Jimmy M

Hi everyone!

Would like to install my fuel-kit asap, and need some help on what to do with the primary fuel rail.

Bought the "ultimate fuel-kit" from rx7store with 850pri and 1600sek.

I`m aiming for 300+ rwhp with stock twin`s, and was wondering; Should I change both pri and sek, or should I stick with the 550 primaries?

Read something about this a while ago, bad idle and fuel smell was mentioned with running 850 pri`s...

Thank`s

-Jimmy

catch-22

iTrader: (2)

stick with the stock primaries thats way to much for stock twins. the 1600s are pushing it. i made 301 with the stock fuel injectors a pfc and a walbro. how much boost are you going to run?

Jimmy M

Just enough to make it to 300, that`s what I had in mind...
I`m running 13-14psi now (I think, 0.9Bar), this is on the map that came with the pfc from rx7store. Duty cycle is seeing 100% at full throtle, and my afr is 13, that`s to high right?

I have walbro, pfc, 3" exhaust, fmic, twin power... Mild street port on engine...

badddrx7

iTrader: (7)

Stay with the 550 primary setup

later

catch-22

iTrader: (2)

yes thats way to high afrs your going to blow your engine. somethings not right with your tune. i was getting 300 with stock boost and ports. what im thinking is that you just need a tune. if you dont have enough fuel after a tune then put the 1600s in.

Mahjik

iTrader: (1)

You can make 300 rwhp on the stock fuel system easily. There is no need for larger injectors for that kind of power. High injector duty cycles aren't necessarily a problem. It sounds more like you need some tuning for your car more than anything at this point.

Jimmy M

Ok, thank`s...

Should I go down on the boost then? Or are the stock fuel system supose to backup 14psi ?

janrx7

i made 290whp at 14psi with stock injectors and a very conservative tuned. You can reach easily 325whp with stock injectors but thats it. Upgrade your fuel pump to a walbro or denso and replaced your fuel filter if you never done it.

hwnd

iTrader: (4)

whats wrong with 850cc/850cc? my idle is wonderful at 900rpms using 850cc injectors.

Mahjik

iTrader: (1)

You'll have to define your own idea of "safe". Take a read through these:

https://www.rx7club.com/showthread.p...threadid=85818
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/what-situation-do-you-have-259912/

People have made a lot of power on the stock fuel system. Safely? Well, that depends on what you consider safe. I think people today are a lot more worried about their engines than they were 7-8+ years ago. Most people on this forum today will recommend a fuel system upgrade when trying to go over 300rwhp.

gracer7-rx7

iTrader: (16)

I'm running stock 550 primaries w/ the stock 850s bored out to 1300cc. This setup supported my cars fuel needs to 350 rwhp. I have a street ported motor and sequential twins. Mahjik has some good links there.

Its easier to tune 550 primaries from what I understand.

Jimmy M

Thank`s alot everyone!

Have been reading the post`s you attached Mahjik, and that was good info...

Just don`t understand why I`m seeing 13 in afr, with 98~100% duty cycle on 14psi boost. Maybe I have low voltage suply or something to my walbro!? But, that said, I have not changed my fuel filter, so that is on top of my to do list now!

If that dosen`t help on the afr, I`ll probably have to install the secondary rail with the 1600cc injectors.

I also have a Aeromotive fpr that came with the fuel-kit, should I run this with my stock injectors?

hwnd

iTrader: (4)

Ensure you have no vac leaks. is this car still on the stock ecu? if so, ensuer your fuel pressure is at the within range, etc.

your duty cycle being 80% at 10v or 11v... or 21psi fuel... all those things make a difference in the final volume of fuel sprayed..

Dudemaaanownsanrx7

iTrader: (23)

Yeah check your fuel pressure, and make sure the vacuum is hooked up to the FPR, if it's disconnected it wouldn't raise fuel pressure with boost. Fuel filter is a good idea, as is rewiring the fuel pump. Even the stock fuel pump will flow a lot of fuel when rewired. There is no reason you cant get 300+ HP with the stock injectors even w/ the stock pump even more so with the larger pump.

Jimmy M

Working on the rewireing right now, and have ordered fuel filter!

I have a "how to" on the rewireing, that tell`s me to bypass a blue wire from the CIRCUIT OPENING RELAY to the +12 on the battery, with 20A fuse inline.

Would like to ask if it`s this blue one I should bypass?

-Thank`s

Dudemaaanownsanrx7

iTrader: (23)

Here's how I like to bypass mine. It gets rid of most of the stock system so if there is any issues it's very simple to figure out.

Jimmy M

Thank`s!

Nice write up and diagram. But than I`ll have to run a new wire all the way back.
But it`s not that much work... Just tought I read a write up on this one time where it wasent nesacery

-Jimmy

Dudemaaanownsanrx7

iTrader: (23)

Yeah there are several ways to do it. One uses the existing stock wires. I already had a wire for an amp run back and i put a distribution block in and split a 4 gauge into a 10 gauge for the pump and 8g for the amp. With a battery relocation its really easy to run a short wire over.

Raziel

iTrader: (1)

i got my stock secondary injectors bored out to 1300cc. Supported 300+ rwhp. Only issue had then were my stock twins wastegate and boost creep.