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  1. Join Date
    Sep 2006
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    1,335
    #411
    Injecting diesel is a long process which starts before the engine piston is at top dead center (BTDC), continues during top dead center (TDC), and further goes on and ends after top dead center (ATDC). Injection timing is the precise crankshaft angle when injection starts. This is determined by the manufacturer as the optimal setting for their engine.

    It is normal to see an engine with an injection starting point of 20 deg BTDC, and an ending point of 40 deg ATDC, or a total injection duration of 60 degrees.

    Using the above as a reference, injection begins at 20 deg BTDC, and initial burn commences a few microseconds after. Initial burn is used to ignite main injection which occurs slightly past TDC, and ends at 40 deg ATDC. Main bulk of fuel comes in, and is used ATDC during the piston's downward power stroke.

    If timing is advanced to 25 deg BTDC, part of main injection will be coming in too early, and will ignite while piston is still on its upstroke. This condition forces the piston back, and applies heavy parasitic load on the engine. Noise and clatter is indicative of excessive combustion pressure and engine load.

    Advancing timing basically means that more fuel is injected during the compression stroke, and less fuel during the power stroke where it is most needed.

  2. Join Date
    Feb 2008
    Posts
    235
    #412
    Quote Originally Posted by Dieseldude View Post
    Injecting diesel is a long process which starts before the engine piston is at top dead center (BTDC), continues during top dead center (TDC), and further goes on and ends after top dead center (ATDC). Injection timing is the precise crankshaft angle when injection starts. This is determined by the manufacturer as the optimal setting for their engine.

    It is normal to see an engine with an injection starting point of 20 deg BTDC, and an ending point of 40 deg ATDC, or a total injection duration of 60 degrees.

    Using the above as a reference, injection begins at 20 deg BTDC, and initial burn commences a few microseconds after. Initial burn is used to ignite main injection which occurs slightly past TDC, and ends at 40 deg ATDC. Main bulk of fuel comes in, and is used ATDC during the piston's downward power stroke.

    If timing is advanced to 25 deg BTDC, part of main injection will be coming in too early, and will ignite while piston is still on its upstroke. This condition forces the piston back, and applies heavy parasitic load on the engine. Noise and clatter is indicative of excessive combustion pressure and engine load.

    Advancing timing basically means that more fuel is injected during the compression stroke, and less fuel during the power stroke where it is most needed.

    Sir Dieseldude,

    Ibig nyo po bang sabihin ay advancing the timing would not help the engine to perform better otherwise it would only add stress on the engine? Tama po ba pag kakaintindi Ko?

    * Sir 4JGtootsie

    Sir Mon anung klase po ung air filter na pinalit sa stock ng tup nyo? Nag try po kasi q minsan na gamitn ung sa akin ng walang filter ramdam q na ginhawa ung engine q at noticesable po ung pag ka bawas sa black smoke sa exhuast may be becaused the air can flow freely up to the combustion. so balak q din mag palit ng open type filter. May cons po ba pag ginawa q to?

    Thanks..

    Batosai
    Last edited by batosai; December 16th, 2008 at 12:19 PM. Reason: unfinshed typing

  3. Join Date
    Jan 2006
    Posts
    1,682
    #413
    Batosai,

    Hanap ka lang ng 45 degree tube 3" I have a picture sa Isuzu club just surf it.

  4. Join Date
    Jan 2006
    Posts
    56
    #414
    Thanks sir dieseldude. One last question what if sir your engine starts its injection * TDC just like the toyota 3C-T engine its said in the shop manual yung autodata that Injection timing is * 0deg TDC, correct me if I'm wrong, what if you would adjust it to 10Deg BTDC would there be any benefits from doing so?

  5. Join Date
    Jan 2006
    Posts
    2,105
    #415
    Sir DD, how about overboosting a diesel? like a 4d56T non vgt. if 4d56t max boost is 12psi. can you go over 13-14psi? since 12psi is barely achievable on uphill full load. while highways, It will never reach 12 psi. but for certain my 7psi on higway will be higher than it. therefore reaching 13-14psi would only occur very few times...
    Last edited by rion; December 16th, 2008 at 04:10 PM.

  6. Join Date
    Sep 2006
    Posts
    1,335
    #416
    Sir Dieseldude,

    Ibig nyo po bang sabihin ay advancing the timing would not help the engine to perform better otherwise it would only add stress on the engine? Tama po ba pag kakaintindi Ko?

    Hi Batosai,

    If present timing is on retard, advancing it to the correct timing angle will improve engine performance. But if present timing is already correct, advancing it further will only stress the engine.

    Before considering any timing change, we first have to know the present timing setting of the engine, or we will just be guessing.....

  7. Join Date
    Sep 2006
    Posts
    1,335
    #417
    Thanks sir dieseldude. One last question what if sir your engine starts its injection * TDC just like the toyota 3C-T engine its said in the shop manual yung autodata that Injection timing is * 0deg TDC, 0deg TDC is the required crankshaft position during pump intallation. This is not the starting point of injection. The Toyota shop manual and Autodata both mention of turning the pump's shaft, setting, and measuring plunger lift to a certain dimension during installation. This means that plunger has started to rise, injection has already started before TDC, and that the pump is now in the process of injecting fuel.

    correct me if I'm wrong, what if you would adjust it to 10Deg BTDC would there be any benefits from doing so? You don't have to as this pump's starting point of injection is somewhere before TDC. I don't know the actual crank angle though.

  8. Join Date
    Sep 2006
    Posts
    1,335
    #418
    Quote Originally Posted by rion View Post
    Sir DD, how about overboosting a diesel? like a 4d56T non vgt. if 4d56t max boost is 12psi. can you go over 13-14psi? since 12psi is barely achievable on uphill full load. while highways, It will never reach 12 psi. but for certain my 7psi on higway will be higher than it. therefore reaching 13-14psi would only occur very few times...
    Hi Rion....... Boost is a function of exhaust gas heat due to engine load. How do you intend to increase boost pressure? Many things can be done to increase boost, but this may not be good for the engine.....

    A dynamometer test would be the best way to measure and adjust boost pressure as load can be continuously applied to the engine. However boost pressure achieved on a dyno will be higher than if the car is driven at full load on a steep grade.

  9. Join Date
    Jan 2006
    Posts
    2,105
    #419
    I can increase boost by adding a pair of washer between the wastegate and turbo. later I intend to use a boost controller.

    can diesel engine take a 2psi additional pressure? could the gasket hold another 2psi? since it will hardly,barely reach there anyway on our driving habbit. information provided with the boost gauge.

  10. Join Date
    Sep 2006
    Posts
    1,335
    #420
    I can increase boost by adding a pair of washer between the wastegate and turbo. later I intend to use a boost controller. Use a manual hand pump or regulated air pressure. Start from any pressure below 12 psi, about 5 psi, and gradually increase pressure. When you see a 1 mm movement on the actuator rod, this means that the wastegate is now opening and bypassing exhaust gas. This will also be your maximum boost pressure if your system can attain it. Use shims to adjust.

    can diesel engine take a 2psi additional pressure? could the gasket hold another 2psi? since it will hardly,barely reach there anyway on our driving habbit. information provided with the boost gauge. Additional 2 psi is no problem for the engine as this is only air. Problem starts if fuel setting is increased.... high combution pressure, high exhaust temp, high engine load, smoke..... etc.

    Ingat lang.

Diesel Fuel Injection System Help Desk