Project Potential... variable vane turbo on 1.6l

[DVST8R]

all of that oxy-fuel welding will make you a quick learner on tig! same basic priciples just heats quicker and more control over the heat.

[veeman]

>>I have another fabrication job for this project coming up... modifying the NA diesel intake manifold for forced induction.

Jake...

Have you considered possibly using an A1 or A2 gas intake for that purpose?    Are you running an intercooler on that one?  (this is your Dad's, right?)

I'm thinking you could remove the throttle body and then make a plate to attach to whatever tubing you'd like for either the turbo to intake pipes or intercooler to intake pipes.  If you use the A1 style (I've got a few by the way) you might actually end up with a better location for the intake opening.

Here's a pic of a CIS rabbit type intake (not mine).  You'd have some ports and get/make a digifant cold start injector hole block plate, but I think it might work well for you....



Might be easier than welding up that diesel box and trying to pressurize that huge box.  I wonder if it would clear that turbo setup back there?

I researched intakes quite a bit when doing my gas FSP car (soon going to standalone) and some argue that the A2 intake with its longer, tapered runners provides some torque benefits.  For right now, however, I'll be using a G60 intake on mine.  It opens to the driver's side, has bigger runners and less ports for me to block off for the EFI system.

Let me know and I can get you pics if you like...

[QuickTD]

Can anyone help me with a plenum volume calculation of the NA intake manifold and tell me if it's adequate, too much, or not enough?

Try this:
 http://www.grapeaperacing.com/GrapeApeRacing/tech/inductionsystems.pdf

Some good info regarding intake tuning.

[fspGTD]

Veeman - I plan on at least initially to put the motor back together without intercooling.  Although eventually we might put one on there, I plan instead to fuel conservatively and monitor EGTs to start.  Adding an intercooler and associated boost tubes is too big of a chunk to bite off all at once.

Also as mentioned previously, I have an A2 gasser long-runner intake, but I found that test fitting it to a junk head I've got in the garage that it does not clear the TDI manifold.  The problem is that the TDI exhaust manifold has an EGR port and flange that sticks up way too far - it's not even close.

The runner lengths of the NA Diesel manifold are identical as far as I can tell to the A2 gasser intake.  The NA Diesel intake manifold is close - but I can and I did design the EGR block off plate and fastening system specifically so that the NA Diesel manifold just fits.

I have not yet measured the plenum volume of the NA Diesel manifold, but just from eyeballing it, and also knowing it was originally designed for the naturally aspirated motor (which has no different plenum requirements from a turbo motor unless you subscribe to the "minimal plenum for turbo to reduce boost lag" school of thought, which I am not sold on), it is probably approximately the right size.  I know that it's runners are a good design with very smooth radius bends and specially shaped "D" runners to minimize air resistance through the bends.  The runner lengths are also designed to fit the working RPM range of the 1.6l diesel (the heating of the intake air charge from the turbo will effect the tuned frequencies somewhat, but based on my calculations the impact is small and acceptable, at least for an intercooled motor.)  If I want a specicic plenum volume with the 1.6lNA manifold, I can do it by varying where I decide to weld the front plenum wall to the manifold.

I don't have an A1 gasser long-runner intake to try fitting up to the test head with TDI VNT installed, so I'm not sure if that would clear or not.

My latest thoughts are that initially I will bolt up the stock TD intake manifold to get this thing back up and running and minimize downtime.  Then at a later point as a separate project and experiment, I can fiddle with adapting and installing the NA Diesel intake manifold.  That way I will be able to test the difference it makes to the HP and TQ vs RPM curve real scientific-like, which I've been wanting to see done for a long time!  :wink:

[fspGTD]

QuickTD: I guess what I meant to ask was has anyone measured the plenum volume already on a 1.6lNA manifold?

(Alternatively, I guess I could do a ballpark estimation myself pretty easily by measuring length, width, and height and then multiplying.   )

[QuickTD]

Or, for more precision, just plug the ports and fill the thing with water. Dump out and measure the volume.

[fspGTD]

all of that oxy-fuel welding will make you a quick learner on tig! same basic priciples just heats quicker and more control over the heat.

Yeah... if I only had $1400 burning a hole in my pocket to buy a TIG setup!    :wink:

[fspGTD]

Hey guys - I can weld aluminum with my oxy-acetylene rig!  The trick I needed was using water instead of alcohol to mix the flux... check out these results...  My first successful aluminum welding project (it's an oil return fitting for the TDI VNT):


After being cleaned up with the file (ready to be bolted on!)


It is so cool to see how the weld bead is solid aluminum... now I am re-thinking doing the long-runner intake.  In fact, I already started removing unnecessary metal from the 1.6lNA intake manifold:


Plenum size is indeed large.  I estimate based on measuring the dimensions a displacement of about 170 cubic inches.  According to the grape ape racing plenum calculator (50-60% engine displacement plus 30% if boost is desired at "low" RPM of 2500-3500 RPM), the optimal plenum size would be about 70 cubic inches.  So I am over twice that with the 1.6lNA manifold if I were to just weld a plate to the outside edges of it.  On the other hand, the plenum is an air capacitor... and I don't see much problem with having a little extra.  That VNT turbo should fill it up quite quickly I'd bet.  When I added a quite large Audi5000 intercooler and 2" to 2.25" boost tubing runs to my 1.6lTD, I didn't notice much significant increase in turbo lag.  So my intuition is telling me that a little extra plenum wouldn't hurt.  Grape ape racing states "The good thing about plenum sizing is that there is a pretty wide range that it can be and still be effective"  I'm wondering if I should weld the 1.6lNA manifold up at approx 170 cubic inch plenum volume, hacksaw the thing down to reduce the plenum volume, or try and locate an A1 gasser intake to see if it fits... what do you guys think.

[DVST8R]

I think with your new found Al skills, you can pretty much do any type of intake you choose. Nice looking oxy-fuel weld! I think a custom Al intake manifold is in order to showcase those skills. Well seeings how the VNT already will push the low end torque way up, I think that the plenum should be tuned more for the mid to high rpm range, in what ever shape that takes.

[veeman]

Nice job on the welds... looks fantastic.  A friend of mine on the Audi lists started making his own intake manifold and he used the stock runners and connected them to an aluminum pipe / tube around three inches in diameter.  

You could simply saw off the "box" part of an NA manifold and start from there.  For him, he would have had to attach a specific throttle body type adapter to one end, but you could do anything you wanted.

Using the pipe method, you could do the calculations, mock it all up with PVC to make sure everything clears, then set out to weld it all together.  I can find pics if you want.

...Or if you like, the offer still stands to check out one of my A1 gasser intakes.

[fspGTD]

Just wanted to update you guys... the exhaust manifold/turbo is all ready to install with the following modifications: VNT boost pressure control conversion, custom AN-10 aluminum oil return fitting fabricated and installed, compressor inlet sanded down on the outside to take 1.5" ID aeroduct, and inlet bell-mouth smoothed and polished.  A pre-turbine thermocouple hole was drilled and tapped and the thermocouple installed (will post pics later), EGR block-off plate fabricated and installed with special countersunk hardware to maximize clearance with long-runner NA diesel intake, and intake to exhaust manifold support bracket fabricated (to structurally tie together intake manifold to exhaust manifold).  Stainless downpipe flange fabrication is also completed and fits nicely to the turbine outlet and fasteners (just needs filing flat on one side.)

The head is all cleaned up ready to go, and it came out flatter than any used diesel head I've laid a straightedge across!  While the specs call for not being able to slip a 5 thousands feeler under it anywhere on the combustion chamber sealing surfaces, I could only slip a 1.5 thousandth feeler gauge under when the straigtedge was laid over the prechamber inserts!  No warpage here (at all.)

I found evidence of where the head gasket leak had happened too.  Like other overheated IDI VW headgasket failures I have observed, it was a leak between coolant port and combustion chamber on the back side (opposite of prechambers.)  The metal fire ring around the combustion chamber was actually eroded and pitted all the way around in the cylinder that had the leak, and the fire ring was cracked near the leak also.  I think the degradation of the fire ring was from hot exhaust gasses and/or coolant slipping by it and eating away at it.  I had not seen a cracked fire ring before.  But the good thing is the overheat was caught early enough that the head was not permanently warped.

The engine besides needing head bolt holes and it's deck prepped (might clean the piston tops up a little) and grease cake cleaned off the back side of the block, is ready for the head to be installed, with all four motor mounts replaced with brand new and also now sports the factory air-water oil cooler.

[DVST8R]

Are you going to stud the block and use a 1.9 HG?

[fspGTD]

Nope - going to run just a standard fiber head gasket (this is a solid lifter head, so not that easy to adapt a 1.9 head gasket... due to the difference in water jacket / oil return)  I do have some used raceware head studs sitting around however which I'll throw in there.

I cleaned the deck and measured piston projections today and found that the 3-notcher that I bought (same as came off the car) was not the correct thickness!  The piston projections call for a 2 notcher, although it was very close to a 1 notcher.  The 3 notch is definitely incorrect and is too thick (must have been a sloppy mechanic who worked on this...)  Tomorrow I'll need to track down a 2 notcher.  I'm basically ready to install the head and the manifolds!

[fspGTD]

Pics of the EGR block off plate and the manifold to manifold support bracket:

You can see I beveled the edge of the stainless block off plate as well as replaced one of the original studs and nuts with a countersunk screw in order to gain more clearance with the long-runner NA Diesel intake manifold:



It's a tight fit, but it works!

[fspGTD]

And some pics of the pyrometer thermocouple installation:

drilling the hole:



I rigged up the shop vacuum to blow the chips away from the turbine.  I tried an interesting test which was to move the variable vanes when the vacuum was blowing and see what difference it made.  The vacuum noticeably loaded and airflow significantly increased when I opened the vanes!


Completed thermocouple install:


By the way, don't worry, that head pictured above is a junk head I just use for testing the fit of manifolds.  Here is the good head after being cleaned up: (flat as a board!)