[crystal_Imprezav]

I am planning on getting protuned in June, and was looking into a couple of mods for a better tune. I am planning on buying an APS inlet pipe, NGK plugs, Walboro fuel pump, and some Helix 860cc injectors. I was looking at a post in nasioc about someone who just got protuned at Agile and the injectors seemed to help out a lot. He made 340whp and 380tq on pump and 350whp and 403tq on c16. My question is how much and is it necessary to buy some higher flowing injectors for a stock turbo tune? I am planning on getting a 20G in the future so I suppose I will be getting injectors eventually anways. Anyone have opinions on this? Thanks

[sciolist]

My opinion is that the OEM fuel system is adequate for the VF39.

[SoaReS]

The original fuel management IMO, is good enough for a tune on the stock snail. Plugs + the APS inlet is a good idea though. Um... I dont mean to hijack your thread but if you dont mind could you send me some pics of your rf-ti, because Im ordering the full tbe and Im just curious how it looks installed.

[2fas4u]

having been down this road and friends of Agile/Hill, I can tell you that the stock fuel system is more than adequate for the VF-39 tuning. The only reason I could see to increase would be if you are seeing 90%+ duty cycles on your injectors....

[izzodesh]

i am interested in this too... i know ppl with injectors have been putting down over 300 whp... not just 290whp at stg2

ps i have the rfl ti in the mail and it looks beautifulllllllllllll and sounds like a beast!

[bah14]

stockers are fine.

if you go bigger, i'd suggest what Cobb (and others) suggested at an EFI 101 tunning session in ohio this past feburary: DeastchWerks STi injectors (sp?)

Modded, flow tested and marked for proper PnP installation. Hard to beat that. And, they run like 100-150 less than the pe850's.

just a thought.

Good luck,
Brett

[bah14]

also....what you really should do is call your tuner and see what they suggest and what they are willing and able to do.

[WolfPlayer]

The stock injectors work just fine for a high power VF39. No need for injectors. They won't get you anymore power. Yes, I have upgraded injectors on my Stage 2 setup ... and I am here to tell you they aren't needed on a VF39 setup (I installed them because I'm preparing for a turbo upgrade and I have the ability, knowledge, experience, and equipment to tune my own car). Granted, the IDCs are high with stock injectors on a high power VF39 setup. However, I have yet to see a single VF39 setup fail due to maxing out the stock injectors. They work. Many many tuners have tuned hundreds of STIs at Stage 2 with the stock injectors. You don't need bigger injectors for a stage 2 setup. Will they give you the warm and fuzzys due to reducing the IDCs dramatically? Yes. But, that is all you will get - warm and fuzzys. Period.

t

[2fas4u]

Originally Posted by izzodesh

i am interested in this too... i know ppl with injectors have been putting down over 300 whp... not just 290whp at stg2

ps i have the rfl ti in the mail and it looks beautifulllllllllllll and sounds like a beast!

I ran 308 Whp on stock injectors... There is no need for upgraded units to get over 300 Whp. I guarentee you if you go with Hill, your gains will come from timing and proper tuning, not add-ons and mods....

[bah14]

Originally Posted by WolfPlayer

Will they give you the warm and fuzzys due to reducing the IDCs dramatically? Yes. But, that is all you will get - warm and fuzzys. Period.
t

yea well....maybe he's a lonely kinda guy. lol

well put.

[dexterous]

Originally Posted by sciolist

My opinion is that the OEM fuel system is adequate for the VF39.

Not to flame you or anything but your dead wrong. I assume you have never data logged your car stock or otherwise. If you do this and some searching you will find that its common knowledge that stock STI's have IDCs in the upper 90s.

I was running 113% IDCs until I got my modified injectors installed. Moving from the PDX stage 2 to stage 3 map (only the addition of injectors and fuel pump) lowered my EGTs 60c!!!

Depending on your final level of modification you may want to stay below 800cc. I found that once I went over 800cc my idle started to be noticeably rougher. Its not far from stock but its not as smooth as I would like it to be. The nismo 740cc injectors are most likely the best turnkey option for most people wanting to keep the stock turbo. I went the stock modified route and I have found it to be wonderful.

[WolfPlayer]

Originally Posted by dexterous

Not to flame you or anything but your dead wrong.

No, he is not dead wrong. You are. Adequate means adequate. We're not talking about theoretical perfection. We're talking about what is adequate and what works. Period. I ran up to 110% IDCs too. So have hundreds of others. HUNDREDS. Do you understand the magnitude of that? HUNDREDS of people running 100+% IDCs and there has not been a single point of failure due to maxing out the injectors. That's as simple as it gets. You are saying it is not adequate because of the IDC. I agree that the IDC is worrisome from a theoretical standpoint. However, the fact remains, the stock injectors supply enough fuel to make a lot of power on the VF39. Lots of cars tuned even just this past weekend with horsepower up to 320whp with no problems and good AFRs.

Your EGTs didn't come down because of the injectors.

t

[Delaware Subaru]

I just got tuned at Agile 3/24.
My mods that matter are-

1) Cobb catless TBE
2) Cobb SF intake
3) Walbro fp
4) 1 step colder plugs
5) Prodrive boost solenoid
6) Protuned accesport by Hill
7) STOCK fuel injectors

My #'s were 326.7hp@5547rpm & 330.7ft/lb@3873rpm. My AFR's were a steady 11:1 & IDC's 90%. I will be back at Agile on 4/15 to install my SMC kit running meth/h2o & Cobb crank pulley. I expect around 350hp & 375tq all on STOCK injectors. When Hill & I get finished with the meth my IDC's should be around 80%.

*edit* This was on a 05 STi

[91TB78]

Another option would be to go with an injection system. This route would lower your IDCs significantly by running a 100% meth tune or a 50/50 tune.

Just thought I'd throw that out there since an injection kit should be less than injectors.

[ChristianCGM]

I want to start off by saying that I know nothing about tuning and what IDC's numbers mean, but if you say that it is possible to run IDC at 100%+ safely then I will skepticaly believe you base on my lack of knowledge on this; to me this means that they are running out of room in their efficiency range. So in my minds eye it makes sense to use a larger injector that easily runs the same capacity as the stock injectors at 100%. Does this make sense to anyone else, but me?

I don't want to cause trouble, I am curious about this as well. I am debating doing larger injectors sometime soon, probably Nismo 720cc because I will be running a stock turbo untill much later in the year and don't want to go too large.

Also, would running some kind of injection, whether it be water, alc or a mix lower your injector duty cycle?

Wolfplayer - does your auto IC sprayer have any effect on your IDC's?