, the blade profile is not a factor. Clipping the wheel is to decrease back pressure and therefore EGTs at steady state operation. This raises the flow limit of the turbine to better match the larger compressor wheel.
So what happened to the IC test?
Last edited by speedsterr; 04-24-2015 at 07:17 PM.
#60
04-25-2015 | 02:51 PM
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It seems you can't compare to .1. .1 is different from all of them. The .2, GT2, and probably 991 are all the same it may be. Makes sense for Porsche to do something like this.