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  1. #26
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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    It's possible the fuel limitation we're seeing with the piggyback is really a fuel tirms/IPW limitation. But some data casts doubt on that. The high fuel pressure and low fuel pressure drop at those levels. If we had a simple IPW limitation then I would expect fuel pressure to hold steady as the AFR started to tank.
    What I remember seeing, and I can double check it, is that the fuel pressure at the rail is virtually unchanged stock vs. 20psi with the cobb tune...seems like raising fuel pressure isn't being done much by the DME to meet AFR targets and it "seems" that the way it accomplishes most of its targeting is by varying IPW...when I get some time, or maybe even you can check that using your AP, what the rail pressure curve looks like on the stock simulation tune (stage0 I think they call it) vs. a stage2+...i'd think they're very close if not identical both rail and low pressure wise..low pressure actually i'm certain doesn't change as I've already logged/looked at it many times before while diagnosing misfires...

    I also ran a few maps where I asked Cobb to raise fuel pressure, max it out, just to see effects and while the fuel pressure was indeed maxed it didn't affect AFR targets as the DME just corrects for it...

    What I "think" is going on in terms of HPFP and LPFP pressure drop we see with piggies is that the pumps are just asked to work too hard, possibly at the edge of their capacity...HPFP raises demand on the LPFP, maybe even going beyond what the LPFP can supply causing IT to drop in pressure and then in turn causing HPFP pressure to drop x the multiplier...assumption though of course...approaching it differently and leaving HPFP pressure alone but changing the IPW "may" prove to extend the capacity a bit or a lot or not at all but that remains to be seen...maybe down the road we'll need to do both IPW changes as well as rail pressure changes...remains to be seen
    Last edited by dzenno@PTF; 10-19-2011 at 04:04 PM.
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  2. #27
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    Get on the dyno and lets see some dynojet AFR traces at 20psi / 500+rw with the Cobb mapping! Click here to enlarge

  3. #28
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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    Get on the dyno and lets see some dynojet AFR traces at 20psi / 500+rw with the Cobb mapping! Click here to enlarge
    LOL for sure...as soon as this map is worked out...i tried it last night and it was 20psi down to about 18psi at 6.2k rpm and then some throttle closure post 6.2k...it'd be way easier if they were with me to see wgdc on the car and tweak it but it is what it is i have to be patient, its raining out here anyway can't do any testing today and probably not even tomorrow either...as you know even the JB4 the standard wgdc we had to adjust a bit to fit the RBs wastegates in midrange and top end in order to have boost follow target more closely...

    60-130 is the first thing that'll be tested Click here to enlarge actually i'm down to testing 60-90mph now, no point winding it out to 130 if I can't beat the 60-90mph time first...best 60-90mph is 2.6sec (that was part of the 8.1 and 8.2sec 60-130mph runs)...need to at least match or beat 2.6 first then i'll hit the dyno Click here to enlarge
    Click here to enlarge

  4. #29
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    lol I'm thinking more about the AFR. Would impact longevity a bit but not so much performance, unless it was really lean.

  5. #30
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    AFR on the above mentioned 20psi map just goes to 12 immediately...no ifs or buts Click here to enlarge
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  6. #31
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    60-130 is the first thing that'll be tested actually i'm down to testing 60-90mph now, no point winding it out to 130 if I can't beat the 60-90mph time first...best 60-90mph is 2.6sec (that was part of the 8.1 and 8.2sec 60-130mph runs)...need to at least match or beat 2.6 first then i'll hit the dyno
    don't be so sure man. just because your torque stays consistent doesn't mean top end hp has been altered, even with the same boost pressure. i would wind it out if you have the road (no traffic/cops) and have the gas money Click here to enlarge at least a 60-110 (3rd's ending)
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  7. #32
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    AFR on the above mentioned 20psi map just goes to 12 immediately...no ifs or buts Click here to enlarge
    Any graphs you can show? Interested in seeing this sucker in action.
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  8. #33
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    Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
    don't be so sure man. just because your torque stays consistent doesn't mean top end hp has been altered, even with the same boost pressure. i would wind it out if you have the road (no traffic/cops) and have the gas money Click here to enlarge at least a 60-110 (3rd's ending)
    I was just saying that 60-90 is easier to do on an "airfield" if you know what i mean...if i see an improvement there of 0.1 there will certainly be an improvement overall but it doesn't mean that if there isn't an improvement there that a stronger 4th gear pull won't also mean there will be improvement Click here to enlarge

    you seem to love to push my car to the bleeding edge in the past while, what's up with that car of yours man? i want to see that ASR monster deliver after all this time damn it!

    Click here to enlarge Originally Posted by Irishace Click here to enlarge
    Any graphs you can show? Interested in seeing this sucker in action.
    I have some logs but its not worked out yet so I'd rather hold off posting until its working right...you know how it goes down on the forums lol
    Click here to enlarge

  9. #34
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    you seem to love to push my car to the bleeding edge in the past while, what's up with that car of yours man? i want to see that ASR monster deliver after all this time damn it!
    heh its true, i guess i have been asking you to push the envelope. but i don't mean to harm your car or put you in any danger (cops etc) i just want the best your car can deliver. and my car is back to normal after the belt fix, and you and me both! if the weather holds up (been raining nearly constantly in the past 3 days, flood watches and even a tornado watch, in $#@!ing Miami?!) i actually hope to dyno tomorrow with my buddy (owns a 2011 5.0) but it may not happen. it was also short notice for him. i wish i had a vbox or similar device to capture my times. it seems just so much easier to do some highway runs than dyno, could be just me. maybe i will hold back and save up for a vbox in the near future. cant let you RB guys have all the fun Click here to enlarge
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  10. #35
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    AFR on the above mentioned 20psi map just goes to 12 immediately...no ifs or buts Click here to enlarge
    Yeah I know... But dynojet trace or it didn't happen. Click here to enlarge

  11. #36
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    Hey guys, here's some new info posted on e90post by Mike@VAC Motorsports about the N54 internals, pistons specifically...adds even more to the mystery surrounding the N54 piston material Click here to enlarge
    Looks like there is no clear answer but I would venture to think that cast is correct...

  12. #37
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    I am gonna check my old pistons and see if they look inside as the one posted by Mike at VAC.
    07 335i AT - MOTIV 750 - MHD BMS E85 - BMS PI - JB4G5 - Okada Coils - NGK 5992 Plugs - Helix IC - Stett CP - Custom midpipes with 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - LUX H8 - Level 10 AT upgrade
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  13. #38
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    Click here to enlarge Originally Posted by enrita Click here to enlarge
    I am gonna check my old pistons and see if they look inside as the one posted by Mike at VAC.
    Now that is a good idea.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Looks like there is no clear answer but I would venture to think that cast is correct...
    Perhaps they're hypereutectic? They have their advantages in modern, high-specific output yet "clean" engines--as long as detonation resilience does not enter into the discussion...

  15. #40
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    Click here to enlarge Originally Posted by M1Fan Click here to enlarge
    Perhaps they're hypereutectic? They have their advantages in modern, high-specific output yet "clean" engines--as long as detonation resilience does not enter into the discussion...
    Never heard of hypereutectic.

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    3 out of 3 members liked this post. Yes Reputation No
    Here's but one primer: aych tee tee pee colon slash slash webpages.charter.net/beckracing/page11.htm (sorry, newbie here)

    They're cast, so you can get piston structures not possible with forgings and they have less thermal expansion, so you can run tighter tolerances. GM uses them in the supercharged LSA because they also offer lower NVH (which we CTS-V owners dutifully mod right back in...) than a forged part...

  17. #42
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    Click here to enlarge Originally Posted by M1Fan Click here to enlarge
    GM uses them in the supercharged LSA because they also offer lower NVH (which we CTS-V owners dutifully mod right back in...) than a forged part...
    If tighter tolerance was the better option than the forged pistons (which should also have tight tolerances?) why wouldn't the ZR-1 use the same setup? I'm guessing this is a cheaper option?

    Nice to learn new things.

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    1 out of 1 members liked this post. Yes Reputation No
    Yes indeed, less expensive. Also, NVH was less of a concern in the ZR1 and the LS9 is more of an "all-out" motor (well, as all-out as a motor with a 100,000 mile warranty can be). The LS9 has a higher rev limit than the LSA, so it also has lighter valvetrain components and titanium con rods. Oh, and a dry sump!

  19. #44
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    Click here to enlarge Originally Posted by M1Fan Click here to enlarge
    Yes indeed, less expensive. Also, NVH was less of a concern in the ZR1 and the LS9 is more of an "all-out" motor (well, as all-out as a motor with a 100,000 mile warranty can be). The LS9 has a higher rev limit than the LSA, so it also has lighter valvetrain components and titanium con rods. Oh, and a dry sump!
    All makes sense.

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    The block, and cylinder head is made from alluminum alloy (al 226). The crankshaft is forged steel, and the pistons are made by mahle, and are forged aluminum alloy.

    The N55 in contrast has a cast iron crank shaft.

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    Click here to enlarge Originally Posted by Turkeybaster115 Click here to enlarge
    The block, and cylinder head is made from alluminum alloy (al 226). The crankshaft is forged steel, and the pistons are made by mahle, and are forged aluminum alloy.

    The N55 in contrast has a cast iron crank shaft.
    Is the N55 crankshaft really cast iron?

    The new N20 crankshaft is forged.


  22. #47
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    Click here to enlarge Originally Posted by Turkeybaster115 Click here to enlarge
    The N55 in contrast has a cast iron crank shaft.
    I'd be surprised...are you sure?
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    I'd be surprised...are you sure?
    I doubt it very much, would be pretty shocking if that's the case.

  24. #49
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    The N54 piston pics terry posted in another thread were cast. If there were forged pistons it was only some and not all...

  25. #50
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    good point. maybe its true about the mid '07 switch-over.
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