I just put some 36lb Seimen Deka injectors in my car. They were flowed at 43.5psi. I have the fuel pressure set a 45psi. I put the injector constant at 37.2lbs in the PROM. I had some Ford 30's in there that were flowed at 39psi. I had the fuel pressure set at 45psi and the injector constant at 31lbs. The BLM's were about 125.
Will the car run rich or lean now? I don't have a scanner right now and don't want to hurt any thing by going to rich (wash out the rings) or too lean (we all know what happens then).

 

First of all, there is more than one BLM value.

But, I will make a wild guess, your one BLM value will increase above 128.

And to run 117mph in the 1/4, the "some stuff" might be a supercharger.

How am I doing? Is this a test? I hate tests!!!

 

All motor. Thats the *** honest truth. Actually that is with a cam floating the valves at 6,100 and a converter slipping 16%. All untuned. Cam makes full power at 6,500. I also have to shift into O/D at the 1,000ft mark. With the valve float problem fixed and the converter back down to 6% where it belongs and tuned, that number should be around the 123-124 mark. Once I hit that goal I will think about the bottle. I did 117 on some 245 kuhmo aquatreads. My best 60ft was a 1.85. So there is more left in it as it sits but I have to baby it out of the hole. PM me for details on the motor if you are interested.
Does lowering the injector constant richen the fuel mixture?

 

That is right, lowering the injector constant richens the fuel mixture.
You should set the injector constant to what the injectors really flow and tune the VE, if you tune the car using the injector constant you can get the BLM's to 128 but that messes up alot of other stuff.

 

When I switched to the Ford 30's I didn't know there flowed at a different psi than Chevy injectors. I noticed that it was a little off so I just tuned from there. Once I was "done" tuning I found out they were flowed differently. I was lazy and left it the way it was.

 

So what is the correct inj. constant value if you have 24 lb. FORD SVO's and you have the fuel pressure set to 44 lbs. with vac. line connected?

I'd like to get the this straight before I start altering the VE tables.

Thanks,
Mike (1bad91Z)

 

Ford injectors are flowed at 39 or 39.5 psi. Chevy injectors are flowed at 43.5. You set the fuel pressure with the vacuum hose off. My cam only makes 10hg. So the pressure drop is 5psi connected. If your cam makes 14gh the drop will be different.

The equasion goes like this.
fuel pressure no vacuum / flow pressure x lbs
44 devided by 39.5 = 1.113924
1.113924 multiplied by 24 = 26.7 injctor constant

 

if you put the correct injector constant in at the constants table how can that mess anything up?

i was just wondering because i'm trying to start tuning a 165 maf setup for my afr headed 383.... it's running pig rich with the stock chip so i modified a bin and set the constant to 31.5 for the psi difference... how can letting the computer know what size injectors it has mess things up?

theyr'e ford 30lb injectors