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  1. #201
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    Click here to enlarge Originally Posted by shiv@vishnu Click here to enlarge
    We spun a single turbo n54 6AT up to 7900rpm the other day. Running 25psi of boost no less. Engine is still running Click here to enlarge
    Interesting.

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    Click here to enlarge Originally Posted by 654 Click here to enlarge
    Interesting.
    Ooops! LOL Now the question is, was the N54 designed and built for 7k rpm or 8k rpm Click here to enlarge BMW really didn't want to screw up with these first turbo motors after 2-3 decades of not building them

    Let's see a dyno to 7900rpm!
    Click here to enlarge

  3. #203
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    Ooops! LOL Now the question is, was the N54 designed and built for 7k rpm or 8k rpm Click here to enlarge BMW really didn't want to screw up with these first turbo motors after 2-3 decades of not building them

    Let's see a dyno to 7900rpm!
    There was a post on another forum about a guy who money shifted into second at around 80 mph. I can't remember what the actual numbers were, but I thought his RPMs stayed under 8k. His engine was completely borked though...

    Would that have been an issue with the mis-shift alone or a combination of the shift and the engine not wanting to be over 7k?

  4. #204
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    Ooops! LOL Now the question is, was the N54 designed and built for 7k rpm or 8k rpm Click here to enlarge BMW really didn't want to screw up with these first turbo motors after 2-3 decades of not building them

    Let's see a dyno to 7900rpm!
    Interesting in many ways. How to get AT to rev so high, at what RPM is the choke point and drop in the power (w/ stock head), what about with upgraded inlet ports and finally, how high is the piston speed with the short rods.. the last one can be easily calculated.

  5. #205
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    Click here to enlarge Originally Posted by 654 Click here to enlarge
    Interesting in many ways. How to get AT to rev so high, at what RPM is the choke point and drop in the power (w/ stock head), what about with upgraded inlet ports and finally, how high is the piston speed with the short rods.. the last one can be easily calculated.
    There's the issue of valve float on a high spinning motor to worry about. Me thinks the springs are not stout enough to handle the high RPM.

  6. #206
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    Click here to enlarge Originally Posted by Eleventeen Click here to enlarge
    In all fainess, this is the only case of a failed rod bearing I've heard of on the N54. People keep bringing the rod bearings up, but one failure does not point to a common weakness. I've heard more reports of damaged pistons in the N54. Not sure where the rod bearing fear is coming from.
    It's not a fear. It has actually happened on a number of engines; the one I mentioned is just the first where I've seen it myself first hand. There's a tuner in Germany that uses lead based (i.e. softer) rod bearings just out of this reason for his highly modded N54 projects (with bigger turbos etc., not just stock FBO).

    I agree with you that you will probably not see this happen very often in the US, as (unfortunately for most in this forum) you simply cannot drive fast enough for extended periods of time there, e.g. driving between 250 and 310 km/h for one hour (German motorway) or doing a track day with 25 laps (520 km) on the Nürburgring. It's under those conditions that the immense torque of this engine at full tilt creates the kind of heat environment where the rod bearings can be damaged.

    As I however would like to have a car that is reliable even under these extreme conditions, I think it bears mentioning (pun intended) that the rod bearings may be a weak point if you push the car to the limits constantly and over extended periods of time.

    And as far as the Vishnu project is concerned - give me that single turbo car for a track day and I assure you that you can collect the engine parts from the pavement before the day is over.

    Alpina_B3_Lux
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  7. #207
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    I suspect most of the road bearing failures we have heard about on the track have been due to oil starvation during high sustained G cornering (usually left turns). I've seen this personally at Laguna Seca and at Thunderhill. Both on FBO cars at moderate power levels. There may very well be a torque-induced failure mode but I have yet to see it. Then again, we don't do much more than 10 seconds of full throttle at a time. With a 650whp car starting at 60mph, you'd probably get to 200mph by then Click here to enlarge

    Sorry to turkeybaster if this post offends him.

  8. #208
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    Click here to enlarge Originally Posted by shiv@vishnu Click here to enlarge
    We spun a single turbo n54 6AT up to 7900rpm the other day. Running 25psi of boost no less. Engine is still running Click here to enlarge
    More details please.
    2010 e92 M3 Jet Black | DCT | ESS Tuned | Akrapovic Slip-on | Challenge X-pipe | AFE Intake | 18" Volk TE37SL | KW V3 Coilovers | RPI Scoops | Under Drive Pulley

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  9. #209
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    Click here to enlarge Originally Posted by nafoo Click here to enlarge
    More details please.
    unfortunately for us shiv can only post once per day, as any guest vendor. have a drink, relax, or, if you are impatient, ask him on e90 with a PM.
    Click here to enlarge
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  10. #210
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    Click here to enlarge Originally Posted by Alpina_B3_Lux Click here to enlarge
    It's not a fear. It has actually happened on a number of engines; the one I mentioned is just the first where I've seen it myself first hand. There's a tuner in Germany that uses lead based (i.e. softer) rod bearings just out of this reason for his highly modded N54 projects (with bigger turbos etc., not just stock FBO).
    Ok, but still is not concrete proof of either the oem rod bearings being an inherently flawed design, nor that the bearings cannot handle the heat.

    Click here to enlarge Originally Posted by Alpina_B3_Lux Click here to enlarge
    I agree with you that you will probably not see this happen very often in the US, as (unfortunately for most in this forum) you simply cannot drive fast enough for extended periods of time there, e.g. driving between 250 and 310 km/h for one hour (German motorway) or doing a track day with 25 laps (520 km) on the Nürburgring. It's under those conditions that the immense torque of this engine at full tilt creates the kind of heat environment where the rod bearings can be damaged.
    I'm not sure how to take this comment. It's reads like a subtle jab at the U.S. taking it objectively, though, you still wouldn't have the foggiest, of what you are talking about. The problem is that most americans view BMW's in general as more as a status symbol, and thus, you really don't see them driven for very long journeys on the highway. However, we have southern states, with summer temps in excess of 117F, and LONG highways with very little law enforcement. Several of our guys have tracked the 335I in these temps at tracks like button willow, Las Vegas motor speed way, Laguna secca etc, and we haven't seen any issues. Not the ring, but then again, Germany is not a desert with 125F ambient temps.

    Click here to enlarge Originally Posted by Alpina_B3_Lux Click here to enlarge
    As I however would like to have a car that is reliable even under these extreme conditions, I think it bears mentioning (pun intended) that the rod bearings may be a weak point if you push the car to the limits constantly and over extended periods of time. And as far as the Vishnu project is concerned - give me that single turbo car for a track day and I assure you that you can collect the engine parts from the pavement before the day is over.
    Alpina_B3_Lux
    God I wish you lived the US. Unless you have some professional driving experience, I'd love you race you at any track of your choosing, with some serious $$ put on the table, so we stop being arm chair, lap top racers here. I just want to prove that compared to me, you don't know what driving hard means.

    My car came without an oil cooler stock, and even back then the guy that thought me how to drive (an ex-professional racer), drove my car with the needle at 300F, with me in it for a full hard track day, and countless more track events since, my engine is still running strong, at 95K miles on the odo. silent as a ghost.
    Last edited by Turkeybaster115; 06-30-2012 at 12:08 AM.

  11. #211
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    3 out of 3 members liked this post. Yes Reputation No
    Click here to enlarge Originally Posted by Turkeybaster115 Click here to enlarge
    Ok, but still is not concrete proof of either the oem rod bearings being an inherently flawed design, nor that the bearings cannot handle the heat.
    I don't think it's a flawed design at stock power levels. If however you increase the power output by 50% or more, I do think that under certain conditions the combination of rod and rod bearings are not up for the task.

    Click here to enlarge Originally Posted by Turkeybaster115 Click here to enlarge
    I'm not sure how to take this comment. It's reads like a subtle jab at the U.S. taking it objectively, though, you still wouldn't have the foggiest, of what you are talking about.
    I have no idea why you seem intent on turning a technical discussion into a personal attack, or an attack on the US in general. Maybe try reading what I wrote again - I simply stated that there are certain driving conditions in Germany that you cannot replicate in the US because of a different legal framework as far as speed limits are concerned.

    Click here to enlarge Originally Posted by Turkeybaster115 Click here to enlarge
    The problem is that most americans view BMW's in general as more as a status symbol, and thus, you really don't see them driven for very long journeys on the highway. However, we have southern states, with summer temps in excess of 117F, and LONG highways with very little law enforcement. Several of our guys have tracked the 335I in these temps at tracks like button willow, Las Vegas motor speed way, Laguna secca etc, and we haven't seen any issues. Not the ring, but then again, Germany is not a desert with 125F ambient temps.
    Outside temperatures in themselves are not a problem at all. The problem is the heat generated in the combustion chamber by continuous full-throttle driving of a highly tuned car.

    As I wrote previously, the car I mentioned was driven under very extreme conditions - more than 20.000km on various race circuits. That is not comparable to the occasional track day at Laguna Seca or elsewhere, and which is why I believe we have not seen similar failures more often (or also on my car).


    Click here to enlarge Originally Posted by Turkeybaster115 Click here to enlarge
    God I wish you lived the US. Unless you have some professional driving experience, I'd love you race you at any track of your choosing, with some serious $$ put on the table, so we stop being arm chair, lap top racers here. I just want to prove that compared to me, you don't know what driving hard means.
    See above. I'm not sure what you intend to achieve with these comments, but it does not contribute anything constructive here. It rather seems you have some sort of inferiority complex that you need to discuss here, but let's stay on topic.

    Alpina_B3_Lux
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    Gone: Audi R8 V10 2010 manual, ice silver, grey side blades, MTM tune, MTM air filters, Michelin PSS tires
    Gone: BMW 335i Individual (Öhlins, PFC brakes, RB turbos etc.)

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