Confused about injectors. - Subaru WRX Forum
 
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#1 Old 02-28-2011, 05:35 PM
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Smile Confused about injectors.

First off I'm Andy and I'm new here. I've been reading around the FAQ and searching but I would still like some input on this aspect.

Background -
03 WRX 2.0 engine. Modifications are: STI top mount, Short Ram air intake, 3 port solenoid, 68 hta turbo in the mail on the way, turbo up pipe, 3 inch turbo back exhaust.

I am shooting for 18 lbs, max of 20, and I was looking at the 850cc deatchwerks injectos. Are these overkill? Should i go smaller? Will I need an adjustable fuel pressure regulator or can I adjust accordingly with my cobb tuner?

Thanks for any input.
Rep given to anyone who helps.

EDIT: I don't think i have any rep points to give out... sorry.
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#2 Old 02-28-2011, 06:09 PM
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850's won't be overkill, they'll probably be just right. If you know what sort of bhp you think you'll be making you can use this injector size calculator:

DeatschWerks.com | Fuel Calculators

I use 90% IDC, .6 BFSC, obviously four injectors. Assuming you can get 350 or so whp out of the HTA68, I'll go with saaaay 430bhp. That kicked out 750's. 850's will be just right.

Hopefully your transmission likes you though, that's a lot of power for the Bugeye.

-Chris
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#3 Old 02-28-2011, 06:26 PM
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Thank you! any clue about the fuel pressure regulator?
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#4 Old 02-28-2011, 06:33 PM
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Stock is fine. No need to bump pressure, when you get tuned they just scale the injectors on the ECU.

-Chris
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#5 Old 02-28-2011, 07:45 PM
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Dont forget about getting a fuel pump. The stocker wont like trying to push that much fuel for too long.

Joshua
"2007 WRX- PPG'd, 20G- Tim Bailey tuned
Stage 2 2005 WRX
Cobbtuning.com"
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#6 Old 03-03-2011, 04:15 AM
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You're best bet is to talk everything over with whoever is going to tune the car. Do some research and make sure it's someone you will trust. Tell him what you're looking for in your car and he should be able to point you in the right direction of all of your mods.
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#7 Old 03-04-2011, 12:34 PM
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Quote:
Originally Posted by RcrsWetDream View Post
850's won't be overkill, they'll probably be just right. If you know what sort of bhp you think you'll be making you can use this injector size calculator:

DeatschWerks.com | Fuel Calculators

I use 90% IDC, .6 BFSC, obviously four injectors. Assuming you can get 350 or so whp out of the HTA68, I'll go with saaaay 430bhp. That kicked out 750's. 850's will be just right.

Hopefully your transmission likes you though, that's a lot of power for the Bugeye.
Should I be looking to upgrade gears inside the Trans or should I just be looking to swap a better one in?
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#8 Old 03-04-2011, 12:51 PM
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Either way, just matters on money. You basically have 4 options

1) Stock replacement. Usually costs ~$500 in parts and $1000 in labor. No added strength
2) Better gears, everything else stock. Usually costs $1500 in parts and $1000 in labor. Doesn't add much strength. Good for 02-07 WRX's that will only do small bolt on mods or small turbo upgrades.
3) Full transmission upgrade. Labor here is very hard to do on your own. Total cost here is $3500-$6000. Usual options are something like a PPG gearset which includes casing modifications, often upgrades to the diffs as well.
4) Replacement, usually USDM 04-11 STi 6-speed. More expensive than it seems, the STi is a sufficiently different car in terms of driveline that this requires several additional pieces not the least of which is the entire rear end of the car's driveline to also be swapped. General cost is $6000-$9000 mattering on the donor's condition. The STi 6-speed is considerably stronger than the stock 5-speed, but it's been argued that a proper built PPG 5-speed upgrade may be even stronger than the 6-speed. The gearing on the 6-speed is also extremely short, and most people will prefer a longer set of ratios possible in a custom built 5-speed. The main advantage of the 6-speed is it's ease of drivability and durability for general/normal driving. Not an extreme solution in other words despite the cost.

If you build some 500whp+ monster, then you'll be looking at a more custom built transmission and diffs based on either the stock 5-speed or the 6-speed. The 5 is more flexible, more shops provide options. The 6-speed is stronger so gets messed around with less.

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#9 Old 04-27-2011, 04:24 PM
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Originally Posted by newtothegame View Post
Dont forget about getting a fuel pump. The stocker wont like trying to push that much fuel for too long.


And what's the flow rating on the stocker?
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#10 Old 04-28-2011, 03:53 PM
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120-140lph iirc.

Jon
"We live for a good time, not a long time."
RIP Colin McRae
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#11 Old 04-28-2011, 09:46 PM
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Lightbulb

For a second I thought iirc was a unit of measure, but that wouldn't make sense since fuel flow is typically measured in lph (liters per hour) and different back-to-back units of measure would be conflicting.

"if I recall correctly"

John
07 WRX

Last edited by man show; 04-28-2011 at 09:47 PM. Reason: had to insert lightbulb icon
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#12 Old 04-29-2011, 06:00 AM
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IIRC... Half the flow of the Walbro is what the stocker flows.

Paul
2007 XT
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