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Thread: TDI VNT Turbo Upgrade +++

  1. #41
    Join Date
    Jan 2010
    Location
    Melbourne
    Posts
    1,792
    Melbourne 《》Seymour
    2220kg at the weigh bridge
    Ambient temp 22c
    All recorded speeds true GPS

    Out of the weigh bridge the slip road leads straight onto the hill. This hill used to trouble 5th and I would often have to drop a gear to hold 110kph. 110kph in 4th uphill would get EGT up to 600 - 650c. I made the test harder this time by taking it on from a dead stop at the base of the hill. She accelerated up through the gears to 110kph in 4th, then shifted to 5th and didnt just hold, she continued to accelerate! I ended up cresting the hill a little faster than I expected. TDI VNT Turbo Upgrade +++

    Max EGT 540c , Max Boost 19psi

    Not once when cruising up and down the Hume today did I need to drop 5th. I would 'guess' that it can now accelerate in 5th from 100 to 130 up a slight incline. Where as before 5th needed the road to be dead flat and not too windy to get going.

    On the way back there is a steep and long 110kph climb with a truck cool off stop at the top. It crippled my D1 300tdi one time. I thought this hill would surely knock me out of 5th. On the steepest section she started to drop off 110kph, I prepared to shift down but at 106kph she bounced back and accelerated up the rest of the hill. Yes!

    Max EGT 575c, Max Boost 20PSI

    No smoke!

    So it seems she can take a bit more fuel and push on even harder. But I think I will leave it as is! Very happy with it.

    Take off speed through 1st and 2nd is still slugish. The gears are too tall. I tried adding more fuel pre-boost but the only noticable difference is black/grey smoke. So undid that. The 0 - 100kph would certainly not be impressive. It only really kicks off from around 40kph once its rolled over those 33s.

    Engine temp was steady 89 - 92 on the highway and the thermo fans didnt need to kick in. Not a hot day but already convinced the two side vents are helping to keep her cool.

    Took her off road for some low range work. She feels harder to stall. Thermo fans were kicking in a bit more often, perhaps due to all that extra low range boost.

    Exhaust noise is not noticable in the cab at highway speeds.

    Few things not done up tight:
    - loose header tank support bolt
    - loose alternator terminal
    - oil filter drip

    TDI VNT Turbo Upgrade +++















  2. #42
    Join Date
    Mar 2007
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    Living the dream!
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    Very nice!

  3. #43
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    Melbourne
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    Well thats this project done, near enough.

    I did plan to upgrade the brake discs to vented, bigger calipers and brake booster but the story so far has taken a while longer than expected - I just want to drive it now 🤩

    I figure the extra power will put some extra stress on the big end bearings, so whilst the dump pipe is off for ceramic coat I will drop the sump and renew them.

    Thats pretty much it for this thread.

    Cheers TDI VNT Turbo Upgrade +++

  4. #44
    Join Date
    Jan 1970
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    NSW far north coast
    Posts
    15,148
    Good thinking re the big ends, my last set in the Tdi only lasted about 80,000km

    Cylinder pressures were a little too high methinks....

    I never ran flex in my exhaust but from what Inc has said, it reduces a lot of harshness so it'd be a good thing to do.

  5. #45
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    Well I think Im done with power tweaking.

    Renewed the big end shells, rebuilt the oil pump whilst I was at it, got the dump pipe ceramic coated to match the manifold..... and then turned up the fuel!

    I knocked the anti-tamper collar off the max fuel screw and gave it one full turn. Idle screw adjusted back to 900rpm. Then smoke screw above boost diaphragm wound back three turns.

    Wow, what a difference!

    Boost now sits on 22psi in 5th

    So now I can accelerate off from 110kph in 5th up the steepest section on the Hume out of Broadford. I wont say how fast I was going but I could have seen 125kph rising up that hill before the egt alarm reigned it in. Thats pretty amazing for this old 90, considering the car in front held me up at 105kph right until the steepest section and I didnt need to downshift to get going when he moved out of the way.

    The gearing is so tall on this thing that I would see 180kph at 3797rpm in 5th if the motor could overcome the air resistance. How close could I get to that on the flat!? I dont know but 140kph would not be hard. 2 inch lift, 33 inch mud tyres and any speed over 130kph is not comfortable, so I may never know exactly where it tops out.

    EGT alarm was set at 680C and I can bring that on by selecting 5th, mashing the accelerator to the floor and holding it there for a while. Im fine with that, I am the HCU for this motor (equivalent of an ECU).

    With all that boost coming in early smoke is not an issue, but its hard not to put out a puff of black smoke when I launch on 1st. I may be able to improve that at the boost pin, failing that I will have to train my foot.

    How many kms before it explodes? I guess that has alot to do with the HCU. Place your bets!













  6. #46
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    Might I suggest you do the brakes as a priority, now!?
    -----
    You have the right to remain silent. Anything you say will be misquoted, then used against you.
    -----

    1999 Disco TD5 ("Bluey")
    1996 Disco 300 TDi ("Slo-Mo")
    1995 P38A 4.6 HSE ("The Limo")
    1966 No 5 Trailer (ARN 173 075) soon to be camper
    -----

  7. #47
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    I will get onto that for sure! Planning on puma spec vented fronts, larger calipers and brake booster.

    I shouldn't have said I am done with tuning and smoke is not an issue, that was just asking for a slap. I took it for another drive around town today and realised it is a bit offensive.

    Its not quite rolling coal, but when I take off the line with any decent amount of throttle I get around a 3 second dash of thick black smoke. The throttle position between smoke and no smoke is too fine for foot training. Its a shame because as soon as I get a decent amount of boost on, it burns really clean.

    The plan is to get the engine up to temperature and then do some off the line tests with the boost compensator disconnected and boost compensator screw wound all the way back out (maximum fuel restriction at zero boost):

    - If I'm still getting black smoke on take off I will have to reduce the max fuel delivery screw until I'm down to a haze.
    - If no black smoke, then its the boost compensator pre tension that needs to be increased.

    Almost there...

  8. #48
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    Disabled the boost compensator and the black smoke pattern was the same. So all the overfueling was happening before any movement of the compensator pin.

    The boost compensator pin had been rotated to apply the least fuel restriction possible. Effectively this gives some fuel restriction at zero boost and no restriction at full boost.

    I rotated it 180 to apply maximum fuel restriction at zero boost and some restriction at full boost. Result was zero smoke. Not a puff.

    So I settled for a position between the two that gives a slight haze of smoke off the line.

    It still drives great but I have lost some power/fuel at max boost.

    The solution it would seem, is to get a replacement boost pin. One that can go from maximum fuel restriction to zero.

  9. #49
    Join Date
    Jan 2010
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    Fitted a boost pin today. Off ebay, hardened stainless, shipped in from Poland.

    Pin was put in and nylon spacer removed for the full plunge effect. It now travels from full restriction all the way to zero restriction. So I can have the usual fuel on take off, and then way more on boost!

    Not done a proper drive, but a blip on the pedal in the rev range and she wants to launch!

    Still getting some black smoke on take off and now a bit of black smoke on boost too. So dialling back the max fuel screw a tad should even it all out for a clean run of power.

    Any one with a runway want to host a Aulro drag race? We could put it on youtube. Is there a comedy category in motor sport? Get a drone in, a chequered flag and some Top Gear style editing..... Billion views, surely!

  10. #50
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    Still tweaking, trying to burn as clean as possible.

    I'm not happy with the fuel delivery curve on boost, I am now a little under fuelled pre boost with a burp of smoke between 4-10psi, and plenty of air at 20+psi

    So its time to set the spring tension on the boost pin with a star wheel adjustment.

    But how to guage exactly how much tension to put on the spring, how many turns of the star wheel?

    Enter the MityVac!


    The mityvac should also help me diagnose a VNT overboost issue that recently popped up:
    VNT overboost


    I hooked up to the boost compensator feed at the turbo end


    Removed the boost pin and coated it in a thick antiseize paste, then manually pushed it all the way in to find the limit at full compression.

    Here is a pic that shows the mark left by the fuel restriction pin after the boost pin travelled its full range:


    Here is a pic of the pin travel when fed just 10psi


    Pictures not great, but 10psi was enough for full depression, near enough. I really need to up the spring tension!

    Another thing worth mentioning, the restriction pin would only mark up against the boost pin if the throttle was held on (engine off). There is a possibility that the IP needs fuel pressure for the restriction pin to push out against the boost pin all the way through the stroke. I should probably test again with engine on!

    Only had a wee bit of time today, so I have left it all set up to tune another day. I will try and set the spring tension for full depression at 20psi.

    TBC

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