E89 Z4 HPFP nightmare

nahor

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No You will stretch the factory head bolts and lift the head of the block.

its not about the power level, its cylinder pressures and many have found out the hard way.

21psi is about as much as you want to run on a stock motor with stock head bolts.
21 psi at what RPM though? Because 21 psi at peak torque RPM will be a very different level of cylinder pressure than 21 psi at 7000 RPM. I think ignition advance will also likely play a role, even if only in peak pressure rather than average pressure. Do you have any more details on the cars that have had heads lift? Would love to have some data to try and tailor my tune for more longevity.
 

martymil

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unless your running e85 there is no real point of revving to 7000rpm, your better of using the torque of the motor but that really depends on your curve.

I use to rev mine to 7k but realized short shifting at 6500 would shave a .5s of the quarter mile time until I got cams.

Why I say 21psi because sometimes the motors will over boost to 22psi or more, 22 to 24 psi is where the bolts start to slowly stretch.

Also yes the advance will play into it but not so much on pump gas but cylinder temps will as they will be much higher on pump.

I dont really care how much boost one wants to run, you have been advised what can and will happen eventually.

Its up to you what you like to do and its ones car.

If your going to run 21psi or any more than 500 crank hp and rev it to 7000rpm I suggest you look into
and crank hub and bolt capture solution of your choice especially with DCT. Thanks @fmorelli for reminding me.
 

nahor

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unless your running e85 there is no real point of revving to 7000rpm, your better of using the torque of the motor but that really depends on your curve.

I use to rev mine to 7k but realized short shifting at 6500 would shave a .5s of the quarter mile time until I got cams.
7000 RPM was just an example; the same would apply at 6000 or 5000 RPM, only to a lesser degree. The VE of an engine changes throughout its RPM range and, especially on a stock head/cams N54, will have dropped a decent amount by redline. That's why I mentioned peak torque RPM as the other extreme, ie. where VE and therefore cylinder pressure will be the highest.

Why I say 21psi because sometimes the motors will over boost to 22psi or more, 22 to 24 psi is where the bolts start to slowly stretch.
Sure, but again, what RPM are we talking about? As I previously mentioned, VE changes throughout the rev range, and as a result so will cylinder pressure at a given boost level. I'm not doubting your 21 psi number, but given that we're talking about torque/cylinder pressure, a boost level on its own isn't enough information. If we're talking about a car that was hitting 26 psi at 3500 RPM, then it makes sense that it would lift a head, as that's very aggressive. But if we're talking about a car that had a slow taper up to 24 psi at redline, with no knock and reasonable ignition advance, then that's a totally different story.

Also yes the advance will play into it but not so much on pump gas but cylinder temps will as they will be much higher on pump.
Cylinder pressure for a given torque level shouldn't change with fuel type (although don't quote me on that, there may be some differences, albeit fairly small I'd imagine). Unless we're talking about knock, but that's a separate issue. My point here was that for a given boost level, if you retard ignition timing, peak cylinder pressure should drop, as you aren't starting combustion until later in the piston's stroke, meaning there's less time where the piston is traveling upwards while combustion is happening. And lower peak cylinder pressures means less chance of head lifting/rod bending/etc.
 

martymil

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There is not set formula of when it will happen as every engine is different but from what I have observed
21psi is the reliability sweet spot for an n54.

Pump fuel will have a lot higher cylinder temps than e85 on the exact same tune.

Put an EGT sensor on your DP's and have a look for yourself.

I'm not going to get into the science behind it, want to run and rev your n54 go for it.

These engines are not indestructible as many have found out and blown their n54's here.
 

martymil

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This is what a perfect pump fuel tune should look like, I'm running a small blend of e20 to keep knock at bay just like a octane booster but much cheaper to blend e85 or reduce the timing until you have very little correction.

This is on a fully built motor with cams but to suit pump gas and its more that the car can handle as it breaks traction in 3rd rolling the boost on.

 
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nahor

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There is not set formula of when it will happen as every engine is different but from what I have observed
21psi is the reliability sweet spot for an n54.
Right, and that's exactly my point. Saying "21 psi and no more" is trying to make a set formula for a situation that's much more nuanced and complex. Which is why I'm trying to have a discussion on that.

Pump fuel will have a lot higher cylinder temps than e85 on the exact same tune.

Put an EGT sensor on your DP's and have a look for yourself.
Yes, obviously, but that has no relevance in a discussion about cylinder pressure (outside of potential knock). My point specifically was that retarding ignition timing will reduce peak cylinder pressure, to which you responded:
Also yes the advance will play into it but not so much on pump gas but cylinder temps will as they will be much higher on pump.
I am simply clarifying that ignition advance plays into peak cylinder pressures an equal amount regardless of what fuel you're running. Cylinder temps are a different topic entirely.

Either way, I think we're getting a little bit off topic, better not to fill up OP's thread. The only reason I brought this up in the first place was that, based on your post, it seemed that you knew some people who had had this happen, and I was hoping you'd be able to give us some more detailed info on their setups/how they had their cars tuned. That way we might be able to come to a more accurate conclusion than simply that 21 psi in general is the limit, as that on its own doesn't quite tell us enough. Either way, thank you for the info.
 

fmorelli

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Right, and that's exactly my point. Saying "21 psi and no more" is trying to make a set formula for a situation that's much more nuanced and complex. Which is why I'm trying to have a discussion on that.
Generally more information is good ... but I don't agree that it is conclusive if not misleading. In my experience fuel quality is a huge factor, for example. One can think that having additional data somehow more conclusively informs them. I picked 19psi for a reason ... ;-).

It is nuanced and complex - to the degree that it won't get figured out in a forum. And not applicable from one car to the next, for sure. ... and a bad tune at 15psi can likely do the same damage.
 

martymil

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The op was advised on what he needs to do to fix his HPFP issue

Lower the boost or get a OD for his HPFP but will need to figure out how to keep an eye out on the LPFP pressure if he gets an OD.

The rest is up to him and was advised to lower his boost as its cheaper and safer.

Original question answered.

One wants to discuss how to work out the reliability point of an n54 start another thread or join the dozens of others.
 

nahor

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Generally more information is good ... but I don't agree that it is conclusive if not misleading. In my experience fuel quality is a huge factor, for example. One can think that having additional data somehow more conclusively informs them. I picked 19psi for a reason ... ;-).
Certainly. I think conclusion is the wrong word, it's good that you point that out. I suppose hypothesis would work better. My intention is definitely not to come up with a conclusive "run this boost and no more" type of thing, more so to try and put as much data/info out there as we can for individuals to make what they will of it. Said data always needs to come with a "your mileage may (will) vary" clause.

And not applicable from one car to the next, for sure. ... and a bad tune at 15psi can likely do the same damage.
Yep, 100%. Which is exactly why I was hoping for more info. It won't necessarily be conclusive, but in my opinion it's always better than not having any, as long as it's taken with the appropriate amount of consideration/grains of salt. My main point though was that boost level on its own simply isn't enough, at a bare minimum we need to be considering RPM as well when talking cylinder pressures.
 
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fmorelli

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Certainly. I think conclusion is the wrong word, it's good that you point that out. I suppose hypothesis would work better. My intention is definitely not to come up with a conclusive "run this boost and no more" type of thing, more so to try and put as much data/info out there as we can for individuals to make what they will of it. Said data always needs to come with a "your mileage may (will) vary" clause.


Yep, 100%. Which is exactly why I was hoping for more info. It won't necessarily be conclusive, but in my opinion it's always better than not having any, as long as it's taken with the appropriate amount of consideration/grains of salt. My main point though was that boost level on its own simply isn't enough, at a bare minimum we need to be considering RPM as well when talking cylinder pressures.
Agree ... I short handed "conclusive" ... my experience ... especially with tech people ... the more "data" they acquire the more they convince themselves (a line asymptotic to truth) that they know. Yes more data is good ... but at the end of the day, the guidance will always be coarse because anything else is complexity reduced to certainty by a subset of known information assumed to be largely computed to determinism. While 21psi or 19psi are finite numbers, they intend to be a generalized target ... e.g. "if all your stuff is in reasonably working order, you should be pretty safe around this number" ... and here's the problem ... those that know enough about what it means to be "reasonably working order" DON'T need this guidance. So what does that say ... ;-)
 
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nahor

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Agree ... I short handed "conclusive" ... my experience ... especially with tech people ... the more "data" they acquire the more they convince themselves (a line asymptotic to truth) that they know. Yes more data is good ... but at the end of the day, the guidance will always be coarse because anything else is complexity reduced to certainty by a subset of known information assumed to be largely computed to determinism. While 21psi or 19psi are finite numbers, they intend to be a generalized target ... e.g. "if all your stuff is in reasonably working order, you should be pretty safe around this number" ... and here's the problem ... those that know enough about what it means to be "reasonably working order" DON'T need this guidance. So what does that say ... ;-)
Sure, and I have no problem with (conservative) generalized guidance, it's just that in this case a boost target on its own can be both conservative and too aggressive at the same time. Someone with big turbos may never run into issues at 19/21 psi, but someone else with stock/small turbos that will make peak boost well before 3000 RPM could take the guidance to heart and still end up lifting a head. It's not the boost level guidances themselves, more so the way they are presented, missing a key variable. I completely agree that we're likely never going to find a silver bullet of configuration/tuning that will maximize power while keeping a stock motor intact, but I think that a boost target on its own is just too oversimplified. Having more data can certainly lead to a false sense of security, but especially in this case, I think oversimplification is more dangerous.

All that being said, my primary intention was never really to come up with my own safe guidance, or even to question the existing one; I mainly just wanted some more data to help augment my own tune. I've taken as much of a data driven approach as I can, and it's worked out well so far, but I'm also willing to accept any failures that may come. I'm very much aware of the risk inherent in trying to push more power out of a stock motor, but to be honest, for me, part of the enjoyment of this hobby is being able to test my own knowledge, learn from my own mistakes, etc.
 
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Neg89

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Wow,did not notice discussion continued.The tuner say, maybe the issue is on EKp, i have one spare, and ibcan tey to swap that in. No big hopes on that. Then i will try to pull out filter. From hpfp. Shame i can not log LPFP maybe that is dragging presure down. Any opinion on EKPM WEAKNESS? I have no luck to find Pod distributor in Europe and no luck with VC pump billet cover ether. Is there any? Spool wants 200$ for shipping 59$ part.Maybe someone can help me out.?
 

Neg89

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Fmorelli, yes i have access to e85, but do not want to use it because car purpose is driving in alpine region abroad. There will no be any e85 near.Only 98
 
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fmorelli

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Fmorelli, yes i have access to e85, but do not want to use it because car purpose is driving in alpine region abroad. There will no be any e85 near.Only 98
Flex fuel (Motiv) solution would not be useful for you?
 
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Neg89

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Yes i was inrerested in it.But i have pressure problem on straight fuel,with e85 it will be much worse.
 

SLOWESTN54

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You could go with with motiv reflex add in flex fuel and pi, it would solve all of your issues. Or as marty stated you could go with a POD overdrive, I have one in my car and I've had zero issues with my unit so far. I highly suggest adding in a fuel low pressure sensor, as i think its more then your simply running out of hpfp. And if its true that your simply out of hpfp it's crazy how each hpfp varies so vastly. On my old V8Bait tune we got up to 26psi with just a 450 in tank pump and never saw fuel pressures below 1300psi ish, while running a E50 mix.

Another question for @Neg89 where did you get your HPFP from was it refurbished or a new unit? Maybe you got a faulty pump?
If someone thinks I'm simply wrong, I'd love to hear why, and the reasoning.
 

martymil

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You can't buy a new hpfp even the ones from bmw are refurbished these days, that's why buying from fcp euro is an absolute must as their lifetime warranty can't be beat.

I'm still running the original pre release pfs pod I was testing for them and it has been flawless close to three years now.

Unless your aiming for 700hp plus don't waste your time with pi.

I can run straight e85 if I wanted to no problem.

I ran 128mph the other night at the track on e20 at 21psi and my fuel pressures were perfect.
 
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Neg89

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It was new HPFP from bmw in the box.Seemed new to me.I want to keep my 500 whp, no intentions to go further.
 

Neg89

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Hello. I just received PFS POD. Can you please tell me what exactly to say to my tuner to change in tune to avoid the cold start rattle etc. My car is Z4 e89 INAOS. I have read one thread but do not exactly understand all the information . Thank you.