So I've been thinking of upgrading my fuel injectors to the stock WRX (blue) injectors.

I've searched other threads and have found this one helpful: here

However, based on my modifications I wanted to know if there would be any benefit in upgrading my injectors? After installing the cams and getting a tune to suit, I notice that the car is running very well low-mid range, but top end isn't all that great. I mean, the car is quick, but it sounds much more powerful than it actually is.

I am certainly sure that I am running lean top end. Will increasing the injector size help lean the car out in the upper range ( ). It's almost as though it is breathless? Gains?

Mods: CAI > UDP > HEADERS > CBE > HFC > CAMS + CAM GEAR > ECU. Other: > Torque Damper > Short Shifter > Shifter Light.

Pushing about 200whp + give or take.

Thanks for your time

 

I did upgrade to blue injectors, however if you try this without any fuel management you will feel you car too rich at low RPMS and nice at high RPMS. Do know that you are trying to accomodate 100cc more out of each injector. Try to tune it and it will definitively give you some gains. WHat I did notice was that at third gear and WOT it pulled a lot harder so install them and tune ....!!!!

 

Sounds sweet.

Well after I put the blue injectors in, I'll give it another tune and make sure the tune is focused on mid-top end.

Anyone else would like to shed some light on their experience?

 

When you install it, slap it on a dyno. Bigger injectors means more fuel. More fuel means you'll be running richer, and less power. Tuning is everything. I learned from my experience. I'm richer than a pig in **** right now, and i only have 230 whp and 240 tq... embarassing...

get a dyno!

 

If you are not leaning out up top I am not sure you need injectors. Do you have a way to monitor you injector duty cycle? unless it is over 80% I don't think you would benefit.

 

Thanks Dan and Rol.

I am more than sure I am leaning out top. I'll ask my mechanic to see if he can monitor the injector duty cycle. (probably give more of a read on that).

I'll ask if i'll benefit by larger injectors as well based on my modifications.

 

you should edit the OP then.

why do you think you are lean up top? do you have wideband sensor logs that show it leaning out? I thought you had RPW/Haltech tune your car

you injector duty cycle will tell you how hard the injectors are working. the percentage is how much time they are open, so when it's 80% they are open 80% of the time. The longer they stay open the less effective your fuel flow is, that's why the target is 80% and not higher: the injectors aren't doing anything but staying open after a certain point. you have to figure this out before you decide your injectors are causing the problem.

 

i dont know if you really need larger injectors?

wasnt chowetime/rpw running turbo on stock for quite a while?

anyways, if u get them in, get the tune and monitor afr and get a dyno chart if u can

good luck

 

RPW have never tuned my car. They're on the West Coast of Australia and I am on the East Coast.
Haltech tuned the car before the cam and cam gear was installed. (Another tuner tuned after). Prior to the new tune, the car was running beautiful. The curve was linear and the power was distributed evenly across all rpms.

The only reason I ask because when I am driving, the car seems to be running lean up top. I feel as though the car is "gasping for air" top end. The tune before that seemed to be more stable in the upper range and the rev actually moved quicker to red-line.

Seriously, to be honest, it's not easy to explain online. Also, I can't confirm this without a wideband sensor as I am only going on instinct here, but I am pretty sure I am correct but who knows.

I'll speak to my mechanic about this, get him to drive it around see what he thinks.

I always get dyno charts for you guys

 

If your tuner guy dyno tuned the car after the cam and cam gear were installed he would of noticed the air fuel ratios and would of informed you of this if the injectors were going beyond the 80% duty cycle - my advice is that you get the car onto a dyno and do a run and take a good look at the air fuel - and this will tell you if the injectors are not as good as they could be it may also be that the internals in your car are starting to settle in and the current tune is not as effiecent as it was when it was all new - you may find that the car is not running lean but could e over fueling and giving you this sluggish feeling - what is you fuel economy like ? you could of gotten a bad batch of fuel ?

Our injectors are 275cc which is plenty for the car and the mods you have - I have 390cc injectors in mine and mine were installed when the turbo was installed

 

Actually, I think I'll talk to my mechanic (personal tuner) first. Let him drive it and see what he thinks.

Then I'll get him to slap her on the dyno and have a print out on the air fuel ratios, hp, torque etc.

Then probably analyse where the problem lies. As you mentioned, it could be the injectors, overfueling, bad fuel or perhaps even a poor tune. I do know for a fact the guy who tuned the car, tuned low-mid power, when I specifically told him mid-top. Anyway different story.

I'd take it to Mitsubishi, but then again, they'll probably see all the modifications and take down my VIN number and void any future warranties (not that I care, but if it comes to trade in time.. then )

 

Also, in regards to the above post, regarding air fuel, whats a good ratio for N/A applications.

I think it was like 13 or something?

 

you have lots of reading to do if you want to understand these concepts. for unleaded gasoline 13.3:1 is considered "ideal."

 

13 for na
11 for fi
iirc

 

sweet, stevo jump on msn.