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  1. #51
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    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    LOL so physics change when you got WOT?
    No, but you aren't running ultra lean when you go WOT, you are running quite rich. PI or DI at full throttle is going to be dumping a lot of fuel so where is the advantage at the same compression here? All I see is an advantage at part throttle for efficiency due to running ultra lean, not in performance.

    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    You reference the GT3 motor and S65. Guess what, they don't make more power because they stuck with Port Injection, they make more power because spin a hell of a lot faster!
    Guess what, they both aren't DI, why? Because it isn't used for performance, that's why. If it was necessary it would be there, wouldn't it? Maybe there is a reason the cheaper Porsche model gets it but the performance model does not? Doesn't look to me like there is a performance advantage if a smaller displacement motor whoops on it hard.

    If it was better for performance the top of the line performance engine would have it. The cheaper/lower perofrmance model gets it though, just like the 335 has it vs. the M3.

    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    Exactly, more performance given the same fuel limitations.
    No, higher compression and even so the S65 is 12.0:1 on 91 octane. That exceeds many direct injected motors. It is all about the compression really and as BMW shows you can do high compression with port injection outperforming direct injected counterparts. It is a for fuel efficiency and MPG, not for performance. Same reason BMW is dropping NA motors, all about being green not all out performance.

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  2. #52
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Yes, if Ferrari had it in their 599 it may make me think more about it.

    If it is for performance why does the 3.6 liter GT3 motor outperform the 3.8 direct injected carrera S motor? Which one is higher performance?

    DI allows is higher compression on pump gas, it is the compression boost that is seeing the power increase. The RS4's motor isn't as efficient as the S65 even with higher compression and 4.2 liters of displacement, what does that tell you?

    Direct injection is for fuel efficiency, it isn't added for performance or the top performance models (like the M engines) would have it. It actually makes things more difficult in the performance realm.
    Thank you!
    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    What disadvantages? You aren't adding any % of disadvantage, you are simply adding more fuel.
    Thank you! I really like your posts!

    OK so let's go with what we have read and talk about the advantages of keeping the DI and adding the PI.
    1) Keeping stock internals. This to me is the most obvious and largest advantage due to cost, reliability (not opening motor for chances of human error) and simplicity.
    2) Fuel efficiency.

    OK so it seems there are the advantages. Now, let's discuss how far the #1 advantage can be pushed. Well, it can be pushed as far as the internals allow it to be pushed, correct?

    So, nobody mentioned and since there are lots of n54 lovers on here who know more than I do...what is the highest whp/wtq on an n54 without nitrous currently? Let's say that another 50 wtq and the rods will bend (hopefully it's another 500wtq but doubtful). Therefore we must replace the engine internals. That takes away advantage #1. So we are left with advantage #2 (not sure how much fuel we are saving with DI + PI instead of just PI and boosting 600+wtq). So really, at that point what are BIG advantages with keeping DI?

    Discuss...


    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I really do not believe AR Design would fake a dyno like that. If they did, it would ruin their reputation and I would likely be the first one to point it out. We know they had a single turbo setup running I think it is safe to assume that is the setup that was dyno'd. Nothing leads me to believe otherwise.
    True...time will tell. If they have one running and tuning is always the biggest hurdle here with going single...why aren't there kits out there?
    Click here to enlargeClick here to enlarge
    | Finally I got a photographer to take some decent shots from the beach. Me 8/22/2010 loving San Diego! |
    | TRM | The Racers Market | Turbo M3 | 559whp@18psi | Dynojet Confirmed 6-1-2010 |
    | Video of the session when the pic above was taken! In HD! |

  3. #53
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    Click here to enlarge Originally Posted by highboostingm3 Click here to enlarge
    So really, at that point what are BIG advantages with keeping DI?
    For performance, there are no advantages.

    Ditching it provides several advantages.

    Since this is a turbo motor the compression is going to be lower anyway. You lower it more you can add in more boost without detonating. Off-boost drive-ability will be affected and this is where DI would help keep lag to a minimum with higher compression. No performance advantage though as lower compression can just boost higher and make more power.

    Click here to enlarge Originally Posted by highboostingm3 Click here to enlarge
    .what is the highest whp/wtq on an n54 without nitrous currently?
    I'm not sure at this point, hopefully someone can chime in.

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    Well ar made 540? But that was a huge discussion because of there altitude.. Lostmarine made 502 on a dynojet and $#@!ty conditions.. Unfor hasn't publicly announced his whp but I was told it was over 550whp on a dynojet, I don't want to give the actual number since it's not my car and not sure he wants people knowing yet
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  5. #55
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    No, but you aren't running ultra lean when you go WOT, you are running quite rich. PI or DI at full throttle is going to be dumping a lot of fuel so where is the advantage at the same compression here? All I see is an advantage at part throttle for efficiency due to running ultra lean, not in performance.
    The same compression motor with DI will be able to run more boost.......

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Guess what, they both aren't DI, why? Because it isn't used for performance, that's why. If it was necessary it would be there, wouldn't it? Maybe there is a reason the cheaper Porsche model gets it but the performance model does not? Doesn't look to me like there is a performance advantage if a smaller displacement motor whoops on it hard.

    If it was better for performance the top of the line performance engine would have it. The cheaper/lower perofrmance model gets it though, just like the 335 has it vs. the M3.
    Honestly I don't think development for DI is far enough along to handle the 8,000+ revs per minute that those motors make. Who knows? You don't. This is all just speculation anyway. Maybe it is cheaper to right now to build those motors using Port Injection right now, it's been under development and constant improvement for decades. Why change to DI when they can hit their performance goal with PI? They won't, until they want to step even higher. If direct injection was added to those motors, they could up the compression ratio and they would make more power, period. So if a "Top of the Line" motor ever comes out in the future using Direct Injection then your point would be proved completely invalid.

    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    No, higher compression and even so the S65 is 12.0:1 on 91 octane. That exceeds many direct injected motors. It is all about the compression really and as BMW shows you can do high compression with port injection outperforming direct injected counterparts. It is a for fuel efficiency and MPG, not for performance. Same reason BMW is dropping NA motors, all about being green not all out performance.
    Sticky, take a step back and think about your first sentence. You do realize you just compared a NA motor compression ratio to a FI motor compression ratio right? Or are you talking about something besides the N54? The boosted motor is going to have a much higher dynamic compression ratio because we are putting boost through it!!! How much boost can the S65 handle stock comp ratio, 7psi? If the S65 had Direct Injection then they would likely be able to run a even higher ratio, maybe 13:1 on 91 and be ok.

    The only reason the S65 makes more power than the N54 stock is because the S65 is 4 liters, makes X amount of torque and revs to 8500RPM holding most of it, it's not because Port Injection is better than Direct Injection......

    And just because a company uses a performance enhancing technology (Direct Injection) to increase fuel economy on a "non-top-of-the-line" engine doesn't change the laws of physics that PROVE that DI improves the performance of a Internal Combustion Engine by furthering it's ability to effectively extract power from a fuel source.

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    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    The same compression motor with DI will be able to run more boost.......
    No, it depends on the fuel. This holds true on pump gas.

    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    onestly I don't think development for DI is far enough along to handle the 8,000+ revs per minute that those motors make. Who knows? You don't. This is all just speculation anyway. Maybe it is cheaper to right now to build those motors using Port Injection right now, it's been under development and constant improvement for decades. Why change to DI when they can hit their performance goal with PI? They won't, until they want to step even higher. If direct injection was added to those motors, they could up the compression ratio and they would make more power, period. So if a "Top of the Line" motor ever comes out in the future using Direct Injection then your point would be proved completely invalid.
    The RS4 revs past 8k with DI. The Gallardo V10 revs past 8k with DI. So... it can be done and has been done.

    The GT3 isn't a motor that built with huge restrictions. That is why it uses the GT1 block, it is all about the best of the best for performance. It is built for maximum performance and racing. Fact is Porsche puts DI on its cheaper model and its highest performance model doesn't use it. This is actually a major point of contention in the Porsche world. Both are flat-6's yet the motor without direct injection offers more performance. So where is this performance advantage in practice? I think it is added for efficiency at the pump.

    If a top of the line motor has it in the future what happens is that emissions and MPG have become the emphasis. As the current motors prove, you can outperform DI with traditional port injection. Why would performance models not get it and regular models get it? That contradicts that the purpose is performance oriented. Clearly, it isn't.

    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    Sticky, take a step back and think about your first sentence. You do realize you just compared a NA motor compression ratio to a FI motor compression ratio right?
    Yes, I'm saying you can hit very high compression even with traditional injection as the S65 proves. It comes down to the higher compression ratio. I wasn't comparing an NA compression ratio to forced induction.

    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    The only reason the S65 makes more power than the N54 stock is because the S65 is 4 liters, makes X amount of torque and revs to 8500RPM holding most of it, it's not because Port Injection is better than Direct Injection......
    The reason the S65 makes as much power as it does is because of how efficient it is and because it revs very high with high compression. You compare it to direct injected motors that are naturally aspirated and it spanks basically all of them except for the Gallardo V10. So where is this direct injection performance advantage? It is for fuel efficiency, that is why manufacturers are adding it. They are not making performance their first priority.

    No one said port injection is better, simply that direct injection is not a performance oriented addition.

    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    And just because a company uses a performance enhancing technology (Direct Injection) to increase fuel economy on a "non-top-of-the-line" engine doesn't change the laws of physics that PROVE that DI improves the performance of a Internal Combustion Engine by furthering it's ability to effectively extract power from a fuel source.
    It isn't getting more power from the same fuel, it is using it more efficiently. I haven't seen greater thermal efficiency what I see is the power boost coming from increased compression. The exact same thing that affects port injected motors. More accurate fuel dispersion is for fuel efficiency gains.

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  7. #57
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    Ahh Sticky, you are missing my point.


    But it's okay, because the truth is, only time will tell.

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    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    Ahh Sticky, you are missing my point.


    But it's okay, because the truth is, only time will tell.
    I do not think I am, I believe you are missing mine regarding it being used for efficiency reasons instead of performance.

    In time, all the motors will be direct injected but that won't be because of performance considerations.

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  9. #59
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    kit leads me to not be impressed. no figures.
    Click here to enlargeClick here to enlarge

  10. #60
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I do not think I am, I believe you are missing mine regarding it being used for efficiency reasons instead of performance.

    In time, all the motors will be direct injected but that won't be because of performance considerations.
    I understand you. I agree, most of the engines it is being used for currently are using it for extra MPG numbers.

    My argument is that it is a performance enhancing engine technology. Based on the laws of physics it would have to be, and real-world tests have proved it true (higher compression on the same octane without detonation). Do you disagree?

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    *lol @ this thread being pulled out of another thread for going too far OT and this one going down the same road. Classic BB
    Click here to enlarge

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    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    My argument is that it is a performance enhancing engine technology. Based on the laws of physics it would have to be, and real-world tests have proved it true (higher compression on the same octane without detonation). Do you disagree?
    I do not disagree that the performance gain is coming from the compression boost. The compression is the key.

    At the same compression ratio I see no reason to go with direct injection for performance it actually complicates things.

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    DI is great for power because of better efficiency. Of course the masses and governments want the increased efficiency not to be used in increased power, but to keep the power constant and use the efficiency for increased fuel economy, whereas we all in this forum are using the increased efficiency for increased power only Click here to enlarge

    The cooling effect of the injected fuel and the more evenly dispersed mixtures allow for more aggressive ignition, more aggressive ignition means more power. Moreover, the power is increased because of DI having more precise control over the amount of fuel with the injection timings that are varied according to the load conditions.

    DI would enhance the power a lot in all the platforms if the fuel efficiency is kept constant and the benefits are taken out as power increase only.

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    Click here to enlarge Originally Posted by 654 Click here to enlarge
    DI is great for power because of better efficiency. Of course the masses and governments want the increased efficiency not to be used in increased power, but to keep the power constant and use the efficiency for increased fuel economy, whereas we all in this forum are using the increased efficiency for increased power only Click here to enlarge

    The cooling effect of the injected fuel and the more evenly dispersed mixtures allow for more aggressive ignition, more aggressive ignition means more power. Moreover, the power is increased because of DI having more precise control over the amount of fuel with the injection timings that are varied according to the load conditions.

    DI would enhance the power a lot in all the platforms if the fuel efficiency is kept constant and the benefits are taken out as power increase only.
    Exactly what I have been trying to say.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I do not disagree that the performance gain is coming from the compression boost. The compression is the key.

    At the same compression ratio I see no reason to go with direct injection for performance it actually complicates things.
    If it was same compression ratio, but with a boosted motor, the motor would be able to make more boost and/or run more ignition advance on DI vs PI.


    That's probably why you see it used with a bunch of turbo cars so far, it is easier to realize the benefit. Lower spool times and higher boost levels or compression ratio that they normally wouldn't be able to get away with using port injection.

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    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    If it was same compression ratio, but with a boosted motor, the motor would be able to make more boost and/or run more ignition advance on DI vs PI.
    On what fuel? I see the advantage on pump, but if going for max power with race gas + meth who cares?

    That's probably why you see it used with a bunch of turbo cars so far, it is easier to realize the benefit. Lower spool times and higher boost levels or compression ratio that they normally wouldn't be able to get away with using port injection.
    Well manufacturers are switching to turbos for efficiency reasons as well, lower displacement and lower revving motors. That is why we are seeing it there... for fuel efficiency Click here to enlarge

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    Click here to enlarge Originally Posted by 654 Click here to enlarge
    DI is great for power because of better efficiency. Of course the masses and governments want the increased efficiency not to be used in increased power, but to keep the power constant and use the efficiency for increased fuel economy, whereas we all in this forum are using the increased efficiency for increased power only Click here to enlarge

    The cooling effect of the injected fuel and the more evenly dispersed mixtures allow for more aggressive ignition, more aggressive ignition means more power. Moreover, the power is increased because of DI having more precise control over the amount of fuel with the injection timings that are varied according to the load conditions.

    DI would enhance the power a lot in all the platforms if the fuel efficiency is kept constant and the benefits are taken out as power increase only.
    It is the compression ratio boost that is making the motor more efficient.

    I just don't see direct injection at the same compression ratio offering a boost. I had this debate a long time ago on m3post, direct injection by itself doesn't give much of a boost. It needs the compression ratio increase that is where all the gains come from.

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    i think one aspect here being overlooked which drives the production of our street cars is the automotive racing industry.



    Direct injection hasn't been used in big shot race cars because A) Its quite complicated to set up for the power you are asking during racing/qualifying trim (just look at the HPFP issues...would you like to run the 24hrs of Lemans, Daytona or Nurburgring with a car that might $#@! its fuel system on the track under heavy abuse conditions), and B)it would be like bringing all the manufactuers back to the stone age in figuring out how to squeeze these injectors for more hp.

    Companies like Porsche and Ferrari definetly hold huge reserves of profit within the business, but if something works great, and is easy to tune and make more hp with, then why change it? Teams that are racing like to stick with a proven solution that works time and time again, doesnt fail and provides great results. When you start changing the rules it causes a massive amount of spending and trial and error to go back to the drawing board and figure out what to about it....or in some cases (like Porsche) causes them to pull out of racing in protest of the new rules (as they did with the RS Spyders in 2008). But now they are back with a new twist on things, the hybrid RSR.

    Will DI make its way into racing? At some point it will. There are greenies out there that protest racing because it causes too much pollution, and with the way the world is going, we will see it down the road in the attempt to satisfy idiots like them...or maybe we will give them the finger and tell em to go shove it up their $#@!.

    Port injection setups are always the easiest to make big hp numbers with.

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    Click here to enlarge Originally Posted by Matt@Camber-Toe Click here to enlarge
    Port injection setups are always the easiest to make big hp numbers with.
    Exactly, and for max performance you do not need direct injection which just complicates things as you stated.

    We are seeing it because of the greenies, not because of a quest for more performance.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Exactly, and for max performance you do not need direct injection which just complicates things as you stated.

    We are seeing it because of the greenies, not because of a quest for more performance.
    Which comes to my statement from before, If the car has DI then IMO I would keep it, and run extra injectors...but this is determined as to how much hp the factory engine can handle...if we find out 500 is the limit, then you might as well just ditch the entire system and go with 6 big injectors. If it keeps going and we find that 6-700 is the limit, then for most people, the extra fuel rail would be enough to support +20lbs and single turbo conversions. For those interested in going big or going home, switching to a full port injection might be the only way to reach this goal.

    I think what we are forgetting here is that at high RPM these motors tend to run a little bit on the lean side (trying to stay green remember), and adding more fuel up top will not neccessarily hurt the characteristics of the flame front in the chamber. Adding PI will just cause you to eat more fuel as in order for it to be detonation resistant it needs more of itself present (but not TOO much). PI cars like to run around the 11.8-12.5 range to get a good power output and good looking plugs. A DI car can run sometimes in excess of 13:1 and still be fine. Is it leaner than I would like? Yes. What is the proper way to add more fuel to this situation? No one knows as of yet.
    Last edited by Itsbrokeagain; 01-18-2011 at 03:51 AM.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    On what fuel? I see the advantage on pump, but if going for max power with race gas + meth who cares?
    Why would it not apply in that scenario? According to the science, the DI motor should be able to run a bit more max boost and/or extra ignition advance vs the same compression ratio Port Injection motor. DI is much better at extracting heat from the cylinder, helping suppress detonation.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    It is the compression ratio boost that is making the motor more efficient.

    I just don't see direct injection at the same compression ratio offering a boost. I had this debate a long time ago on m3post, direct injection by itself doesn't give much of a boost. It needs the compression ratio increase that is where all the gains come from.
    The benefits of Direct injection can be obtained by either higher compression ratio, or higher boost, or a combination of the two. If you want, you can just increase the boost as a result of the DI enhanced knock resistance.

    Think of X6M (or the next M5 or M3 for that matter), they would lose some 40hp immediately if they would not go DI.

    No worries though, as they are all DI Click here to enlarge

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    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    Why would it not apply in that scenario? According to the science, the DI motor should be able to run a bit more max boost and/or extra ignition advance vs the same compression ratio Port Injection motor. DI is much better at extracting heat from the cylinder, helping suppress detonation.
    +1, as you stated in not so many words, boost is just a byproduct of timing, if you can run advanced timing under high compression you build more boost, faster.

    sticky it is obvious that port injection is able to reach higher power levels at this point in time. how long has PI been around compared to DI, imagine some methanol/nitrometh car running DI lol, its just inconceivable at this point. once DI gets more time to 'advance' we hopefully will see increased efficiency with the extreme power levels we see from racing/drag PI motors.
    Click here to enlarge
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    Just FYI, I heard the future Ford 5.0 motor will be 460HP and Direct Injection.

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    Click here to enlarge Originally Posted by Matt@Camber-Toe Click here to enlarge
    Which comes to my statement from before, If the car has DI then IMO I would keep it, and run extra injectors...but this is determined as to how much hp the factory engine can handle...if we find out 500 is the limit, then you might as well just ditch the entire system and go with 6 big injectors. If it keeps going and we find that 6-700 is the limit, then for most people, the extra fuel rail would be enough to support +20lbs and single turbo conversions. For those interested in going big or going home, switching to a full port injection might be the only way to reach this goal.

    I think what we are forgetting here is that at high RPM these motors tend to run a little bit on the lean side (trying to stay green remember), and adding more fuel up top will not neccessarily hurt the characteristics of the flame front in the chamber. Adding PI will just cause you to eat more fuel as in order for it to be detonation resistant it needs more of itself present (but not TOO much). PI cars like to run around the 11.8-12.5 range to get a good power output and good looking plugs. A DI car can run sometimes in excess of 13:1 and still be fine. Is it leaner than I would like? Yes. What is the proper way to add more fuel to this situation? No one knows as of yet.
    I like this guy. Click here to enlarge
    Click here to enlargeClick here to enlarge
    | Finally I got a photographer to take some decent shots from the beach. Me 8/22/2010 loving San Diego! |
    | TRM | The Racers Market | Turbo M3 | 559whp@18psi | Dynojet Confirmed 6-1-2010 |
    | Video of the session when the pic above was taken! In HD! |

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