Ninjak

I remeber reading somehwere that with the stock injectors at one bar i would be running at 100% duty cycle, the most the injectors can pump out.... Even though i wouldnt be running at this level allt he time on the street, i would like to know what injectors i would need to drop in that would make my car reliable at that boost level. Was it 1200cc injectors in the secondary rail?
Thanks in advance
Huy
Open Exhuast,intake,Greddy SMIC, pettit Ecu
Currently Stock Fuel system running only 10lbs.

Ninjak

Bump, someone help please?
Huy

FD Racer

I started a thread a couple of weeks ago on a similar topic. Unfortunitly i had no responses. I do know that running the stock injectors at 100% duty cycle is not a good idea. They max out well before that. I heard even 95% is too high. You end up overheating, posibly damaging, the injectors if you run them too high to often. Theres been some talk about redoing the primarys to put out 850cc, giving you 850 on all four injectors. This was with the Apex PFC.
Anyways, I hope more people respond.. i am very interested to learn more on this.

capt. bill1

You should not run the stock, or any injectors for that matter, at over 80-85% duty cycle for any length of time. And just dropping in bigger injectors for primaries does not seem to be the way to go either. Some of the big names in rotory racing still use the 550 injectors as their primaries.
To do it right you need a programmable fuel computor and large secondary injectors. If you just drop in big injectors while only using an upgraded ECU that is not programed for the bigger injectors you will just end up running way to rich. At least this is what I have found in doing research for my setup.

neevosh

Anything over 85% duty cycle and the injectors will remain fully open(static, I think, is the word I'm looking for). Which means they're just dumping fuel in. An upgraded fuel pump will help to push more fuel in at higher fuel pressures when under boost. Ideally, larger injectors and fuel pump would be best. Optimum injector sizes depend on your HP goals. If running stock twins, 850cc primaries and secondaries, or stock primaries and 1200cc secondaries would probably be enough. I think I've heard the unlimited ecu can be programmed to run 1200cc secondaries. Or get a PFC and have it tuned for the injectors.

GoodfellaFD3S

iTrader: (213)

I've been seeing ~90% inj duty at 13 psi. I have a Walbro high-pressure pump, but I've been getting nervous and thinking of upgrading my injectors.

Chris at RP gave me the idea to run 850s all around. He said it's good for almost 400 rwhp and acc. to the fuel calculator on their site the setup is good for ~435 motor hp. I was able to buy a set of 850cc primaries w/only 15k miles on them for 120 bones. Chris said labor is around 6 hrs; getting to the inj's is a pain in the ***. They do some milling to get the 850s into the 550 fitting. I have a Power FC so it's a snap to reprogram for 850s all around.

I'm sticking w/the stock twins for awhile, so 380-390 rwhp is more than enough for now...

Ninjak

wow, thanks for all the replies everyone

I may not stick with the Pettit any longer, i would like to run the PFC, but if i stay with the pettit and drop in 850's all around will i have a prblem of running even more rich than i am now?
Also, how hard is it to do something like this myself?Installing the injectors....
Thanks

GoodfellaFD3S

iTrader: (213)

If you go w/850s in the primaries you'll have problems with an overly rich idle. Also, if I didn't have the Power FC I wouldn't think of screwing with my injectors.

As far as installing them yourself, Chris said there's some custom fabrication involved, so prolly not a good idea :p

Rich