Boost Level

rdcinvibc · #1 (**permalink**) 07-24-2010, 04:30 PM

I am using a FAST XFI system on a 89 Ford Mustang 5.0 Twin Turbo engine and the engine internals are stock so I would like to keep my boost level between 6-8 psi and definitely no higher than 10psi. My turbos have external wastegates that are set at 8psi but I would like to use the boost control with the ECU I have also wired in an electronic boost controller to Pin C8 and have a 2 bar MAP sensor. Can I change the values in the boost table to use the ECU to maintain the boost levels I spoke with a FAST tech on the phone and he said the default values are used for 20 psi of boost which would blow my block into several pieces.

TurboNova · #2 (**permalink**) 07-25-2010, 12:31 AM

Use closed loop map in the boost control parameters. You will have to find your own PID values, google PiD to get a description.

Using closed loop map makes the boost table a percentage of your map sensor. So 50% of a 2 bar sensor should be about 7.5 psi but start conservitive

Turbo Loyd · #3 (**permalink**) 11-11-2010, 11:56 PM

Have been trying this feature with the default Pid values with decent control, on my Buick V6. I have been using following table for use with a three bar MAP sensor.

kpa . . . psia . . . psig . . . percentage
315 . . . 46.3 . . . 31.6 . . . 105.0%
300 . . . 44.1 . . . 29.4 . . . 100.0%
275 . . . 40.4 . . . 25.7 . . . 91.7%
250 . . . 36.8 . . . 22.1 . . . 83.3%
225 . . . 33.1 . . . 18.4 . . . 75.0%
200 . . . 29.4 . . . 14.7 . . . 66.7%
175 . . . 25.7 . . . 11.0 . . . 58.3%
150 . . . 22.1 . . . 7.4 . . . . 50.0%
125 . . . 18.4 . . . 3.7 . . . . 41.7%
100 . . . 14.7 . . . 0.0 . . . . 33.3%
75 . . . 11.0 . . . -3.7 . . . . 25.0%
50 . . . . 7.4 . . . -7.4 . . . . 16.7%
25 . . . . 3.7 . . . -11.0 . . . . 8.3%
.0 . . . . 0.0 . . . -14.7 . . . . 0.0%

Does this represent the correct interpretation of the instructions ?

Thanks

TurboNova · #4 (**permalink**) 11-12-2010, 12:41 AM

Yes that looks good except the 100% could be either 30 psig or 0 psig depending on how your wastegate is hooked up. If it is a bleeder or adder to the top of the gate.

Turbo Loyd · #5 (**permalink**) 11-13-2010, 12:40 AM

The set up I use is two stock Buick solenoids in parallel bleeding off pressure to keep the waste gate from operating. So far the higher percentage I use the higher boost I am seeing.

Like the feature as I can set the boost to come in harder at higher MPH to keep from breaking loose in first gear on a poorly prepared track