I have 72# @4bar injectors and given the amount of methanol I'm injecting I've never seen the injectors go over ~60% duty cycle. In the hunt for better fuel economy, and more effectiveness in DFCO, could I lower the fuel pressure to essentially downsize the injectors? Obviously some tuning will be necessary, but are there any other downsides?

I have a Walbro 400 in the tank and will be deleting the stock fuel pressure regulator and getting an Aeromotive adjustable one, that's the plan at least.

 

I have the same injectors. Are you sure its not in the tune? My mileage didnt suffer with them.

On an all highway trip after the injectors and blower (granted i had a huge pulley on there and I was only pushing 5.5# of boost) I saw about 18MPG

 

I know for a fact that DFCO is less effective with these big injectors. Since I have a T56 I use DFCO whenever I'm decelerating so it does help quite a bit with gas mileage.

The tune also has trouble with very low pulsewidths, leading to rich decel when not in DFCO. I've made it better but could never get the commanded pulsewidths low enough with the injector data that was provided to me.

 

Shouldn't be any issue with running less fuel pressure, with higher pressure you would technically get better atomization or "mist" out of the injector but the difference would be negligible lowering fuel pressure 10psi or so. Are you running the Siemens 60's? I had the same problem with rich decel and was using the banish dvd data, I purchased the dvd first to see what injectors he had on there, then purchased the injectors. Pm if you'd like, I can tell you how I leaned mine out on decel. After alot of research I found out that with the 60's and 80's and his dvd data, the numbers needed manipulated. Not in all cases though, I attributed that to OS and pcm differences over the years.