VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: fspGTD on June 25, 2005, 09:00:38 am
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On the last update of the Rabbit VNTD (http://www.vwdiesel.net/phpBB/viewtopic.php?t=1306&start=196), I left you guys hanging on what modifications would be next in store for the car. This was after the installation of a VNT turbo from a TDI which was set to 8psi boost pressure.
Time to unveil the wraps on what's going on. :twisted: Sure enough, I am addicted to hot-rodding this thing and can't stop now.
Right now I'm working on mounting a Saab 900 reverse-flow intercooler into it:
(http://www.imagestation.com/picture/sraid174/p7bf3db78194b881a14f84fee57a0b717/f38eaffa.jpg)
After a little trimming of its mounting flanges, this intercooler just barely fit between the westmoreland-Rabbit headlight buckets. It is also thin enough to not have to relocate the radiator. I also am trimming the hose fittings back:
(http://www.imagestation.com/picture/sraid174/pb23b8e6ba62c6b11adb2bc7a18d66d50/f38eafec.jpg)
Going in along with the intercooler will be a bigger .9 bar (13psi) wastegate spring. Can't wait to see what the car's like with an intercooled 13+psi. :P
Also, thanks to Larry (DieselsRcool) for hosting me at his shop and helping me change out the valve seals in-car! When I had the head off recently I noticed some oily residue in one of the exhaust ports, and the car had always had some blue oilsmoke out the exhaust combined with a little bit of oil consumption, pointing to a leak out of an exhaust valve seal. When changing the valve seals, we also found a cracked lifter bucket skirt! I am lucky that Larry had a good spare lifter bucket in his parts stash, which we swapped in on the spot.
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Nice choice of intercooler.
Wide VNT powerband + intercooled 13 PSI + Rabbit = (http://4hoursleep.com/avatars/homerDrool_100.png)
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You are making it more and more difficult for yourself to hand the keys back over to your dad once you are done.
Looking forward to the results!
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Well? Where's the road report? Knowing how excited these hot diesels make you I can't believe you haven't driven it yet.
Thanks for the ride the other day. I must say the performance is quite impressive. :shock: I feels more like a 2+ liter old bug than a lowly diesel rabbit. Nice and light but torquey and full of snap. What a sleeper. I can see the horns growing out of your dads head now.
That does look like the perfect intercooler for the A1 though, good find.
Larry
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Thanks guys, I can't wait to see how it's going to turn out too! :) This car is a little rough on the edges but it's already an awesome daily driver, I already wish I had it for my own!
Larry - the car drove great on the way back home from your place, but I wasn't able to get someone to follow behind while driving it yet to see if the oilsmoking it happening or not. I will check this out more thoroughly very soon though.
I am going to run 1 3/4" SCEET ducting (the pricey dual-ply silicone stuff) for the boost tubes. I am hoping with that size that I can just route it right down the front of the timing belt cover and also have the return flow come back up it right along side it and hopefully have it all fit under the hood with the stock sound absorber mat.
I fabricated an aluminum tubing transition to adapt the compressor outlet from 1.5" to 1.75" and am working on some for the intercooler boost tube connections to change them from 2.25" to 1.75". To make the transitions I first annealed some 6061-T6 aluminum tubing with the oxy-acetylene torch, then used a muffler/tailpipe expander tool I rented from Schmuck's.
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test fitting the intercooler and air baffles:
(http://www.imagestation.com/picture/sraid176/pd1aadcf2c8196af4a1db7468690f3c2d/f35fd06d.jpg)
(http://www.imagestation.com/picture/sraid176/pfbf2b5c95fa1e99cbb163245c6815bca/f35fd036.jpg)
(http://www.imagestation.com/picture/sraid176/p8a18063a061bb48397c9524152c1acce/f35fd0d2.jpg)
(http://www.imagestation.com/picture/sraid176/p99faa5f821f3348306301629aa0996a7/f35fd125.jpg)
Some detail of the top of the intercooler. I added slots to make more clearance for the radiator support and the hood latch release mechanism:
(http://www.imagestation.com/picture/sraid176/p8d4371c24f2c5040de5190a5433efcaa/f35fd0f9.jpg)
And here is an overall shot of the intercooler - it is just about done and ready to be permanently mounted!
(http://www.imagestation.com/picture/sraid176/p95db6879033ca0e0fa1d7a4b4e23702e/f35fcff6.jpg)
But I should be extra careful not to blow a boost tube off with the manually controlled VNT. A blown boost tube would cause the vanes to close completely, which could make the turbo pretty quickly overspeed!
This bead-forming tool I made out of a pair of vice-grips and a steel hook should finish it off:
(http://www.imagestation.com/picture/sraid177/p8dc4af172244ae7729b50d854d9029f1/f353eb1e.jpg)
bead-forming tool in action:
(http://www.imagestation.com/picture/sraid177/p6bf1d2a2ff76e1b33d9c94d5739dddc7/f353d474.jpg)
beaded tube result, close-up:
(http://www.imagestation.com/picture/sraid177/p4f1971b42b05ae084115a7c4367ee9c1/f353ea35.jpg)
The bead height is variable with the tool. I set it so high that the aeroduct just barely slips over! :P
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Bead forming tool... now THAT is slicker than snot. ;) You are a regular MacGyver, Jake! :)
Brendan
84 Scirocco 8v
00 Camaro L36 M49
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YEAH
that is a really GOOD idea.. to bad that I am going to steal it now ;)
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There ya go Jake! That's using the old gray matter. I'm into those kind of homa made tools ya know. Good job.
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Thanks guys! You know, they say imitation is the sincerest form of flattery. :)
Hey I finished the intercooler install yesterday, installing everything and finishing off the boost tubes:
(http://www.imagestation.com/picture/sraid177/p2e738d88dbe4c7525eac7237fece8e5d/f3513e8f.jpg)
(http://www.imagestation.com/picture/sraid177/p598d02fcc18d2f4b19a0b43cdb3ad4a6/f3513ebb.jpg)
It was a chore to route the tubes in that location with them being properly supported and not rubbing on anything. I was concerned about the thin aeroduct chafing against something, but so far the only thing rubbing is one of the rubber-lined adel clamps on the soft hood sound absorber mat. I need to do something about it before driving a lot more, as the sound absorber is wearing where it is rubbing. The boost tubes and intercooler are holding up great though, and I have had no problems with boost tubes getting blown off. :D
I also changed the wastegate from .6 bar (little green spring) to the .9bar (big green spring). Check out the differences in these spring dimensions!
(http://www.imagestation.com/picture/sraid177/pc7888e7dcafd7b36af91aa5a07e7b564/f3513e9e.jpg)
Against the force of the big green spring, holding the spring cover on there while starting the little bolts into their threads was not easy!
After a road test, it looks like the wastegate with the new big green spring is opening and regulating pressure pretty well at about 12psi - a pretty healthy bump over the previous 8 psi setting.
I did several tests to adjust the VNT to increase it's pressure, and I reached the end of it's threaded adjustment range. So I disassembled it and reassembled it with a threaded rod that is shorter, so I could get more VNT spring pre-load to further increase it's regulated boost pressure. I've got it set now so that it starts opening at about 5-6 psi and it opens completely at about 11 psi. I will probably experiment soon with adjusting this a bit higher.
I also adjusted the LDA as well to broaden its working pressure range. I wanted to set it to allow more fueling than stock at the high boost levels to go with the added air, but also wanted to have it minimize fuel at low boost, so that in the event of a blown boost tube, the LDA reduces fueling as much as it can to try and help save the turbo from overspinning on closed vanes. With the LDA set up this way, the car's horsepower and torque characteristic is more closely linked to its boost pressure, so there is a bit more turbo lag powering away at very low RPMs, but it's usually not for very long with the VNT.
The car rocks with added boost - really fun to drive. The way it's set up now, there is a little bit of "hyperactive boost" cruising on the freeway, etc, at around 5 psi where the vanes are nearly totally closed, the boost is very responsive to small throttle changes. But it is well regulated around 10 psi, and creeps beyond that up as RPMs increase to about 12 and then at the highest RPM where there is still max fueling the boost peaks at about 12.5psi. There is definitely more power, and more torque, despite fueling being set to make zero visible smoke detectable out the rearview mirror.
Oh by the way when I was under there removing and reinstalling the VNT can, I noticed that the compressor housing was HOT! I remember there was a heat shield on the TDI exhaust manifold on the compressor housing side of it, and I can see two mounting studs for it sticking out of the exhaust manifold, but on this car it is missing. Maybe I should try and track one of those TDI heat shields down.
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Great work, Jake.
Any EGT numbers yet, with the same fuelling as before, and with the increased fuel?
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Wow - what a difference an intercooler and 4.5 psi of boost can make! Check out these G-tech results:
(http://www.imagestation.com/picture/sraid177/pcb1be898fa1492c343849c9a64c1e7f6/f34c8204.jpg)
The blue and green are the two best results out of four that I measured earlier today (with the intercooler and 12.5psi boost pressure.) Dyno correction factor from today's session was .98.
* Peak power: 80 HP @ 4260RPM
* Peak torque: 108 ft-lbs @ 2790 RPM
The black line was the best recorded non-intercooled, 8 psi run. Dyno correction factor for it was .99... only off by 1%.
TDIMeister: I have not meaured the peak EGTs since the addition of the intercooler, although I have no worries in that area. It is likely to be much cooler than it was before since it now has the intercooler. Also, the amont of fueling per unit of boost pressure in the working pressure area of the LDA is likely to be less now than it was before, since I raised the LDA spring seat and have not altered the max load screw setting or LDA control cone rotation angle.
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80HP 8)
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I think I should g-tech my mom's 2001 Golf TDI Auto and see how variable vane TDI compares to variable vane IDI... 8)
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Nice job! It's nearly into TDI territory for much less $$$ than a TDI.
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Nice job! It's nearly into TDI territory for much less $$$ than a TDI.
I believe it is in TDI territory. G-tech horsepower normally reads lower than wheel and brake horsepower because it factors in aerodynamic drag, drag from rear wheels rolling (unlike on a stationary dyno), etc.
IIRC a stock 5-speed A4 ALH TDI (1999 to 2003) G-Techs at 75n-85hp. Results may vary by G-Tech device, operator, calibration accuracy, etc.
80nhp with 12.5 PSI in a 1.6L IDI is amazing, especially with no noticable smoke from the driver's seat, and considering that a stock ALH TDI runs approx. 12 PSI.
Congrats Jake for a fine tuning job.
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I would love to G-tech my car, I know it isn't that fast, but it sur feels much better than the 90hp it came with from the factory :) With stationary dynos a stock tdi generally comes in around 85-89whp from what I have seen.
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IIRC a stock 5-speed A4 ALH TDI (1999 to 2003) G-Techs at 75n-85hp. Results may vary by G-Tech device, operator, calibration accuracy, etc.
Mark - I was looking all over the web for this info earlier, but wasn't able to find it, so I'm glad you chimed in! Do you have any .gtp files of a stock 5-speed TDI you could send me for comparison?
By the way, based on testing I have done on my GTD autocrosser on both mustang chassis dyno and G-tech runs, I can verify that aerodynamic drag is significant. With the GTD autocrosser, the G-tech reported 73 net hp while the mustang dyno had reported upper 80's wheel horsepower. And mustang chassis dynos are known to give out lower numbers than other brands like dynojets.
So stock ALH TDIs run 12psi... That's also good to know.
I did a couple quarter mile passes yesterday. I am not sure these represent the full perfomance of the current setup, because I had left the floormats in for the tests and noticed right after my runs that the driver's floormat had slipped over and was in the way of the accelerator pedal, limiting full throttle. :oops:
But anyway... here are the results:
Run #1
* ET - 16.6 sec
* Speed - 82.4 mph
* 60 ft - 2.62 sec
* 0-60mph - 8.63 sec
* comments: not the best driving on this one. Slipped the clutch excessively at launch. Upshifted too late.
Run #2
* ET - 16.5 sec
* Speed - 81.2 mph
* 60 ft - 2.48 sec
* 0-60 - 8.42 sec
* comments: Overall I drove this run much better. The launch was more aggressive, tires chirped a little. I felt like I nailed the shift points. I traveled same stretch of road as before but in the opposite direction. After I started this run, a UPS delivery truck approached from the far end of the unstriped 2-lane road I was testing on. I probably should have aborted the test, but I decided to keep the run going and blew past him at probably close to 80mph - and he was approaching me too! Boy am I glad he stayed over on his side... :o
Also - I had an opportunity to do a max EGT test. After keeping the throttle nailed on the freeway up a hill for about 20-30 seconds (had to drag the brakes which I could start to smell to keep speeds below 95mph), the EGTs reached and plateaued at - it was either 1050 deg. F or 1150 deg. F, I can't remember. :oops: (I had to focus primarily on safe driving and safety around other traffic, etc.) But in either case, you can see the temps are WELL into the safe zone - several hundred degrees F below the 1500 deg. F stock 1.6lTD pre-turbine temp limit.
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Those are great numbers, Jake.
Excuse to refresh my memory yet again: Is the EGT probe pre- or post-turbo?
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Wow...16.5 sec quarter in a diesel Raggit. Who'da thunk it...?! :D
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Thanks guys!
TDIMeister: EGT thermocouple is pre-turbine (http://www.vwdiesel.net/phpBB/viewtopic.php?t=1306&start=59).
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Yeah, 16.5 with a 2.48 60' time is fast enough to beat the tar out of most people who arent ready for it. And with an old diesel plainclothes rabbit, NOBODY is going to be ready for it. :D
Very nice work indeed.
By the way, I thought stock ALH TDI's put out around 14 psi at max?? could be wrong.
Brendan
84 Scirocco 8v
00 Camaro L36 M49
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Dad is daily driving the Rabbit again now, and will be monitoring oil consumption as well as the fuel economy.
My dad is working next on sprucing the car up a bit, restoring some Audi4000 multi-spoke (ronal R8 style) wheels for the car next, and also has a euro chin spoiler for it on its way. It's definitely going to stay looking for the most part stock classic westmoreland Rabbit diesel though. I think my work with the engine tuning is for the most part done. I could easily keep going with increasing the boost and fueling, but the car has more than enough power for him. He is just happy as can be about it.
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Dad is daily driving the Rabbit again now, and will be monitoring oil consumption as well as the fuel economy.
My dad is working next on sprucing the car up a bit, restoring some Audi4000 multi-spoke (ronal R8 style) wheels for the car next, and also has a euro chin spoiler for it on its way. It's definitely going to stay looking for the most part stock classic westmoreland Rabbit diesel though. I think my work with the engine tuning is for the most part done. I could easily keep going with increasing the boost and fueling, but the car has more than enough power for him. He is just happy as can be about it.
Where did he get the chin spoiler (duck bill?) from? Last I heard they were out of production. :(
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I just ordered this (http://faroutparts.com/exterior/small_duckbill.html) for him earlier this week.
I did notice that it was coming up as no longer available through the VW dealer. As is now the Rabbit 1.6lTD/diesel automatic cold air baffle I was planning on getting for dad's Rabbit. :(
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Ah, he just got the shorty. That one is actually still available from VW. My friend has been trying to get his hands on one of the bigger 2 peice duck bills.
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Jake...
Nice choice on the Ronals... Those will look sharp, although I believe the offset will be slightly different. I had those on my rabbit for a while. They remind me somewhat of the Corrado rims they had in 15's...
Also... I've never heard of the cold air baffle you mentioned. Do you have a pic? What's the purpose of that part? Does this keep engine heat away from the intake?
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The A1 turbo-diesel cold air baffle pulls cold air from around and above the passenger side headlight. This one pictured is from my Rabbit autocrosser where it has been modified some, but should give you the general idea of the part
[Edit - actually forget that pic! here we go - I found a great picture of the unmodified factory 1.6lTD air baffle:]
(http://home.comcast.net/~vwgtd/b4swap1.jpg)
Jetta turbo-diesels also come with a similar part, but it is different and won't fit a Rabbit.
The Audi 4000 ronal style wheels actually match the 45mm offset of the stock 13x5 aluminum wheels that are currently on the car. But I know that 38mm offset wheels were also found originally on Rabbits too, including the Rabbit GTI's.
[Edit: here is a pic of the 14x6 Audi 4000 wheels. They are the lighter weight, slim-spoke variety:]
(http://www.imagestation.com/picture/sraid108/pf24e63ee100c605e6ca92ffec4b01628/f94a69e1.jpg)
I heard back a report from dad on fuel mileage of his first tank of fuel -it was 51mpg for the first tank. He also said the coolant temperature seemed to be reading 2 notches lower than where it used to read when it was naturally aspirated. Exhaust gas temperatures also seem to be quite low when freeway cruising, about 450 deg. F at constant 65mph. I'm thinking the EGTs are this low because of the extra intercooled air the VNT is pushing through the engine.
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Exhaust gas temperatures also seem to be quite low when freeway cruising, about 450 deg. F at constant 65mph. I'm thinking the EGTs are this low because of the extra intercooled air the VNT is pushing through the engine.
Wow, you'll have to bock the IC in winter to get the heater to work. The 51 MPG is great, city driving?
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City and freeway mix. That tank did include my quarter mile and other "performance tests" though. :wink: It will be interesting to see what it gets on future tanks. Dad drives more than 800 miles a week, so it shouldn't take long before we see more fuel economy data.
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OK, today I just tweaked the fueling up a bit more via a LDA cone rotation. I figured, OK it's time to see what this thing's like set to a reasonable and stock-like "whisp" of smoke fueling level at wide open throttle. That was my target smoking level.
I popped the LDA cover, and found that the stock '84 Jetta TD setting of the LDA cone rotation was perhaps 20% rotated towards rich. For the first change, I tried rotating the LDA cone to all the way to rich. On the first wide open burst of testing, I found smoking was evident and trailed off behind the car, a little thicker than I wanted to leave this daily driver set at. So I promptly made a second LDA rotation adjustment - dialing the cone rotation back halfway between full rich and stock (we could call where I set it 60% rich.) A further road test found that now smoking was just barely noticeable - exactly where I wanted it. And driving the car around a little bit more, I found the performance of the car was quite noticeably increased, particularly at lower RPMs, where the VNT reacted well to the extra fuel by spooling up more boost. Based on just a short drive, the car seemed overall quite noticeably ballsier. More usable low-end torque! Can't wait to hear back later from dad what he thinks about it. :P
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I'd love to see pictures around the overall car! :)
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Hey Jake, how about throwing your dyno on that baby for some updated numbers? :D
Looking at the "old" graph, I see that the fueling appears completely stock...i.e., the governor starts pulling fuel out so that power starts falling off rapidly above about 4300 RPM.
(http://www.imagestation.com/picture/sraid177/pcb1be898fa1492c343849c9a64c1e7f6/f34c8204.jpg)
The other factiod that catches my eye is that the HP slope goes from 60 HP at 3000 RPM to 80 HP at 4260. That implies that if the governor wasn't taking fuel out the engine would hit 100 HP at about 5500 RPM...right where I'd like to be! :D
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TDIMeister - will put on my list to take some car pics for ya next time I see the car.
Stan - I have not increased the revv limiter on this motor, and I probably won't either since it's dad's daily driver and reliability is important. Removing the intermediate spring seemed to have helped right before the main governor kicks in, so that probably would be in the high 3000/low 4000 RPM area for the (stock) max RPM screw setting it has. You can also really feel it when the main governor kicks in, it's kind of like "OK, fun's over. Time to shift!" :lol:
This volumetric efficiency plot, taken from the 1.5 D SAE paper, might be useful for our "bench engine builds". :wink:
(http://www.imagestation.com/picture/sraid160/p9296f9b1fc7a1dfaec33db4fe686d1e0/f4e36792.jpg)
You can see the 1.5D hits a VE peak of 92% around 3000-4000RPM. This drops down to 84% at 5000RPM (An 8.6% dropoff), with presumably the dropoff in VE continuing with higher RPMs. Keep in mind the 1.5D, like the 1.6D naturally aspirated, has those long, tuned intake runners, which would probably agument VE around the peak, so without them or perhaps with a tuned runners slightly shorter, perhaps the falloff in VE might not appear to be as drastic.
Despite the VE dropoff, I have come to some interesting findings based on the 1.5D SAE VE plot. In excel, I have done an analysis of the expected shape of the HP curve, given this VE plot and assuming torque is directly related to VE. Despite the dropoff in VE above 4000RPM, the HP should keep climbing as RPMs increase all the way to the end of the given VE numbers at 5000RPM. And extrapolating the VE curve above 5000RPM, if we were to assume it trended in a straight line with the same slope as it has between 4000-5000, I found that the HP peak would occur at 6250 RPM (with the VE being approx 70%.) The HP peak there would be 18.5% higher than at 4000RPM.
I don't know if it's reasonable to assume in a diesel that torque is directly related to VE though as it is in a gas engine... this assumption entails that fuel injection efficiency doesn't fall off at high RPMs, which might not be realistic. But it would be an exciting thing to try, to see if we can modify the fuel injection system to get a HP peak around 6000'ish RPM.
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How well I remember the dreaded 4000 RPM fuel cut in my first VW diesel, a 1980 Rabbit 1.5D. Even bone stock I can still remember hitting that wall...! :lol:
Great illustration! Blessed be those oh-so-thorough VW engineers, eh? :wink:
I would guess that your analysis of the impact of the long runners is correct, and that shorties would work better, but keep in mind that once one adds boost to an engine, VE ceases to have the impact that it does on NA engines. Now, before anyone jumps on their keyboard to point out to me that boost has no real relationship to VE, rest assured that I'm aware of that. OTOH, boost has everything to do with getting air into a cylinder. And if you're boosting your diesel at one bar and your VE is a disgustingly low 70% you're still getting an effective 140% VE compared to the same engine NA, which goes a long ways toward explaining why our seemingly low RPM engines will happily rev to stratospheric levels if given fuel.
I agree that even an untouched head should be able to reach 6250 RPM if given fuel. Just think of what a proper porting job would do for VE at that figure... ;)
I don't think that torque is as directly related to VE in diesels as it is in gassers. Gas engines have such a narrow a/f window that their torque/VE curve is practically linear. Diesels have a much broader a/f window, and I suspect therefore are less sensitive to VE. As VE drops the engine may make more smoke, but I suspect it would continue to develop torque well past where our gasser experience would lead us to believe that the torque curve should fall.
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man your car is so sweet
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Little Mikey: thanks and welcome to the board! As a side note, I wanted to bring to your attention that you are using an avatar that is 500 x 374 pixels. You really should scale it down so to fit within 100x100 pixels so that it meets our guidelines and doesn't skew the display of posts. (http://www.vwdiesel.net/phpBB/viewtopic.php?t=3&start=13) Thanks in advance!
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Update on the VNT Rabbit:
Its oil consumption problem was progressive getting worse and there was noticeably blue smoke out the back, so suspecting the oil scraper rings weren't working right, we tore into the motor to give it some new rings.
We took the pistons to our local VW Diesel machinist to have them cleaned them up on the sandblaster, and get some rings for them. (We went with grant top and bottom rings and total seal gapless middle rings.) He gave us a deal we couldn't refuse on three new pistons which were compatible in bore size and weight (to within about 10 grams.) We used them to replace the three pistons that had some pitting on the combustion chamber surfaces, near the pre-chamber port.
But trouble lurked in the bottom end: we found a trashed thrust bearing surface that the clutch release rod would load when the clutch pedal was depressed. The thrust bearing was the one-piece style integrated main/thrust that Dr. Diesel reported similar bad luck with. At .033" axial play (about twice the wear limit,) all the soft metal had already been worn through and it was already starting to gaul the smooth thrust surface on the crank, but dealing with that was much more of an undertaking than we wanted at the moment, so we just put it back together with a fresh thrust bearing (unfortunately, the only style we could find quickly locally was the one-piece), and will keep our fingers crossed it will last for at least a little while.
I learned that starting the engine with the clutch pedal depressed is hard on thrust bearings, and I will be changing my ways. Doing this loads the thrust bearing at a time when there is no oil pressure.
Yesterday, after getting the the engine put back together with fresh honed/deglazed bores and the oil system pre-lubed with non-synthetic nondetergent 30 weight break in oil, it fired right up. After allowing it to warm up, I gave it a few shots of decent loading and boost to try and get the new rings nice and seated in, and it felt pretty good. Fingers are crossed that those rings seat and stop the oil consumption.
Thanks to LarryB for lending me the bottle hone and a few other necessary tools.
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I popped the LDA cover, and found that the stock '84 Jetta TD setting of the LDA cone rotation was perhaps 20% rotated towards rich. For the first change, I tried rotating the LDA cone to all the way to rich.
Can you explain that a bit more, I noticed that the cone is not symetric and there is a dot on the rubber, standing infront of the car my GTD pumps' dot was at 12 o'clock so I dropped it in that way into my 1.9 AAZ pump. But which way is rich, and what is all the way to rich?
Keep us posted on the great project :)
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Moving the cone toward the end of the pump with the injection lines will allow more fueling when your foot is pressed down far enough.
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>> so suspecting the oil scraper rings weren't working right, we tore into the motor to give it some new rings.
What a bummer to have to tear back into the engine just after finishing the "tuning" portion... Did you end up pulling the motor?
>>At .033" axial play (about twice the wear limit,) all the soft metal had already been worn through and it was already starting to gaul the smooth thrust surface on the crank,
Does that mean that the crank would need to be turned as well?
>>(unfortunately, the only style we could find quickly locally was the one-piece), and will keep our fingers crossed it will last for at least a little while.
What's the alternative bearing option? Is there a different design or material in a two piece?
>>I learned that starting the engine with the clutch pedal depressed is hard on thrust bearings, and I will be changing my ways. Doing this loads the thrust bearing at a time when there is no oil pressure.
I had no idea... I wonder if the gassers are the same. That'll change my thinking on starting the FSP car. I had never heard that, but it seems possible.
>> Fingers are crossed that those rings seat and stop the oil consumption.
Hopefully that'll be peace of mind for another 150k miles....
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I learned that starting the engine with the clutch pedal depressed is hard on thrust bearings, and I will be changing my ways. Doing this loads the thrust bearing at a time when there is no oil pressure.
Hmm, that is interesting... :?
Neither of my VW diesels will start without the clutch pedal being fully depressed. :roll:
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I learned that starting the engine with the clutch pedal depressed is hard on thrust bearings, and I will be changing my ways. Doing this loads the thrust bearing at a time when there is no oil pressure.
Hmm, that is interesting... :?
Neither of my VW diesels will start without the clutch pedal being fully depressed. :roll:
You can "fix" the switch so the car will start wit your foot off the clutch, I did it witha smal piece of wire bent into a "U" shape and held it into the plug for the clutch switch with a zip tie.
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What a bummer to have to tear back into the engine just after finishing the "tuning" portion... Did you end up pulling the motor?
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Does that mean that the crank would need to be turned as well?
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What's the alternative bearing option? Is there a different design or material in a two piece?
This was just a quick and dirty re-ring. We didn't remove the block from the chassis, or the crank from the block.
Ideally, (IE: if this motor were completely rebuilt "correctly"), the crankshaft thrust surfaces would be restored so as to fully tighten up the axial play to like-new clearance spec (which is in the neighborhood of .002".) I can't say if it would be as simple as just machining the crank, or it it might take welding... but there becomes a point where the crank is not worth saving, and the one in this motor may be in that category.
There is a main bearing set available that has the 3rd main bearing separated from the thrust surfaces. It looks like this:
(http://www.qualityvwparts.com/mains.jpg)
Here is a close-up of the thrust washers:
(http://www.qualityvwparts.com/mainthrust.jpg)
It is from what I hear a better design, although it is more costly and harder to find.
Compare that with the integrated 3rd main/thrust style, which is the kind that was in the car and it looks like this:
(http://img.eautopartscatalog.com/live/A201013798KS.JPG)
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I'm pretty sure that all OEM main bearing sets have the separate thrust washers. At least every set that I ever sold at VW did. :)
Did the old set that you took out have the separate washers? If not then that engine has been dug into before.
Interesting. :)
Also, a good reminder seeing that this could be caused by clutch pushrod loading over time, is to stop the habit of holding your foot on the clutch at a stoplight. I've never done it as I was always told not to while learning but I know a LOT of people who do. 8)
Brendan
84 Scirocco 8v
00 Camaro L36 M49
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>>There is a main bearing set available that has the 3rd main bearing separated from the thrust surfaces. It looks like this:
Ah... Ok. I see what you mean. The 5-cyl's I rebuilt had the separate thrust bearings, but the air-cooleds I did have the one piece bearings.
I'm wondering whether the 1pc versus the separate bearings included with a kit is purely a cost issue... Obviously they must be "interchangeable" but the factory had a preference, right?
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The VNTD Rabbit engine was definitely rebuilt once during the previous ownership; we got the receipts for it. It is hard to say how many miles ago it was done because the odometer was skipping (since then fixed.) But it could very well be in the hundreds of thousands since the rebuild. It was done by Tom Noble Engineworks in Ballard, WA. This is the same guy who rebuilt the engine in my Rabbit GTD autocrosser (he has since retired and his business is gone) so I've probably got the same main bearings in it.
That is interesting Brendan about you remembering selling the separate thrust washer / main bearings while working at VW. What I am seeing in ETKA and also what is pictured in Bentley seem to be the one-piece integrated main/thrust bearings. So I am now curious what kind of bearing really did originally did come on these motors... Certainly the "tangs" that hold the separate thrust washers are machined into the main bearing saddles (probably on all watercooled VW motors) so they could be updated easily.
As to what would make the bearing wear out like it did... I don't know but I suspect besides using the clutch while cranking, it could possibly be that they don't get installed right. My local vw specialist engine builder was telling me about how he would set those one-piece integrated thrust/main bearings squarely into place by taking a dead blow hammer to each side of the crank with it installed but before the 3rd main cap was fully tightened. It might help to square the thrust surfaces up to the crank and help them last longer. Anyone heard of or use this procedure for installing the one-piece mains with the integrated thrust bearings?
Dr. Diesel has some bad things to say about the one-piece integrated thrust bearings here: http://www.vwdiesel.net/phpBB/viewtopic.php?t=399
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Funny that Etka doesnt list the separate thrust washers until 87. I'm pretty sure they are all the same size. (within similar engines that is) I remember one customer called about a JH engine he was rebuilding and wanted the thrust washers from a later model. Must have worked. :)
Brendan
84 Scirocco 8v
00 Camaro L36 M49
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Can you please tell me about your intake/air filter setup? I want to ditch the stock airbox on my '92 Eco and am looking for a replacement. I also was thinking of installing an intercooler and a straight-thru exhaust (no cat). Thank you.
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It's a PRM air filter. More info about it on this thread from the old GTD forum:
http://www.hostboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=4037&t=291
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Thank you. Great information.
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Digging this one back up from the depths... :D Was browsing Bildon Motorsports site, and came across this: http://www.bildon.com/catalog/DetailsList.cfm?ID=056198451SP&Nav=6
So the thrust washer problem is solved- and at $40 a set, not too bad really when you know you are getting good stuff.
Brendan
84 Scirocco 8v
00 Camaro L36 M49
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VNT Rabbit update: it was down for a while due to another leaking headgasket. The original cause of the headgasket leak (before the VNT turbo was added...) apparently wasn't fixed.
We believe to have found the culprit: the head was improperly rebuilt. Although the deck measured perfectly flat, the cam bearings didn't So it was warped but someone tried to fix it by maching the deck flat. That's no good.
Since the head wasn't worth saving (it was naturally aspirated anyway...) It's now got a shiney, brand new aftermarket soid lifter head on it. It was amazing how fresh and shiney the aluminum was!
(http://www.imagestation.com/picture/sraid208/pd0767eddb041707423037a08d063a6dd/ee46c326.jpg)
Interestingly, check out how this head casting (not a genuine VW head, but still seemed very high quality...) has the extra "bulge" usually associated with the extra oil drain of a hydraulic head (This is a solid lifter head)
(http://www.imagestation.com/picture/sraid208/p0e4c0cabd285b79d70a31d8c1876b5df/ee46c254.jpg)
We used a 1.9lTD multi-layer steel headgasket. No more worries about excessive boost pressure on a cold motor now.
(http://www.imagestation.com/picture/sraid208/p6c1a466af63bc3d649dc3afd2902494b/ee46eeb3.jpg)
It seems to be running very strongly and reliably!
We also drilled some extra holes in the water jacket to further improve cooling system reliability. Details are posted in this thread:
http://vwdiesel.net/phpBB/viewtopic.php?t=4308
Another change made with the new head, was to try out a TDI cam profile. Subjectively, it seems to give a bit more low-end torque. It's running great (and good to have back running!)
Now... if I can just get my Rabbit GTD autocrosser back up and running...
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Nice work on the VNT project! I always wait for updates to see your next inovations. Where did you get the aftermarket cylinder head ? Is that one of the made in Spain cyl. heads? I haven't been able to find those anymore.
Thanx,
Pete
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is there a post anywhere that talks about how to use a 1.9 head gasket?
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Jake... that cylinder head sure does look nice. Any info/prices on the source for those? I just had a really bad day with my TD and will most likely be shopping for one.
I'd also be interested in the metal headgasket fitment.