BPW setting??

[blue68deville]

How important is the BPW setting? Which way does it change fueling, more fuel when you go with higher #s??

The reason I ask is when I first ran my tbi with the stock ANTY bin, it was pretty rich across the board. BLMs were all around 100-110. The BPW in that bin is 134, and when I did the calculation to change BPW it was 151. I'm using 74lb injectors in a 7.7L engine. That seemed like it would just add more fuel (unless I've got it backwards in my head), so I left my BPW setting at 134 and started tuning VE. I had to lean it out a bit, but it seems to be doing well now. I'm within 120-140 in all my cells.

[dave w]

BPW is often a moving target. Injector flow ratings and actual injector flow are often not the same. It's interesting that a 7.7 liter engine with 84 lb injectors would have a BPW of 132.

dave w

[blue68deville]

The stock 454 (7.4L w/80lb injectors) BPW was 134, my Cadillac 472 setup (7.7L w/74lb) calculated out in the spreadsheet to be 151.
Not sure if this is a big deal or not, the car is running well. I've just never done any efi tuning before and wasn't sure if there's some weird effect that will pop up later.
I've heard that this Caddy engine design was pretty efficient, figured it was just talk. Maybe not??

[dave w]

I don't think it's a big deal that the BPW is not exactly to the spreadsheet calculator. Injectors flows can vary; for example if an 80 lb injector was flowing 5% more than the rated flow, the flow would be 84 lbs. Typically, when I have a set of injectors cleaned, the flow difference between the two uncleaned injectors is 2% ~ 3%.

dave w

[RobertISaar]

BPW/BPC is quite the fudged value anyways.... it isn't anywhere near critical, since you'll make up for it in the VE table.

running too high of a BPC will cause your VE table/tables to add to above 100%, which will cause issues.

running too low of a BPC will cause your VE table/tables to look very low and you'll lose table resolution.

[sgtpoliteness]

Not meaning to hijack here...

I've got a 16197427 $0D and am unable to locate where I would change BPW, if I needed to. I was also messing with the calculator and was curious if what I came up with and what GM had are close. =) I've hunted through the scalars and tables to no avail.

[dave w]

Not meaning to hijack here...

I've got a 16197427 $0D and am unable to locate where I would change BPW, if I needed to. I was also messing with the calculator and was curious if what I came up with and what GM had are close. =) I've hunted through the scalars and tables to no avail.

The $OD definition uses actual injector flow, not BPW. See attached screen shot

dave w

[sgtpoliteness]

Thank you, Dave!