1.9TDI PD compound sizing

miniCotulla

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Passat B5 1.9TDI PD
Hello,

I want to do a compound setup on my car. I want 320 - 350hp. As my car is pretty much the heaviest 1.9TDI you can get (1800kgs, it's a quattro Passat) I want great spool.

The car already has 272 deg cams, 100% nozzles, 12.9 strength head bolts and a Sachs performance clutch. Engine code: AVF.

The problem is the sizing. I already saw the post from TDIMeister(staged-turbo-sizing-math) on how to select the correct turbos. But I can't find compressor maps for any of the available turbos. (GTD 1756 or GTB2060VKLR as HP stage)

I asked a tuner and he wants to use the 2.5TDI stock turbo(GT2052V) as HP stage, which on it's own already spools bad on the 1.9tdi.

Does anybody know where I can find that data? Or has anybody already built a similar setup and can tell me what turbos will fit my goals best? (with stock like spool and transient response)

Thanks!
 

[486]

Top Post Dawg
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02 golf ALH
not to be a debbie downer, but vanes and compounds don't mix well for me
they might work better on the LP side like the ford 6.4 did, but I've never tried it that way

same with running a really tiny HP turbo that'll wake up real early, the little tiny thrust bearings hate life when they're being fed air that's 4 times denser than STP, even if you're setting your wastegate up to be sequential you still need to block off the turbine side and bypass the compressor side completely since unloaded choke flow seems to destroy them too

what I'd want to do if I were doing it again? Grab the unitized borg warner sequential setup off a BMW or mazda or whatever. They've got simply actuated HP bypass plumbing already integrated in there, the HP is something absolutely tiiiiny for off-idle spool, and the LP is IIRC fairly meaty, like a K27
and they should be fairly junkyard-available by now
 

miniCotulla

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Passat B5 1.9TDI PD
not to be a debbie downer, but vanes and compounds don't mix well for me
they might work better on the LP side like the ford 6.4 did, but I've never tried it that way

same with running a really tiny HP turbo that'll wake up real early, the little tiny thrust bearings hate life when they're being fed air that's 4 times denser than STP, even if you're setting your wastegate up to be sequential you still need to block off the turbine side and bypass the compressor side completely since unloaded choke flow seems to destroy them too

what I'd want to do if I were doing it again? Grab the unitized borg warner sequential setup off a BMW or mazda or whatever. They've got simply actuated HP bypass plumbing already integrated in there, the HP is something absolutely tiiiiny for off-idle spool, and the LP is IIRC fairly meaty, like a K27
and they should be fairly junkyard-available by now
A sequential setup? How would I possibly control that accurately? This can't be controlled with original ECU.

The GTB2060VKLR already does 280HP, I thought adding another turbo to that would bring me to my goal. What's unloaded choke flow?

I don't know where you are from but used turbos are expensive here, even if 10+ years old.
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
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At the most basic level when it comes to compound turbocharging, adding an additional turbocharger does NOT add horsepower, so, having a GTB2060VKLR that supports 280HP doesn't mean that another turbo adds to that power figure.

You ALWAYS size the LP for the full target power, so, if you want 350 HP, size the LP for the full 350. Maybe something in the S300 family or GT35.

Then the HP is just to bridge the gap from the low-end to when the LP spools up and operates efficiently. As far as I'm concerned, you can use the stock turbo as the HP, but as mentioned before, it's not built to take a large amount more pre-compressed mass flow so, this makes it imperative to design the system to bypass the HP when the LP is fully spooled in a sequential setup. To prove this concept, I was involved in a series-sequential Otto engine prototype that used a Borg-Warner KP35 WG turbo (similar in size to a GT14) as the HP stage.

The choice of WG vs VGT is a matter of personal preference and tech savviness along with the individual's controls/programming knowledge. Either approach can and has been done successfully. The WG is more common among do-it-yourselfers because it is definitely easier to realize and implement, but there are benefits to the VGT approach. Sequential setups are also possible but, again, raise the level of difficulty and demand that you know what you're doing and why. That said, when you use the WG on the HP stage, it is already sort of a sequential system as you're bypassing - at least partially - the HP.
 
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BustedBolts

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Gtb2056vk or gtd2060vrk as high pressure and s300/hx5x as low pressure have been quite a few times. Using vnt for high pressure and gated turbo for low pressure is the easiest and best way. I have actually modified the stock ecu and done some coding adjustments so I can run 2nd map sensor "4bar sensor on lp and 6bar in overall stage" to read low pressure boost and thereby limiting pressure ratio on high pressure stage and also make fueling, soi, and vnt adjustments based on low pressure boost. For example not allowing full fueling until lp is making over 0.5bar to keep stress on high pressure from being to high. Then for tuning you need emp gauge on both stages to dial everything in.
 

miniCotulla

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Passat B5 1.9TDI PD
At the most basic level when it comes to compound turbocharging, adding an additional turbocharger does NOT add horsepower, so, having a GTB2060VKLR that supports 280HP doesn't mean that another turbo adds to that power figure.

You ALWAYS size the LP for the full target power, so, if you want 350 HP, size the LP for the full 350. Maybe something in the S300 family or GT35.

Then the HP is just to bridge the gap from the low-end to when the LP spools up and operates efficiently. As far as I'm concerned, you can use the stock turbo as the HP, but as mentioned before, it's not built to take a large amount more pre-compressed mass flow so, this makes it imperative to design the system to bypass the HP when the LP is fully spooled in a sequential setup. To prove this concept, I was involved in a series-sequential Otto engine prototype that used a Borg-Warner KP35 WG turbo (similar in size to a GT14) as the HP stage.

The choice of WG vs VGT is a matter of personal preference and tech savviness along with the individual's controls/programming knowledge. Either approach can and has been done successfully. The WG is more common among do-it-yourselfers because it is definitely easier to realize and implement, but there are benefits to the VGT approach. Sequential setups are also possible but, again, raise the level of difficulty and demand that you know what you're doing and why. That said, when you use the WG on the HP stage, it is already sort of a sequential system as you're bypassing - at least partially - the HP.
Ok, I know that the Stock turbo will be to small to run it fully as a compound, that's why I thought maybe a GTB2060VKLR makes more sense as a HP turbo, but will this even be enough to avoid the added complexity of bypassing the HP turbo?
 

[486]

Top Post Dawg
Joined
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Location
MN
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02 golf ALH
That said, when you use the WG on the HP stage, it is already sort of a sequential system as you're bypassing - at least partially - the HP.
I've most often seen that as the delineation between compounds and sequential both in their simplistic form
sequential setups you're offloading the HP in some manner or form, where what I'd call a compound setup you're shooting for the HP to be contributing to the overall PR of the system the entire time

I have actually modified the stock ecu and done some coding adjustments so I can run 2nd map sensor "4bar sensor on lp and 6bar in overall stage" to read low pressure boost and thereby limiting pressure ratio on high pressure stage and also make fueling, soi, and vnt adjustments based on low pressure boost. For example not allowing full fueling until lp is making over 0.5bar to keep stress on high pressure from being to high. Then for tuning you need emp gauge on both stages to dial everything in.
That sounds very slick. Your time investment into the binaries to get that working has gotta be immense.
 

miniCotulla

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Passat B5 1.9TDI PD
Gtb2056vk or gtd2060vrk as high pressure and s300/hx5x as low pressure have been quite a few times. Using vnt for high pressure and gated turbo for low pressure is the easiest and best way. I have actually modified the stock ecu and done some coding adjustments so I can run 2nd map sensor "4bar sensor on lp and 6bar in overall stage" to read low pressure boost and thereby limiting pressure ratio on high pressure stage and also make fueling, soi, and vnt adjustments based on low pressure boost. For example not allowing full fueling until lp is making over 0.5bar to keep stress on high pressure from being to high. Then for tuning you need emp gauge on both stages to dial everything in.
I'd guess the GTB2060vklr should perform similar to the GTD2060vrk then? If not even spool a little faster. You modified your stock ECU? This can't be done only through software, right? Or does the Stock ECU(EDC15 in my case) already have a spare input for the additional sensor?
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
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I've most often seen that as the delineation between compounds and sequential both in their simplistic forms equential setups you're offloading the HP in some manner or form, where what I'd call a compound setup you're shooting for the HP to be contributing to the overall PR of the system the entire time
Yes, that's right. With a WG (especially an internal one), you never fully deactivate the HP even at full open, so it is always contributing to the overall PR. And the compressor side is not being bypassed at all.

In the industry, the terms bypass and wastegate are essentially distinguished only by the method of control of the valve. Bypass is basically on-off and wastegate is regulated in a closed loop.
 

BustedBolts

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I'd guess the GTB2060vklr should perform similar to the GTD2060vrk then? If not even spool a little faster. You modified your stock ECU? This can't be done only through software, right? Or does the Stock ECU(EDC15 in my case) already have a spare input for the additional sensor?
I always prefer slightly larger turbine on hp stage, and vklr might be a bit weak for compound stage imo. Depending on fueling it's still almost certainly needed to have hp turbine bypass wastegate, also you should 100% use hella pwm actuator for vnt activation on hp turbo, especially since it's so accurate and fast movement. There is also more benefit to using it than I have time to explain right now. Stock edc15 is possible to do those mods to ecu. It's small hardware mod to utilize input channel, and rest is done in binary.
 

miniCotulla

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Passat B5 1.9TDI PD
I always prefer slightly larger turbine on hp stage, and vklr might be a bit weak for compound stage imo. Depending on fueling it's still almost certainly needed to have hp turbine bypass wastegate, also you should 100% use hella pwm actuator for vnt activation on hp turbo, especially since it's so accurate and fast movement. There is also more benefit to using it than I have time to explain right now. Stock edc15 is possible to do those mods to ecu. It's small hardware mod to utilize input channel, and rest is done in binary.
Ok, I didn't know the vklr's were weaker. Even if I open VNT fully I need a bypass? How do I control that bypass? Does the LP turbo need ECU control (extra N75) or should the WG just open at a fixed max pressure? Do you sell that software service for the second sensor?
 

TDIMeister

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I'd guess the GTB2060vklr should perform similar to the GTD2060vrk then?
Since the frame size, i.e. turbine inducer diameter, and compressor exducer diameter of the two are the same, the main way to tell the "performance" is to compare the trims of both wheels. Higher trims support higher flows. Multiple turbos with the same GTx2060 designation but used in different applications will have different trims. The tell-tale sign is to look at what the is original OEM HP rating. Compressor maps are nice to have, but you don't really need them because the OEM has done its homework.
 
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TDIMeister

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For me, the bottom line of the choice between full-time compound vs. sequential boils down to these factors:

Compound:
  • Turbos sized relatively close to each other
  • Simple to implement and control (but can result in dangerous boost pressures if not done correctly because you're not controlling the share of HP and LP - that's why they're compounding all the time)
  • Low-end boost threshold and transient response limited by the size and characteristics of the HP turbo - transient response is worse than stock because it needs to be larger than in a sequential setup, plus the extra plumbing inevitably adds undesired flow restrictions through the limiting HP stage

Sequential:
  • Turbos can be sized quite far apart from each other
  • More difficult to implement and control
  • Low-end boost threshold and transient response can be as good or better than stock depending on HP turbo selection, whilst not compromising top-end performance
 

[486]

Top Post Dawg
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Compound:
  • Simple to implement and control (but can result in dangerous boost pressures if not done correctly because you're not controlling the share of HP and LP - that's why they're compounding all the time)
well, you can also set it up with an interstage wastegate that has chambers on both sides of the diaphragm, LP on top and HP underneath
then you're asking a consistent pressure ratio across the HP turbo

allows for somewhat more disparate sizing, and tames down the runaway tendencies that turn fabricated intake manifolds into aluminum balloons

eta: not as applicable to 'properly' tuning a vaned HP turbo in such a setup, though
 

shanky887614

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For only 320-350 you can easily get that with a gtb2365vk.
Mine makes over 44psi at 3k rpm (request is 40psi)

You have to think if you really want the hastle of a compound for such low power figures

You might as well go for 400bhp if your going compound (
 

TDIMeister

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The only problem is that a gtb2365vk doesn't exist from Garrett. It's just a made-up designation by someone who has created a Frankenstein turbo out of a bunch of parts, some of which may have OEM Garrett origins with varying proportions of aftermarket components. Since there is actually no gtb2365vk, you don't know exactly what you're getting except to trust the vendor's claim that it's somewhere between a GT20 and a GT25 (e.g., a bored-out gtb20 with a larger turbine wheel and a 65mm compressor wheel - but what trim?) and it will support the power output that's claimed. On the latter point, you can bet that they don't have access to compressor maps so their guess is about as good as any educated one out there.
 

miniCotulla

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For only 320-350 you can easily get that with a gtb2365vk.
Mine makes over 44psi at 3k rpm (request is 40psi)

You have to think if you really want the hastle of a compound for such low power figures

You might as well go for 400bhp if your going compound (
This is my daily driver, i can't wait for 3000rpm before boost comes on. I tow heavy trailers too, that won't be possible with such a big turbo.
 

adamss24

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Gtb2260vk does 450nm at 2500 rpms on golf mk5 4Motion 2.0tdi with AL injectors. A gtb2260vklr will have no problem doing what you ask while being on full boost by 2500-2800 rpms with excellent transient response and no complications as running compounds !
It looks like you already have most ingredients already in place which will support a larger vnt turbo ! I would look at f10 gtb2260v turbo with modern AMG turbine wheel and 69mm compressor wheel if you don’t want vklr turbo ! It’s v band on both exhaust inlet/outlet so will require a new manifold to be fabricated but it’s the best flowing cast stock hot side you can get ! You can also fit the vklr chra in it- what most turbo rebuild shops do when they call gtb25xx vklr hybrid turbos !
 

diffas

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Even gtb2260vk on stock form spools quite nice on 1.9tdi it is still too big for HP under 400hp setup, it just wont spool under 2000rpm. I'd rather look something like gtb1752vk (or gtb1749vk) from 2.5tdi i5 for example fpr HP and have decent size LP...like S257SXE for example or bigger s362sxe.

Oh not mention you need really good tuner for controlling vnt and boost on compound setup. Some really small frame WG turbo as HP should be also as option, it makes everything easier to build itself. I've been watching GBC14-200 from garrett that might be pretty decent for hp turbo for self build setup.
 
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miniCotulla

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Gtb2260vk does 450nm at 2500 rpms on golf mk5 4Motion 2.0tdi with AL injectors. A gtb2260vklr will have no problem doing what you ask while being on full boost by 2500-2800 rpms with excellent transient response and no complications as running compounds !
It looks like you already have most ingredients already in place which will support a larger vnt turbo ! I would look at f10 gtb2260v turbo with modern AMG turbine wheel and 69mm compressor wheel if you don’t want vklr turbo ! It’s v band on both exhaust inlet/outlet so will require a new manifold to be fabricated but it’s the best flowing cast stock hot side you can get ! You can also fit the vklr chra in it- what most turbo rebuild shops do when they call gtb25xx vklr hybrid turbos !
I get that, but my car is not a 1200kg Seat or Golf. It's already really hard to start on a steep hill especially with that long gearbox. That's why I want compounds. I'm from Austria btw.
 

TDIMeister

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Maybe not exactly what you're looking for, but @Fix_Until_Broke did a compound of a GTC1444VZ and Holset HE221. Most importantly, he has dyno numbers and has put considerable daily-driven miles, some with heavy trailer towing. He doesn't hold back from the bad and the good of his experiences.
 

miniCotulla

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Maybe not exactly what you're looking for, but @Fix_Until_Broke did a compound of a GTC1444VZ and Holset HE221. Most importantly, he has dyno numbers and has put considerable daily-driven miles, some with heavy trailer towing. He doesn't hold back from the bad and the good of his experiences.
This looks very promising, would be intresting what kind of top end it gets in the compound setup.
 

shanky887614

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The only problem is that a gtb2365vk doesn't exist from Garrett. It's just a made-up designation by someone who has created a Frankenstein turbo out of a bunch of parts, some of which may have OEM Garrett origins with varying proportions of aftermarket components. Since there is actually no gtb2365vk, you don't know exactly what you're getting except to trust the vendor's claim that it's somewhere between a GT20 and a GT25 (e.g., a bored-out gtb20 with a larger turbine wheel and a 65mm compressor wheel - but what trim?) and it will support the power output that's claimed. On the latter point, you can bet that they don't have access to compressor maps so their guess is about as good as any educated one out there.
Yes they support the power output claimed, the place i used makes there own custom cast manifolds and all setup on a flowbench measuring the wheel speed and flowrates

The parts are all genuine parts so there are compressor maps etc availible for them but yes getting a stock turbo that is sized correctly is a lot better option
 

shanky887614

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This is my daily driver, i can't wait for 3000rpm before boost comes on. I tow heavy trailers too, that won't be possible with such a big turbo.
Its not waiting for 3k for boost to come on its peak boost of 4bar absolute at 3k rpm

Even with a compound setup i doubt your going to get 4bar at 2k rpm in a 1.9tdi
 

TDIMeister

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Well, tell us the name of this company instead of, "this place that I used." Why keep it a secret?
 

shanky887614

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fair enough im using a small company called pioneering performance. sorry thought it was quite obvious as i only know of one company making custom casts for the pd 8v's
 

miniCotulla

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Passat B5 1.9TDI PD
Its not waiting for 3k for boost to come on its peak boost of 4bar absolute at 3k rpm

Even with a compound setup i doubt your going to get 4bar at 2k rpm in a 1.9tdi
It doesn't need 4 bar at 2K, it needs 0.6 bar at 1,5K and 1 bar at 2K.
 
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