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Increase hp for a diesel engine

  1. Jan 2, 2009 #1
    hey guys i rebuild diesel engines and i am a facing a very serious problem as i am required to increase a diesel engine hp by at least 20% without adding a turbo charger i tried changing the fuel pump but it only increase 5% which is not enough do you have any idea what i should do ????

    right now we are thinking about increasing the piston diameter , do you think this will work???

    the engine i am rebuilding is a 5 cylinders produced by deutz germany, and it should be 160hp and max rpm is 2500 r/m

    the problem is it achieved the maximum power which is 150hp at 1700 r/m and what is required is to achieve the maximum hp at the maximum speed which is 150 hp at 2500 rpm

    ps. it is a fully mechanical engine no electronics involved in it

    any ideas ??????????
    Last edited: Jan 3, 2009
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  3. Jan 2, 2009 #2

    Ranger Mike

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    i am proud owner of a DODGE 1 ton 3500 pick up..has Cummins..I added a chip from EDGE perofrmance..the truck had 505 Ft Lbs torque and 300 hp now it has 705 ft lbs of rip roaring torque and another 50 hp..no way will i ever go back..pure awesome brute strength..
    not all chips are equal,,i recommend the chip..hands down..
    also fuel mpg went dramatically up..even when hauling 30 ft trailer, formula car and golf cart to the track..

    chip costs $ 500.00 but best $$$$ i ever spent regarding towing..

    ps..when pulling the trailer up very steep hill on way to Mid Ohio Sports car roadcourse, i nailed the throttle..i smelled clutch ..literally spun the 13 inch diameter clutch while puling the load up hill..super tork
  4. Jan 3, 2009 #3


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    Ranger, a chip won't do anything for a mechanical engine. There's not even anywhere to put one!

    Sobhyasaad, more info please! (My usual response.)

    - What is the engine rated at? 160hp @ 2,500rpm? Or a different speed?
    - You tested the engine which gave 150hp at 1,700rpm? What did it produce at 2,500rpm?

    Developing ratings for a diesel engine is not easy work to do properly. Is this a new engine? Is it a one-off? Why do you need more power out of it? What's the application? Why are you reluctant to turbocharge? At higher speeds (2,500rpm) the power limitation is likely to be on air flow, not cylinder bore, but it's impossible to tell without engine test info and more details. Just blindly increasing the bore might cause you lots more problems, and not produce any more power.
  5. Jan 3, 2009 #4

    Ranger Mike

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    thanks..i just re-read the post..missed that line about electronics..
    there is no substitute for cubic inches..is cheapest way to more HP and torque
    boring and stroking will do it..you need new psitons anyway..if you stroke it, the wrist pin will be moved higher and you have to get custom pistons but change in stroke adds most cubes..and no addaional messing with timing etc..
  6. Jan 3, 2009 #5


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    Easy mistake to make these days, aren't electronics great!

    This is a common misconception, and only really holds true in a few cases these days. With the information given, there's a chance there's a good reason the engine isn't performing as it should. Even if it is, just increasing bore/stroke might do more harm than good. The breathing must always be considered first, and that's not even to mention geometrical issues (casting wall thicknesses, piston contact areas etc). If air flow is the limiting factor in this case, increasing bore/stroke could worsen volumetric efficiency, might affect in-cylinder turbulence and worsen fuel atomisation, or at the very least be an expensive and risky waste of money.

    A change in capacity will almost certainly require an ignition timing change for optimisation, and a valve timing change may also be beneficial.
  7. Jan 3, 2009 #6
    why not add a turbo ????
    or a supercharger

    I know you said no turbo

    better injectors to make use of the new fuel pump may help
    as well standard hot rod teck porting and gasket matching
    then new or reground cams and bigger valves

    but slapping a turbo on the puppy is far eazyer and cheaper
  8. Jan 3, 2009 #7


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    If the engine is not following it's published power curve, have you called the Deutz folks and asked them what is going on? 20 HP is nothing to sneeze at. You're not going to get there playing little tricks like fuel pumps and the like.
  9. Jan 4, 2009 #8

    Ranger Mike

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    only three things cause an engine Not to run..
    with IC..it is no gas, no spark or no spark at the correct time

    with diesel it is no diesel fuel
    no compression
    no fuel introduction at proper Top Dead Center piston position

    if you are pulling 150 hp way earlier than factory specs this tells me
    1. engine is basically in good shape ..has good compression other wise it would not make almost peak power
    2. valve timing event is off

    check cam shaft to crank shaft timing..a lot of times you can be way off by just lining up the marks on the cam shaft/crank shaft gears. for max output you need to use centerline method to find Top Dead center of crank and max lift of cam shaft with degree wheel
    do you have degree wheel? did you use above method..

    if not you may be off a tooth and installed cam to retarded...or too far advanced
    one other thing..was it an old cam or did you install a new bumpstick?

    this is where i would start...
    Last edited: Jan 4, 2009
  10. Jan 4, 2009 #9


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    Mike, I'm still trying to find out from the OP whether the rated speed is 2,500rpm; he only said that was the engines maximum speed.

    In any event, there's not much chance the a naturally aspirated engine could produce its intended rated power if the cam timing was out.
  11. Jan 5, 2009 #10
    dear friends thanks so much for caring here are some info for you this engine is applied for a winch, and and we are rebuilding for a customer of ours and he required no turbo charging or else it would be a very easy task to do !!!!

    here are some more info for you if the timing isn't correct the engine would not start from the beginning or maybe it will not have a rythem

    it says on the pallet that speed is 2500 rpm, and 160hp
    i do not is that is the maximum rpm only or the pallet is saying that the engine achieves 160hp at 2500 rpm but anyhow if anyone sees any hp curve you will notice that the max hp is at the max rpm, what goes up and down is the torque and the max torque wouldnt be necessarily at the max rpm what we have done is that we have measured the maximum torque which was 560 newton/meter at 1700 rpm and we have converted this into hp by multiplying torque X rpm / 7021 the problem is that we have tried the same experiment at the maximum speed which is 2500 rpm and we have only achieved 320 n/m
    which should mean that it is only about 117 hp really it is making me crazy how come this happens and the hp curve is always going up with the rpm any more ideas???
  12. Jan 5, 2009 #11


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    Firstly, like Fred said, have you been on to Deutz to find out what the engine should actually be producing?

    Secondly, (although I don't think this is the problem), just because the timing is out doesn't mean the engine won't run. There are many cases of engines starting just fine, not performing quite as they should, and the timing being out.

    Finally, a few more things to think about. Is the governor hitting the fuel limiter on the dyno? How old is the engine? What condition is it in? Have you conducted a compression test? What do the bores and valves look like? How about the valve gear? Have you checked the injection timing?
  13. Jan 5, 2009 #12
    the engine is fully rebuilt we only used the old block other wise everything else is new and yes we have conducted a compression test and it is 92% and more than that it would be only theoretical and not applied in real life as the engine when it is new the compression is somewhere between 95 and 90 % and under certain controlled conditions and no one is hitting the fuel limiter i think that all the adjusments would lie within the fuel pump what do you think ???
  14. Jan 5, 2009 #13
    and why a bigger bore wouldnt mean higher hp ??? bigger bore for the piston means more air and more fuel !!!! what do you think on that ????
  15. Jan 5, 2009 #14


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    Well if you're not hitting the fuel limiter when trying to pull full load, then either the calibration of the fuel system is to cock, you have a restriction on the breathing, your method for measuring power is suspect, or you're expecting too much.

    Have you been on to Deutz to find out what the engine should actually be producing?

    Bigger bore doesn't always mean more power; if power is being limited by breathing because of manifolds, cylinder heads, or exhaust or inlet systems, then you can't get enough air in anyway. Even if you could, you might not be able to get enough fuel in. Increasing bore size doesn't mean more fuel will be injected; this is a diesel engine so fuel isn't ingested with the charge air like a spark ignition engine.

    I'm not saying don't overbore the engine, I just strongly advise getting the facts straight first before spending lots of money and (potentially) not fixing the issue.
  16. Jan 23, 2009 #15
    What about milling off a bit of the block (or head) to increase the compression ratio? This should help you squeeze out a bit more power. Also, advancing the injecting timing could help as well. But i guess this would mean getting a different injection CAM, which could be tricky. Keep in mind that both these mods will likely increase NOx emissions as well, so if you also need to pass air-care this might be an issue. Tricky problem, good luck!
  17. Jan 24, 2009 #16

    Ranger Mike

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    do not up the squeeze
    will blow out cylinder walls
  18. Jan 25, 2009 #17


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    We still don't know whether there's a problem with the engine. If there is, and you try and uprate it further (without fixing a root cause), well that's a good way for "con rod exit stage left".
  19. Jan 25, 2009 #18
    I keep getting stuck on the question of why you are willing to go to the trouble and expence of boreing the cylinders and changing the pistons when a turbocharger will get you there cheaper and easier. And probably without needing to pull the engine out of the vehicle.
  20. Feb 1, 2010 #19
    hello guys,need some tips here...i got diesel engine(2.5 cc)....i already bolt it with garrett ar60 turbo,costum manifold,tial wasgate,evo 3 intercooler,rebuild the fuelpump(icluding toprom),2.5' piping.....now my car power really changing 100%(i liked it) but i want more power......can i get more usful tips? i really want to put piggyback on my car but sadly.....my car dont had computerbox now im focus with mechinical.....give me some tip plz....tq
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