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Thread: Reclaiming factory boost level

  1. #1
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    Reclaiming factory boost level

    Before and After



    When I fitted my intercooler I span the turbo compressor housing around and relocated the waste gate actuator.



    I've only been able to get 9 psi from the turbo, but the factory spec is 13 psi, so I decided to see what I could do about it.

    First thing was to fit an EGT gauge so I could see what was going on with the fueling.
    I got this one from the States for AU$159.87 including post.



    After advise from other members on here and other forums, I fitted the probe pre-turbo. I was impressed with how fast the gauge responds to the slightest touch of the throttle.



    My first road test with the EGT gauge and still at 9 psi boost, I reached a max of just over 600*C, so it didn't look like I could adjust the fuel too much at this stage. I know you can run hotter than that, but 600 is hot enough from what I have learned from others, so I left it for the time being.

    Next, I wanted to make sure the turbo was in fact capable of the factory figure of 13 psi before I started altering things. So I disconected the waste gate actuator so the waste gate would stay closed. I took it for a drive and found that the boost topped out at 15 psi. This was a good sign.
    So, I removed the actuator, cut a section out of the pushrod and fitted a threaded sleeve to make it adjustable. I just guessed and set the rod 10mm shorter than it was.





    The next road test resulted in 14.5 psi of boost (not a bad guess for the length of the pushrod ) The EGT had actually gone down to around 590*C. I'm guessing this is because of the increased amount of cooled air, but the same amount of fuel entering the cylinders. So, I decided to tweek the fuel a little with a quarter of a turn to start with.



    This brought the EGT back to around 600*C. Another quarter turn took the temp to a max of 635*C.

    The road tests were done in mild conditions, on a very steep, long hill on the highway. When I get around to it, I will re-test it with a heavy trailer on the back to really load it up, but that will do for now.

    I deffinately wasn't expecting a dramatic change in performance, but it deffinately has changed for the better with some power gain, and more importantly holds it's ground on the uphill suggesting an increased amount of torque.

    Cheers, Murray
    '88 County Isuzu 4Bd1 Turbo Intercooled, '96 Defender 130 CC VNT
    '85 Isuzu 120 Trayback, '72 SIIA SWB Diesel Soft Top
    '56 SI Ute Cab


  2. #2
    Bearman's Avatar
    Bearman is offline TopicToaster Gold Subscriber
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    Smile

    Great stuff Murray,
    I am thinking of upping my boost to about the same with the new motor. Have been running 9psi also up till now. Pyro temp is pretty silimar to yours at moment..Bearman

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    Quote Originally Posted by Bearman View Post
    Great stuff Murray,
    I am thinking of upping my boost to about the same with the new motor. Have been running 9psi also up till now. Pyro temp is pretty silimar to yours at moment..Bearman
    G'day Brian,
    Until now I've been reluctant to 'play' with the turbo, being such a fresh engine, and the fact that I've had very little first hand experience with turbos, and tuning aspects of diesels. But now I've had a bit of a tweek of things, I realise it's not too big a deal, as long as you're mindful of the vitals like EGT etc.
    I wouldn't/couldn't have done this myself if it wasn't for the advise and information I've gained from AULRO and it's members. Thanks to all here for contributing to bettering my knowledge, and I hope I've helped some of you out along the way too.

    Now, I'm off to do some more tweeking

    Cheers, Murray
    '88 County Isuzu 4Bd1 Turbo Intercooled, '96 Defender 130 CC VNT
    '85 Isuzu 120 Trayback, '72 SIIA SWB Diesel Soft Top
    '56 SI Ute Cab


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    good work, thats about how Id go setting it up...

    keep a`close eye on the condition of your oil and crankcase ventilation for a few weeks..
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
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    Quote Originally Posted by Blknight.aus View Post
    keep a`close eye on the condition of your oil and crankcase ventilation for a few weeks..
    Dave,
    What should I expect to see in regards to this ??

    Cheers
    '88 County Isuzu 4Bd1 Turbo Intercooled, '96 Defender 130 CC VNT
    '85 Isuzu 120 Trayback, '72 SIIA SWB Diesel Soft Top
    '56 SI Ute Cab


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    clean32 is offline AULRO Holiday Reward Points Winner!
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    you might pick up some extra diesel in the oil if you work it while its cold so watch for dilution and frothing.

    you might also pick up some extra blow by which will cause some oil useage by catching the spray from the piston head cooling jets and misting it out the breather.

    they are the main things but there also exists the remote posability of any carbon deposits on the pistons and rings coming off and mixing it up with the existing oil and the outside chance of (assuming your going to routinely use all the new power youve got) your current oil cooking if its old or not up to the spec for the raised temps that will turn up under the pistons.

    Id also be toying with the idea of after its had a chance to settle a little doing a float check on the turbo spindle.

    you shouldnt need it but an ounce of prevention beats a pound of cure.
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
    Tdi autoManual d1 (gave it to the Mupion)
    Archaeoptersix 1990 6x6 dual cab(This things staying)


    If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
    If you think you're in front on the deal, pay it forwards.

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    Quote Originally Posted by Blknight.aus View Post
    you shouldnt need it but an ounce of prevention beats a pound of cure.
    As my engine was fully rebuilt only 29k ago, I would hope there will be no issues with blowby and the like, but I will certainly keep an eye on things anyway.

    Cheers
    '88 County Isuzu 4Bd1 Turbo Intercooled, '96 Defender 130 CC VNT
    '85 Isuzu 120 Trayback, '72 SIIA SWB Diesel Soft Top
    '56 SI Ute Cab


  9. #9
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    I gave the fuel screw another quarter turn and took the County for the first proper drive since mucking around with things, 44 kms, into Geelong and back again.
    EGT was approx 300 at 60kph on the flat with light throttle, 350 at 75kph and 400 at 100kph. Max temp reached was approx 660 at 14.5psi of boost, flat out in 4th going uphill.
    The biggest difference I noticed was the extra power in the mid-range when already on boost. Put the foot down at say, 80 to 90kph just cruising with approx 7 to 9psi, and the boost immediately goes to maximum just nudging 15psi. Acceleration feels better than before. I'd describe it as enough of a difference to be satisfying without being a massive difference.
    It would be nice to have boost come on earlier in the lower rev range, but I guess that would be a case of a different turbo.....would I be right ?

    Murray
    '88 County Isuzu 4Bd1 Turbo Intercooled, '96 Defender 130 CC VNT
    '85 Isuzu 120 Trayback, '72 SIIA SWB Diesel Soft Top
    '56 SI Ute Cab


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    clean32 is offline AULRO Holiday Reward Points Winner!
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    Quote Originally Posted by rijidij View Post
    I gave the fuel screw another quarter turn and took the County for the first proper drive since mucking around with things, 44 kms, into Geelong and back again.
    EGT was approx 300 at 60kph on the flat with light throttle, 350 at 75kph and 400 at 100kph. Max temp reached was approx 660 at 14.5psi of boost, flat out in 4th going uphill.
    The biggest difference I noticed was the extra power in the mid-range when already on boost. Put the foot down at say, 80 to 90kph just cruising with approx 7 to 9psi, and the boost immediately goes to maximum just nudging 15psi. Acceleration feels better than before. I'd describe it as enough of a difference to be satisfying without being a massive difference.
    It would be nice to have boost come on earlier in the lower rev range, but I guess that would be a case of a different turbo.....would I be right ?

    Murray
    so your waste gate is still opening at 14.5 psi ?
    what size turbo do you have again ?

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