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Thread: Duration Vs Rail Pressure Findings

  1. #1

    Duration Vs Rail Pressure Findings

    Alright, many of you know that I have been fighting some smoke at my high altitude for a while now. I have a pretty laggy turbo for this altitude and 50 hp injectors. People have always said just lower pulsewidth. Well, that works at the cost of losing all my power. So I have started lower PW to the point where power and smoke drop off, then upping the rail pressure in these areas. This seems to be working well so far. In addition people also said, advance timing in smoky areas. This does not work as the turbo cannot spool up worth a crap. So I have retarded timing in these areas slightly as well. So far so good on these results. I know there has not been much said about lowering PW and raining RP so I thought I would mention my findings.
    2004.5 Cummins.
    Borgwarner 13009097047 s300sxe 63-73 compressor 63/80 super core turbine housing 80mm .83 A/R Twin Scroll Housing,
    50HP BMS/Exergy Injectors
    BD T4 manifold,
    BD CAI,
    5" turbo back exhaust,
    turbosmart ext wastegate,
    BD lift pump with 2 mic filter and h2o separator,
    banks intercooler, Banks intake horn,
    slightly built tranny.......

  2. #2
    Advanced Tuner MAIDENCR's Avatar
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    Lower pulse and higher pressure help...atomization is better...lower timing before boost come up too....i use these 3 method in my tune
    03 cummins,175% flux injectors,dual cp3,s467.7/83 1.00
    Nv5600 with valair triple disc clutch

  3. #3
    Advanced Tuner JaegerWrenching's Avatar
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    I'd also assume most people who said "lower your PW" really meant you do it by raising rail pressure lol. I know they may not have made it seem that obvious. I view it like this, If you need X fuel to make X power like at idle or cruse well lowering fuel amount isn't doable because of the engine dying or not being able to actually cruise from power loss, so raising rail pressure is the only way to achieve your goal of same total fuel amount while having a shorter PW. BTW how many flashes do you guys have on a single ECU using HPT on your trucks? Any failed ones? or any bricked PCMs?

  4. #4
    Advanced Tuner MAIDENCR's Avatar
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    You can lower pulse without adding pressure...because for exemple if your engine need 800 us to do the work but the cell at thay rpm/mm3 is 1000us if you are on acceleration it will use the 1000us and will smoke...put the cell at 850us and will be able to do the work but with less smoke on acceleration

    I would nee to count my revision/test but 100 for sure
    03 cummins,175% flux injectors,dual cp3,s467.7/83 1.00
    Nv5600 with valair triple disc clutch

  5. #5
    Quote Originally Posted by JaegerWrenching View Post
    I'd also assume most people who said "lower your PW" really meant you do it by raising rail pressure lol. I know they may not have made it seem that obvious. I view it like this, If you need X fuel to make X power like at idle or cruse well lowering fuel amount isn't doable because of the engine dying or not being able to actually cruise from power loss, so raising rail pressure is the only way to achieve your goal of same total fuel amount while having a shorter PW. BTW how many flashes do you guys have on a single ECU using HPT on your trucks? Any failed ones? or any bricked PCMs?
    Easily over 100. I have had some failed tunes that get stuck in the middle ant its a bi*ch to get it back to working again. I think my failed tunes could be due to my batteries getting weak. It seems to be happy when I put a charge on them while I write the tune.
    2004.5 Cummins.
    Borgwarner 13009097047 s300sxe 63-73 compressor 63/80 super core turbine housing 80mm .83 A/R Twin Scroll Housing,
    50HP BMS/Exergy Injectors
    BD T4 manifold,
    BD CAI,
    5" turbo back exhaust,
    turbosmart ext wastegate,
    BD lift pump with 2 mic filter and h2o separator,
    banks intercooler, Banks intake horn,
    slightly built tranny.......

  6. #6
    Advanced Tuner MAIDENCR's Avatar
    Join Date
    Sep 2018
    Location
    Quebec,canada
    Posts
    207
    Noah i sent you a pvt message
    03 cummins,175% flux injectors,dual cp3,s467.7/83 1.00
    Nv5600 with valair triple disc clutch

  7. #7
    Potential Tuner
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    Nov 2021
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    I know this is a little old but what should i do on a 6.7 cummins to spool compounds the compounds are a gated s367 with a t6 s475/96/1.32?.

  8. #8
    Advanced Tuner JaegerWrenching's Avatar
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    How's the waste gate for the s367 setup? Does it bypass the s367 and feed into the s475? or bypass both? I'm assuming it bypasses the s367 into the s475. Since you have a non VGT primary you can help it by staying slightly more positive around cruse area 3-5ish BTD with timing lowering towards 0 degrees BTD as you tip in towards spool up keeping it around 0 until it lights the s367. This helps keep the truck peppy until you get enough RPM to have enough flow to actually light the s367. Because your primary is a non VGT you need exhaust flow to get it moving, and that requires some engine speed no matter what. But don't waste potential power with low timing until you need to like with tip in trying to light the turbo. There is no one tune fits all or one style fits all, play with it and see what works best for you. You could start at 7* heading towards 3* BTDC each truck and fuel setup is different. Also try upping fuel pressure some as timing drops towards spool up to help with smoke.
    Quote Originally Posted by cracummins View Post
    I know this is a little old but what should i do on a 6.7 cummins to spool compounds the compounds are a gated s367 with a t6 s475/96/1.32?.