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  1. #26
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    1 out of 1 members liked this post. Yes Reputation No
    3.0l I6 crank is roughly 50% longer than 4.0L V8 with equal bore spacing...at some point crank begins to look like a noodle...not saying it can't be made to rev high just you're running into issues worth looking at carefully.

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    You guys are rough. N54 owners should be happy that someone is pushing the limits and trying new things.

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I don't know what engine is in the car and I see no dynograph.

    Regardless, it isn't a guessing game to look at the architecture, rods, stroke, direct injection, etc., and say the motor was not built to rev. It IS a guessing game to write 9k arbitrarily on paper.

    You aren't going to hit 9k. You don't even need to hit 9k. People need to concentrate on addressing fueling issues at the current redline and there is more than enough turbocharger available to exceed the fuel system now let alone needing to rev it up more to get more power where the injection window and fuel requirements just become more difficult.
    Can you explain what about the n54s architecture, rods, stroke ect makes it not be able to rev high? I honestly do not know and am not being a smart ass. Just curious

  3. #28
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    Click here to enlarge Originally Posted by blaster3500 Click here to enlarge
    You guys are rough. N54 owners should be happy that someone is pushing the limits and trying new things.



    Can you explain what about the n54s architecture, rods, stroke ect makes it not be able to rev high? I honestly do not know and am not being a smart ass. Just curious

    It's always more beneficial to learn on your own, here is a great place to start. It's a honda article, but the information applies to all engines alike.


    If there's one truth about Honda enginesClick here to enlarge, it's that they like to scream. And Honda enthusiasts like to make them scream. The numbers on the tach reach so high, Honda practically offers the license: Go ahead. Make it sing. It's good at it. So long as you don't miss a shift, all is bliss.
    Lightweight components, stronger materials and shorter strokes enable modern four-cylinder engines to spin very fast, yet last longer than ever. A tremendous amount of science goes into engineering and creating these high-spinning machines, most of it rooted in elementary principles of physics and geometry-fundamentals anyone planning to build an engineClick here to enlarge should know.
    Understanding rod/stroke ratio, or the amount that a rod deviates from an imaginary straight line extending from the center of the crank journal to the center of the piston, is key to knowing how these machines deliver power at high rpm.
    Determining the Rod/Stroke Ratio
    To determine a motor's rod/stroke ratio, divide rod length (distance in millimeters from the center of the big and small ends) by stroke. A B18C1, for example, combines 138mm rods with an 87.2mm stroke for a 1.58:1 ratio.
    Most engine builders shoot for a ratio between 1.5:1 and 1.8:1 on a street motor, with 1.75:1 considered ideal, regardless of application. (The most highly developed four-stroke engines in the world-F1 and motorcycle engines-have rod ratios of more than 2:1.)
    The rod/stroke ratio affects several engine dynamics, including piston speed and acceleration, piston dwell at top dead center and bottom dead center, piston side loads, cylinder loading and bearing loads. Many of these elements play roles in engine aspiration, combustion and wear.
    Generally, a lower ratio means a high rod angle, creating greater potential for accelerated wear to cylinder walls, pistons and rings. A low enough ratio, due to the severity of its rod angle, can drive a piston right into the cylinder wall.
    Higher ratio engines, on the other hand, don't have the same friction concerns, but compromise in other areas. Air does not fill the intake ports with the same velocity, and there is less demand for the ports to flow as well since there is more time to fill and scavenge the cylinder (we discuss this phenomenon later). This typically means stagnant airflow at low revs and weaker torque. Hey, you can't have it all.
    Lower Ratios-A Honda Characteristic
    As the chart on this page indicates, many Honda ratios-designed for economy-fall on the low side. Honda produces compactClick here to enlarge, short four-cylinder engine blocks that don't require long rods. Most Honda blocks also feature a small bore. When coupled with a short stroke, the rod angle is still harsh, though not as bad as if the piston were larger in diameter.
    Some tuners take the geometry into their own hands with longer rods. A longer rod makes more torque with the same piston force, and since it's less angular than a shorter rod, reduces sidewall loading and decreases friction. All of this adds up to more power.
    Click here to enlarge

    Longer rods also give the pistons more "dwell," the brief periods of time the piston is at top dead center and bottom dead center. A longer dwell allows for better flow of intake and exhaust gases since the piston moves slower between up- and downstrokes.
    Longer dwell also offers more time to fill the cylinders during the intake stroke and more time to scavenge during overlap. And since the piston hangs out at or near TDC longer, the combustion stroke has more time to deliver a thorough release of energy on to the piston.
    In a stroked motor, the piston ultimately reaches greater speeds to cover the additional stroke. The speed makes intake, compression and exhaust strokes more turbulent and, consequently, more powerful. It also comes with its price in component wear, something to consider when looking into parts that increase stroke.
    With a short stroke and a long rod, however, the piston accelerates more gently from TDC. It picks up its greatest speed further down the bore, at the point where the crank pin relative to the rod angle reaches 90 degrees. Since the pistons move from TDC slower, the entire bottom end absorbs less mechanical stress.
    Advancing Toward A Thin Line
    Even the short-stroke/long-rod combo has its limits. To accommodate extra rod length, some builders will move the piston pin higher into the slug, or opt for a deck plate. Either method requires an experienced wrench with access to a lot of custom parts.
    Longer rods in a stroked motor can act to offset any increase in rod angle, but also requires a shorter piston. The deeper you dig into a piston to shorten it, the greater your odds of cutting into the oil ring groove and wreaking havoc with oil consumption. Most piston companies in the sport compact market engineer pistons with tighter ring packs and bridge rings to help avoid this problem.
    Regardless of whether you take the stroker route or just run longer rods, you reach a point where you can no longer shorten a piston any further without compromising dependability.
    Friendly Advice
    Most engine builders believe longer rods are better, but a fringe of enthusiasts still dig the low-rpm torque that shorter rods can make. We advise builders who want a ratio of less than 1.6:1 to use the strongest aftermarket rods they can find, given the angle. We also recommend aftermarket sleeves to better fend off the lateral stress created by the rod angle.
    Here's one last nugget to impress your friends with: a formula for calculating piston speed in feet or meters per second. The equation illustrates the point that the longer the stroke, the faster the piston travels at the same rpm.
    Take a B16A2 vs. an H23. At 7000 rpm, the B16 slug moves 18 m/sec. At the same rpm, the H23 piston hauls additional ass-22 m/sec. Simply multiply stroke by rpm, and voil-minutes of endless doodling in class.
    2011 E90 M3 \ Melbourne Rot Metallic

    Click here to enlarge

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    I will read up on it thanks lulz

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    2 out of 2 members liked this post. Yes Reputation No
    Just to add to the above, the issue with a long crankshaft harmoincs on I6 engines is simple. One commonly hears about how smooth I6 design is, and that is true for 1st and second vibration modes in the radial plane (up down side side), perfectly balanced. However the stresses and modes in the torsional (twisting) direction are still there and every engine has them, and must be damped. They just happen to be worse in a long crank engine. N54 like others comes with a tuned harmonic balancer to damp the targeted modes, up to designed rev limit and a little beyond. BTW the dual mass flywheel is part of this damping system. I see people take that off for SMFW's and also use underdrive crank pulleys, removing ALL damping from a long crankshaft...yikes. Flywheel is less of a concern as a damper as when clutch is engaged the rest of the driveline adds damping. But the crank pulley end is free. The point here is you need to make sure when you exceed the designed RPMs, there are no undamped harmonics lying around where you're planning to go. And when I did some simpleton calcs long time ago there were some, real close.

    The DI window is also simple. DI sprays fuel directly into the combustion chamber, so if you think about it, it can only do that for a very short period, much shorter than port injection which can pretty much spray fuel whenever. So you have much shorter period of time to get ALL the fuel in, so you need much higher pressure (And other things, atomization etc.)

    Anyway this means as RPM's go up, time window shrinks to spray fuel. HPFP is already pooping out at stock redline on higher HP applications, will become even harder at 9k or whatever.

  6. #31
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    Click here to enlarge Originally Posted by ajsalida Click here to enlarge
    Just to add to the above, the issue with a long crankshaft harmoincs on I6 engines is simple. One commonly hears about how smooth I6 design is, and that is true for 1st and second vibration modes in the radial plane (up down side side), perfectly balanced. However the stresses and modes in the torsional (twisting) direction are still there and every engine has them, and must be damped. They just happen to be worse in a long crank engine. N54 like others comes with a tuned harmonic balancer to damp the targeted modes, up to designed rev limit and a little beyond. BTW the dual mass flywheel is part of this damping system. I see people take that off for SMFW's and also use underdrive crank pulleys, removing ALL damping from a long crankshaft...yikes. Flywheel is less of a concern as a damper as when clutch is engaged the rest of the driveline adds damping. Bot the crank pulley end is free.

    The DI window is also simple. DI sprays fuel directly into the combustion chamber, so if you think about it, it can only do that for a very short period, much shorter than port injection which can pretty much spray fuel whenever. So you have much shorter period of time to get ALL the fuel in, so you need much higher pressure (And other things, atomization etc.)

    Anyway this means as RPM's go up, time window shrinks to spray fuel. HPFP is already pooping out at stock redline on higher HP applications, will become even harder at 9k or whatever.
    Good post - the primary and secondary order harmonics are of course the "worst", and as you said they are cancelled out due to it's inherent design. I didn't know that they had other balancers in there, but what you say makes sense... Cool stuff.

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    Click here to enlarge Originally Posted by inlineS54B32 Click here to enlarge
    Good post - the primary and secondary order harmonics are of course the "worst", and as you said they are cancelled out due to it's inherent design. I didn't know that they had other balancers in there, but what you say makes sense... Cool stuff.
    Well, let me be 100% accurate. Every engine I've ever pulled a crank pulley off of had a harmonic balancer of some sort as a crank pulley. I have not pulled one off an N54, hope to never need to. They are heavy and usually have alternating metal/bonded rubber layers. They are tuned via weight of the metal and thickness of the rubber (a simple tuned spring-mass damper system). People take them off for lightweight pulleys generally because they slept through the engineering classes that talked about undamped resonances.

    edit: also bad things happen to high tech valve trains that run off the crank when you remove the damper, or get into resonance, even if you don't snap a crank.

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    Click here to enlarge Originally Posted by ajsalida Click here to enlarge
    Well, let me be 100% accurate. Every engine I've ever pulled a crank pulley off of had a harmonic balancer of some sort as a crank pulley. I have not pulled one off an N54, hope to never need to. They are heavy and usually have alternating metal/bonded rubber layers. They are tuned via weight of the metal and thickness of the rubber (a simple tuned spring-mass damper system). People take them off for lightweight pulleys generally because they slept through the engineering classes that talked about undamped resonances.
    LOL - yeah, I have heard both negative and positive for dropping OEM dual-mass flywheels/pulleys/etc. and throwing on something lightweight. You get the the better response + more torque via less rotating mass, but have also heard it can cause issues with harmonics like you mention above. I have only worked with small 2-strokes, and all my knowledge on the subject comes from books/forums/people like you - so glad to hear you have this stuff to share. Comp sci for me, no engineering degree. Click here to enlarge

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    Click here to enlarge Originally Posted by ajsalida Click here to enlarge
    Some reason the boards went down as I was editing above post. Anyway long time ago was surprised to find torsional issues on I6 engines of 3.0l or so begin to crop up around 8k RPM according to back of the envelope calc. Point is it is worth paying attention to may be an expensive experiment to crank it up beyond 8k under large loads.

    The other thing is fuel window on DI engines is very narrow already, main reason we need huge PSI is to get all the fuel into the CC after the intake valves closes but prior to spark. That much worse @ 9k other issues aside.
    IIRC (it's on the site) - someone once mentioned that the ECU wasn't up to the task for high RPM use. I forget exactly what it was, but it wasn't the mechanical/physical limitations of the DI, it was more on the soft(hard)ware side of things. I will see if I can find it.

  10. #35
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    Click here to enlarge Originally Posted by inlineS54B32 Click here to enlarge
    LOL - yeah, I have heard both negative and positive for dropping OEM dual-mass flywheels/pulleys/etc. and throwing on something lightweight. You get the the better response + more torque via less rotating mass, but have also heard it can cause issues with harmonics like you mention above. I have only worked with small 2-strokes, and all my knowledge on the subject comes from books/forums/people like you - so glad to hear you have this stuff to share. Comp sci for me, no engineering degree. Click here to enlarge
    No engineering degree here either, applied math, but spent my whole professional life doing engineering for some reason. I once put a lightweight pulley on my E36 M3. Will never do that again. Didn't break anything but it sure did not like running up to redline as much. Read up on it and took it off immediately.

    FYI the basic reference for anything in this area are CF Taylor's books, worth every penny:

    http://www.amazon.com/Internal-Combu.../dp/0262700263

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    Click here to enlarge Originally Posted by inlineS54B32 Click here to enlarge
    IIRC (it's on the site) - someone once mentioned that the ECU wasn't up to the task for high RPM use. I forget exactly what it was, but it wasn't the mechanical/physical limitations of the DI, it was more on the soft(hard)ware side of things. I will see if I can find it.
    Well that would be another limitation, my point was it gets harder and harder to push the needed amount of fuel through a shorter and shorter window. There may even be clock speed limitations on sample rates etc as you say, in the code/electronics.

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    Click here to enlarge Originally Posted by ajsalida Click here to enlarge
    FYI the basic reference for anything in this area are CF Taylor's books, worth every penny:

    http://www.amazon.com/Internal-Combu.../dp/0262700263
    Added to cart on Amazon - thanks for the recommendation.

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    1 out of 1 members liked this post. Yes Reputation No
    No problem. FYI there are 2 volumes...Haven't looked into the I6 harmonics issue for a while, but clearly others have, eg:

    http://www.vacmotorsports.com/catalo...per-by-ati.htm

    no affiliation just popped up on first Google search

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    Click here to enlarge Originally Posted by BTMFR Click here to enlarge
    Again i know the risks of revving high and i know that the n54 isnt the best platform to try to rev high but there are plenty of other motors out there that do with the same issues the n54 has. Will the n54 be ok no one knows so i will at least give it a shot if it blows up i rebuild..
    Any open decks? Also, would be cool if we could compare cylinder wall thickness to some other motors. I think one of the biggest concerns for the N54 will be piston velocity. You don't plan on longer rods for the build do you? I think you'll need shorter rods to have any chance of revving past 8krpm. I'll be honest, I am no expert here, and just trying to learn and ask questions along the way. I think why so many have red flags throwing your way is because we are all wondering what type of specs changes you have planned for the motor re-build. I personally think it's awesome to see what you're doing, whether I think it will happen or not, you absolutely have my full support. Lets see what this thing can do.

    That video VAC made about the N54 on the engine dyno; when I first saw it I was hoping to open it up and see them revving it to something well above 7500rpm, was pretty disappointed when they only took it to like 6500...weak sauce...but I do remember how quickly it heated up at even 6500rpm. I dunno, I just thought of that.
    2009 335i coupe back to stock...for now

    Click here to enlarge

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    Click here to enlarge Originally Posted by ajsalida Click here to enlarge
    No problem. FYI there are 2 volumes...Haven't looked into the I6 harmonics issue for a while, but clearly others have, eg:

    http://www.vacmotorsports.com/catalo...per-by-ati.htm

    no affiliation just popped up on first Google search
    I'd recommend anything written by John Heywood. He's the most brilliant person I know when it comes to modern mechanical engineering, even dissertations written by his students are great reads when he has his hand in them.

    Click here to enlarge Originally Posted by ajsalida Click here to enlarge
    Sure would be nice if somebody made a higher flow DI injector, if that in fact is a bottleneck.
    I recon it will most definitely be a bottleneck for E85+lots of power+9,000 RPM

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    I've been reading a little and some GDI systems not only can inject past intake phase over into combustion phase, but AFTER initial combustion has taken place (whoa). Multiple injector pulses IOW. Needless to say some serious fuel pressure needed there. I have no idea what the N54 does in reality as far as pulse duration, number, or timing, obviously less than 2 full phases and more than 1 duration wise.

    Also reading some common rail DI diesels run up to 44k PSI! Had no idea tech has moved this far.
    Last edited by ajsalida; 01-13-2014 at 07:47 PM.

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    no, you were talking about what it's 'designed' to do. Ignoring the pure RPM discussion. YOu can make things do things the designers never even dreamed of, it just takes a) money and b) talent... I don't really have enough of either in this, so i'm not going to be a person owning a 9k RPM N54 any time soon lol.
    Ok go do that. You can turn the pyramids into octagons too.

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    i have actually mentioned rod:stroke and stroke, which implies piston speed as a concern. The stroke isn't super long, and the R:S while not optimal, isn't terrible, and can easily be increased into the 1.6x range... which alleviates the piston angle issue.
    It alleviates them does it? On paper everything is alleviated.

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    Yes it (your S65) was designed for revs, but it wasn't designed for boost.. same thing.. the N54 is the opposite.. you have to do the same amount of work either way to achieve what you want. just think about it for a second.. in one you have to overcome a design not built for boost (high comp, light weight all the things, not the strongest block material.. other inherent issues... not to mention the DCT designed for quick shifts not bulk torque).. and the other you have to overcome a design built for a moderate 'sporty' car (rod length, piston speeds, direct injection supply/fuelling.. and potentially/likely also block strength) both of these issues take time, design and money... both can be fixed.
    A motor that comes boosted versus a motor designed to rev is not the same thing whatsoever. That does not even make any sense. BMW themselves has taken motors not designed for boost in their cars and boosted them. Why would that be an issue?

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    the 'king of power' japanese motors were never designed for what they can now do (some packages are built for regular 12k RPm abuse... do you really think when the engineers built their 7k rpm.. then 8k rpm, for RB.. motors, that spinning to 12k rpm in built billet stroker kits was a concern? absolutely not.
    RB motors were some of the highest revving inline-6 out there. The reason they didn't make them big displacement is so that the camshafts would not be too long resulting in vibration at high rpm. You clearly aren't even aware of how the motors were designed or what is involved in getting an inline-6 to rev high as there are several areas that need to be addressed.

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    do you constantly $#@! all over the N54 just so everyone takes it as a challenge?.. seriously. say.. people who like putting LS*s into cars that have no business accepting them, and are going to have nothing but chassis flex until they tear in half... is it a good idea? ehhh.. is it cost effective? hah. is it safe? LOL.. is it $#@!ing awesome? is the sky blue?
    I constantly need to address ridiculous pipe dreams. The next thing we know you'll be typing 'oh the N54 can rev to 10k and make 1500 wheel horsepower because some supra did it." It's absurd daydreaming and not within the realm of possibility.

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    again, there's no reason it can't hit stupid revs.. whether it's a good idea or not is irrelevant, it just takes enough money.
    There are plenty of reasons why it can't and although I love your blind optimism there's a reason an S65 has already done it right off the showroom floor and the N54 hasn't.

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    Click here to enlarge Originally Posted by ajsalida Click here to enlarge
    3.0l I6 crank is roughly 50% longer than 4.0L V8 with equal bore spacing...at some point crank begins to look like a noodle...not saying it can't be made to rev high just you're running into issues worth looking at carefully.
    You also have to worry about the cams.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    You also have to worry about the cams.
    Yeah good point forgot about those big old long cams.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Ok go do that. You can turn the pyramids into octagons too.
    now you're just being stupid

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    It alleviates them does it? On paper everything is alleviated.
    yes, because physics.

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    A motor that comes boosted versus a motor designed to rev is not the same thing whatsoever. That does not even make any sense. BMW themselves has taken motors not designed for boost in their cars and boosted them. Why would that be an issue?
    it's exactly the same damn thing.

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    RB motors were some of the highest revving inline-6 out there. The reason they didn't make them big displacement is so that the camshafts would not be too long resulting in vibration at high rpm. You clearly aren't even aware of how the motors were designed or what is involved in getting an inline-6 to rev high as there are several areas that need to be addressed.
    firstly, R32's redline was at 7500, later were 8000.. and pretty much because of their super short stroke.. they're not low displacement due to length, they're low displacement because of their 73.7mm stroke... their bore is pretty normal at 86mm. Where are you getting this info from? lol... claiming that *I* am the one who doesn't know how they were designed...

    And even with a 3.2 stroker they can rev to the moon... yes, because of the added bracing/reinforcement and everything being forged or billet etc. it will rev higher than our N54's ever can, but my point is, doing things they were never designed to do through modification, not 'hurr durr N54 can do this because the RB32 can'.

    i'm aware there are several areas, and i've certainly mentioned more than one...

    now, more what i was talking about are built RB30/32 motors, where incredible amounts of work have to be done to get them to not be a stump puller, yet they can still rev well past 10k. They literally vibrate themselves to pieces after 6500rpm stock (RB30)... a 6500RPM factory motor that can be modified to 12k RPM. that's an even worse case than the n54's! just with a $#@!load of time and money spent improving it to it's peak.

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I constantly need to address ridiculous pipe dreams. The next thing we know you'll be typing 'oh the N54 can rev to 10k and make 1500 wheel horsepower because some supra did it." It's absurd daydreaming and not within the realm of possibility.
    except these daydreams still aren't quite on that level lol. if someone wanted to custom machine everything ever and make a 10k rpm 1500whp n54.. well the only concern i'd have is that it's hardly an N54 in anything other than spirit lol. I see no reason why you couldn't make a billet closed block/head combo in the same basic 'design' as the N54, with some big port injection, a ridiculous turbo, and call it a 1500whp 10kRPM N54.. Sure, it's not what we're talking about (modifying existing motors beyond what was intended) but it counts.

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    There are plenty of reasons why it can't and although I love your blind optimism there's a reason an S65 has already done it right off the showroom floor and the N54 hasn't.
    My optimism isn't blind.. i'm right here doing numbers that are telling me the N54's direct injectors can't make the power anyone wants, let alone enough to cause real issues with anything strength wise.

    I'm 110% aware that the N54 can't do everything perfectly right off the bat.. parts need to be changed/modified/replaced/upgraded, much work to be done.. but saying 'hurrdurr it can't do this because it wasn't designed from factory' is idiocy.

    you're just an S motor fanboy, plain and simple.

    the reason is it was designed to. they could have made the S65 to only rev to 7500rpm, and were we to have this discussion based around that.. the answer would still be 'you can do almost whatever the hell you want if you can redesign it enough'... saying you can't reasonably increase the N54's rev limit is like saying it for any motor. No i don't think the N54 will ever hit 1500whp without shattering (or at least closing the deck, if ever possible and it even adds strength).. no i don't think the N54 will ever hit 9k RPM safe for everyday use, without incredible amounts of modification... but 1000whp would be nice (fuelling aside) as would 8000rpm. i think they're realistic goals.

    name me one petrol motor that you can't increase the redline at least moderately.
    Last edited by Flinchy; 01-13-2014 at 09:13 PM.
    boop

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    now you're just being stupid
    But it can be done. I'm sure someone could turn the pyramids into octagons. How dare you say it can't be done just because nobody has tried.

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    yes, because physics.
    Then you show know how idiotic it is to argue in favor of trying to make an N54 do what physics tells you it was not designed to do.

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    it's exactly the same damn thing.
    LOL ok so trying to make a low motor rev into a high rev motor is the same thing as adding boost to a naturally aspirated motor. One of these requires redesigning the architecture of the engine and the other does not. So the S2000 because it was naturally aspirated when it gets boost and revs to 9k rpm without any internal changes is the same as taking the engine in the CRV and making it rev to 9k? What?

    Good naturally aspirated motors are great candidates for boost because they usually have strong internals, good flowing heads, and don't require as much boost pressure to hit the same hp figures.

    You're out of your element.

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    firstly, R32's redline was at 7500, later were 8000.. and pretty much because of their super short stroke.. they're not low displacement due to length, they're low displacement because of their 73.7mm stroke... their bore is pretty normal at 86mm. Where are you getting this info from? lol... claiming that *I* am the one who doesn't know how they were designed...
    Holy crap man do you have any idea how impressive an 8k rpm redline from the factory is for a turbocharged inline-6? Especially considering Nissan was doing that what, almost two decades ago? Even the S55 in the upcoming M3 isn't matching that.

    The stroke is part of it (check the S65's stroke btw, thanks) but if you have a large inline-6 it is going to be fairly long and that means if you rev very high you will run into camshaft vibration due to the length of the cams in an inline-6. You will be able to get a V8 to rev higher than inline-6 simply due to the architecture which you can't change because physics yo.

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    except these daydreams still aren't quite on that level lol. if someone wanted to custom machine everything ever and make a 10k rpm 1500whp n54.. well the only concern i'd have is that it's hardly an N54 in anything other than spirit lol. I see no reason why you couldn't make a billet closed block/head combo in the same basic 'design' as the N54, with some big port injection, a ridiculous turbo, and call it a 1500whp 10kRPM N54.. Sure, it's not what we're talking about (modifying existing motors beyond what was intended) but it counts.
    You're daydreaming. That's all you're doing. You're blindly grasping at straws 'hoping' someone does this or that or that it is 'possible' to do.

    Sure some billionaire could also buy BMW, tell them to cease production on everything, hire the best engineers in the world, and tell them their sole purpose is the hit the highest possible rpm they can on the N54. Sure, it's possible and all.

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    you're just an S motor fanboy, plain and simple.
    Considering it's a better motor no kidding. ECU flash to raise the redline and the factory S65 can hit 9k all day. For the N54 to do the same you need a team of engineers to turn it into something it was never designed to be. Stop trying to make it something it isn't and accept what it is.

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    the reason is it was designed to. they could have made the S65 to only rev to 7500rpm, and were we to have this discussion based around that.. the answer would still be 'you can do almost whatever the hell you want if you can redesign it enough'... saying you can't reasonably increase the N54's rev limit is like saying it for any motor. No i don't think the N54 will ever hit 1500whp without shattering (or at least closing the deck, if ever possible and it even adds strength).. no i don't think the N54 will ever hit 9k RPM safe for everyday use, without incredible amounts of modification... but 1000whp would be nice (fuelling aside) as would 8000rpm. i think they're realistic goals.
    Nobody said you can't increase the rev limit. What I'm saying is picking a number like 9k arbitrarily and stating it's 'possible' to hit is idiotic. It makes far more sense to try to address the fuel where it's already revving to and enjoy the turbo options coming to market rather than trying to re-engineer the entire motor and its valvetrain. Fortunately with an S65, S54, S62, S85, S14, you don't need to do that now do you?

    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    name me one petrol motor that you can't increase the redline at least moderately.
    Name me the post where this was the discussion.

    THE N54 WASN'T DESIGNED TO REV HIGH. Get over it, move on, S motors win for revs and always will. Even BMW changed the damn design for the higher redline of the S55.

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    Click here to enlarge Originally Posted by alex@ABRhouston Click here to enlarge
    fixed it for ya Click here to enlarge
    Ha ha valve train noodles

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    http://www.conti-online.com/www/down...cts_pdf_en.pdf

    for basic specs.. page 25 i think.

    i had a look at other DI platforms like VAG stuff, and they hit similar issues.. but they had the ability to find/modify even higher flowing injectors... >_<... and easily port inject.

    pulse... well 14.5mg/s +-10% @ 0.4MS, but seems like it can flow for a very wide pulse, with 35g/s static flow rate (so roughly the same as the pulse rate... must vary due to heat or something) and 40mg/ms @ 200bar, .. other specs like open/close time and useful things in that thing, and on the thread on n54tech

    >1 and <2 strokes sounds reasonable for injection window to me. I think they have the ability to run fully stratified (cruising etc.), but don't from factory or with any really simple modification.

    and yes, the diesels could probably literally blow a hole through the hood hahaha

    if it's all true and the injectors really will limit.. well short of a miracle injector flow rate upgrade, my hopes are sadly back in supplementary injection like other platforms (as far as i can tell, the VAG stuff does it with their FSI motors)
    Good comments here, has me wondering if one way around limitations on existing N54 fueling if they are ever found is to try to exploit some of this more exotic injector pulse timing. Assuming it has not already been done as part of basic OEM (which I doubt or we'd have heard by now). For example run multiple pulses across/during intake thru combustion cycle after spark, maybe with higher pressures. Pretty wild stuff, to me at least, who grew up on carbs and thought they were mysterious.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    But it can be done. I'm sure someone could turn the pyramids into octagons. How dare you say it can't be done just because nobody has tried.
    Because an octagon is a 2 dimensional shape and a pyramid is 3 dimensional
    If you mean octagonal prism or 8 sided die.. well buildings have already been deigned as such, so if we disregard the whole enraging the world… absolutely it’s physically possible were some mad billionaire genius to want to do it.


    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Then you show know how idiotic it is to argue in favor of trying to make an N54 do what physics tells you it was not designed to do.
    Just as idiotic as you wanting to supercharge your NA high revs designed motor. Actually probably less idiotic. Doesn’t matter, it works though, and it’s cool.



    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    LOL ok so trying to make a low motor rev into a high rev motor is the same thing as adding boost to a naturally aspirated motor. One of these requires redesigning the architecture of the engine and the other does not. So the S2000 because it was naturally aspirated when it gets boost and revs to 9k rpm without any internal changes is the same as taking the engine in the CRV and making it rev to 9k? What?

    Good naturally aspirated motors are great candidates for boost because they usually have strong internals, good flowing heads, and don't require as much boost pressure to hit the same hp figures.

    You're out of your element.
    Stronger everything (sleeves, internals, bearings), lower compression.. that’s not an architectural redesign? Well I’ll be
    Not to mention head design DOES differ based on NA vs FI.. as well as cam design (extensively)

    also, the S2k when boosted needs a minimum massively thicker head gasket (or deck spacer), and realistically does need new internals. Why not get the CRV motor to hit 9k if you wanted?... for what it’s worth, the CRV has a K24.. https://www.google.com.au/search?q=h...sm=93&ie=UTF-8
    I know what you were trying to do, just saying, people have actually done it kinda lol.
    Another good joke on the good NA motor being great candidates… high compression and light weight internals are super good for boost, yeah. Sounds like you’re talking for low power builds, which you’re usually the opposite of (not worth it if it can’t get 4 figures LOL)

    Yeah, you’re right, I’m out of my element… not used to arguing against people who insist on such ridiculous things Click here to enlarge


    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    You will be able to get a V8 to rev higher than inline-6 simply due to the architecture which you can't change because physics yo.
    Wow you’re actually joking now, I can see it. V8’s revving higher than I6’s on average, now I’ve heard it all. You should know that 1st+2nd order imbalances are worse than 3rd/torsional. The V8’s will tear themselves a part long before the I6’s… How many 10-12k RPM V8's (streetable preferably) do you know of and how many 10-12k RPM I6's?

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    You're daydreaming. That's all you're doing. You're blindly grasping at straws 'hoping' someone does this or that or that it is 'possible' to do.

    Sure some billionaire could also buy BMW, tell them to cease production on everything, hire the best engineers in the world, and tell them their sole purpose is the hit the highest possible rev they can on the N54. Sure, it's possible and all.

    Uh, no, what I just said was purely for discussions sake, I don’t believe anyone will ever do that with the N54, it’s utterly ridiculous on a DIFFERENT LEVEL lol.
    I mean, hell, people made 3.2 stroker kits for the N52… some guy in south Africa (or UK?) decided to add ITB’s and rev it to the moon. Things it was never designed for (seriously, it’s a reasonable performing economy motor). But it was done.

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Considering it's a better motor no kidding. ECU flash to raise the redline and the factory S65 can hit 9k all day. For the N54 to do the same you need a team of engineers to turn it into something it was never designed to be. Stop trying to make it something it isn't and accept what it is.
    Or, we have fun doing what we want?
    Why not just accept what your S65 is and leave it, you should follow your own advice and raise the compression, forget boost, because you KNOW it was designed as a high revving NA motor. Let it sing over 10k 4.4 stroker or whatever, because that’s what it was designed for, you’re just ruining it and being stupid you realize?


    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Nobody said you can't increase the rev limit. What I'm saying is picking a number like 9k arbitrarily and stating it's 'possible' to hit is idiotic. It makes far more sense to try to address the fuel where it's already revving to and enjoy the turbo options coming to market rather than trying to re-engineer the entire motor and its valvetrain. Fortunately with an S65, S54, S62, S85, S14, you don't need to do that now do you?
    It’s a point of discussion, it’s not harming anything, and if you paid attention, without your interjection led to ‘hold on, how much can the injectors really do’. You added no value to the discussion by going ‘LOL GUYS NO LOL’.

    And what you’re suggesting is basically ‘guys, stop development on the N54, it’s done, this is all it will ever be’ which is clearly not the truth.
    Hey, it’s not like with the S65 you have to lower compression and sleeve the motor for big power do you? Nah of course not. It’s perfect.

    Seriously, if EVERYONE had your attitude, I doubt any motor would ever have broken 1k WHP, because it’s NORMAL to have to have a totally redone valvetrain/cams/internals/fuelling system for engine builds. NORMAL.

    Back to RB motors, even with same volume strokers, there's still R/S to consider, different rod lenghts, pin heights... yes, they all go through massive redesign

    RIPS for the RB30 builds has to build a full bracing kit for them so they don't flex apart. that's even more extreme than what we're discussing here.

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Name me the post where this was the discussion.

    THE N54 WASN'T DESIGNED TO REV HIGH. Get over it, move on, S motors win for revs and always will. Even BMW changed the damn design for the higher redline of the S55.
    If you don’t realise that this is the discussion, why are you bothering? We’re obviously not on the same page lol
    Where did I say it WAS designed to rev high.. I have said it wasn’t… I’m saying it could were someone to want it to.. Christ.
    And how was the design changed to rev higher? It’s barely an increase, they probably needn’t have changed a thing. Maybe stiffer springs?
    Last edited by Flinchy; 01-13-2014 at 10:00 PM.
    boop

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    Click here to enlarge Originally Posted by ajsalida Click here to enlarge
    Good comments here, has me wondering if one way around limitations on existing N54 fueling if they are ever found is to try to exploit some of this more exotic injector pulse timing. Assuming it has not already been done as part of basic OEM (which I doubt or we'd have heard by now). For example run multiple pulses across/during intake thru combustion cycle after spark, maybe with higher pressures. Pretty wild stuff, to me at least, who grew up on carbs and thought they were mysterious.
    Carbs are still almost mysterious to me, don't get a chance to work on them much (just mates with celicas/datto's and stuff Click here to enlarge) haha

    any of that may be possible, idk, i don't know anywhere near close to enough on the software/fuelling/internals side in depth... But at that point it's probably way easier and probably more effective just to add port injection. Things like pressure is dictated by HPFP, which the dual HPFP should be able to keep up. at any flow rate.
    boop

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