Fuel system recommendations? stock twins
 

Hi,

I'm looking to increase the boost with my factory twins to 15psi on pump gas. I already have a Supra fuel pump installed and I'll be porting the wastegate of the turbos. My car is mostly a weekend car and is only driven about 200 miles a month or so.

What other fuel upgrades will I need to support this amount of boost? I've been reading a lot of recommendations to NOT run bored out secondaries, so was thinking of going with the FFE step up kit+ ID injectors - would 1300cc or 2000cc be the better choice if i go this route?

Or would it be best for me to upgrade both the primary and secondary rails now and run ID injectors in both of them? I eventually want to run a single, but I'm not sure how far out that will happen.

FFE Step up kit should be more than enough (I'd choose ID2000 as price difference is tiny and extra insurance for the future). Also, while there, I'd send out the primaries for service/cleaning.

Ditto, the FFE step up with ID2000 and stock(cleaned) 550 primaries is my twins setup.

Edit - you'll want to get the low profile banjo bolt if keeping the hard pipes for the boost control solenoids. I have the halman MBCs so those hard pipes were removed.

I just went through this
If you keep the primary rail with your new step-up kit, you won't need the low-profile adaptor but you WILL need an alternate (relocated) method of boost control

Not to thread jack but I was looking into the step up kit as well, can the power fc control the 2000cc secondaries fine?

Yes, if your tuner knows what they're doing it isn't a problem. I ran 1000cc/2000cc injectors on a PFC and it was smooth as warm butter.

Thanks. I believe my primaries were serviced a year ago, but I guess it wouldn't hurt to just send em out again for peace of mind.


I'll be doing the simplified sequential mod and installing a greddy profec B. Would this work as the alternate boost control?

You don't need anything. If your injectors are still flowing fine and your fuel pump is fine you don't need anything. I have run just about that amount of boost before on a stock fuel setup. Injector duty cycle is max c.90% at WOT and I was still safely a bit rich. Backed it off back to around 13-14 PSI as until very recently I was still running the stock intercooler so didn't make sense to push it so hard until I could get a Greddy SMIC.

At most hotwire the fuel pump and then tune it. The stock pump and injectors can take more than you think and 15 PSI is still within their comfortable operating range.

I agree wiyh cib24
you dont realy need anything changed or extra whith the twins.

i run my twins at 15 psi and the oem pump and injectors are up to it. the car has 330whp on a safe tune.

if you want to uograde something for just peace of mind just add a big pump like a bosch 044
onky with that uograde my entire fuel map became 30% reacher . i had to lower the map (injection times)
so now even on wot the injectors only go up to 77% duty

Is that on pump gas? Our premium is only 91 octane here in CA.

As long as your boost control system allows you to cut away the stock hard vacuum lines that are used for the stock boost control system, you can make it fit

Some people only have 95 octane in the UK in places like Scotland and Northern Ireland (which is equivalent to 90-91 octane in the USA - different rating system), and they run several pounds more boost. With rotaries its more about the tune and level of timing and ignition retard than the quality of fuel used unless you are looking to push serious boost figures. Not saying it's not a limiting factor but you should be able to run 15 PSI without an issue on California 91.

Why do you even need a Greddy Profec? Just use the boost control baked into the Apexi Power FC. Works fine. Don't even need to port the wastegate or drill the pills as has been talked about on here ages ago. The PFC is sufficient with the right tuning setup and controls boost fine.

I still run sequential above stock boost levels around 13-14 PSI and my transition and boost control is significantly better than it was on the stock ECU, and all I have is a Power FC with a tune by my tuner. No extra boost control kit.

Cool good to know. I just happened to have one sitting around from another build. Haven't ported my wastegate yet either, so I'll talk to a local tuner and see if I can get by without it too.

It's not because the PFC is incapable, it's because the FFE Fuel Step Up kit doesn't fit with the stock vacuum lines used for turbo control

https://www.rx7club.com/3rd-generati...ation-1113015/

This is like watching the deaf try to lead the blind... :lol:


If you're going to make the effort to up the boost on your stock twins, why not just do it right instead of cheaping out and trying to push 20 year old injectors that are based on even older technology :lol:

Honest question: Do you understand how boost creep works?