1.9TDI PD compound sizing

[[486]]

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?

I've got a vf27 I was going to do this with long ago, never ran it though, kinda gave up on trying to get tiny turbos to live before it got tried out
they were available used for cheap back then, dunno about now. Came off ebay.co-uk for under 150 bucks...

anyways, if you take your idea and simplify it further to a couple stupid wastegated turbos, you've got the set off the bmw "M57D30TÜTOP" engine, which includes all the bypass valving already assembled
ETA: https://www.ebay.com/itm/165189856584? they got more expensive than they used to be...

 

[miniCotulla]

I've got a vf27 I was going to do this with long ago, never ran it though, kinda gave up on trying to get tiny turbos to live before it got tried out
they were available used for cheap back then, dunno about now. Came off ebay.co-uk for under 150 bucks...

anyways, if you take your idea and simplify it further to a couple stupid wastegated turbos, you've got the set off the bmw "M57D30TÜTOP" engine, which includes all the bypass valving already assembled
ETA: https://www.ebay.com/itm/165189856584? they got more expensive than they used to be...

My fear is these might be too big, the M57 even has excellent spool with one large turbo. Might not be the best idea on a 1.9tdi.

 

[[486]]

My fear is these might be too big, the M57 even has excellent spool with one large turbo. Might not be the best idea on a 1.9tdi.

dunno,

Smaller turbo KKK KP39-1873
-turbine wheel 38,5/32 (9-blade)
-compressor 33,5/46 (4+4 blade)

Bigger turbo KKK K26-2871
-turbine wheel 64,3/54,5 (12-blade)
-compressor wheel 50,3/71 (base exducer 72,6 and blades ”shorter” so design is opposite to extended tip design) (7+7 blade)
-turbine housing 8bm^2

whereas old 1749vb is 36/49 on the compressor
I'd imagine them to be using a quite tight volute on the BMW one too, as it is screaming along pretty good at idle on those, and they've got all the bypass hardware so there is little reason not to...

 

[miniCotulla]

dunno,



whereas old 1749vb is 36/49 on the compressor
I'd imagine them to be using a quite tight volute on the BMW one too, as it is screaming along pretty good at idle on those, and they've got all the bypass hardware so there is little reason not to...

Looking at the images it seems like the exhaust from HP to LP is flowing throught the manifold. Remaking this manifold for the 1.9tdi seems like a nightmare.

 

[[486]]

Looking at the images it seems like the exhaust from HP to LP is flowing throught the manifold. Remaking this manifold for the 1.9tdi seems like a nightmare.

yup that's where the bypass valving lives
doesn't seem horrible to me, little cut and weld action on the castings, but you know they're cast steel nowadays and not iron, so they do weld fairly nicely

 

[miniCotulla]

yup that's where the bypass valving lives
doesn't seem horrible to me, little cut and weld action on the castings, but you know they're cast steel nowadays and not iron, so they do weld fairly nicely

Do you mean cut and weld the BMW manifold? I don' t think port spacing and bolt holes are even close.

 

[[486]]

Do you mean cut and weld the BMW manifold? I don' t think port spacing and bolt holes are even close.

yup, hack off the two manifoldy bits, plug one of the holes and then weld the other hole to a manifold or flange that'll fit the 1.9

Packaging constraints are going to dictate that it be at some odd angle that would not have worked with the OE flange or manifold no matter if it were close enough on the port spacing to be massaged into fitting
this way you can have the turbos put where they'll be positioned best and run some fabricated up and down pipes

 

[Fix_Until_Broke]

A simple control scheme is using a VNT for the HP turbo and a fixed geometry (with or without wastegate) on the LP.

Let the ECU run the VNT on the HP just as if it were a single
At low RPM, low load, it behaves just like a small single anyway since the airflow is low and the LP turbo is a minimal restriction

At low RPM, high load, the HP has met the MAF/MAP target and the LP is starting to wake up and help the HP out

At mid-high RPM, high load, the HP is typically vanes/WG wide open and the LP is in it's prime and getting pressure amplified by the HP. Hitting requested boost in these conditions is much less important so the system can run "open loop" where boost is what it is. You need properly sized/ratio between the HP/LP turbos and to ensure the shaft speeds, surge, choke conditions don't come into play to do this, but the control scheme is literally stock OEM. Depending on your HP turbo, you may need a wastegate around the turbine, but that is relatively easy to do and manage using both sides of the diaphragm.

More work on the front end with maps/calculations, but less work on the tuning.

 

[[486]]

How many miles on your setup with the 1444? also, that's ball bearing right?

running it sorta like that I couldn't get more than 30k miles out of a set of thrust bearings in the HP turbo on all my junk, but that was with plain bearings in GT17 or even the upsized GT22 pieces

 

[Fix_Until_Broke]

Call it ~115k miles so far on the compound setup and I put 40k miles on the 1444 as a single before that.

I don't recall which bearings are in it - I think they're just regular bearings, not ball bearings?

 

[[486]]

huh, odd
You are running LP boost as dome pressure in your interstage WG, correct?
If you are, then it is set up the same as mine so far as bypassing and all.

 

[adamss24]

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.

YOU don’t say which 2.5 tdi engine was in it ! I tuned a couple of a4 b5/6/7 with the old v6 tdi engine and gtb2260vk turbo and bosio race 683 nozzles, they were mental !
perhaps you’re expecting too much from a small displacement engine but I can assure you that I have a pd engine in a golf mk2 with large injector nozzles and gtb2260vk turbo… it’s a screamer with full boost at 2500rpms ! Darkside it’s quite conservative with their claims and surge is the-thing to worry on the gtb2260vk turbo and how fast you can shift trough the gears ! I broke inner ball cage on driveshafts twice on my golf so low speed gear pulls are a no-no for me !

 

[Fix_Until_Broke]

huh, odd
You are running LP boost as dome pressure in your interstage WG, correct?
If you are, then it is set up the same as mine so far as bypassing and all.

Actually, the interstage WG is blocked shut. The main exhaust restriction is the turbine on the HE221

 

[miniCotulla]

YOU don’t say which 2.5 tdi engine was in it ! I tuned a couple of a4 b5/6/7 with the old v6 tdi engine and gtb2260vk turbo and bosio race 683 nozzles, they were mental !
perhaps you’re expecting too much from a small displacement engine but I can assure you that I have a pd engine in a golf mk2 with large injector nozzles and gtb2260vk turbo… it’s a screamer with full boost at 2500rpms ! Darkside it’s quite conservative with their claims and surge is the-thing to worry on the gtb2260vk turbo and how fast you can shift trough the gears ! I broke inner ball cage on driveshafts twice on my golf so low speed gear pulls are a no-no for me !

It was a 2.5TDI BAU, with ported heads, custom exhaust manifold and big intercooler, below 2K rpm it was dead, every stock Diesel engine has more power under 2K then that thing.

 

[diffas]

Yeah no surprise there - ****ty tuning as usual with those engines. I have had few small turbo projects on 2.5tdi that had gt2260v and newer gtb2260vzk, id say I prefer vzk for daily. Gives somewhat stockish spool and over 500nm @ 1800rpm if not limiting torque and decent ~300hp. But needs good tuner and good knowledge. Also i have worked with those engines from 2007 and what i've noticed they like to rev happy when in good condition and indeed bit mild on lowend torque. I have nothing under 3k rpm on my tdi (with low cr), luckily i have working gearbox! I've chosen "too big" HP turbos for my compund setup but thats how i wanted it...no vnts, HP stage is wastegate controlled and LP is non wg with bit too small housing. Actually this setup spools still better than previous singe turbo setup.

 

[[486]]

I have nothing under 3k rpm on my tdi (with low cr), luckily i have working gearbox!

no, you don't got nothing, there's gotta be at least 50-60 hp hiding down there

which really is quite sufficient for first gear and puttering around in town. Or even some abusive second or third gear launches off the limiter

 

[diffas]

Haha yeah well it is for sure drivable but isn't that lively as you want from your daily. Thats why its not my daily

 

[miniCotulla]

Haha yeah well it is for sure drivable but isn't that lively as you want from your daily. Thats why its not my daily

And that's the difference, I want a daily. 2.5 TDI will leave me stranded at the worst times (VP44) a new VP44 costs 3500€, hell no! And I can't swap the engine in my Passat without huge costs!

 

[miniCotulla]

Haha yeah well it is for sure drivable but isn't that lively as you want from your daily. Thats why its not my daily

Yeah no surprise there - ****ty tuning as usual with those engines. I have had few small turbo projects on 2.5tdi that had gt2260v and newer gtb2260vzk, id say I prefer vzk for daily. Gives somewhat stockish spool and over 500nm @ 1800rpm if not limiting torque and decent ~300hp. But needs good tuner and good knowledge. Also i have worked with those engines from 2007 and what i've noticed they like to rev happy when in good condition and indeed bit mild on lowend torque. I have nothing under 3k rpm on my tdi (with low cr), luckily i have working gearbox! I've chosen "too big" HP turbos for my compund setup but thats how i wanted it...no vnts, HP stage is wastegate controlled and LP is non wg with bit too small housing. Actually this setup spools still better than previous singe turbo setup.

Gearboxes are great, but you can choose the original one, great for starting on steep hills but way too short once you start driving + the engine is permanently stuck at 3K rpm on the Autobahn + hard to shift.

Or you take a newer transmission, way better gearing for 300hp+ and better shifter feel but you also get longer 1st and reverse gear. + Only 2K rpm on the Autobahn (way less noise and -1,5 liters/100km)

You can't have both.

 

[diffas]

Not sure what newer trans you are referring to but at least 0A3 behind the 3.0tdi on b7 has really short first four gears, almost the same as 01E on 2.5tdi on b5. 171kw 3.0tdi has bit longer final drive, so it is bit longer lower gears but has shorter sixth gear. 0B4 from b8 is different story, but mounting it to the older chassis is own story. 01E runs 156kmh @ 3000rpm, 0A3 150kw b7 runs 2700 @ 160kmh, 0A3 171kw runs 158 @ 2700rpm.
B8 trans would be awesome since it goes 100kmh on second gear but pain in the ass to install it.

I don't see much revs under 4k on my car so i put bigger ones. You want really small HP turbo on your setup, i would suggest gbc14-200 from garrett or k03-029 (needs bv50 bearings) from bw and something like s257sxe as LP.

3.5k for vp44? What a ripoff. Here we have it almost 1/3 the price with all new parts...my modified pump was like 1.4k.

 

[miniCotulla]

Not sure what newer trans you are referring to but at least 0A3 behind the 3.0tdi on b7 has really short first four gears, almost the same as 01E on 2.5tdi on b5. 171kw 3.0tdi has bit longer final drive, so it is bit longer lower gears but has shorter sixth gear. 0B4 from b8 is different story, but mounting it to the older chassis is own story. 01E runs 156kmh @ 3000rpm, 0A3 150kw b7 runs 2700 @ 160kmh, 0A3 171kw runs 158 @ 2700rpm.
B8 trans would be awesome since it goes 100kmh on second gear but pain in the ass to install it.

I don't see much revs under 4k on my car so i put bigger ones. You want really small HP turbo on your setup, i would suggest gbc14-200 from garrett or k03-029 (needs bv50 bearings) from bw and something like s257sxe as LP.

3.5k for vp44? What a ripoff. Here we have it almost 1/3 the price with all new parts...my modified pump was like 1.4k.

1.9tdi had a very short 01E gearbox, I switched to the longest 0A3 gearbox(HXQ). With stock turbo it's absolutely no issue but giving up even a little bit of that low rpm tourque makes it very hard to start on steep hills/with a heavy trailer.

I never liked the 01E, I tried several and the all are hard to shift, not smooth and often have syncro problems.

3,5K is a renewed pump from Audi to Audi spec. Many people had nightmare experiences with a renewed bosch unit so I would avoid those. The VP44 has so many possible ways to break so a shop who spezialieses on the VP44 ECU can't fix/prevent future failures of the other parts. My brother now has 3 different VP44s with 3 different problems, it sucks.

 

[TDIMeister]

1.9tdi had a very short 01E gearbox, I switched to the longest 0A3 gearbox(HXQ). With stock turbo it's absolutely no issue but giving up even a little bit of that low rpm tourque makes it very hard to start on steep hills/with a heavy trailer.

I'm interested to learn how you got the 0A3 into your B5, in case I might ever be interested to replace/upgrade mine (which has a 5-speed 01A) one day. As I understand it, it's not a straightforward drop-in swap - mounts and even the front subframe might have to be swapped from a B6.

As you can see, there are many ways to do compound/sequential turbos. There's no real right or wrong way - except noting important things like max *controllable* boost (letting it be whatever is, by definition, not controlled), EGT, EMP, surge, shaft speed, etc. - other than what works for you and what you're happy with.

 

[miniCotulla]

I'm interested to learn how you got the 0A3 into your B5, in case I might ever be interested to replace/upgrade mine (which has a 5-speed 01A) one day. As I understand it, it's not a straightforward drop-in swap - mounts and even the front subframe might have to be swapped from a B6.

As you can see, there are many ways to do compound/sequential turbos. There's no real right or wrong way - except noting important things like max *controllable* boost (letting it be whatever is, by definition, not controlled), EGT, EMP, surge, shaft speed, etc. - other than what works for you and what you're happy with.

You need front axleshafts from an A4 8E, trans mounts from a late BDG FWD Passat or Superb(the came with the FWD version of this gearbox), I also used the gear selector from the BDG but looks very much identical to 01E. The A03 doesn't have a speed sensor for your instrument cluster you need to wire one cable from your ABS module to the IC. Many early B5s especially the A4 B5 have older ABS modules where this doesn't work but there is a guy who made some electronics to get the correct speed output.

The rear diff(01R) came with the bigger axle flanges, these need to be swapped or W8 axleshafts installed.

The gearing is so much better and shifting feels like a modern car.

 

[miniCotulla]

I'm interested to learn how you got the 0A3 into your B5, in case I might ever be interested to replace/upgrade mine (which has a 5-speed 01A) one day. As I understand it, it's not a straightforward drop-in swap - mounts and even the front subframe might have to be swapped from a B6.

As you can see, there are many ways to do compound/sequential turbos. There's no real right or wrong way - except noting important things like max *controllable* boost (letting it be whatever is, by definition, not controlled), EGT, EMP, surge, shaft speed, etc. - other than what works for you and what you're happy with.

I forgot: you also need the driveshaft from an 5HP19 automatic + spaccers or bring yours to a machine shop to get it shortend as the 0A3 is longer then the 01E gearbox!

I think we also didn't reinstall the spaccer that sits between the 1.9TDI and 01E but I'm not 100% sure on this.

 

[miniCotulla]

After some consideration I have a new idea that might be easier to implement/control. I always wanted to switch to an electric steering pump from an Opel, this would make room on the right side of the engine for a supercharger, something like a Aisin AMR300 or Aisin AMR500. Only switched on when needed in lower RPMs when the turbo isn't ready yet. This could be done with an AC compressor clutch. As there is a lot of room on this side of the engine it should be an easy fit with custom brackets. Is it possible to implement a map on the ECU to control a DO whenever boost is requested under a certain rpm to then use a relay to trigger the clutch? Is there even a spare DO on the EDC15p+? And do I still need a bypass once the turbo is spooling? This would not only deliver boost but also help to spool the turbo quicker without the typical efficiency downsides of a supercharger only system as it's only active for a short period of time when needed.

 

[Fix_Until_Broke]

If you don't drive the supercharger all the time, you're going to need a bypass before the turbo is spooling as those are positive displacement superchargers.

 

[[486]]

After some consideration I have a new idea that might be easier to implement/control. I always wanted to switch to an electric steering pump from an Opel, this would make room on the right side of the engine for a supercharger, something like a Aisin AMR300 or Aisin AMR500. Only switched on when needed in lower RPMs when the turbo isn't ready yet. This could be done with an AC compressor clutch. As there is a lot of room on this side of the engine it should be an easy fit with custom brackets. Is it possible to implement a map on the ECU to control a DO whenever boost is requested under a certain rpm to then use a relay to trigger the clutch? Is there even a spare DO on the EDC15p+? And do I still need a bypass once the turbo is spooling? This would not only deliver boost but also help to spool the turbo quicker without the typical efficiency downsides of a supercharger only system as it's only active for a short period of time when needed.

or just use a pressure switch, any time the turbo ain't making 'whatever pressure' the clutch is engaged
yeah it'll engage at light load, but it doesn't really matter much

I've been wanting to screw with a centrifugal blower for a while, just haven't come across one for cheap enough yet, got a mazda millennia screw-type blower, but I'd need a real big pulley on the crank, or a jackshaft in order to run it

 

[miniCotulla]

If you don't drive the supercharger all the time, you're going to need a bypass before the turbo is spooling as those are positive displacement superchargers.

What do you mean with positive displacement? This drawing shows what I'm thinking of: (SC=Supercharger, IC=Intercooler)

 

[turbobrick240]

The screw type blowers are positive displacement, as opposed to the centrifugal ones.

 

[miniCotulla]

The screw type blowers are positive displacement, as opposed to the centrifugal ones.

What does that mean for this setup?