Need help with injector constant

[R_Andersen]

Guys, I'm running Bosch 42.5 lb injectors and need some help with the injector constant for the chip. I'm currently running a 30 (hex value) constant and with this constant I have to run about 35psi static fuel pressure for the blm's to be close to 128. I'd like to change the constant to bring the fuel pressure up to about 43 psi. I'm just not sure what I should change the constant to. I was thinking something on the order of 26H-28H but I'm not really sure. Is there a formula to convert the constant to a real world value, i.e. 48H = 28 lb/hr?

Also, is this the best way to get my fuel pressure to where I want it? Any advice will be greatly appreciated.

 

[JayC]

Define "even close" to 128. For some odd reason lately people are putting way too much importance in the block learn being right on 128.

 

[R_Andersen]

With the static fule pressure at 35 psi the blms range from 115 to 140 (most in the 120-135 range). I would like to keep them in the same range but at approx. 43 psi static pressure. I am getting poor milage and I want to see if a higher fuel pressure cleans up the injector spray pattern and helps milage at all. Thanks for the help.

 

[JayC]

So why do you think there is a difference in fuel delivery with the different fuel pressures? You do understand the BLM is a scaling factor for the fuel delivery and as long as it's not bottomed out, it doesn't really matter what it is, your fuel delivery is going to be about the same. The ECM is still controlling how much fuel the engine gets so by varying the BLMs basically you just get the same amount of fuel in a different length pulsewidth.

 

[GNandGS]

Formulas? They are published on gnttype.org... info you need is in the spreadsheet.

Shawn

 

[R_Andersen]

Correct Jay. I'm not trying to change the fueling. I just want to run a higher static fuel pressure. This way the pulse width will be shorter but at a higher pressure for the same amount of fuel. I believe this will geive me a better spray patter from the injector and possibly help with milage.

 

[R_Andersen]

Originally posted by GNandGS
Formulas? They are published on gnttype.org... info you need is in the spreadsheet.

Shawn

Doh, stupid me. I didn't even look to see if they were in the spreadsheet. I got them now. Thanks.

 

[TurboJim]

I use 2D or 2E for 009's, I use 29 for 50's.

Havent had the need on 009's since theyre fat to begine with, but set the closed loop temp and timer to 00 9A (403-404) and enable temp to 68 (405) to get rid of the rolling idle during warm up.

Seems the delphi injectors all like these values. Havent had a need with Lucas, but ya never know. Maybe I can save you some trial and error.