i plan to upgrade my top feed to 1600cc injectors, do i need a new fuel rail? lines and clips? i plan to move my 850cc injectors down, do i need fuel rail there as well?

i have a walbro 255 pump, i plan to have 400whp do i need 2 pumps?

 

the 1600 will need a new rail, the 850's fit in the stock primary rail but it has to be ground down a bit because the stock 550's are longer with these injectors your going to need a fuel pressure regulator.

If your only going for 400whp you can use 1300 in the stock secondary rail and save alot of money I made 400whp with 850's and 1300's on 1 supra fuel pump and no aftermarket lines or regulator

 

The cheapest easiest option to safely support 420WHP or less (but no more), would be 4 850's stock rails eliminate PD an run an aftermarket FPR bumped to 55 psi base pressure, with a supra pump, the single walbro may be enough for 400 depending on which version it is.

The 1300's can be unreliable, mine once stuck open (but didn't technically fail just left me stranded).

No need to go crazy for only 400 WHP, more info:

https://www.rx7club.com/showthread.p...tors+max+power

 

slo thanks alot. i used the calculator and with 850cc stock on both top and side feed i reach my goal of 400whp with about 75-80% duty cycle. is this safe? my walbro is the 255lph. do i need a upgrade?

 

If you only want about 400whp and if you will be using a PFC ECU, do not use 850 primaries as they are hard to idle tune.

I run 550/1600 at 15.8 psi boost with my almost stock port GT35R engine without any problems.

 

do you have any stumble near 4000rpm when the secondaries comes in?

 

With regards to idle there is no substitute for good tuning.

I was able to get 1680CC primaries to idle good at 1K rpm with an E8 and I am far from a pro tuner yeah a PFC is a different beast, but I'm sure its possible.

There are a few different versions of the walbro 255, some of them are better than others.

 

my car idles fine with 850's and starts with ease
also I have a supra pump FS if you need it

 

oh

 

Unfortuneately the PFC has a few more limitations and although my idle is smooth with my 850/1680 setup my AFR at idle is pig-rich at 11.2. The 550/1680 will suppourt 400rwhp.

On your fuel pump, I think you will get some to say you can, and others say you cannot use it. Honestly I think it is borderline being able to feed that much fuel so I think it would be better to error on he safe side and get a bocsh or supra pump. Or I guess you could always get the drop-in dual walbro pump hanger from rx7store and just buy another walbro. That is another good option.