Any easy way to convert existing VE table from static FP to BRFP regulator?

I have had my turbo 5.3 tuned for a few years now and it has run very well. I originally tuned it to run a constant 58 psi, so my VE table is based off of that. I recently switched my fuel system around to run a boost/vac referenced regulator setup and have been tuning around that. Injector data is all set up correctly (0 KPA value across the board in IFR) and the car ran excellent with very minimal tune changes during normal cruising. Under boost however, as one would expect, it runs EXTREMELY rich considering it is now adding 15 psi of FP on top of the normal 58 psi. I'd hate to start from square one re-tuning the boost area of my VE table, so I'm wondering if there is an equation or chart someone made up that will convert the necessary fueling adjustments based on the increase in fuel pressure?

Here's my thoughts......

Ball park would be to reduce the VE at the Boost map values equal to the delta fueling. If its a Boostapump style then it equates to about 12% increase in fuel so to keep the same AFR you need to decrease the VE by that amount. I would recommend a 12% decrease at the MAP that it is enabled and up.

If its a 1:1 style then I would pull the 12% from the highest boost area anticipated and interpolate from there down to the 105kPa row. reduce above by 12% like above.

Ed M

Thanks a lot for the tip mowton. I figured it was quite a bit richer, and 12% sounds about right. My AFR used to be in the low 11's under boost and now it pegs my wideband at 9.9 under boost, so it's getting much more fuel. Forgot to mention I'm on a speed density tune but that was probably assumed anyways. I am using a 1:1 style reg, so the fuel increase is linear with boost. I'll go ahead and give that a shot. After having the car tuned for so long, it's killing me not being able to use the "loud pedal" haha.

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Originally Posted by nightmareta

Thanks a lot for the tip mowton. I figured it was quite a bit richer, and 12% sounds about right. My AFR used to be in the low 11's under boost and now it pegs my wideband at 9.9 under boost, so it's getting much more fuel. Forgot to mention I'm on a speed density tune but that was probably assumed anyways. I am using a 1:1 style reg, so the fuel increase is linear with boost. I'll go ahead and give that a shot. After having the car tuned for so long, it's killing me not being able to use the "loud pedal" haha.

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Your welcome, just for notes, the 12% came from the differnce in flow rate from 58psi to 73psi fuel pressure based on my injector calculator.

Good luck,

Ed M

ok so what happened?