What size pulley

[Chargedup14GT]

Have 2014 GT with full Roush stage 3 power upgrades. 47lb injectors, what is the smallest pulley I can put without changing injectors

 

[Pentalab]

Have 2014 GT with full Roush stage 3 power upgrades. 47lb injectors, what is the smallest pulley I can put without changing injectors

Either email roush... or VMP tuning. VMP will have the answer asap. I'm assuming pump gas, like 91/93 octane..and not E85. I forget the basic formulae for injector size vs max crank hp. I believe you will be ok with a smaller pulley, but you may require a BAP... which in turn will require a new tune, which u will need anyway with the smaller pulley. The BAP (boost a pump) is just an unregulated to regulated DC to DC converter ..which outputs a constant 17.0 vdc to the fuel pump at all times. The BAP may also require a wiring upgrade from eng bay ( typ right off the battery) to the trunk area.

I upgraded mine from oem small gauge wire to 10 gauge. Some will even use 8 gauge. That alone decreased my FPDC ( fuel pump duty cycle) by 10 %. In a lot of cases, the wiring upgrade alone will alleviate the requirement for a BAP. Run it by VMP. At best, you may have to do nothing. Next up would be the wiring upgrade. If that doesn't work, then the BAP is easily added. VMP also sells BAPS, as do several other vendors, like K bell and Roush, etc.

 

[redfirepearlgt]

The full Roush phase three package already has a boost a pump.

First and foremost I would encourage you to dump the ROUSH tune and purchase a tune from VMP. The difference in that alone will be amazing. I learned this first hand with a phase one package. I turned my back on Roush from that point forward and referred all future upgrades to VMP Performance and have never regretted it. What I do regret is not having the VMP supercharger head unit over the inferior Roush head unit.

As mentioned VMP will give you good direction. They won't short change you or treat you like a second rate customer as was my experience with Roush engineering when I tried to resolve issues being caused by Roush's nanny strategy tune.

For reference I am running an 82mm with 47lb injectors with a VMP boost a pump, JLT 123 intake, and dual 60mm TB on my Roush head unit with the rev limit set at 7700 RPM. Everything is fine at that level. I was considering dropping to a 79mm pulley and was told I could do this without updating anything but that they would have to restrict the rev limiter to a lower setting. Based on that I considered that half doing it, so 56lb fuel injectors along with the 79mm and retune are the potential direction this year after the stall converter goes it if my goal is not achieved at the current power level.

Best of luck.