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      12-04-2017, 03:43 PM   #1
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Post Limits of the N20 engine? Beyond 27psi

It's been a few months now I've been running the Pure Stage 2 turbo on my 2016 428xi at 25 psi. I recently updated the JB4 firmware to "N20_OBDII_EWG_5_T2.hex" and like some others here my default boost safety changed to 36 psi and the N20 tmap sensor turned on.

I knew the car could push more and with this new range of PSI from the JB4, I did a few runs on map 6, targeting 27 psi & 30 psi and then on Map 7 (30+psi). I haven't really seen or read about other people raising the boost on the N20's, but I've posted a few logs for references and a list of my mods below.

It seems like 27 psi is the limit these little engines are happy with. On the 30 psi Map 6 run and the Map 7 run, I was getting misfires around 55k RPM and 45k RPM respectively and had to let off the throttle. It wasn't any better if I tried raising Meth additive to 75. That being said, I had a few runs reach 30+ psi but it was very inconsistent, if anybody has any other input to safely increase boost, it would be appreciated.

Mods: Pure Stage 2 Turbo, JB4, Eurocharged Back End Flash, Fuelit LPFP, ER turbo CP, BMS Methanol Injection kit (50:50), Injen Intake, Wagner Catless DP, AWE Quadtip Exhaust. BMS spacers, H&R springs. 94 Oct pump gas
Attached Images
File Type: pdf 27 Psi Map 6 Graph.pdf (1.32 MB, 505 views)
File Type: pdf 27 psi Map 6 Log.pdf (35.8 KB, 226 views)
File Type: pdf 30 psi Map 6 Graph.pdf (1.33 MB, 269 views)
File Type: pdf 30 psi Map 6 Log.pdf (38.6 KB, 241 views)
File Type: pdf Map 7 29 psi Graph.pdf (1.20 MB, 170 views)
File Type: pdf Map 7 29 psi Log.pdf (28.1 KB, 265 views)
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      12-04-2017, 04:38 PM   #2
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Quote:
Originally Posted by take1step View Post
It's been a few months now I've been running the Pure Stage 2 turbo on my 2016 428xi at 25 psi. I recently updated the JB4 firmware to "N20_OBDII_EWG_5_T2.hex" and like some others here my default boost safety changed to 36 psi and the N20 tmap sensor turned on.

I knew the car could push more and with this new range of PSI from the JB4, I did a few runs on map 6, targeting 27 psi & 30 psi and then on Map 7 (30+psi). I haven't really seen or read about other people raising the boost on the N20's, but I've posted a few logs for references and a list of my mods below.

It seems like 27 psi is the limit these little engines are happy with. On the 30 psi Map 6 run and the Map 7 run, I was getting misfires around 55k RPM and 45k RPM respectively and had to let off the throttle. It wasn't any better if I tried raising Meth additive to 75. That being said, I had a few runs reach 30+ psi but it was very inconsistent, if anybody has any other input to safely increase boost, it would be appreciated.

Mods: Pure Stage 2 Turbo, JB4, Eurocharged Back End Flash, Fuelit LPFP, ER turbo CP, BMS Methanol Injection kit (50:50), Injen Intake, Wagner Catless DP, AWE Quadtip Exhaust. BMS spacers, H&R springs. 94 Oct pump gas
I'm actually surprised you're brave enough to run an upgraded turbo with that fragile engine and without building it.

You'll probably have to get your EC BEF revised for higher boost. The misfires you're getting may be coming from running too rich up top or your spark plugs aren't gapped correctly or not iridium.

Try unplugging the MAF and do the run again, if it still misfires, then it's either the tune or plugs.
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Last edited by lens; 12-04-2017 at 05:09 PM..
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      12-04-2017, 06:26 PM   #3
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Quote:
Originally Posted by chaungo View Post
I'm actually surprised you're brave enough to run an upgraded turbo with that fragile engine and without building it.

You'll probably have to get your EC BEF revised for higher boost. The misfires you're getting may be coming from running too rich up top or your spark plugs aren't gapped correctly or not iridium.

Try unplugging the MAF and do the run again, if it still misfires, then it's either the tune or plugs.
I think you’re right, most likely tune. I’ll have to bring it back to EC in the spring for a reflash. The plugs are iridium but might need to be gapped a little more as well. Appreciate the input, maybe I’ll see you at a track day next year
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      12-04-2017, 06:45 PM   #4
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More boost does not necessary mean more power if your running outside the efficiency range of the turbo. Running higher boost ranges will increase the chances of you blowing the motor. The difference here is the water injection has been tuned by someone who knows what they are doing. The advantage of water injection is its able to cool the intake temps by running the higher boost level and make up for the car running lean. The problem with these engines is they run hot and proper cooling is essential.
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      12-04-2017, 07:44 PM   #5
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I would not run anything over 23/24 psi on an N20 without rebuilding it forged. Anytime I have heard of the N20 running higher PSI than 23/24 stock it bricks the engine.
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      12-04-2017, 07:48 PM   #6
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Quote:
Originally Posted by take1step View Post
I think you’re right, most likely tune. I’ll have to bring it back to EC in the spring for a reflash. The plugs are iridium but might need to be gapped a little more as well. Appreciate the input, maybe I’ll see you at a track day next year
I would recommend .018 gap, I believe your stock n20 plugs should be good as it's slready iridium.

Just run safe and efficient boost till you get the revision
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      12-04-2017, 09:20 PM   #7
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Will do, I’ll be keeping boost around 24/25 psi until I could put it on a Dyno again and tune it safely. Some cooling mods might be necessary eventually. Thanks for the support
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      12-05-2017, 10:37 PM   #8
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Quote:
Originally Posted by take1step View Post
It's been a few months now I've been running the Pure Stage 2 turbo on my 2016 428xi at 25 psi. I recently updated the JB4 firmware to "N20_OBDII_EWG_5_T2.hex" and like some others here my default boost safety changed to 36 psi and the N20 tmap sensor turned on.

I knew the car could push more and with this new range of PSI from the JB4, I did a few runs on map 6, targeting 27 psi & 30 psi and then on Map 7 (30+psi). I haven't really seen or read about other people raising the boost on the N20's, but I've posted a few logs for references and a list of my mods below.

It seems like 27 psi is the limit these little engines are happy with. On the 30 psi Map 6 run and the Map 7 run, I was getting misfires around 55k RPM and 45k RPM respectively and had to let off the throttle. It wasn't any better if I tried raising Meth additive to 75. That being said, I had a few runs reach 30+ psi but it was very inconsistent, if anybody has any other input to safely increase boost, it would be appreciated.

Mods: Pure Stage 2 Turbo, JB4, Eurocharged Back End Flash, Fuelit LPFP, ER turbo CP, BMS Methanol Injection kit (50:50), Injen Intake, Wagner Catless DP, AWE Quadtip Exhaust. BMS spacers, H&R springs. 94 Oct pump gas
Wow that's aggressive! I've long suspected that it's Tuning that killed other engines.

Did you also replace your FMIC? Or is that stock? I guess the meth keeps your charge cool.

You should get Bootmod3, then you can adjust the tune in the fly with a tuner over OBD, and won't have to keep removing the DME each time you want to revise.
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      12-06-2017, 07:30 PM   #9
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The FMIC is stock for now. But I’ll most likely upgrade next year depending on how temps get in summer weather.

I was looking into Bootmod3, but I don’t think Protuning Freaks does custom Dyno tuning. So I drove to Toronto (from Montreal) to put my car on Eurocharged Dyno for a custom tune.

You’re right that the tune you have will make or break the engine, so I really wanted to get a custom dyno tune and make sure everything was running optimally.
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      12-06-2017, 09:02 PM   #10
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Quote:
Originally Posted by take1step View Post
The FMIC is stock for now. But I’ll most likely upgrade next year depending on how temps get in summer weather.

I was looking into Bootmod3, but I don’t think Protuning Freaks does custom Dyno tuning. So I drove to Toronto (from Montreal) to put my car on Eurocharged Dyno for a custom tune.

You’re right that the tune you have will make or break the engine, so I really wanted to get a custom dyno tune and make sure everything was running optimally.
They do custom dyno tuning. They can also do remote custom tuning as well as it's the same thing.
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      12-06-2017, 10:24 PM   #11
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I’ll have to see if they could build on my current tune if I make the switch.

Once you get near the power threshold of the engine, the power differences won’t be that significant. More boost and timing won’t necessarily result in more power so the dyno is important, but anyways what do I know lol, that’s why I’d rather let the experts handle it. But they both offer similar services.
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      02-13-2019, 08:16 PM   #12
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Quote:
Originally Posted by F30_Adler View Post
I would not run anything over 23/24 psi on an N20 without rebuilding it forged. Anytime I have heard of the N20 running higher PSI than 23/24 stock it bricks the engine.
what parts would i have to get forged?
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      02-14-2019, 01:55 PM   #13
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Originally Posted by sirzakington View Post
what parts would i have to get forged?
Entire block. Pistons+ rings, Rods +Bolts, wrist pins etc. Basically entire bottom end.
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      02-14-2019, 02:01 PM   #14
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Quote:
Originally Posted by Stubok View Post
Wow that's aggressive! I've long suspected that it's Tuning that killed other engines.

Did you also replace your FMIC? Or is that stock? I guess the meth keeps your charge cool.

You should get Bootmod3, then you can adjust the tune in the fly with a tuner over OBD, and won't have to keep removing the DME each time you want to revise.
You are right on the money there. I strongly believe this motor can handle between 350-400 safely but the high peak in Torque early on in the low end from these small turbos puts lots of stress on the rotating assembly.

To make this motor last, you want to get a big turbo and tune it like a traditional map. Starting low and building up gradually as you go through the RPM rang and peaking up near the top end. These cars from factory were designed to have peak power on low RPM to feel fast during daily stop and go but run out of steam real quick. My advise is to get a big turbo and tune it to gradually increase boost and power much like a N/A tune and your motor will last.

Also since OP has METH an IC is not that big of a concern, as Meth helps far more efficiently to cool the air than any IC will.
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      02-14-2019, 03:38 PM   #15
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Quote:
Originally Posted by D041987 View Post
You are right on the money there. I strongly believe this motor can handle between 350-400 safely but the high peak in Torque early on in the low end from these small turbos puts lots of stress on the rotating assembly.

To make this motor last, you want to get a big turbo and tune it like a traditional map. Starting low and building up gradually as you go through the RPM rang and peaking up near the top end. These cars from factory were designed to have peak power on low RPM to feel fast during daily stop and go but run out of steam real quick. My advise is to get a big turbo and tune it to gradually increase boost and power much like a N/A tune and your motor will last.

Also since OP has METH an IC is not that big of a concern, as Meth helps far more efficiently to cool the air than any IC will.
Just for the sake of continuity in this thread, OP's engine did blow up eventually. He's now in the process of getting the engine built, and is giving updates in this thread: https://f30.bimmerpost.com/forums/sh....php?t=1529312.

Anyway, what would you consider a "big" turbo? There's a lot of options out there. MHI, Pure, Mamba etc...
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      02-14-2019, 03:48 PM   #16
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Quote:
Originally Posted by D041987 View Post
To make this motor last, you want to get a big turbo and tune it like a traditional map. Starting low and building up gradually as you go through the RPM rang and peaking up near the top end. These cars from factory were designed to have peak power on low RPM to feel fast during daily stop and go but run out of steam real quick. My advise is to get a big turbo and tune it to gradually increase boost and power much like a N/A tune and your motor will last.
These are my thoughts exactly. Once the stock turbo is at end of life this is my intended path. I like how linear comfort mode is but I can't help but feel mechanical sympathy for how harshly torque is pushed through the motor in sport mode. I track the car and cannot see myself running more than 22 pounds because 1) I want her to last and 2) I'm satisfied with peak power.

Is Pure Stage 2 the only option for us or is there a larger turbo that is more budget friendly?
Edit: just say rjd's post, I'm gonna check those out. Cheers.
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      02-14-2019, 06:44 PM   #17
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Quote:
Originally Posted by MacklinUSOB View Post
These are my thoughts exactly. Once the stock turbo is at end of life this is my intended path. I like how linear comfort mode is but I can't help but feel mechanical sympathy for how harshly torque is pushed through the motor in sport mode. I track the car and cannot see myself running more than 22 pounds because 1) I want her to last and 2) I'm satisfied with peak power.

Is Pure Stage 2 the only option for us or is there a larger turbo that is more budget friendly?
Edit: just say rjd's post, I'm gonna check those out. Cheers.
Yah, I agree as well. That's definitely the right idea, to push the curve over to the right, higher in the rpms, relieving some of the stress all that low end torque puts on the engine. I also am just waiting for my stock turbo to die, assuming it will by 100k miles, but maybe not, and then I'm gonna replace with MHI.
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