Adjusting tune for higher fuel pressure 43.5 - 58psi

[evilstuie]

Hi All,

I've been replacing system after system in my car chasing a cause for a backfiring and stall at high rpm when I go WOT and the car kicks back a few gears and I've just replaced the fuel pump and regulator.
It's an 85 TransAM with 400SBC and 24x conversion, and has the 2001 LS1 firebird fuel tank in it.

Long story short after putting a walbro 450 in and new aeromotive regulator, I can't seem to get the pressure down to 43.5 psi.
I have AN8 lines from the tank to the front of the car, then go to AN6 from the filter to the rail and 6AN from the regulator return line to the AN8 line back to the tank.

I'm using Ford EVO 36lb injectors rated for 43.5psi.

My question is, in order to adjust the tune for the higher pressure, as I can adjust the regulator to sit at a stable 58psi, what do I have to change?
The regulator has the vacuum hose attached, and I'm assuming the rest of the tune is set up for the injectors.

I'm also wondering if I have to change any of the crank settings to get it to start easier/with the right fueling?

I've attached the tune if anyone is able to take a look and either edit the tune for the higher psi, or let me do it and tell me what to change.

Thanks in advance guys.85TransAM-Stock.hpt

[5FDP]

Change the injector flow rate to whatever they flow at when set to 58psi.

Then go over the airflow model tuning again to touch it up for the increase in fuel pressure. So go back over the VE and MAF if you are running one. Those are the biggest things, then if you need to touch up idle airflow you can do it then.

[evilstuie]

Change the injector flow rate to whatever they flow at when set to 58psi.

Ok, unfortunately I can't seem to find any data on what they'd flow at 58psi though
This is everything I could find:

The Bosch 0280155868 flows 375 cc/min at a tested pressure of 3 bar (43.5 psi).
Latency (dead time): 12 volts, 0.605 ms; 14 volts, 0.305 ms
Our lab routinely tests and retests incoming parts.
Recent open flow test of six injectors showed a flow of 366-378 cc/min at a constant pressure of 43.5 PSI for each injector tested.

Length: 3 inches, 74 mm
Diameter: 17 mm
O-rings: New Viton Top and bottom, 14.5 mm
Resistance: 15.4 Ohms

They have 24508208 stamped on the side of the injectors.

Then go over the airflow model tuning again to touch it up for the increase in fuel pressure. So go back over the VE and MAF if you are running one. Those are the biggest things, then if you need to touch up idle airflow you can do it then.

This bit went way over my head, sorry I should have mentioned I'm fairly new to tuning in general.
I'm running MAFless so that's one less thing to worry about, VE I can adjust with the wideband once it's running, but idle airflow etc, I'm assuming it'll be the same and just trim with the wideband or narrowband o2 readings?

I guess really I'm just stock on the flow rate to pressure conversion. Is there a formula or excel program that can do it?

In the tune the table values are all set to 4.54 but I'm not sure what is a measurement of (lbs/psi/volume?)

[evilstuie]

Ok, tried using my brain a bit and figured it out.

Flow rate = g /sec

Then used the raceworks calculator to work out the effective lb/hr rating of the injectors, so 375cc @3 bar = 35.7lb/hr and @4 bar = 41.2ln/hr
which is 5.199 g/sec using the HP tuners conversion.

I then did the conversion using the 3bar values and it matched what was in the tables already.

I'll see what that does to idle and go from there on the rest of the VE.

Thanks 5FPD (and me :P)

[2xLS1]

4.54 g/sec = 36 lb/hr Use this to scale your injectors. Don't slope the IFR if the regulator is vacc referenced.

[5FDP]

I always have my table set to show Lb/hr and not g/sec like yours is now, it's easier for me that when I'm putting new values in.

[evilstuie]

Ok thanks guys.
I've got the fuel pressure flow rates uploaded and I'll take the car for a drive tomorrow and see how it goes.
I think everything should now be ready to do some fine tuning and get my wideband dialled in for cruise, acceleration and WOT/PE

[cobaltssoverbooster]

Monitor afr error against injector flow rate axis.
Throw number in there you think is close and then tune the fuel error down within 2 %.
Go into the fuel table you are tuning and add 10%. Record the resulting error, it should be close to a 10% shift from the values you recorded in earlier after tuning it in.

If you record less than a 10% increase in error then make the flow rate smaller.
If you record more than 10% then make the flow rate larger.
You only need to be within a few percent of the 10% you commanded extra. Obviously the closer you get the better. After adjustment start back over on the steps because your base data will change.