1.6lTD long-runner intake manifold

[caddy]

what do you think about this?

lengh is about 46cm ( 18p)

[fspGTD]

Thanks for the info....  18 inches? wow!  That should get you some low-RPM torque.  

[jtanguay]

hey i know this is off topic, but by low rpm torque do you mean in the range of 1800 rpm?

I was wondering why a TDI gets full torque at around 1800 rpm while the IDI gets full torque at around 2500 rpm?

Is that something to do with the high compression, or the intake runner length/turbo size???

thanks!

[Blades]

Not all mk1 intake created equal.

early mk1 have slightly bigger runners and smaller TB (but who cares about the TB)

Later mk1 and mk2 (cabriolet 90-93, G60 engine and all mk2) have the same runner configuration.

My opinion, there's way better.

Meet my 1.8 8v Turbo secret weapon. (mot mine pictured)

The Audi 5KTQ intake manifold

It's got bigger runners and better airflow

(Audi left, G60 right)


Another interesting intake is the 2 piece Audi 90 intake (counterflow); it's got 4 injector holes in the intake for stuff like propane or nitrous.

[QuickTD]

I was wondering why a TDI gets full torque at around 1800 rpm while the IDI gets full torque at around 2500 rpm?

I'd say its got more to do with the nature of direct injection combustion. Mixture formation tends to be best in DI engines at low RPM's, permitting a larger injected quantity without smoke. Mixture formation and burn speed is better at higher engine speeds in prechamber engines.

 The early 1.9TDI uses the pretty close to the same turbo as the 1.9TD (both K03's) and both manifolds are very similar, pretty much logs. No tuned length runners on either one.

I like that manifold. It has me wondering if the transporter 2.4 5cyl NA diesel has D shaped ports like the 1.9TD. It has some seriously long runners...

[caddy]

I like that manifold. It has me wondering if the transporter 2.4 5cyl NA diesel has D shaped ports like the 1.9TD. It has some seriously long runners...

no d shapped, i have to chek if it have same size as the 1.6 or bigger....

[fspGTD]

hey i know this is off topic, but by low rpm torque do you mean in the range of 1800 rpm?

The 18" runner length might help add some torque that low in particular when compared to the stock 1.6lTD intake, but it's going to give it's greatest gains probably higher up, I'd imagine.  I haven't done the calculations but I'm sure it wouldn't peak that low.  I'm pretty sure you'd need something way longer that is practical to fit under your hood to give peak torque from intake runner inertia tuning at 1800 rpm.  The air columns that long would also severely choke volumetric efficiency at high RPMs, since they require time (not available at higher RPMs) to get that long column of air movin'.

I was wondering why a TDI gets full torque at around 1800 rpm while the IDI gets full torque at around 2500 rpm?

Is that something to do with the high compression, or the intake runner length/turbo size???

It's not the compression, or the intake runner length.  I think it's the turbo design.  The TDIs have very small and quick-spooling non-variable or variable vane turbos that gives peak boost pressure at about 1900 RPM, while the 1.6lTD has a "bigger" turbo that doesn't kick in until a higher RPM.  Regardless of which VW Diesel motor you're talking about, generally the torque peak occurs at the lowest RPM that the turbo can deliver full boost.

I'd imagine the 1.9lTD (coming with the small, quick-spooling turbo) would also peak at a low RPM when it's boost peaks, but I don't have hp/torque and boost pressure vs RPM plots for that motor handy, so I can't verify that.

[VWRacer]

Jake, doesn't your GTD have a flat torque curve, with no real drop-off until you start running out of fuel?

Hint: Paste some dyno runs on your website and update that "Last updated in 1996 line...

[jtanguay]

thanks for the info!  Seems like it takes forever for my turbo to spool up.  Should I go with a 'dinky' K03, or would buying an expensive hybrid turbo be worth it?  I don't want mean power, just less turbo lag

[fspGTD]

Hint: Paste some dyno runs on your website and update that "Last updated in 1996 line...

Couple of problems there:
  1. I have no additional disk space on the web site
  2. If I start modifying it, I know I would be tempted and it would be a very slippery slope of bringing it fully up to current, which would take a lot of my time that I don't have...

So I think I will just continue using imagestation, unless someone knows of a better option.  Although it does tend to reduce the size of the pics, it works well with this board, and seems able to relentlessly store all the pics I can throw at it!  

Jake, doesn't your GTD have a flat torque curve, with no real drop-off until you start running out of fuel?

The torque peaks at the RPM where the wastegate opens, and either hold that amount, or drop, from there going on into higher RPMs.  Horsepower, on the other hand, generally climbs up a little bit after the wastegate opening point, but is generally flatter than torque in this area.  This characteristic is probably because the efficiency of the combustion drops off as the RPMs climb.  Whether aero drag is being included in the measurement, or not, also does influence the shape of the curve recorded (as aero drag increases with increasing vehicle speed and RPM)

* Plot from G-tech, after aero drag, 3rd gear, not SAE corrected:


* Plot from a chassis dyno, at the wheels, SAE corrected:

[fspGTD]

1.6lTD long runner intake manifold idea, take 2:

Instead of putting the long runners in the factory location behind the motor close to the firewall, another option is to make the runners go over the top of the cylinder head, like this:




A test fit revealed I was able to close the hood down all the way and there was still a little bit of room.  Although the throttle mouting flange clears the hood, I might want to cut it up to get a little clearance with the valve cover, and perhaps position the plenum down a little bit more.

To make service under the valve cover easy, the intake manifold should be a 2-piece design, with all the bolts for the upper piece being accessible without needing to remove the turbocharger.  The upper piece could be an A1 gasser manifold that is stock except for a few unneded protrusions cut off, while the lower piece could be a special fabricated piece made from the bottom of an 1.6lTD intake manifold that allows the A1 gasser manifold to bolt up in the proper position.  It would start with this piece:


Compared to the other long-runner intake manifold design, this would leave the exhaust manifold and exhaust system, turbo location, air intake and compressor outlet tubing, oil feed and oil drain, etc, all unchanged.  The boost tube run from the front mounted intercooler would be shorter with less distance to travel to get to the plenum. The intake manifold also wouldn't be positioned over the hot turbocharger but in a location that's a little bit cooler, requiring less heat shielding.

As a con to this design, it uses the 1.6lTD intake manifold's tighter radius runner bend, which might restrict airflow somewhat versus a design putting the plenum behind the motor.  I wonder if it that tight bend would make it much more restrictive.

Also due to more limited clearance, I wouldn't be able to easily substitute or test various types of long-runner manifolds (In particular, the A2 manifold, which has longer runners than the A1 manifold, would stick up too far and interfere with the hood.)

I have had trouble oxy-welding thin tubing (.065" tubing) but have had good results with thick (1/4").  But I need to see how well I can do cast aluminum.  I'll need to do a little experimenting first to build my confidence.  I suppose at worst case, I could always prep the parts for welding and take them to someone who can TIG things together.

[935racer]

You deffinately don't want the crappy tight bend right before the ports style manifold, I know its like the factory manifold but that one sucks too. There is definately a big differnece in having the air going into your ports straight and cleanly and smoothly than making it make a 90 degree turn right before it goes into the cylinder. One idea I had while looking at some manifolds today was taking a a2 na intake and taking off the plastic airbox crap and buying a premade plenum and welding it on, I think it would make a really nice low cost long runner intake. The audi 5000 intake witha  runner cut off is an awesome one too. I know you probably want to run the turbo in the stock postion and I would want to as well cause that would be a lot of work flipping everythign around. I am flowing huge amounts of air with a pd130 manifold on malones engine but it is a short runner and it has the d shaped ports.

[fspGTD]

I tried some aluminum welding with the cast manifold material and although I can get good fusion sometimes, it's just not reliable and when it doesn't work, the oxides prevent things from sticking with my oxy-acetylene setup.  I think I really would need an AC TIG setup to do the required work without becoming very frusterated.  I do have a aluminum braizing rod I can use and is very strong, but it only works for gluing pieces together, not really good for the building up of material I'd want to do with the lower plenum.

So my latest idea is to fabricate a completely new lower part out of stainless steel tubing and either mild and stainless flanges.  Stainless runners would help slow down the transfer of heat from the head and turbo into the main upper aluminum runners and plenum.  I can very reliably weld stainless, and maybe use some thin-walled stainless mandrel tubing bends that have slightly more generous bend radii than the factory 1.6lTD manifold has.  It's still going to be tighter than most stock manifold designs, but hopefully it won't give up a whole lot, it might be worth a shot!  Flipping the turbo manifold upside down is just so much work, that it's unfeasiable for me at this time.

I did some more cutting, filing and deburring of the upper manifold piece that made it look prettier, and found cutting off a corner of the throttle body flange made it sit even closer to the valve cover.  It is definitely looking workable!

[935racer]

Flipping the manifold is definately a lot of work. I have an ac tig you are not too far from my shop so if you ever feel liek wandering north stop by and we could weld you up one that way. But until then I might be able to help you out with the flanges, my buddy is autocading out 1.6 intake flanges and 1.9 intake flanges and the exhaust flanges for both heads. He should be done early this week than I will mail the the drawings to my other friend with a cnc plasma cutter. So I can get them cut in aluminum, mild steel or stainless. Hey  maybe we could trade some flanges for those new nozzles you are working on :twisted:

[Baxter]

Just out of curiosity I picked up a 1Y inlet manifold a while back, would that not be woth modifying to suit? either port the head and use a AAZ/TDI inlet manifold gasket or weld the manifold and port that to suit a 1.6l?
1Y is a european 1.9D, basically the non turbo version af a AAZ as I understand.
I picked up the manifold for my mechanical TDI when I get around to it...