Project Potential... variable vane turbo on 1.6l

[92A2VWJTD]

I did some testing today...  I verified that I can still reach the upper end of the 15 psi boost gauge at high load/high RPM even with the vanes all the way open!  This is with stock, unmodified 1.6lTD fuel injection pump and settings.  

 :shock: Nice!
 So, Jake, given the 15psi full load boost (or close to that) with stock fueling and fully open vanes, it must be assumed that if one were to increase fueling to match that boost level, the boost would stabilize at an even higher level yet again. Any idea what full load boost level one might stabilize at with fueling to match in a 1.6 IDI setup? I'm just curious if the wastegate would be a truly necessary piece of hardware for a 20psi max. setting. Then again, me thinks there might be an issue with touchy throttle response at highway speeds all the same without WG control as well, after reading some of what 2383 GTD posted about his project. :roll:

Your really doing an incredible job of keeping us all in loop about this project Jake! I for one am grateful and am learning new things to be sure. Thanks.

[fspGTD]

I wouldn't expect the wastegate to eliminate the "touchy boost/throttle" problem, since it only operates at peak boost levels (IE: you would want to tune the wastegate so that it only opens when the vanes are completely open).  I have noticed with the VNT controller set to begin closing vanes at low boost, so it operates over a broad pressure range, IE: it gets rid of that "over-reactive" boost feel on the highway.  But having the VNT control operate over a broad pressure range also means that you will only see a portion of peak boost low in the RPM range, so it is a tradeoff.  I plan on doing some experimentation through after the wastegate gets installed and I have the fueling turned back up, to see if I might happen upon a "happy medium" kind of setting.

If you were to install a VNT without wastegate and were to keep increasing fueling, I have a feeling that the boost pressure would keep rising and keep pushing more air into the engine, and always keeping one step ahead of the fueling.  It just seems to be the nature of this turbo... I think it just has too low of a turbine A/R ratio for efficient non-wastegated operation.  Ideally, you can inject enough fuel to burn the air, at least up until the point where it is on the verge of starting to smoke.

If you were willing to live with modest fueling levels or really high boost levels, you could do it without a wastegate.  I can't experiment in that area given I have no intercooler installed on this motor, no piston cooling oil jets, and also need to keep risk levels of damaging the motor from high cylinder pressures and temperatures low, since this is my dad's daily driver.

I did another VNT adjustment, which positively enhanced the torque band: I pre-loaded the VNT adjustment by 1.5 turns so it takes a little boost pressure before the VNT controller starts to close the vanes.  Seems to build more boost pressure a little more quickly now, but it still seems well-regulated at around 7-8 psi (after which point creep is gradual with increasing RPMs at wide open throttle to a max of 10psi.)  Why it's not creeping up to 12psi like it did before when I had the vanes wired closed, I am a little curious about.  I wonder if the vanes may have opened up a little bit more, or if it's somehow a fuel density thing (hot versus cold fuel), or some environmental factor making the turbo have to work harder to develop the same amount of boost pressure.  (Has been wet here lately... but was dry before.)  It is a little bit curious though.  That is tested with WOT runs in both 2nd and 3rd gear with RPMs increasing all the way until the point where the intermediate spring starts working to decrease the fueling.

[jtanguay]

hmmmm now where the heck can I get me a VNT for my 1.6 TD?

 :twisted:

[malone]

Just thought I'd show this picture of someone else's VNT:

http://www.teamkorhonen.com/~dbwarrior/peugeot/turbo%20002.jpg

The entire vacuum actuator was swapped to a regular boost actuator. If you look closely you'll see a weld on the lever.

I don't have any further details, other than reading that it "works well".

If I get a VNT to experiment, I'll post details. fspgtd, your posts have been fascinating.

[malone]

hmmmm now where the heck can I get me a VNT for my 1.6 TD?

 :twisted:

I can get a few VNT-17s off Euro PD150 TDIs. Less than 10,000km and costs $400 USD each, thanks to high shipping costs but it is still relatively inexpensive compared to other turbos. If we get a group buy going and import a few turbos at the same time, then we can save a bit on shipping.

Last year I sold my VNT-15 (identical to fspGTD's) from a 90HP ALH TDI with 70,000km for $350 USD in cash 4 days after I posted the ad.
 
The VNT-17 also has a casted in exhaust manifold, nearly identical to the VNT-15. The weight is 9kg per turbo+manifold.

It should be important to note that the VNT-15 and VNT-17 will not clear the rear motor mount in MK2s and MK3s. MK1s like fspGTD's Rabbit has a passenger side mount instead of a rear mount, so VNT fitment isn't a problem for them. Here's a picture of a VNT failing to clear a MK3's rear motor mount :



Modifying the rear mount can be done, of course.

There are many different VNTs at ebay.de (use search keywords "turbolader" "TDI"), some of them have detachable exhaust manifolds that also make the turbo sit higher, clearing the rear motor mount.

[RedRotors]

Any update of the beast Jake ?

Marc/

[fspGTD]

According to the FedEx delivery tracker, it looks like the wastegate arrived in a distribution center in kent, wa this morning, which is less than an hour's drive away.  I think it might arrive tomorrow or maybe even later today!  

I will probably begin installation work later this week.  The first thing I will need to do is hold the wastegate in position in the engine compartment and determine if its exhaust should be coupled into the downpipe, or left as a separate dump tube.  Then I will have to track down some materials probably (IE: stainless tubing and possibly a flex bellows, etc.)

I am leaning toward coupling the wastegate exhaust into the downpipe, rather than making its own separate exhaust dump tube.  Does anyone know if a stainless flex bellows is required for coupling the wastegate exhaust to the downpipe, even if the tubing run was pretty short?  I understand the bellows is to allow the tubing to expand and contract separately from heat cycling.

Dad drove the Rabbit with the turbo for his first time yesterday.  He seemed pretty pleased with it, although I don't know if he realizes how much performance has been temporarily "sacrificed" with the reduced fuel.  He may have a surprise after I install the wastegate and turn the fuel back up to stock 1.6lTD specs...  I've also been driving it around a few days now and found it to be realiable, so I told him to go ahead and drive it home.

Edit: Pics to entertain you guys while we are waiting for the wastegate to arrive...
car shot:

engine compartment shot:

air cleaner & boost tube close-up:

[lord_verminaard]

Wow, that Rabbit is super-stupid clean!  I wish my Rocco was half that clean, then I'd have a lot less work to do!   She looks great.

Brendan
84 Scirocco 8v
00 Camaro L36 M49

[veeman]

Jake...  FWIW, as you might know, the five-cyl turbo (gas) Audi's had the accordian (bellows) on the wastegate that you're refering to.  I couldn't find a pic of the normal 5000 turbo type that I have, but here's one that similar (not my pic by the way):



These pieces are stainless and I can confirm that the wastegate definitely dumps back into the exhaust via another tube.  The one pictured looks a bit bigger in diameter than the one on my engine.  I'd guestimate it's probably 1.5 inches or so in diameter.

I probably have one or two spares at home that I can snap more detailed pictures / measurements of if you'd like.  It'd be great if one of those would work for your application.

Originally, I thought the accordian type piece was put in there to help with vibrations and possibly noise, but you're probably right about the expansion due to heat.

[TDIMeister]

Dad drove the Rabbit with the turbo for his first time yesterday.  He seemed pretty pleased with it, although I don't know if he realizes how much performance has been temporarily "sacrificed" with the reduced fuel.  

Install a tweaked pump and that thing would be stupid fast!  I dare say faster than Dr. Diesel's car  :lol:

[dieselpower]

hey,
what kind of tubing/hose is that going from the turbo to the intake? and do you think it could handle 30 psi boost?
good job so far

Mark

[jtanguay]

that tubing will easily hold 30 psi.  It's only the connections I'd be worried about.

Looks like vacuum hose (flexible and its reinforced)

I just got an idea for intake tubing.  Get the special hose for pool jets.  That stuff is rigid and a little flexible (might even be what Jake used)

[fspGTD]

Ok guys, the wastegate arrived!  First reactions plus initial disassembly pics are in this thread: http://www.vwdiesel.net/phpBB/viewtopic.php?p=11567

Holding it in the engine compartment, it's a bit larger than I was thinking it would be, but I think it will still fit well.  I'm going to fabricate a flange that adapts the EGR outlet to the wastegate bolt pattern and will bolt the wastegate directly to the EGR outlet flange.  For the wastegate's exhaust, I am leaning towards mounting the wastegate so its outlet is toward the rear of the car, then having the 1.5" exhaust tubing bend downwards and welding on a section of stainless flex bellows (happend across a local source for this today...) and then I think I might merge it in to the downpipe right before the flex joint.

Veeman- Thanks for the pic of the audi wastegate dump tube.  Wow, that wastegate dump looks nearly as big as the main exhaust out of the turbine outlet!

Mark and jtanguay - as previously mentioned, I used Aeroduct for the intake ducting.  It seems to be often used on road race applications in larger diameters to get cooling air to hot brakes.  But Aeroduct makes some nice quality ducting in four different styles and all kinds of sizes, which you can get from homebuilt aircraft suppliers.  I found that it flexes very nicely, but does not conform to changes in diameter very well due to the spiral spring steel reinforcement.

[jtanguay]

thanks for the info Jake!

[fspGTD]

Started in to the wastegate mounting project yesterday.

Here is the space I have to work with... where I hope to have the wastegate soon occupying!  :twisted:


Unfortuntely, the bolt spacing of the VW EGR flange is narrower than the wastegate mouting flange.  Wastegate is too fat to modify it to bolt directly up, so I need to fabricate a spacer that can bolt to the EGR flange and then have the proper bolt pattern on top to mount the wastegate.  In order to recess the bolt heads holding the flange to the EGR plate down below the surface so they don't interfere with the wastegate, I decided to make the flange out of two pieces which I'll weld together.  I can just use the flange that came with the wastegate for the upper piece, and for the lower piece I would get by just drilling and cutting it out of steel stock:


I am also having the flange rotate the wastegate as much as is practical to orient the wastegate exhaust towards the firewall.