Ever since I stroked the 350 in my Scarab to 393 I've been hitting 100% duty cycle on the 61 lb/hr injectors in my PowerJection III EFI unit whenever I try to go full 10 psi boost. Not being able to enjoy all the potential of the stroker motor I knew I had to do something. After doing a lot of research I boiled solutions down to 2: 1, Buy a new Holley Super Stealth EFI which comes with 100 lb/hr injectors for about $1500 or; 2, find larger injectors that will fit into my PowerJection III unit.
Besides expense, starting over with a new EFI would entail tuning from scratch which was a huge pain in the rear when I first converted to EFI.
A couple years ago I used AUS Injection in Mesa to rebuild my 61 lbs/hr injectors and they did a great job at a good price. So I called them to see if they could come up with some 100 lb/hr injectors for my application. After providing the specs I had they said they could probably build injectors for me. To be certain I took my unit to them so they could see how tight the injectors fit:
After inspecting the existing unit, they said they could build me 4 95 lb/hr injectors for $360 in a day! And shipped to Payson for free saving me another trip to the valley. The new injectors are the exact same dimensions and use the same harness plug as the old ones so no adaptor harness needed!
I installed the new injectors and upon their advice, I started out with the same tune I used with the old injectors. I first adjusted fuel pressure down to 48 psi from 75 psi. At 48 psi the injectors would push 100 lb/hr, what I calculated I needed to stay under 90% duty cycle at 10 psi boost. The car started and idled, albeit a little rough, on the first try. A little adjusting of the throttle plates and idle IPW to get the IAC down below 10 and I had a pretty smooth idle. Played with the throttle off idle for a while to see how it was learning, made a few adjustments to smooth that out and hit the road.
I drove around the neighborhood letting it learn a little more, made corrections to the fuel table before taking it out on the highway where I made several passes with a little more throttle, a little more boost, making adjustments to the fuel table based on the learning table after each pass. Way smoother, no hesitation, so far so good. I'll continue this cycle until I get the nerve to do full throttle full boost passes but I'm really happy with the new injectors.
If I find I'm exceeding 90% duty cycle, I'll increase the fuel pressure according to a curve I created from the injector specs to add another 10 lb/hr until I get to the right level. That'll require re-tuning but I'm feeling pretty comfortable doing that now.
If you need injector work, I can highly recommend AUS Injectors, they know their stuff.