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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Meth with stock downpipes?



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      05-31-2011, 07:54 PM   #45
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Originally Posted by tibra1 View Post
I am not confused at all..Jeff clearly stated I was correct and I knew i was correct b4 that..and you just proved my point a more efficient system overall at the same power level will decrease turbo stress hence increase longevity, turbos running 16psi will see harsh duty cycles w stock DPs, even more so w meth..so your point is moot..u have gone WAY off topic here im not sure why..

The OP clearly asked: post 1




Why are you hopelessly arguing something that has no basis in fact..
- Stock DPs plus boost > 16 psi + meth = higher duty cycles and wear
- Catless DPs plus boost > 16 psi + meth will allow for less duty cycles hence less wear..

This is the EXACT reason why almost EVERY tuner for this car mandates use of catless DPs at these boost levels..and even more so w meth.

If you want to run this setup fine..but dont advise the OP incorrectly that it safer to do so w Stock DPs then catless DPs.
There won't be a big difference in DC. DPs will add efficiency to the turbos, but it's not a huge difference dropping maybe out of the peak efficiency island... But I don't think so. if we were talking about higher boost targets then it's a concern, but not in this case.
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      05-31-2011, 08:08 PM   #46
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Originally Posted by Joshboody View Post
There won't be a big difference in DC. DPs will add efficiency to the turbos, but it's not a huge difference dropping maybe out of the peak efficiency island... But I don't think so. if we were talking about higher boost targets then it's a concern, but not in this case.
You dont think 16+psi and meth is high boost??..LOL ok man i tried.
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      05-31-2011, 08:14 PM   #47
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OP im sorry but you really need to do some more research b/c ur statements are iffy at best..u dont need cats in the DPs period..others have told you they are not that loud..u seem to be grasping on to a hopeless cause to sacrifice the longevity that u said was MOST important for sound..it just one contradiction after another..why dont you just go stock n or at least run a less agressive tune..13 psi if u wanna keep stock DPs
I'm brand new to modding cars. I did many hours of research but I usually run into posts that provide me with incomplete or misinformation and go off topic. Most threads just talk about power and not reliability. I just moved and have nobody to advise me with my new hobby, so I turned here. I don't want to go stock or less aggressive. I'm trying to get more power while minimizing the risk to my daily driver. You've been a great help btw.

You can see I'm in definite need of more power in my video. The Hankook Ventus V12 evo tires you personally recommended hook up real good. Now I need to adjust my power to the wheel spin threshold and I'm done modding. -------->
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      05-31-2011, 08:27 PM   #48
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You dont think 16+psi and meth is high boost??..LOL ok man i tried.
Of course it's high boost, but I took the OPs question as to whether DPs are required... i don't think it makes much difference in turbo longivity at similar boost pressures. It does matter if maxing boost or maxing power, but he was asking if he can keep stock DPs.
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      05-31-2011, 08:30 PM   #49
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Without a tune and with catless DPs and better FMIC your duty cycles on the turbos would drop to nothing and operate more freely and easily..not sure if thats what u meant by efficiently? but longevity a big yes
Exactly what I meant.

Thank u sir.
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      05-31-2011, 08:36 PM   #50
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Quote:
Originally Posted by 335i 07 View Post
I'm brand new to modding cars. I did many hours of research but I usually run into posts that provide me with incomplete or misinformation and go off topic. Most threads just talk about power and not reliability. I just moved and have nobody to advise me with my new hobby, so I turned here. I don't want to go stock or less aggressive. I'm trying to get more power while minimizing the risk to my daily driver. You've been a great help btw.
OP,,first off welcome..I have been trying to address the specifc concerns u raised in the opening post..i think i have demonstrated to you what will provide u the results that you are looking for. At the end of the day..its ur call..btw I modded very carefully as well w longevity as a primary concern so I applaude what you are doing..

I like to have the power on tap..but does that mean that I blast to 16psi n every gear all the time..NO..but when I do..i like knowing that i have a lower pressure drop cooler IATs thru FMIC and minimal ar restriction thru intake, DPs and exhaust..
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      05-31-2011, 08:38 PM   #51
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Exactly what I meant.

Thank u sir.
NP..
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      05-31-2011, 08:57 PM   #52
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LMAO,,i didnt even realize u were the OP on that thread..i went to war w all those guys telling u run the Michelin PS2 for $400 more...u should go back and post how u like the Hankooks..VINDICATION..
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      05-31-2011, 09:30 PM   #53
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Quote:
Originally Posted by Joshboody View Post
You are not catching the point and I think Jeff confused you more. Jeff is stating that a more efficient system overall AT THE SAME POWER LEVEL will decrease turbo stress.

My point is that DPs at similar boost will actually increase stress due to the increased power, efficiency, flow, etc. Turbo stress is not a factor of hardware as much as the power, torque target you are trying to reach.
No man... From your posts I think your confused.

If your talking about catless DP's when you mention DP's above. Your not running the turbo's any harder. The gained power comes from efficiency. To achieve 300 rwhp with catted DP's you need to run x psi, to achieve this number with catless DP's you could run less target boost because the system is more efficent.. meaning less power lost through wasted energy, primarily heat.

Your not asking the turbos to do any more at 10 psi to make 300 rwhp then you are asking them to run at 10 psi to make 340rwhp, the power gained is not from the turbo's working harder, its from the increase in flow efficiency between the cats and FMIC.

Quote:
Originally Posted by Joshboody View Post
Of course it's high boost, but I took the OPs question as to whether DPs are required... i don't think it makes much difference in turbo longivity at similar boost pressures. It does matter if maxing boost or maxing power, but he was asking if he can keep stock DPs.
Eh.. see tibra1's reply, I'm not even trying to explain this. You obviously run with stock DP's as other have done successfully, but is ideal for longevity, absolutely not. Why do you think tuners tell you not run the higher maps until you have supporting mods.. longevity.

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      05-31-2011, 09:47 PM   #54
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Originally Posted by ///M3THOD View Post
No man... From your posts I think your confused.

If your talking about catless DP's when you mention DP's above. Your not running the turbo's any harder. The gained power comes from efficiency. To achieve 300 rwhp with catted DP's you need to run x psi, to achieve this number with catless DP's you could run less target boost because the system is more efficent.. meaning less power lost through wasted energy, primarily heat.

Your not asking the turbos to do any more at 10 psi to make 300 rwhp then you are asking them to run at 10 psi to make 340rwhp, the power gained is not from the turbo's working harder, its from the increase in flow efficiency between the cats and FMIC.
Great analogy ..explains it perfect.
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      05-31-2011, 09:49 PM   #55
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I went ahead and bought the AA DPs to accommodate my future meth kit and boost increase. Such a good deal with this Group Buy. http://www.e90post.com/forums/showth...57#post9722057
If they sound loud or raspy I will just sell them here and take a $100 loss. O well. The question is will the stock exhaust still sound the same after I put miles on it. Guess only time will tell.
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      05-31-2011, 09:55 PM   #56
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Congrats,,yeah that AA group buy is a deal..dont forget to pick up the BMS o2 simm..so u dont get the running rich/lean codes froming being catless. It wont sound bad at all especially w stock exhaust..just more growl when u get on it
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      05-31-2011, 09:59 PM   #57
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Don't think I need the Sim. Im running a JB4 tune.
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      05-31-2011, 10:01 PM   #58
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Don't think I need the Sim. Im running a JB4 tune.
Oh sorry u r rite..us reflash guys dont have that perk..
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      05-31-2011, 10:04 PM   #59
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Next on your list s/b FMIC..def
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      05-31-2011, 10:08 PM   #60
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Got the HPF
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      05-31-2011, 10:13 PM   #61
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Guess i should have read ur sig w mods..lmao

That thing is a monster..how was it fiiting it in there?
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      06-01-2011, 12:55 AM   #62
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Originally Posted by ///M3THOD View Post
No man... From your posts I think your confused.

If your talking about catless DP's when you mention DP's above. Your not running the turbo's any harder. The gained power comes from efficiency. To achieve 300 rwhp with catted DP's you need to run x psi, to achieve this number with catless DP's you could run less target boost because the system is more efficent.. meaning less power lost through wasted energy, primarily heat.

Your not asking the turbos to do any more at 10 psi to make 300 rwhp then you are asking them to run at 10 psi to make 340rwhp, the power gained is not from the turbo's working harder, its from the increase in flow efficiency between the cats and FMIC.



Eh.. see tibra1's reply, I'm not even trying to explain this. You obviously run with stock DP's as other have done successfully, but is ideal for longevity, absolutely not. Why do you think tuners tell you not run the higher maps until you have supporting mods.. longevity.
There's a difference between engine and turbo efficiencies. Turbo efficiency is a result of flow and boost. Efficiency starts to decrease after a certain point in the rpm range due to increasing flow. DPs will decrease the turbo efficiency due to the higher flow at X psi, but result in more power (in the upper rpms). At Xpsi DPs will hit max turbo efficiency faster, but leave this range earlier. Engine / volumetric efficiency, the abilty to fill the cylinder, increases with DPs or non-cats and your load target is obtained easier which requires less boost. If a boost target of 16psi is the question, then DPs do NOT help in reaching it... IATs and octane are the concern. DPs for power, IATs determine boost ceiling, turbo reliability depends on boost and rpm.
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      06-01-2011, 11:31 AM   #63
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There's a difference between engine and turbo efficiencies. Turbo efficiency is a result of flow and boost. Efficiency starts to decrease after a certain point in the rpm range due to increasing flow. DPs will decrease the turbo efficiency due to the higher flow at X psi, but result in more power (in the upper rpms). At Xpsi DPs will hit max turbo efficiency faster, but leave this range earlier. Engine / volumetric efficiency, the abilty to fill the cylinder, increases with DPs or non-cats and your load target is obtained easier which requires less boost. If a boost target of 16psi is the question, then DPs do NOT help in reaching it... IATs and octane are the concern. DPs for power, IATs determine boost ceiling, turbo reliability depends on boost and rpm.

Geez guy give it up.
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      06-01-2011, 11:57 AM   #64
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Geez guy give it up.
Yeppers, I give up. If you think 16psi with DPs versus non is better then you are mistaken. Depending on driving habits and how long you are trying to sustain 16psi, DPs can be worse for turbo efficiency. anyway...
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      06-02-2011, 01:40 PM   #65
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Ok, I didn't give up and had a little extra time today. DPs matter for power only, and no advantage to turbo life when comparing boost pressure. If you lower boost, of course it's better for the turbos.

Now, a little visual aid on this topic. Below is our compressor map with the approximate plot of the N54 making around 400hp... these calcs were done by Cobb Tuning. I added the black lines representing DPs. DPs increase flow, so you can move the plot to the right at same boost, or lower boost to equal flow. I think this is a fairly accurate depiction of DPs or no cats. Clearly DPs are not needed for turbo efficiency and because of the extra flow, power you start decreasing efficiency sooner. N54 has very small turbos. IATs and octane to sustain the extra cylinder pressures and heat at increased boost is the concern.
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Last edited by Joshboody; 06-02-2011 at 02:13 PM. Reason: revised attached map
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      05-03-2013, 08:54 AM   #66
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how come this discussion went to a dead hault after this graph was posted?
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