Does Boost Dynamics (Boost Based Tuning) do anything?

[SJP0tato]

Hey guys,

I've spent the past few days trying to use the boost dynamics table to control my 4th gear boost spike. I have my WG Duty Cycles set pretty high, with the hopes BD would keep things under control. My only modification is a Corksport SRI/TIP, so pretty close to stock. I'm targeting 16.5 psi via boost based tuning.

WG Duty Cycles

	500	1000	1500	2000	2250	2500	3000	3500	4000	4500	5000	5500	6000	6500	7000
0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
6.25	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
12.5	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
18.75	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
25	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
31.25	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
37.5	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
43.75	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
50	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
56.25	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
62.5	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
68.75	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
75	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
81.25	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
87.5	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
93.75	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0
100	50	50	50	50	50	20	35	35	35	35	40	42	42	30	0

Here's the stock BD table for comparison:

Stock Boost Dynamics

-9.00	-7.00	-5.00	-3.00	-1.00	0.00	1.00	3.00	5.00	7.00	9.00
0.35	0.15	0.08	0.05	0.00	0.00	-0.01	-0.10	-0.15	-0.30	-0.70

First I tried heavily increasing the correction for over-boost values:
V-1.0

-9.00	-7.00	-5.00	-3.00	-1.00	0.00	1.00	3.00	5.00	7.00	9.00
0.35	0.15	0.08	0.04	0.01	0.00	-0.10	-0.19	-0.30	-0.48	-0.70

But I still got the same amount of overboost as stock BD values (between 19.5-20.5 psi):
V-1.0



Then I tried decreasing the values for under-boost, thinking maybe the momentum from building boost reaching the 16.5 psi target is too much:
V-1.1

-9.00	-7.00	-5.00	-3.00	-1.00	0.00	1.00	3.00	5.00	7.00	9.00
0.35	0.15	0.05	0.02	0.01	0.00	-0.06	-0.15	-0.25	-0.40	-0.70

With pretty much the same result:
V-1.1



Lastly I tried decreasing the under-boost values even further:
V-1.2

-9.00	-7.00	-5.00	-3.00	-1.00	0.00	1.00	3.00	5.00	7.00	9.00
0.35	0.10	0.04	0.02	0.01	0.00	-0.05	-0.15	-0.25	-0.40	-0.70

And once again haven't seen much/any change:
V-1.2


It seems like I should be seeing some kind of change, but it's like the different values have no effect.

I've thought of just using the WG Duty Cycles to limit the amount of wastegate allowed (as I've seen others doing), but in these 4th gear pulls the boost spike happens anywhere from 3k-4k rpm. I'd have to neuter the values in the WGDC all the way through 4k to solve this issue. Maybe BD does a better job adding boost than subtracting it from the WGDC table values?

[Fobio]

unfortunately, there's no definitive answer from Cobb regarding the true relationship between the Boost Dynamic tables and the Boost Target and WGDC tables.

But from my understanding, Boost Dynamics may be used more to control boost or keep it in check in regions with high temp swing (like here in Toronto).

Try lowering your WGDC @ 3000rpm...WGDC table values are LEADING indicators...your 3000rpm values will affect boost AFTER 3000rpm, not right on...so the spike you see @ 3500rpm, will likely have to be tuned with lowed WGDC @ 3000rpm.

[R.MS3]

You would want lower WG and almost stock boost dynamics to prevent boost spikes, not the other way around.

Start with 20 WG across the board from 68.75 tps and up, starting at 2500rpm.

Then on the boost dynamics, put 0.01 for for -1 boost error and -0.01 for +1 boost error.

Log again.