[ayyrabmoney93]

Hi all,

Just looking to understand a bit more.

I upgraded from a 430i to a 2021 m440i and moved my jb4 into the new car.

The m440i is absolutely amazing but my only complaint is that unlike the 4 cylinder bmws my b58 doesn't seem to respond that well to added boost from the jb4. Anything over 21 psi and I get ignition timing drops-not sure why. I've seen a lot of comments about people maxing out their stock turbos but I'm failing to understand how people are doing that.My turbo has plenty more boost to give but the engine just doesn't want it.

Do I just need a downpipe? Is that the solve?

I just feel like I'm not really getting that much out of the jb4 in this 6 cylinder when I compare it to how much added boost the 4 cylinder could take.

Let me know what you guys think.

Thanks!

[xnick101]

You can't max out your stock turbo on JB4. You need a full tune to do that. On ecutek, I run 25 psi. Around 27 is the max. Anything past that, it won't last very long. Also, JB4 does not control timing. On the e30 JB4 map, you will get a bit more boost.

[mike@x-ph.com]

you need better quality fuel, E85 or methanol injection

[totalone]

Originally Posted by ayyrabmoney93

Hi all,

Just looking to understand a bit more.

I upgraded from a 430i to a 2021 m440i and moved my jb4 into the new car.

The m440i is absolutely amazing but my only complaint is that unlike the 4 cylinder bmws my b58 doesn't seem to respond that well to added boost from the jb4. Anything over 21 psi and I get ignition timing drops-not sure why. I've seen a lot of comments about people maxing out their stock turbos but I'm failing to understand how people are doing that.My turbo has plenty more boost to give but the engine just doesn't want it.

Do I just need a downpipe? Is that the solve?

I just feel like I'm not really getting that much out of the jb4 in this 6 cylinder when I compare it to how much added boost the 4 cylinder could take.

Let me know what you guys think.

Thanks!

What map are you running?

[karayel]

Originally Posted by xnick101

You can't max out your stock turbo on JB4. You need a full tune to do that. On ecutek, I run 25 psi. Around 27 is the max. Anything past that, it won't last very long. Also, JB4 does not control timing. On the e30 JB4 map, you will get a bit more boost.

I'm looking to get a custom ecutek tune later this month on my 2020 m340i. Tuner said that they'd keep boost in the low 20s. Mods would include catless dp and flex fuel sensor to be able to run up to e50.
I'm all for not maxing out the turbo is 27 psi really the high end on these? Did you get your car dyno'ed? curious to learn how much hp the car made with 25psi

[xnick101]

Originally Posted by karayel

I'm looking to get a custom ecutek tune later this month on my 2020 m340i. Tuner said that they'd keep boost in the low 20s. Mods would include catless dp and flex fuel sensor to be able to run up to e50.
I'm all for not maxing out the turbo is 27 psi really the high end on these? Did you get your car dyno'ed? curious to learn how much hp the car made with 25psi

32 psi is pretty much the max for the stock turbo. My car has never been on a dyno so no idea what it makes. But 25 psi is the peak. It hits at the very beginning and goes down (turbo loses efficiency due to heat)

[340TBD]

Jesus, I consider 23 absolute max for stock b58 turbo. Do you have a log? 25 and 27 is nuts lol

[ayyrabmoney93]

Originally Posted by totalone

What map are you running?

I made a custom map 6 that basically mirrors map 2 but smooths out some of the areas where map 2 overboost in the higher rpm range.

Car runs like a dream!

[cyam]

Your limit is your fuel, not the turbo. Better fuel = less detonation = less timing being pulled

[mike@x-ph.com]

Originally Posted by ayyrabmoney93

I made a custom map 6 that basically mirrors map 2 but smooths out some of the areas where map 2 overboost in the higher rpm range.

Car runs like a dream!

[ichigom340i]

This guy with the Supra said the stock makes about 34 lbs max. interesting video he says it about the 44:38 mark
https://youtube.com/watch?v=xTYPT_Oz...p4j0yPj_3R-uVa

[AshtonPJT]

Originally Posted by ichigom340i

This guy with the Supra said the stock makes about 34 lbs max. interesting video he says it about the 44:38 mark
https://youtube.com/watch?v=xTYPT_Oz...p4j0yPj_3R-uVa

34 is way out of the efficiency range id say 24-27psi max. the stock s58 turbos can make around 45-46psi but max out at 32-33psi after that they lose efficiency. In testing we found just a 2psi jump from 33 to 35 slowed us down by .5 in 60-130(this was done within a span of 10 minutes only adjusting boost. S55 same boat 27psi with a taper to 21psi is the efficient range but turbo is good for 29-30.

This post is not to bash anyone it’s just a warning to be careful what you ask for. More boost doesn’t = more power all the time

[340TBD]

Also on jb4 I wouldn't boost past 20, the engine runs at lamba 1 14.7ish until egt gets too high or the protection timer hits 30sec of wot. To run high boost you need a flash tune or a bef to adjust fuel maps and timing and a downpipe.

[ichigom340i]

He also mentioned that they lost power on more boost on that video too. I just thought it was crazy that he said 34lbs of boost!!

[xnick101]

Originally Posted by ichigom340i

This guy with the Supra said the stock makes about 34 lbs max. interesting video he says it about the 44:38 mark
https://youtube.com/watch?v=xTYPT_Oz...p4j0yPj_3R-uVa

He said 34 psi on his own car, but wouldn't do that on a customer's car. He said the wastegate was completely shut. At that point you are not wondering when it will blow, it will blow up. But that's with a custom tune and lots of cooling (Meth and e85). This is not achievable on JB4.

[Info@mad-us.com]

More boost does not always equate to more hp.

[AshtonPJT]

Originally Posted by info@mad-us.com

more boost does not always equate to more hp.

🙌🏻

[340TBD]

Really wanna see a compressor map on the b58 turbo to see what psi it will fall out of the islands. Also does the m340i have a bigger turbo than the 340i? I saw someone mention it a while back but it's never been discussed since then. On my m340i I can easily do 23 up top on like 70 to 80% wgdc whereas on 340i is starts to fall off with similar wg position tables.

[xnick101]

Originally Posted by 340TBD

Really wanna see a compressor map on the b58 turbo to see what psi it will fall out of the islands. Also does the m340i have a bigger turbo than the 340i? I saw someone mention it a while back but it's never been discussed since then. On my m340i I can easily do 23 up top on like 70 to 80% wgdc whereas on 340i is starts to fall off with similar wg position tables.

Yes B58TU turbo's have a 15% larger hotside over the B58 cars.

[Gryph8n]

Adding ethanol will help with your timing issues. Optimal range is E30-40 with stock turbo. Lower than E30, you don’t get enough octane boost. Higher than 40, you max out trims. For my M440i, I mix E85 with 91 octane for a blend that ends up around 98 Octane with the ability to up the boost on JB4 over 93 octane.

[mike@x-ph.com]

Originally Posted by Gryph8n

Adding ethanol will help with your timing issues. Optimal range is E30-40 with stock turbo. Lower than E30, you don’t get enough octane boost. Higher than 40, you max out trims. For my M440i, I mix E85 with 91 octane for a blend that ends up around 98 Octane with the ability to up the boost on JB4 over 93 octane.

target E35 and you will always be in the safe zone
i mix 4 gallons of E85 and 8 gallons of 91.

[Gryph8n]

Originally Posted by mike@x-ph.com

target E35 and you will always be in the safe zone
i mix 4 gallons of E85 and 8 gallons of 91.

Exactly, I target E35 for that reason. Do you know the tank capacity for M440i if you fill to top? I’ve seen 15.5 gallons but when filling to top 17.2 gallons too.