Injectors TOO big to idle? - Subaru WRX Forum
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post #1 of 19 Old 08-16-2008, 01:32 AM Thread Starter
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Injectors TOO big to idle?

hi all.

i've just ordered 800cc injectors but my tuner says they're too big and won't idle on my MY03 2.0 non-sti.

he's recommended 550cc pink stis.

my mods will be:

1. td05-16g
2. turboxs tmic
3. utec delta
4. equal length headers
5. 3" tbe.
6. cold air intake


can anyone speak from experience??
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post #2 of 19 Old 08-16-2008, 02:27 AM
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The injectors are a little out of my expertise, but lose the CAI, it'll hinder more than help. A short ram is the way for WRX owners.
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post #3 of 19 Old 08-16-2008, 05:30 AM
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800 is a little over kill. But better than being on the short side. If he is a tuner, he should be able to have them work just fine for you. CAI is up to you, but you really shouldnt need it as of right now. Just be sure your A/F ratios check out and all when its tuned.

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post #4 of 19 Old 08-16-2008, 09:47 AM Thread Starter
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whats the advantage of the ram? i've seen the short air by SPT but thought these are a little too close to where heat is
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post #5 of 19 Old 08-16-2008, 09:48 AM Thread Starter
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so they SHOULD be able to run youre saying.
well he doesn't have dyno so would just street tune it.

qn: by turning down the fuel pressure, that means the injectors would not flow as much and effectively you'd lower the cc right??
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post #6 of 19 Old 08-16-2008, 11:12 AM
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I am running 800cc injectors with my setup and it idles just fine.

My name is Ken and I am a HP Junkie.
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post #7 of 19 Old 08-16-2008, 11:33 AM
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Yeah he should be able to tune them to whatever is necessary. Although, 800cc is very overkill for a 16g, the pinks would be fine for a 16g, and you would save a little money.
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post #8 of 19 Old 08-16-2008, 11:34 AM
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My gosh, you should always listen to your tuner, but in this case, you need to find a different one. IMO

800's should be very easy to get to idle.
I have a utec on both my cars, one has 850's and it idles just fine.

I would get the 800's especially if you think (and you probably will) you will be going a bit bigger in the future.
I would also start searching a new tuner. If this is what he had said, then I would really worry about him tunning my car!

Good Luck!
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post #9 of 19 Old 08-16-2008, 12:21 PM
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I have 800cc injectors and mine idles fine. Although I agree with everyone else, 800 is not necessary for a 16g.

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post #10 of 19 Old 08-16-2008, 12:36 PM Thread Starter
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Quote:
Originally Posted by Vew View Post
I have 800cc injectors and mine idles fine. Although I agree with everyone else, 800 is not necessary for a 16g.
thanks guys...
i would upgrade to a 18 or 20g in the future.
would the 650cc cope or 800cc be needed?

i would like to have injectors that can be used on 16-20g if possible....

final words?
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post #11 of 19 Old 08-16-2008, 01:45 PM
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Im running 850cc injectors on my WRX and it idles fine.
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post #12 of 19 Old 08-16-2008, 02:16 PM
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My tuner recommended 650cc Deastchwerks for my 18g... Im not sure what he would say about them for the 20g.
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post #13 of 19 Old 08-16-2008, 02:33 PM
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You should go 750's or higher, if you think a 20g could be bolted on, anytime in the future.

The way I read your original post is....
"i've just ordered 800cc injectors"

So just stick with what you ordered, it wont hurt the car to have too much injector, the tuner will tune for that.

What that means is, your injectors will work about half as hard as they can. I.E. 55% injector duty cycle rather then 95% injector duty cycle. (95% not being a very good number, in the 80's% area would be about as high as I would like to run them)

You won't be able to tell a difference except for in your wallet.

Obviously, the higher cc injector you go, the more expensive it cost.

Again, I would run your 800's with no problems, and they will work well for you future mods.

Have Fun!
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post #14 of 19 Old 08-16-2008, 03:14 PM
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i have 820 cc injectors with a vf-39 on my 03 2.0 and it idles perfect

Dom Tuned 2003 WRX Wagon
251.3 WHP
235.8 WTQ

If it's worth doing, it's worth overdoing
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post #15 of 19 Old 08-16-2008, 11:24 PM Thread Starter
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Quote:
Originally Posted by Racer_X_X View Post
You should go 750's or higher, if you think a 20g could be bolted on, anytime in the future.

The way I read your original post is....
"i've just ordered 800cc injectors"

So just stick with what you ordered, it wont hurt the car to have too much injector, the tuner will tune for that.

What that means is, your injectors will work about half as hard as they can. I.E. 55% injector duty cycle rather then 95% injector duty cycle. (95% not being a very good number, in the 80's% area would be about as high as I would like to run them)

You won't be able to tell a difference except for in your wallet.

Obviously, the higher cc injector you go, the more expensive it cost.

Again, I would run your 800's with no problems, and they will work well for you future mods.

Have Fun!
thanks.

the tuner says the orifice on a large injector is so large that even on a low duty cycle, it would flow too high making it hard to idle and give you flat spots when you get back on the gas.

re: turning down the fuel pressure, would that do the trick?
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