G-Teched my 1.6TD - Part 2

[Maarten]

Small typo, I have a K24, but thats about comparable to the T3.

[fspGTD]

Of course, our TDs are not comparible to VR6s at all but I don't mind the 3" diameter anyway; it doesn't bother me and I don't feel like shelling out $ again for 2.5" exhaust with the possibility that it may hinder flow even a little bit.

Actually, I just did a quick calculation and found that an ungoverned, high-revving 1.6lTD boosted to 30 psi would flow the same exhaust gas volume as a VR6-T does at 14 psi.

The thing to do to test whether a larger exhaust is useful is to insert a pressure tube into the exhaust system at the turbine outlet, and run it to a pressure gauge.  During a WOT run, any reading above perhaps 1 or 2 psi would likely mean that a freer flowing exhaust system offers increased performance.

[malone]

Actually, I just did a quick calculation and found that an ungoverned, high-revving 1.6lTD boosted to 30 psi would flow the same exhaust gas volume as a VR6-T does at 14 psi.

The thing to do to test whether a larger exhaust is useful is to insert a pressure tube into the exhaust system at the turbine outlet, and run it to a pressure gauge.  During a WOT run, any reading above perhaps 1 or 2 psi would likely mean that a freer flowing exhaust system offers increased performance.

Thanks Jake! Can I see your calculations?

[fspGTD]

Sure, Mark:

assuming both engines turn same max usable RPM (which I think is reasonable comparing a stock valvetrained VR6 with governor-removed 1.6lTD), and for simplicity, ignoring imperfect intercooler efficiency and volumetric efficiency (assuming they are perfect):

1.6lTD air flow per crank revolution at 35 psi:
= manifold absolute pressure * (1/2 of engine displacement)
= (1 + 35/14.7) * .8 liters
= 3.38 bar absolute * .8 liters
= 2.71 liters of air moved per crank revolution

solving for manifold absolute pressure of 2.8 liter VR6 with the same air moved per revolution:
2.71 = manifold absolute pressure * 1.4
manifold absolute pressure = 2.71 / 1.4
manifold absolute pressure = 1.936 bar absolute

On the VR6, the needed 1.936 bar absolute intake manifold pressure is .936 bar boost pressure, or about 14 psi boost pressure.

[1985JettaTD]

i know it is a bit off topic of this thread but i think a lot of people would like to know what kind of economey goes along with thoes numbers on Molones 1.TD if you know that would be cool if you would post them

[malone]

i know it is a bit off topic of this thread but i think a lot of people would like to know what kind of economey goes along with thoes numbers on Molones 1.TD if you know that would be cool if you would post them

No odometer = no accurate MPG reading. I hope to get a GPS mapping/mileage device sometime around Christmas.

Anyway it's still quite early to record consistent MPG numbers. The TD isn't in its final tune: There'll be a different turbo, major fueling adjustment, low RPM smoke fix, etc. The non-intercooled 132 Gtech HP or approx. 150 wheel HP is a far cry from the ultimate goal. Until then I'm not going to bother trying to record MPG.

[malone]

Update:

I found that the HP peaks at approximately 5,000 RPM. That's quite out there for a TD! The OEM injectors that were recently swapped in are still in but when GTD nozzles are reinstalled and when the intercooler is functional, I will do a complete Gtech run and re-post.

In case anyone is wondering, the injection pump has a 9mm head. I doubt I will go for a 12mm head like a few people are because of some negative effects including RPM limitation. I redistributed a 12mm head to a friend and his pump was destroyed at 5,200 RPM. I later learned that there are least 338 different 12mm heads and only one of them has the highest max. RPM of 2,150 to 2,250 IIRC. Multiply that by 2 to get the crank RPM. That definitely will take a chunk off my upper powerband. I saw a 1.9L ALH TDI dyno at 190whp with a 12mm but he let off just prior to 4,500 RPM for fear of the pump's reliability.

10mm or 11mm are possible candidates for my application but I'd like to try upgrading injector nozzles first and then decide on the pump head upgrade.

I don't consider GTD nozzles as big nozzles because it's OEM off a ~70 to 80 BHP TD, still a relatively small upgrade from OEM 1.6 TD injectors. I'm starting to look into larger nozzle options.

The fuel screw on the injection pump was recently turned up to improve cold start. It did help. For the first time ever, I saw a grey cloud behind me at WOT before full boost. EGTs are the same during normal driving. As each day passes by I think I'm smoking less white/blue below 2,000 RPM. It still smokes a lot for about 3 city blocks after cold start, but overall it seems to be a little less now. I failed Aircare (emissions) a few days ago due to excess white smoke during an idle test (hardcore revving in neutral). The criteria to pass is 0-30% exhaust opacity. The average of all passing diesels is 6%. I got 49%. I don't think the white smoke right now is low enough to pass.. we'll have to do something about it. I might consider permitting Aircare do a rolling test because under load there's virtually no smoke and drives like a dream, although they'd probably do the hardcore neutral revving thing too.

[BlackTieTD]

emissions testing... there's one area where my 1.6L TD rabbit has you beat, no e-test required  :wink:

excellent work malone. keep us posted like you have been. i'm interested to see how the GTD nozzles will do vs. stock.

[jtanguay]

emissions testing... there's one area where my 1.6L TD rabbit has you beat, no e-test required  :wink:

excellent work malone. keep us posted like you have been. i'm interested to see how the GTD nozzles will do vs. stock.

Hehe!  20 years or older... gotta love it.   I love how diesels are tested here in Ontario as well... visible smoke test at idle!  You just can't fail that with a vw!

[malone]

excellent work malone.

Most readers tend to assume that the person presenting the information about a project is the person who did all the work on the project. I want to be clear that I can't take all the credit for this 1.6TD project. It would not be possible without Passenger Performance they deserve more credit.

jtanguay: That's how diesels are tested here as well. It's also known as an opacity test.

I Gteched the TD on dry road an hour ago. During my previous Gtech plots (shown on first page) I had injectors w/ GTD nozzles and higher opening pressure. Now I have smaller OEM injectors because we were trying to diagnose the low RPM white smoke issue. The pump's fuel screw was also turned up recently. The peak HP really isn't at 5,000 RPM - it's more like around 4,800 RPM.  

The green and blue lines are two runs from before.. one of these runs were already shown in the first post of this thread. The black and red lines are from today.


The recent Gtech plots confirmed my suspicion that the turbo indeed spools up slower now, which I find odd. However, after 3,200 RPM, holy crap the power/torque picks up real quick. Woo! what a ride It felt a lot like having a larger turbo now but I still have the same turbo with no change in boost control. Quite odd. The low boost/torque during lower RPM explains why I have grey smoke - the grey smoke is not just because of the fuel screw being turned up.

So why the turbo lag? Could it be because I downgraded to OEM injectors from GTD injectors? Highly unlikely. Could it be because we adjusted the fuel pump timing? Or could there be a small leak in the charge piping? There's still more tuning to come. Will check for boost leaks, etc. and then Gtech again when GTD injectors are reinstalled.

*edit; during daily driving in the last couple days I did notice less power below 3,000 RPM but it didn't feel significant. The car's still perfectly comfortable to drive in traffic with this power curve. However if I need accelerate quickly I did sometimes see a small puff of grey smoke @ low RPM because of less boost available.

[935racer]

So are you comming out this weekend to try some injectors? We could go down to the 1/4 strip by the shop and try the oem, gtd, and benz injectors right there on the side of the road. Also I think its time we test the custom cams in this thing. Let me know.

[BlackTieTD]

if you guys could post g-techs of the OEM vs. the GTD injectors with no other changes, i'd appreciate it  

[malone]

So are you comming out this weekend to try some injectors? We could go down to the 1/4 strip by the shop and try the oem, gtd, and benz injectors right there on the side of the road. Also I think its time we test the custom cams in this thing. Let me know.

Dave I'll be at Paul's again today, tomorrow, and possibly Sunday to work on one or two diesel swaps, as well as cutting one MK1 Rabbit into half to make a trailer.

I might have time Sunday (evening?) to do Gtech runs with some injectors and cams. One WOT gear pull without intercooler is OK but I wouldn't want to try these Benz injectors until we can get some water system going on for the a/w intercooler... or install the FMIC. The EGT is already pushing it.

BlackTieTD: I'll try to do that, Gtech with only GTD injectors and no other changes will do Gtech runs with OEM injectors again on the same day just prior to nozzle upgrades.

[malone]

*

[malone]

Found the problem: the LDA wasn't responding during lower RPM because of a small boost leak illustrated below:



That's pretty common and not a big deal. I will get better clamps for some hose ends to ensure that the system remains air tight & fully pressurized.

The low RPM WOT smoke is now back And the torque below 3,200 RPM is restored as well.

I took a Gtech run again and compared it against the Oct 30 run. The recent Gtech plot should be disregarded:



Yep, that seems about right - what I expected after the fuel screw was turned up despite downgrading the injectors; more torque across the RPM range.

I will raise the LDA starwheel to increase tension on the boost pin's spring to eliminate smoke during lower RPM. Below 3,200 RPM I may expect similar torque to the Oct 30 setting, which is still more than enough, but after approx. 3,200 the extra torque should remain unchanged. The boost pin is fully depressed well below 30 PSI so I don't have to worry about losing top end if I raise the starwheel a little.

There is still no smoke after around 25 PSI or 3,200 RPM... need more max. fuel!

In the near future I will run an extra hose or two to the LDA, each having restrictors to limit airflow to the LDA. A wide open hose will maximize airflow to the LDA, allowing plenty of fuel starting at low RPM. A restricted hose will minimize airflow to the LDA, eliminating smoke during lower RPM and may not affect high RPM fueling depending on how easily the boost pin is depressed. The hoses will be controlled via an electronic switch in-car. Basically a Street mode and Race/anti-Tailgater mode. I won't be able to hold all the power to the road in either mode this Winter anyway

Next up: Gtech with GTD injectors.