austinramsay

Im kind of confused about upgrading my fuel system on my fd. So if i was going to boost more and my injectors went over 85% duty cycle, id need bigger injectors right?

What is the point of replacing primaries if you really dont need that much fuel in lower rpms anyways? Could i just get bigger secondaries? How do you know what size to get? Stocks are 850cc (secondaries correct? Can you get too big of secondaries? Like say if i went with 1600s, your tune would say how much of that injector to use so as long as its not too small (restrictive) it doesnt matter right?

When do you need to upgrade the stock fuel pump? How do you know which one to get, what are the options for the fd? How do you make sure you arent going too big? Or too small?

When upgrading your fuel pump do you need a fuel pressure regulator since your pressure is being increased with a bigger pump? What pressure do you want to aim for?

Sorry for all the questions im just trying to learn about all this haha

rejckt

iTrader: (5)

Alot of people do just upgrade the secondarys, take a look at rx7store's extreme fuel system, which is a kgparts rail, aeromotive fpr + 2 secondary injectors. As far as fuel pumps go, I believe most people opt for the bosch044, nippondenso, or warboros.

I think you'll need to post your setup if you want more accurate help, are you running stock twins or single turbo?

Rxmfn7

iTrader: (4)

https://www.rx7club.com/auxiliary-in...turbos-888852/

Some good info there ^

To address some of your questions specifically, going with too large a secondary in comparison to you primary can lead to some staging issues when tuning. As ECUs as well as injectors have gotten better, this may be less of an issue but still should be considered. With some of the new ID style injectors, guys are now running much larger primaries than would have been advised in the past and still are able to have good tip in and idle control due to the better atomization and flow characteristics.
Fuel pump sizing shouldnt be too hard to figure out once you know how much injector you will be running. Common upgrades are the supra pump and regular gas and normal base fuel pressures should be good for close to 500. There are many other options and opinions, search is usually your friend

austinramsay

Im running a single garrett t78 turbo on 13 pounds. I have an apexi pfc also. Im just aiming to get a good reliable tune at 400whp. The previous owner didnt really know all the specs of everything so i dont even know if my injectors are stock or if any of the fuel systems been upgraded or anything haha. But i was just trying to understand what i need to do in case i need to upgrade. And yeah i tried searching but its hard finding all these answers

needspartsnow

iTrader: (10)

I can't answer any questions about your car because I'm still learning my self, but as far as searching for info around here, the search feature on this site is garbage. I've learned to just Google whatever I'm looking for then add "FD rx7" at the end. It will usually bring you to a thread on this site. Example: secondary injectors FD rx7

rejckt

iTrader: (5)

If you want to use google and search the rx7club site only, add "site:rx7club.com" at the end.

@austinramsay, just take a look at your primary/secondary rails, I highly doubt your on stock fuel with that setup, but the stock system uses a side feed rail and most aftermarkets are top feed.

austinramsay

Yeah thats how ive been searching. And alright cool. Sounds like a dumb question but whats the difference of top feed and side feed? Im guessing top feed the injectors would be on top, but on side feed rails where are they at on a stock fd? How do you convert from side to top?

austinramsay

Yeah thats how ive been searching. And alright cool. Sounds like a dumb question but whats the difference of top feed and side feed? Im guessing top feed the injectors would be on top, but on side feed rails where are they at on a stock fd? How do you convert from side to top?

Slow2k

iTrader: (9)

Easiest way is to tell is to google a picture of the stock rails or find them for sale here and see if yours look like those. Or check your pfc settings..

Tem120

iTrader: (5)

if you upgrade to 1600's you'd need a new fuel rail . if you upgradeto 1300's which are bored out 850's you have enough fuel for 14 psi on the stock twins . and no rail needed . if you plan to go single turbo and the works then yeah upgrading the secondary rail with an aftermarket is a good idea . and

even though at low rpms you dont use that much fuel , when in boost you use all4 injectors . so if you went with some 750 primaries , and 1600 secondaries you'd have lots of fuel for like over 400 whp .

IRPerformance

iTrader: (41)

Because having a huge variance in injector sizes makes it more difficult to stage and tune them. While the stock 550s may be enough with a larger secondary, they are old and will eventually fail. It is also sloppy trying to adapt the stock primary rail to an aftermarket secondary rail. Newer style injectors also have a far better spray pattern and atomization. I've had 3 sets of 1300s fail this year alone. I will not use them. Bosch EV14/ID injectors is all I will use these days. Everything else is a waste of time. I have the best results with a 725/2000cc EV14/Id combination for 99% of cars.