VNT20 M-TDi Questions - page 1 - TDI Engine -General Info - VWDiesel.net The IDI, TDI, and mTDI source.

• VNT20 M-TDi Questions by Henk on 08 May, 2012 08:38
• I'm sorry if this has been asked before, probably a lot. I have been looking on here for the past few hours and have a pretty good idea. Engine is an AHU, aiming to make about 150hp
  Fuel pump will be off a Land Rover, 200 or 300tdi, is there any difference?
  And all I have to do is modify the pump bracket is that true?
  As for the turbo, I'm aware there is no bolt-on manifold, but what's the nearest? I don't mind making an adaptor, have use of a lathe and mills at work. Would like to have the turbo help up behind the intake so it's visible too ideally
  Finally, controlling the VNT, the age old question. Have read about the small electronic control on dmn.kuulalaakeri.org but got told mechanical was better. have see various mechanical designs, ideally I want something tidy and hidden as I'm going for a show-quality engine bay, hopefully. Also partly the reason for not going e-tdi. Have also seen vacuum controlled VNT's by modifying the actuator
  
  Just trying to clear this all up so I know what I'm up against, with a reasonably clear idea on how to go about it.
  Also please bear in mind I've very little experience with cars, never had a pump or turbo in pieces so no doubt I'll be asking more.
  Thank You!
  -Henk
• #1 by CRSMP5 on 08 May, 2012 10:15
• i have the landy 300 pump on a ahu..
  
  yes the pump bracket needs opened up for the larger snout..
  
  now mods..
  
  throttle linkage/cable holder for vw cable..
  rear mount under the lines needs built.. i took the stock and landy one.. cut welded the lower ear on..
  govener mod
  my timming is set to 118
  
  pump gear... most use a alh set up.. doing a search here, you will find my looking for educatioon thread in which has a link to how to fit a alh pump on a ahu.. people shim the pump via washers and such, the gear needs shaved down so on... think of landy pump as its this conversion.. 
  
  what i did.... had the stock ahu pump gear modded into a adjustable one much like how they make adjustable cam gears for a gasser vw... no shimming/thinning so on.. like the other option requires..
  
  with the stock ahu turbo, set to 18-21psi and gov mod im pulling 6200rpm till there is no more pull.. stock tdi tranny ~78mph in 3rd via gps.. i am guessing 150ish hp.. will hold its own no issue with stock vr6/1.8t..
  
  so the turbo you think of should put you much more then 150... the people over the pond say t3 is good for 200hp on this set up.. i just have not found one to bolt on mine yet.. the stock little turbo works.. but makes it hard to drive in under 50*f if wet out.. boost too soon lets my tires rip free with ease if you use the go pedal spiritedly.. id prefer some lag to be honest..
  
  the stock t3 style turbo from a old 1.6td puts the turbo up top like you seek... so that manifold is the one you seek to build the vnt20 onto.. or just try the t3 1st..
• #2 by libbydiesel on 08 May, 2012 10:28
• Re vane control, you want the vanes to close based on load or demand for power.  You want them to open to maintain your max boost pressure.  I've done quite a few different mechanical vane controls (was actually working on an updated design this morning).  The simplest and least effective control would be to keep the vanes stationary.  Really no point to that as an appropriately sized wastegated turbo will do better.  Next up would be a boost can acting on the vanes.  The issue there is that there is no load input.  Vanes always revert to closed; and so excess back pressure is created in a slew of circumstances like idle, cruise and decel, basically any time you are not at your max boost.  Next up is where you have a link to the pedal and close the vanes based on pedal position and have a boost input that opens them back up again for your max boost.  That's the style I've been building for a while.  One caveat is to make sure the pedal can return from full pedal even if the boost input has opened the vanes up.  Another design goal would be to minimize the impact on the feel of the pedal.  FWIW, 150hp with a VNT20 on an AHU would be an easy goal for me to reach.  Good luck with the project.  Pics are always fun to look at. 
• #3 by Henk on 08 May, 2012 12:34
• great reply, thank you very much.
  Opening out the bracket shouldn't be too hard, clock up and bore out. wasn't aware of the rear pump mount, d'you weld it onto the aluminium pump bracket? I'm sure I'll find out in good time, just trying to find a decent pump for cheapish (skint apprentice  )
  Gov mod i was going to have a go at, read the how-to on vwcaddy.com and doesn't seem too hard
  Yup was reading that thread earlier today in fact, will search for a pulley after i get the pump. Was it hard to do the mod? There's a guy in work who's just made one of them out of aluminium for his kit car, does it work well then?
  Impressive boost from that teeny little turbo, I thought they maxed out at about 18PSI? Maybe you have different turbos over there... anyway that's damn impressive! You using standard injectors too?
  aye if you stock turbo can see 150 I might see 180 at the crank with a bit more work. Would be nice to double the original power of the engine  
  
  I do like the idea of a VNT with the less lag and whatnot, and my GT2052V should be here tomorrow, off an A6 2.5 V6 TDi so pretty settled on which turbo to use :p only cost me about $80
  
  Yeah it seems like the accelerator actuated VNT is best, then having the max boost over-ride the pedal actuation, am i right there?
  Maybe i should have a go at the electronic boost controller then?
  regcheeseman advised me to just not bother with the vanes and run it as-is
  As for photos i have a thread in the User Rides bit, she'll be something a bit out of the ordinary
• #4 by libbydiesel on 08 May, 2012 16:42
• Running a VNT without taking advantage of the vanes is worse than using an appropriately sized wastegated turbo.
• #5 by CRSMP5 on 08 May, 2012 19:21
• the mk4 pully set up. alh is like 10lbs... so i just used steel on the stock ahu pully.. simple in design.. and no shimming/messing around.. get plate.. drill holes.. slot outter holes on plate.. i slotted it for 2 teeth of adjustment. and then split the pully... loctite inner perameter bolts.. and lock washers and such on outter adjustment bolts..
  
  now i did screw up and forgot to drill a hole for a lock pin (will be alh style as the big round hole is taken up with pump snout.. ).. was not 100% positive #1 was where it is (people said this but seemed unpositive).. but its same place the AHU is aka 11'o'clockish position via the keyway.. and when/if i ever have my pully off ill drill it then.. 
  
  rear bolt mount.. i removed thefactory steel plate mount.. the landy plate mount.. over lapped them.. marked where the stock one needed cut.. then welded to the bottom of landy one.. real easy.. bolt plate back on.. when you have 2 pumps in hand you will see..
  
  for the throttle linkage... i used a old 1.6na idi cable holder.. modded to fit via welding.. and lenghtened the stock arm on the pump..
  
  all that stuff is easy.. if you got a mig/tig..
  
  most landy pumps have a throttle position piece ontop of the throttle stuff.. if you go electric on the vnt it canbe used..
  
  the little stock turbo.. it will push 28psi pretty easy... i just backed it down and the wastegate opens between 18-21psi.. lower then that i was getting a surge at say 70mph on the road.. aka it starting to open/close too soon.. i have mine mounted where i can play with it as i drive.. if i crank it up to 28psi.. it gets really silly..
  
  yep i do have bigger nozzles in it.. but sadly not positive what they are... had myke_w get me the parts.. and he got me upgradedded ones.. just not positive what size.. i have little soot.. enough to blacken my rear wheel... but not a cloud you cannot see thru.. i have not even messed with my mixture screw as im so happy with how it is as it is.. except id prefer more lag..
  
  any questions feel free to ask.. i used 8v's guid on here for the gov mod.. its 90% on.. but there is a strange linkage piece inside you gotta deal with that it does not discuss.. but easy enough to figure out.. cover does not come off so easy due to it.. so do not force.. look to see why..
  
  i had seen people say 130ish for setting inital pump timming (was breaking in the engine due to full rebuild and such so figured it would be better at a lower#).. i tried 118 and like it.. figured id try 130.. just have not.. happy as is.. why screw with it.. one day ill get use of a dyno.. then ill see what it does.. kinda want some base line #s to start and see what fuel screw and timming will do... while on dyno.. maybe this summer.. not top of priority list
• #6 by Henk on 15 May, 2012 04:03
• yeah i did think it'd be a bit pointless. fair size difference between the VNT20 and the pathetic wee turbo that was on there before!
  
  As for the fuel pump, i'll sort the pulley, mount etc and such when i get it. got ripped off on tax this month so I have about £50 left to last the rest of the month  bracket modifying seems fairly simple, have a MIG welder and access to TIG in work.
  Will hopefully be able to do some funky hidden cable routing for the accelerator
  Interesting, wouldn't have to use a pedal mounted TPS then, can't imagine i'll go E- if I can get a machanical VNT control sorted. bought a boost actuator thing for £10 posted so sounds like I need a TPS activated vane control, over-ridden by boost. right? 
  Crazy stuff, hoping to see about 30psi with mine.
  Sounds sensible, not sure where to get new injectors from though over here, the auro 151bhp transporters with the .216s are ideal nut there's a lot of cheap chinese rubbish around too.
  ah okay, thanks for all the pump info, will check it all when I come to set the pump up, still have to strip and paint the engine block...
  
  sneaky turbo picture
  
  
• #7 by R.O.R-2.0 on 15 May, 2012 16:36
• Quote from: libbydiesel on 08 May, 2012 16:42

  Running a VNT without taking advantage of the vanes is worse than using an appropriately sized wastegated turbo.
  

  
  my VNT made more/better boost than a K24 did...
  
  you always said that a VNT would be SIMILAR to a K24/T3...
  
  well, its NOT.. the VNT had WAY MORE top end pull. the K24/T3 turbos seem choked up around 5000rpms/25psi..
  
  where as the VNT would pull until the pump rollers would skip..
• #8 by 8v-of-fury on 15 May, 2012 18:52
• Quote from: R.O.R-2.0 on 15 May, 2012 16:36

  you always said that a VNT would be SIMILAR to a K24/T3...
  

  
  Does it not depend on the size of the VNT? Weren't you using a 17?
• #9 by libbydiesel on 15 May, 2012 20:50
• Running a VNT with the vanes stationary is the same a running a wastegated turbo with the wategate blocked.  There is a very limited window where it is both producing boost and efficient.  With stationary geometry and an operational wastegate, the turbo can be in it's efficiency for a much wider range of rpm/load.  The only advantage to a VNT with stationary is that you could choose a reasonable middle road.  The VNT15 on a 1.6TD with vanes closed responds faster than a K03.  With vanes fully open it responds slower than a K24 or T3.  Said another way, vanes closed is better low-end than a tiny turbo, vanes open is better high-end than a big one.  I don't recall ever saying that a VNT was similar to a K24 or T3.  If I did, then it was a miscommunication.   
  
  WRT this particular build, the VNT20 should be a really nice match to a 1.9TDI if an appropriate vane control is used.  Having currently only used a VNT15 and 17 on my 1.9 mTDI, my guess is that it would give low-end response similar to a K14 with excellent high boost potential.
• #10 by Henk on 21 May, 2012 14:02
• Have very little turbo unlike you guys, but i'm sure this will be fine, it cost me like £66 so wouldn't have been much of a loss compared to a VNT17 which is about £200 over here. silly.
  Anyway glad you think it'll be a good match, hoping to see some nice numbers out of the turbo and engine 
  as for running it with stationary vanes i was never planning on doing that, as you say stupid and worse than a WG'd turbo
  
  Well I've come up with a pretty decent design that i'm happy with for the VNT control anyway.
  All mechanical, and pretty tidy/compact which is good because I'm planning on making it a show-worthy bay
  
  
  Throttle pulls the vanes shut as soon as you mash the pedal to the floor for the epic low end boosting, then as soon as the boost comes up it pressurizes the actuator, pushing the vanes back open again
  I should probably spring-load the accelerator as the cable would just hang loose when I come off the accelerator again. Still she's amost there, and i'm damn chuffed! 
  Thoughts?
• #11 by libbydiesel on 21 May, 2012 14:32
• I've been using that design concept for a couple/few years and it is highly effective.  
  
  http://www.vwdieselparts.com/forum/viewtopic.php?f=21&t=11042
  
  There is one issue you have not accounted for.  If you have the accelerator floored and boost rises to the point that the vanes are pushed fully by the boost can, then the accelerator will be held in the fully floored position.  
  
  I've actually recently developed a better design than that one even.  At some point I'll share the details.  
• #12 by Henk on 22 May, 2012 10:47
• have read your thread at least twice before 
  I think it's the same kind of idea isn't it? throttle would be on a cable, not on a solid rod so off the throttle would just slacken it. (no easy the show in MS Paint!)
  Would probably re-design it with a spring in to take up the slack, although would have to be pretty soft i guess. hmm
  Oh and bought a new fuel pump today, off a Land Rover 300TDi, for £40  (about $60)
• #13 by libbydiesel on 22 May, 2012 13:28
• If you add a return spring to the vanes, your foot will always be pulling against it.  My initial designs were that way and I didn't care for the way it affected the feel of the pedal.  With the linked design the pump lever return spring is also the vane return spring and so the pedal feel is unaffected unless the vanes stick.
• #14 by snakemaster on 24 May, 2012 11:21
• take the vnt out and just run the gt15 untill you get your pump ,injectors etc sorted out , then when it is running spot on fit the vnt and make up your vnt linkage , to many things to go wrong at first