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KizmoTek KizmoTek is offline
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Question How to always allow "over boosting" on BMW B48? - 09-18-2020, 02:40 PM

I have a 2019 BMW 430i and I installed a JB4 some time ago. I am running Map 2 with 91 octane.
Whenever push my car hard or if I've been driving around a lot, it feels like my car has less performance so I did some research and it turns out that most turbo cars have temporary over boosting built in for situations where you need more power for short periods.
Normally I would run the other maps that have an absolute target however I am in CA and they charge a lot for gas but don't have 93 octane lol

Is there a way to safely always have the turbo's run at a higher PSI? Map 2 does add +4 PSI however if my car isn't over boosting, its around 16 PSI compared to when it is over boosting at 20 PSI
I'm fine with having lets say 18 or 19 PSI as long as its more consistent

I have no idea on what settings to configure to setup a custom map, I am still a noob at these things. If someone can help out, that would be great!
My other problem with Map 2 right now is that on 1st gear I get too much wheelspin when using Launch Control so it would be nice if I could set the extra boost to come in at 4500rpm on 1st gear instead of I think being at 3000rpm(Might be wrong) by default.
My car is muffler deleted and I ordered an intake so if there is something I can configure to add a bit more power maybe, let me know

If I can't do anything about this, then oh well... Worth a try asking
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KnifeEdge87 KnifeEdge87 is online now
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Default 09-18-2020, 07:05 PM

There is no "overboost" in the B48...

The Ecu constantly checks on a bunch of parameters to determine what amount of boost the engine should get.

If it detects knock, bad octane gas, excessively high intake air temps, etc. The ecu will hold back on the amount of boost commanded.

If you are using an additive map then the ecu's reluctance to command a high boost level will directly affect your actual boost level since you'll just be adding a flat 4psi (even the jb4 has safety logic to hold back on this if certain limits are breached).

California sucks, you can consider getting a water methanol injection system to help mitigate the effects of low octane pump gas or use E85 or E85+pump mix. E85 is preferred for tuning but depending on where you live, access is going to be a concern.

The jb4 can set up boost by gear but I'm not sure whether that is only working for the custom map or whether it applies to the "default" maps as well.
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KizmoTek KizmoTek is offline
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Default 09-18-2020, 07:44 PM

Quote:
Originally Posted by KnifeEdge87
There is no "overboost" in the B48...

The Ecu constantly checks on a bunch of parameters to determine what amount of boost the engine should get.

If it detects knock, bad octane gas, excessively high intake air temps, etc. The ecu will hold back on the amount of boost commanded.

If you are using an additive map then the ecu's reluctance to command a high boost level will directly affect your actual boost level since you'll just be adding a flat 4psi (even the jb4 has safety logic to hold back on this if certain limits are breached).

California sucks, you can consider getting a water methanol injection system to help mitigate the effects of low octane pump gas or use E85 or E85+pump mix. E85 is preferred for tuning but depending on where you live, access is going to be a concern.

The jb4 can set up boost by gear but I'm not sure whether that is only working for the custom map or whether it applies to the "default" maps as well.
Oh okay, makes sense. Maybe the new intake will help with the temps. Thanks!
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KnifeEdge87 KnifeEdge87 is online now
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Default 09-18-2020, 07:50 PM

Post a log of a wide open throttle run from 2nd gear or 3rd gear starting from 2500rpm to a bit after the upshift to 4th.

If you have access to E85 that's the preferred route for tuning (compared to water methanol injection) but in both cases you really need a custom tune to make use of this modification.

If you're really chasing performance it is a good route to take, you'll be dropping stock M4s easy.
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KizmoTek KizmoTek is offline
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Default 09-18-2020, 08:05 PM

Quote:
Originally Posted by KnifeEdge87
Post a log of a wide open throttle run from 2nd gear or 3rd gear starting from 2500rpm to a bit after the upshift to 4th.

If you have access to E85 that's the preferred route for tuning (compared to water methanol injection) but in both cases you really need a custom tune to make use of this modification.

If you're really chasing performance it is a good route to take, you'll be dropping stock M4s easy.
I do have access to E85 however I'm not going to do the mods required to get it working with my car because it's a lease. I'll post the logs on Monday or Tuesday.
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KnifeEdge87 KnifeEdge87 is online now
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Default 09-19-2020, 03:47 AM

Ah then I think you're stuck with map2 or map3 if you can't do hardware mods
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