Hi, what is the Highest Boost on the Stock Twins.
With the Stock Injectors ?
Right now i have mine set at 12 PSI.
car dynoed 303 WHP.

i was aiming at tryin and reach 15 PSI.
but i don't know if these could be reached with the Stock Injectors.
( i have Walbro Fuel Pump and Adjustable FPR)

 

i hope you dont have a stock ecu

you could to ~ 13-14 with aftermarket ecu .. ant may b 15 psi with water inejction and some decent octane fuel

 

You can run 15 psi on stock injectors with the stock turbos. Been done many times before.....my dad has been doing it for years now with a completely stock fuel system. I don't really endorse it, I try and convince him to keep the boost closer to 12 but I'm not sure he listens to me

 

I have replaced my secondary injectors with 1300cc's and I am only boosting 13psi and I hit 85 percent duty cycle. This is on 92 octane and mods are in my sig. I dont see how you can run that much boost unless you dont have that many other mods done. Also, when it is cold out and if I will creep to a little over 14psi and my injectors will hit 95 percent duties.

 

It goes against conventional wisdom, but the stock side feed injectors can be max'ed out at 100% duty cycle for long periods of time with no detrimental effects. I believe it's because the injector bodies themselves are cooled by the fuel and thus do not overheat even from repeated wide open use.

Back in the mid to late 1990's many PFS built cars were making ~400 rwhp on stock injectors.

 

would a standed pump handle 2 880 and 2 1700 at 14psi yes aftermarket ecu ?

 

I personally would try bigger secondaries.. 1300cc's are what i'm getting. Steve Kan just tuned my car yesterday in Atlanta, i was running stock injectors and they were maxed out at 12psi. I guess it also all depends on your other modifications... But best of luck to you!

 

No. It all depends on boost and power levels, but with that much injector you won't be able to take advantage without a larger pump, such as the Supra tt unit.

 

One thing to watch out for with bored-out 850s (which is what the 1300s are)......they've been known to be failure prone over the years b/c they're modified injectors, and weren't originally designed to flow that much.

I ran 1300s for years with no problems, but many people have had issues with them in the past.

 

There are no 1300's you can buy that are true 1300's and not bored out 850's? If there are then i would like to get some because i need them to flow up to their full potential and be reliable. I never knew that about 1300cc injectors though, hmm.. Thanks for the warning Rich.

 

hmm I run 10psi daily with stock injectors and stock fuel system along with PFS PMC.

I rewired the fuel pump directly to the 12v line and my car immediately began to run REALLY rich and bogged down on its face.

Went to the dyno and pulled a TON of fuel out of the base map on the PFS PMC.

10psi - 10.5afr - 260rwhp

I ran all the way up to 15.5psi!!!! on the dyno. Injectors were maxed out and I fuel curve was 10.5 all the way to 75000rpm, after 75000 it dropped to 11afr. I made 320rwhp with stock catback and dp/midpipe/ported wg.

The injectors duty were probably maxed out 100% but it doesn't really matter as long as AFR stay solid.

I ONLY run 10psi now. Maybe I'll bump it up to 12.5. But at 12-13psi there is plenty of fuel on my car...I can easily bog the sh*t out of it with a 9.5-10afr at 12psi on stock fuel

 

if anything you will make more power but detonation will become an issue...

 

How much boost is safe to run on the stock turbos of a third gen rx7? i wanna run 12psi but i dont want to push it either, fuel system and ecu is completely stock but i do have an aftermarket intercooler so would it be safe to run 12psi with manual boost controller...


other things i have read is that theres a fuel cut off aswell if you go over 10 psi

i just kinda wanted to make things more clear there so many different opinions on here

THANKS!

 

Stock injectors with upgraded pump 12psi

4x850cc's with upgraded pump 14psi. Can run 15 psi but your duty cycles will be in the mid-high 90's.

stock 550's and 1300's with upgraded pump and you can run 15psi all day long.

You can also add water injection which requires you to pull fuel from the map and thus have more injector. You would have to get your car retuned but I could see running 15psi on stock injectors with water injection.

 

why risk it? you can pick up 1000cc injectors for less than 150 all day long.