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Tuning Tips - BMW 330e B48

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Good day all,

I have been tuning my car - BMW 330e B48 Hybrid.

Basically I built the motor - CP Pistons, CP rods, lowered compression ratio from 11:1 to 10.25:1, Supertech Valve, Supertech Springs, Supertech Retainers, ARP head studs, ARP Main studs, thicker head gasket to help lower compression further, ACL Race Rod Bearings.

Car has BigBoost Turbo 600Kit, the turbo is equivalent to a G25-550.

Car is currently running on pump gas (low grade 91 octane - best available at my country) and methanol injection (snow performance stage 2.5 kit).

I will be doing a race gas map after.

Currently on factory ECU using Bootmod3 for tuning which requires flashing over the ECU for every change.

These cars are more torque based. See below log:

https://www.bootmod3.net/log?id=617c917fae729b1d1d486358 (20psi map)

https://www.bootmod3.net/log?id=617c95d9c090c66e747d49e0 (22.5psi map)

https://www.bootmod3.net/log?id=61825f4cc090c66e747d5c06 (22.5psi map with reduced timing)

Curious your views and recommendations based on the logs.

What recommendations do you have for the following:

1. How to achieve maximum safe power (I did not adjust any knock sensors as was trying to keep it more safe for pump gas)

2. What recommendations do you have for dyno tuning (I am thinking to slowly adjust timing by 0.5 deg each time and check torque on dyno and when it reaches peak torque then that would be max timing)

3. What recommendations do you have for Timing VS Boost, I wasn't sure if to use more boost and lower timing or more timing and less boost.

Thank you.

Regards,

Shane

Hi Shane, unfortunately nI haven't tuned on this platform so I'm not sure how the various ignition maps are deployed or how the ECU decides which one to use (it looks like there are 4 separate maps in your logs with different timing), so it's difficult to know what the actual timing might be. Here's a couple of points though:

1. There is no knock detected based on the logged parameter however I would suggest using audio knock detection to actually confirm that this is properly detecting knock.

2. Generally I find even on a reasonable quality pump gas that you will find that around 22 psi is about the safe maximum boost you can run before you start chasing your tail with knock which then requires timing to be pulled out. You then start going around in circles adding boost, reducing timing and usually making more or less the same power but with more heat and stress on the engine. Of course that isn't always the case and some engines will happily take more boost but they are the minority in my experience.

3. Onto your specific questions. The process of optimising your tune is demonstrated in both the practical standalone and reflash courses. I would suggest making timing changes initially in 2 degree increments as 0.5 is probably too small to really show the difference (depending on the repeatability of the dyno). Once you're close you can start making smaller changes. It is unlikely that you'll be able to achieve MBT timing with that fuel/compression/boost level so use knock detection and tread very carefully.

4. In regard to timing vs boost, it really depends what you want to achieve - Ultimately it's all about cylinder pressure which is what generates the torque at the crankshaft. This leads back to my earlier point that on a low quality fuel you will be limited by how much boost you can realistically run without severely retarding the timing. f you start at lets say 10 psi and optimise the timing there, you can then start stepping the boost up in 2 psi increments and optimise the timing again. What I'm looking for is where the timing starts to fall off a cliff in order to prevent knock. This is a good guide as to what maximum boost you can tun on your particular fuel.

Hi Andre,

I initially got some knock using 22psi and stock timing tables so I reduced timing on high loads which eliminated the knock.

There are 4 main timing tables.

I am currently working on trying to get boost to stay on target on high rpms.

The B48s have a compressor map (target mass flow VS Boost Pressure setpoint) which can be increases to make boost hit target but when I increase it causes oscillations and over boost (depending on how aggressive, it can also cause throttle closure).

My car is using the factory Electronic Wastegate as well.

Curious if you have any recommendations for better boost control.

Thank you for the response, much appreciated.

Regards,

Shane

Hi Shane, if you're having oscillations in your boost that could be caused by PID gains that are a little aggressive. Particularly if your proportional or integral gain is set too high. If you're also targeting a boost that is unachievable then this can cause the integral component to wind up which can cause oscillations. The first step with tuning any boost control system is to achieve accurate and stable boost in open loop. Then you can start to add closed loop control. This will ensure that your base control is on point and means the closed loop system doesn't need to work so hard.

Hi Andre,

Below are logs from the same map, just re-flashed.

I am not sure why I am pulling timing now and detecting knock (Same fuel in the tank).

[url=https://www.bootmod3.net/log?id=61825f4cc090c66e747d5c06]https://www.bootmod3.net/log?id=61825f4cc090c66e747d5c06 - Log at Wed 3rd Nov Early Morning

[url=https://www.bootmod3.net/log?id=61832e56c090c628cf7bc2f8]https://www.bootmod3.net/log?id=61832e56c090c628cf7bc2f8 - Log at Wed 3rd Nov Night

Do you have any ideas what is causing this?

Do you have any recommendations? I am thinking to lower boost to 20psi for safety on pump gas.

I pulled plugs and all looks good, did a compression test one time and all good as well.

The only thing that was changed from Wednesday morning to night was I tightened the wastegate actuator linkage as I found the nut was running slack, I am not sure if this can cause anything.

Thank you.

Hi Shane, both the coolant temp and IAT are a little hotter in the second log which will make the engine more prone to knock, however the detected knock is actually picked up on the shift after you lift out of the throttle which in itself may not really be a concern. At the point the knock occurs the boost is actually down to about 16 psi too. Is the knock repeatable or was that a one off? If it's a one off then I'd monitor it but not be too worried. Knock under WOT is usually when damage will occur.

Hi Andre,

It appears to be a one off.

I created three maps which I will finalize timing and try to find MBT on dyno unless knock occurs:

https://www.bootmod3.net/log?id=618b142fc090c6283fe0b4f7 - 22.5psi

https://www.bootmod3.net/log?id=618c66cac090c65d65d11447 - 21psi

https://www.bootmod3.net/log?id=618c641ec090c65d65d1143d - 20psi

I don't like how the timing looks on the 22.5psi map and this is reduced timing.

Thank you for the assistance :)

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