i am upping my FP from 13 lbs to 16lbs or possibly higher. in my calculation of BPW it has a correction for FP being used. I believe the ECU(7747) assumes 12 lbs as for GM specs. should i correct the BPW when i up my FP?

 

ttt

 

I would. I am in the camp that thinks your BPW should match what you really have, then tune from there. I don't like the idea of trying to manipulate the BPW to try to compensate for a bad tune.

If you part throttle tune is good, but your going static, if you correct the BPW, your part throttle should still be good, but you will have some more room up top.

 

I'm with Dewey on this one, get the constants accurate so the computer knows what it's dealing with. Here's a thread that deals with it

https://www.thirdgen.org/techbb2/sho...light=bpw+8746

That I see you're already posting in

 

thanks. did the change from 13 to 16.5 this weekend. engine seems to like it. SOP. seems if i did not change the BPW i would have been globally enrichened.

 

I'm with these guys, correct the BPW to what it should be, if you run out of room, kick up the fuel pressure again and adjust the BPW accordingly. So, fuel pressure correctoin would be:

Say you have 80pph injectors at 13psi, then at 16psi you'd use:

SQRT(New pressure/Old pressure)*Old Flowrate to get: 88.75pph injectors approximately.

Now, with some math RBob sent me a while back you can use:

350ci: 350 * 16.39 = 5736.5 = 5.7L

5.7l / 8 = 0.7125l/cyl

88.75#/hr: (88.75 / 3600) * 453.6 = 11.1828 gms/sec

BPC = 1461.5 * (VOL/RATE)

1461.5 * (0.7125 / 11.1828) = 93.1179

BPC = 93

That should be the right BPW to use, I'm sure RBob or someone else will come in and correct it if I butchered that in any way

 

those were my calcs exactly cept i have 80 lbs FI's. i came up with 90 BPW.

 

Near mine as well. With my setup it runs best with 97.