1.9TDI PD compound sizing

[tdi_my live]

It doesn't need 4 bar at 2K, it needs 0.6 bar at 1,5K and 1 bar at 2K.

Again, nothing was understood about how a diesel works. Pressure, Pressure, Pressure. The air mass at 1.5k or 2k is important, not the boost pressure.

 

[turbobrick240]

A good mid-sized single like a gtb2260vk would make things much simpler. Going over 300 HP is probably going to cause longevity issues anyhow. Especially if you're making a lot of torque low in the powerband. Darkside says you can expect full boost by 2800 rpm with a gtb2260vk on a 1.9l.

 

[shanky887614]

It doesn't need 4 bar at 2K, it needs 0.6 bar at 1,5K and 1 bar at 2K.

Which it makes.

It makes over 1.5bar at 2k rpm and there are many options for manifolds.

On inline engines you can buy an adapter to use the stock gtb hotside with your existing manifold.

 

[miniCotulla]

A good mid-sized single like a gtb2260vk would make things much simpler. Going over 300 HP is probably going to cause longevity issues anyhow. Especially if you're making a lot of torque low in the powerband. Darkside says you can expect full boost by 2800 rpm with a gtb2260vk on a 1.9l.

But how won't this kill low rpm performance? I already need to rev it to 1,5K to get going on a really steep hill and that's with a stock turbo. Transient response is also not great with a 2260.

 

[[486]]

yeah I'd certainly go with a real wide spread in turbos if you're looking for off-idle boost, and you're going to sacrifice a lot doing that

Have you considered a mechanically driven supercharger?

 

[turbobrick240]

But how won't this kill low rpm performance? is also not great with a 2260.

I don't think the low end would be that bad w a gtb2260. I wouldn't exactly call 1.5k winding it out. Just seems like a much, much easier route.

 

[miniCotulla]

I don't think the low end would be that bad w a gtb2260. I wouldn't exactly call 1.5k winding it out. Just seems like a much, much easier route.

We have driven a 2.5TDI + 2260 (upgrade) just yesterday, under 2K it's pretty dead. I also have seen the videos with 1.9TDI+ 2260 they are laggy as hell.

 

[miniCotulla]

Which it makes.

It makes over 1.5bar at 2k rpm and there are many options for manifolds.

On inline engines you can buy an adapter to use the stock gtb hotside with your existing manifold.

I already saw that adapter, with a 2260 it has 5mm clearance to the framerail. Thats not enough.

 

[turbobrick240]

We have driven a 2.5TDI + 2260 (upgrade) just yesterday, under 2K it's pretty dead. I also have seen the videos with 1.9TDI+ 2260 they are laggy as hell.

The ball bearing version is supposed to spool up a good bit faster. Compound/sequential setups can be the best of both worlds, but they are 1000% more work, imo.

 

[miniCotulla]

The ball bearing version is supposed to spool up a good bit faster. Compound/sequential setups can be the best of both worlds, but they are 1000% more work, imo.

The best single for the 1.9 should be th 2060vklr from a mercedes engine, it's supposed to spool like stock but reach 290hp with excellent transient response. But 290 ist still quite a bit away from my goals and I'd like to have power up to 5k rpm.

 

[Fix_Until_Broke]

A few comments since I was mentioned earlier in this discussion...

- Spool does not equal response. The GTB2260 in the TT will make 15 psi at 1800 RPM as will the GTC1444 in my Jetta. They both "spool" at 1800 RPM. The difference being that the GTB2260 takes 2-3 seconds to get there whereas the GTC1444 does it as fast as you move your right foot on the pedal. Reading between the lines miniCotulla is looking for response.

300-350HP from 1.9L PD is obviously possible, however will be more difficult doing so with the aforementioned response, hence the compound turbo discussion. This is not a 100 hour project, this is a 1000+ hour project.

- Someone already mentioned this, but tuning is as important, if not more so than the turbo selection. Find a tuner you trust and can have honest conversations with (or learn to do it yourself).

- Make data driven decisions. Get compressor maps, do the math. Put gauges on your car, change ONLY one variable, go collect data in controlled repeatable conditions, analyze it, change another variable, repeat.

- I ran the GTC1444VZ as a single for a year or so before putting the HE221W on. Find the HP turbo you want and make sure it behaves the way you want in the lower RPM's before adding the LP turbo.

 

[TDIMeister]

There are two different things being discussed here. Boost @ RPM is called boost threshold. It has nothing to do with time, just what boost pressure can be developed at a certain engine RPM regardless of time. The vast majority of the discussion about what people call "spool" is erroneously boost threshold but in fact, what people subjectively judge while driving as good spooling or not, and who show videos of their boost gauge dancing about while driving is actually turbo lag.

Turbo lag IS specifically a measurement of time - that is, how much time it takes from the moment any given boost pressure is demanded by a load step to when that demand is fulfilled; it can be any pressure and any RPM. They do generally follow each other: a large turbo will have a higher boost threshold and longer turbo lag - but a small turbo can have similar effects (e.g., ancient tech heavy rotating group, overly large turbine A/R). Nevertheless, boost threshold and turbo lag are different things.

 

[TDIMeister]

F_U_B posted before me.

 

[TDIMeister]

The bottom line for miniCotulla is that if you want to have your cake and eat it, too, that is to say, you want the widest spread of a 350 HP target with very fast response and low-end torque availability, you'll need a similarly wide spread of turbo sizes between HP and LP. Before I go into the specifics of turbo selection, you WILL therefore need to bypass the HP in some way. If you don't, the small HP turbo will be a severe restriction in the upper power and RPM band as Fixed_Until_Broke has found in his setup. If you are willing to embark on this added level of complexity, then you can proceed to the next step of the discussion, and there are a couple of ways to go.

Since you'll need a bypass around the HP anyway, using a wastegated HP turbo may not be such a bad thing, but as such keep it small, something like the GT1446S with the highest possible trim you can find and small turbine A/R (~0.34). The bypass - sufficiently sized external wastegate preferred - is to be controlled based on interstage differential pressure (you can use a dirt simple manual boost controller). DON'T dump the wastegate gases directly into the downpipe but reintroduce it upstream of the LP turbine inlet. In any case, you should definitely use an inter-stage cooler as well as an aftercooler.

The LP can be a VNT unit that is controlled by the N75 as usual (direct to a PWM actuator preferred). Here, I'd choose something fairly large rather than run a smaller turbo (eg. GTB22 frame size with a 60-65 mm compressor wheel - again, the trim is far more important than the headline outer diameter!!!). Some aftermarket companies advertise hybridized turbos based on the GTB22 outfitted with ball bearings that support 400+ HP, for example below.

BMW E9x / E6x / E7x M57N2 upgrade turbocharger | TurboSystems

* Price is shown without VAT and shipping costs. Bolt-on upgrade turbocharger solution for BMW M57N2 engine power gain designed to work with stock exhaust manifold and other engine units. Five versions available from Stage 2 to Stage 5. Specifications and compatibility list written below.

www.turbosystems.info

BMW M57 Universal Vacuum Control Turbocharger | TurboSystems

* Price is shown without VAT and shipping costs. This is our custom ball bearing solution for other M57 engines designed to work with 170KW/231HP exhaust manifold. Instead of electrical actuator vacuum control is used.

www.turbosystems.info

You can also do a bypassed setup with VNT HP and wastegated LP - e.g. Audi's 3.0 BiTdi, or VNT for both HP and LP. The latter sounds extremely complicated but it's not really. The trick is to use the SAME N75 signal to control BOTH HP and LP turbos simultaneously. This is easiest when both turbos use N75-compatible (300 Hz PWM) electronic actuators rather than vacuum. You still need to bypass the HP as before, and the programming needs to be sufficiently sophisticated to know when the bypass has opened or closed and not go into limp-mode as it sees that the boost pressure has fallen or risen without correspondence to the vane position for reasons the ECU doesn't understand but simply adjusts accordingly.

If you want to go with the dual-VNT setup, a great turbo to use for the HP is the GTD1752VRK from the 184 HP BMW 2.0d. It already has a Hella PWM electronic actuator that can be adapted to work with the N75 signal. For the LP, choose from the above URL with the electronic actuator - again, the Hella/BMW actuator is compatible!

 

[adamss24]

I would keep it simple if I was you, get a gtb2260vklr with a better compressor wheel on it and be done with it ! You can’t have everything at once, you have to have a compromise somewhere ! The vklr will do your 300bhp without much bother and give you the transient response you have already at the moment. As it’s a car that’s dependable (towing and long distance trips) I would keep things simple- I am very surprised how a gtb2260vk feels on a pd engine with firad 120% nozzles and 6 speed conversion. I would also look at the gearbox from a v6 tdi Quattro as it has better gear ratios suitable for towing !
I could live with a few seconds of lag if the midrange and top end are what I strive for, in my opinion the best turbo is a vklr 2260 core fitted inside bmw f10 hotside with Audi2260vk cold side. Minimal lag, really good transient response and doable with minimum investment! You will have trouble getting it to fit unless you reposition the turbo on top or make new manifold for it as it’s quite a large turbo.
Alternately look at the euro5/6 sprinter twin turbo setup, they are all vacuum operated and can deliver your airflow low down, trouble it is even harder to implement due to its sizes on the longitudinal Passat as you already know !

 

[miniCotulla]

The bottom line for miniCotulla is that if you want to have your cake and eat it, too, that is to say, you want the widest spread of a 350 HP target with very fast response and low-end torque availability, you'll need a similarly wide spread of turbo sizes between HP and LP. Before I go into the specifics of turbo selection, you WILL therefore need to bypass the HP in some way. If you don't, the small HP turbo will be a severe restriction in the upper power and RPM band as Fixed_Until_Broke has found in his setup. If you are willing to embark on this added level of complexity, then you can proceed to the next step of the discussion, and there are a couple of ways to go.

Since you'll need a bypass around the HP anyway, using a wastegated HP turbo may not be such a bad thing, but as such keep it small, something like the GT1446S with the highest possible trim you can find and small turbine A/R (~0.34). The bypass - sufficiently sized external wastegate preferred - is to be controlled based on interstage differential pressure (you can use a dirt simple manual boost controller). DON'T dump the wastegate gases directly into the downpipe but reintroduce it upstream of the LP turbine inlet. In any case, you should definitely use an inter-stage cooler as well as an aftercooler.

The LP can be a VNT unit that is controlled by the N75 as usual (direct to a PWM actuator preferred). Here, I'd choose something fairly large rather than run a smaller turbo (eg. GTB22 frame size with a 60-65 mm compressor wheel - again, the trim is far more important than the headline outer diameter!!!). Some aftermarket companies advertise hybridized turbos based on the GTB22 outfitted with ball bearings that support 400+ HP, for example below.

BMW E9x / E6x / E7x M57N2 upgrade turbocharger | TurboSystems

* Price is shown without VAT and shipping costs. Bolt-on upgrade turbocharger solution for BMW M57N2 engine power gain designed to work with stock exhaust manifold and other engine units. Five versions available from Stage 2 to Stage 5. Specifications and compatibility list written below.

www.turbosystems.info

BMW M57 Universal Vacuum Control Turbocharger | TurboSystems

* Price is shown without VAT and shipping costs. This is our custom ball bearing solution for other M57 engines designed to work with 170KW/231HP exhaust manifold. Instead of electrical actuator vacuum control is used.

www.turbosystems.info

You can also do a bypassed setup with VNT HP and wastegated LP - e.g. Audi's 3.0 BiTdi, or VNT for both HP and LP. The latter sounds extremely complicated but it's not really. The trick is to use the SAME N75 signal to control BOTH HP and LP turbos simultaneously. This is easiest when both turbos use N75-compatible (300 Hz PWM) electronic actuators rather than vacuum. You still need to bypass the HP as before, and the programming needs to be sufficiently sophisticated to know when the bypass has opened or closed and not go into limp-mode as it sees that the boost pressure has fallen or risen without correspondence to the vane position for reasons the ECU doesn't understand but simply adjusts accordingly.

If you want to go with the dual-VNT setup, a great turbo to use for the HP is the GTD1752VRK from the 184 HP BMW 2.0d. It already has a Hella PWM electronic actuator that can be adapted to work with the N75 signal. For the LP, choose from the above URL with the electronic actuator - again, the Hella/BMW actuator is compatible!

The thing I don't get with dual VNTs is to control it with the same signal, how does that work? If I have to bypass HP won't the LP turbo already be in a fairly opened vane position?

With the modification from @BustedBolts for the second map sensor I could use this to maybe control the LP turbo separately with the EGR output of the ECU?

 

[miniCotulla]

I would keep it simple if I was you, get a gtb2260vklr with a better compressor wheel on it and be done with it ! You can’t have everything at once, you have to have a compromise somewhere ! The vklr will do your 300bhp without much bother and give you the transient response you have already at the moment. As it’s a car that’s dependable (towing and long distance trips) I would keep things simple- I am very surprised how a gtb2260vk feels on a pd engine with firad 120% nozzles and 6 speed conversion. I would also look at the gearbox from a v6 tdi Quattro as it has better gear ratios suitable for towing !
I could live with a few seconds of lag if the midrange and top end are what I strive for, in my opinion the best turbo is a vklr 2260 core fitted inside bmw f10 hotside with Audi2260vk cold side. Minimal lag, really good transient response and doable with minimum investment! You will have trouble getting it to fit unless you reposition the turbo on top or make new manifold for it as it’s quite a large turbo.
Alternately look at the euro5/6 sprinter twin turbo setup, they are all vacuum operated and can deliver your airflow low down, trouble it is even harder to implement due to its sizes on the longitudinal Passat as you already know !

I know the size constraints with the longitudinal Passat. It's a shame that there is no real way to sit the engine upright in the bay as this would at least require a gearbox adapter, custom oil pickup and pan and custom engine mounts.

The car already has the gearbox from a 3.0TDI quattro. This could be a pretty fast setup as it won't spin the wheels till 4th gear and the gears are spread very far apart. This has so much more potential than the typical FWD + short 5 or 6speed gearbox setup.

 

[Festa]

best turbo is a vklr 2260 core fitted inside bmw f10 hotside

Adam at Pioneering performance built me a f10 hybrid using a VKLR core last year. Don't know how it performs yet as still getting stuff together

 

[turbobrick240]

I would keep it simple if I was you, get a gtb2260vklr with a better compressor wheel on it and be done with it ! You can’t have everything at once, you have to have a compromise somewhere ! The vklr will do your 300bhp without much bother and give you the transient response you have already at the moment. As it’s a car that’s dependable (towing and long distance trips) I would keep things simple- I am very surprised how a gtb2260vk feels on a pd engine with firad 120% nozzles and 6 speed conversion. I would also look at the gearbox from a v6 tdi Quattro as it has better gear ratios suitable for towing !
I could live with a few seconds of lag if the midrange and top end are what I strive for, in my opinion the best turbo is a vklr 2260 core fitted inside bmw f10 hotside with Audi2260vk cold side. Minimal lag, really good transient response and doable with minimum investment! You will have trouble getting it to fit unless you reposition the turbo on top or make new manifold for it as it’s quite a large turbo.
Alternately look at the euro5/6 sprinter twin turbo setup, they are all vacuum operated and can deliver your airflow low down, trouble it is even harder to implement due to its sizes on the longitudinal Passat as you already know !

I think you make a good point about dependability. If this car is going to be a daily driver/workhorse, a custom compound setup will be far more likely to leave you on the side of the road multiple times. Something worth considering.

 

[miniCotulla]

I think you make a good point about dependability. If this car is going to be a daily driver/workhorse, a custom compound setup will be far more likely to leave you on the side of the road multiple times. Something worth considering.

Once it's finished it should be a dependable daily driver, in the meantime at least in sommer I have second car I can switch to if something goes wrong.

 

[TDIMeister]

The thing I don't get with dual VNTs is to control it with the same signal, how does that work? If I have to bypass HP won't the LP turbo already be in a fairly opened vane position?

With the modification from @BustedBolts for the second map sensor I could use this to maybe control the LP turbo separately with the EGR output of the ECU?

When the HP is fully bypassed, as is the original design intent (without modulation of an HP wastegate valve), it's like the HP is not even there. So, the HP's vanes will be moving around synchronously with the LP's, controlled by the N75, but with no effect - the vanes are essentially controlling the LP only as if it were a single large turbo.

Ideally, the HP compressor will be bypassed as well. Otherwise, the flow will always flow through its compressor side and act as a restriction. In this case, the HP turbine and compressor bypasses would also act synchronously together. There should be a somewhat more sophisticated control because there should be hysteresis between bypass opening and closing to prevent "hunting" near the switching point.

 

[TDIMeister]

One other thing you should consider: You don't mention where you are in Austria, but I've been there (in fact, in Vienna 2 months ago). Alpine areas at high altitudes could be risky for compressor surge, especially when using a large turbo and demanding high boost pressure at low engine RPM. Measures need to be considered for surge in any case, but it is more urgent when using a large single turbo. So, it's not always the "simplest" option.

There are huge advantages to pursuing simplicity, don't get me wrong. But there are always trade-offs based on stated wants or needs that warrant alternatives. It's an exercise of weighing risk vs benefit. Some people are more risk averse - great for them; others are willing the venture out and assume greater risks for greater benefits real or perceived. The problem comes when taking unnecessary risks relative to the actual benefits, or taking risks that are outside the knowledge or budget to properly solve them. That risk appetite can only be decided by the individual, and the rest of us from our armchairs and keyboards around the world can only contribute our respective knowledge/experience toward helping the OP make that decision. If everyone wanted to KISS above all else, there would be no enthusiast groups like ours pushing the envelope, and we'd be driving completely stock cars. In the bigger picture, there would be no technological progress and we might as well be powering our lives on beasts of burden. Ours is a unique species for being innately capable of and desiring to innovate.

 

[miniCotulla]

One other thing you should consider: You don't mention where you are in Austria, but I've been there (in fact, in Vienna 2 months ago). Alpine areas at high altitudes could be risky for compressor surge, especially when using a large turbo and demanding high boost pressure at low engine RPM. Measures need to be considered for surge in any case, but it is more urgent when using a large single turbo. So, it's not always the "simplest" option.

There are huge advantages to pursuing simplicity, don't get me wrong. But there are always trade-offs based on stated wants or needs that warrant alternatives. It's an exercise of weighing risk vs benefit. Some people are more risk averse - great for them; others are willing the venture out and assume greater risks for greater benefits real or perceived. The problem comes when taking unnecessary risks relative to the actual benefits, or taking risks that are outside the knowledge or budget to properly solve them. That risk appetite can only be decided by the individual, and the rest of us from our armchairs and keyboards around the world can only contribute our respective knowledge/experience toward helping the OP make that decision. If everyone wanted to KISS above all else, there would be no enthusiast groups like ours pushing the envelope, and we'd be driving completely stock cars. In the bigger picture, there would be no technological progress and we might as well be powering our lives on beasts of burden. Ours is a unique species for being innately capable of and desiring to innovate.

Well said, my car regularly sees altitudes above 1000m. And once it's finished I want to visit the stelvio pass in italy. A turbo failure would be quite bad over 500kms from home

 

[[486]]

Ideally, the HP compressor will be bypassed as well. Otherwise, the flow will always flow through its compressor side and act as a restriction. In this case, the HP turbine and compressor bypasses would also act synchronously together.

do not forget to emphasize that bypass alone is not enough, it must also block flow through either compressor or turbine

near zero pressure ratio choke flow still causes extreme shaft speed, make note of the extreme lower right corner of compressor maps

 

[turbobrick240]

Well said, my car regularly sees altitudes above 1000m. And once it's finished I want to visit the stelvio pass in italy. A turbo failure would be quite bad over 500kms from home

It probably sounds like I'm trying to talk you out of a compound arrangement, but that's not really the case. Just trying to be pragmatic, really. I hope this project is brought to completion- please share some photos as it progresses.

 

[miniCotulla]

Does anyone here know someone who can tune a compound setup in Austria? @TDIMeister maybe you know somebody?

I have done tunes on stock cars and DPF deletes myself but I'm already struggling to tune my 100% injectors, is this just trial and error or guessing?

 

[TDIMeister]

Try https://www.z-turbo.at/

Oh, you mean the chip tuning? I don't know. There was an Austrian guy, a trained engineer, who went to work for Upsolute. I think. Gosh, this was more than 20 years ago, so I don't remember all the details, nor do I recall his name or company. Someone else here might. I think it was Stefan, but again, it was so long ago and I'm getting old. Upsolute itself is orginally an Austrian company.

Edit: Speedtuning USA was the company. Don't know if it still exists. But I'm pretty sure the owner was an Austrian who moved to the USA. The guy's name is Oliver. I met him a few times 20 years ago. Unfortunately, in my brief Googling to jog my memory - he doesn't seem to have a very good reputation... I don't think there was a working relationship with Upsolute after all. A lot of drama with that story, mostly with the North American distributorship - ancient history.

 

[Koehn]

You might have already read this thread, but I was a big fan of Machineman's Compound TDI-swapped S4

 

[miniCotulla]

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 think using this Turbo as LP stage and a small wastegate turbo for HP stage could yield good results. With a bypass for both turbine and compressor controlled with a boost controller of the boost differantial of both stages(just the boost of HP turbo) would make programming simpler and also avoid the need for interstage cooling as it's just compound at lower rpms. Is this a good idea? Are there even good small turbos on the market to allow low rpm spool on a 1.9tdi?

 

[miniCotulla]

You might have already read this thread, but I was a big fan of Machineman's Compound TDI-swapped S4

This didn't really go anywhere as far as I can tell OP switched to a 3.0TDI before this project got finished?