Increase Boost confirmation

[jetspeed]

I just want to get a confirmation since it has been a while since I dabbled with my setup.

I saved these notes from my Tuner (Sean @ Church)

Hi, the boost numbers correspond to wastegate duty cycle targets.
Because the response of the engine is not completely linear, in order
to get the boost curve we want across the entire rpm range, we have to
vary the wastegate duty cycle. In an ideal world we would just enter
wastegate dutycycle itself and be done with it, but that wasn't how
Hondata originally structured the S300 boost control (they have made
some additions in the new beta version).

If you are interested in increasing or decreasing boost, the best way
is to add or subtract the same amount to each cell. This will
preserve the shape of the boost curve and just raise or lower it to
the desired level.

Correct me if I'm wrong, I don't have access to my ECU right now, I already changed this once in the past and I'll have to refresh my memory, but to increase or decrease boost I need to change the values obviously in the Boost by Rpm & Gear table and I also need to change the Pressure vs Duty Cycle table values both, also the maximum pressure in the Boost by Rpm & Gear table and also the Duty cycle % have to match.

For example if i wanted to increase boost from 22psi to 32 psi in the Hondata example chart below. Would I add 10 to both the Duty% and Pressure values?

[Spunkster]

No you will need to test to see what pressure specific duty cycles will achieve and make a spreadsheet and then put those values into the table.

You can also have gear based duty cycle or gear based target boost for the control method.

[jetspeed]

Right now Gear based Target boost is selected for control method, so he already did the Fixed method to come up with the values originally.

I know if i want to increase boost to 32psi for example on the Boost by Rpm & Gear table i need to set it to 32psi for X rpm.

What did Sean mean or what do i need to do to the Pressure vs Duty Cycle table values. I know the maximum or last value has to be 32 psi which in the example means I need to increase it to 32psi but what about the rest of the values do i also add 10psi? As you can see from his email to me there is no mention of testing anything just changing the values. I do recall in the past i put the values in a spreadsheet and make a table to give values but they are linear which might not be the best method.

[Spunkster]

You need to use the fixed duty to first determine what duty cycle will get you to 32psi. Then edit the duty vs. boost table accordingly.

[jetspeed]

I see what you are saying and it makes sense, but when i contacted Sean about increasing boost after the dyno, he never mentioned having to get back on the dyno again to use the fixed duty method to get the new desired psi. Now since I believe you mentioned in another thread the formula Hondata uses, is linear, would it be safe to use values based on extrapolated results?

I put the values in an excel spreadsheet and using their extrapolated values that which are based on linear trends, this is the result. Are you saying using this linear formula is incorrect?

4.9 5.2 6.1 7.4 10.7 14.8 18 22 22.55357143 25.09047619 27.62738095 30.16428571
25 35 45 50 55 65 75 85 91.07142857 99.22619048 107.3809524 115.5357143

[Spunkster]

you cannot exceed 100% duty cycle. Talk to your tuner again and explain exactly what you are trying to do and he can set you straight.

[jetspeed]

You are right i missed that. So if i understand you, there is no way to do this off the dyno and requires going back to the dyno again.

What do you think he meant by his statement? Also the example below the duty cycle is already around 85% on mine if i recall at 20psi it was only 40% duty so, would using linear extrapolation allow me to increase the boost granted the duty cycle does not exceed 100% without going back to the dyno?

thanks

[Spunkster]

You may have to change the frequency and make a new boost vs. duty cycle table.

[jetspeed]

The frequency is 78Hz from what I recall, ill have to double check. But just to be clear, are you saying i can use linear extrapolation to increase the boost without going to the dyno again?

[Spunkster]

No, you will need to find out exactly what duty is needed to run the boost you want and fill in the table accordingly.

[jetspeed]

Ok, thanks