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Old 04-13-2017, 01:08 PM   #1
Scooby Newbie
Member#: 437670
Join Date: Jan 2016
2005 2.5 SC OB

Default Preparing for Raptor 6psi kit - injectors, fuel pump, etc.

I'm putting a 6 PSI Raptor Supercharger kit on my EJ253 Outback 5MT.

1) I'm wondering if I can use these injectors?

2) I want to do the injectors first to get it out of the way. That is, I won't be able to do the whole project in 1 day and I can't do the injectors last because the supercharger brackets will be in the way. BEFORE I hook up the blower, can I drive around with the new bigger injectors simply by changing the injector flow scaling (Injector flow constant) in ECUFlash and re-flashing? Will it run correctly this way? Pro Tuner will handle the rest but I don't want to drive around with 420-440cc injectors with no change in programming.

3) I have read that the stock Outback fuel pump is enough for 6 PSI. A lot of other people seems to say it is not. Which is correct? I don't plan on running more than 6 PSI.
The 2005 2.5i and 3.0 fuel pump is the same. The 3.0 puts out ~245hp. My 2.5 won't even put out that much. Not even close in fact. So I'm not sure that I need to upgrade... if it ain't broke???

4) Anything else I should be thinking about replacing preemptively before installing the supercharger and tuning? Already done timing belt, water pump, headgaskets, pulleys, belts, etc. Planning on doing manual trans fluid. I am wondering if I should consider replacing the front (pre cat) AFR/O2 sensors (mine has 2). They are working fine but have read they can "slow" down as they age. I don't have any record of these being changed out ever.

Anything else I should be thinking about?
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Last edited by pcampbell; 04-13-2017 at 02:40 PM.
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Old 04-14-2017, 11:39 PM   #2
Scooby Specialist
Member#: 161832
Join Date: Oct 2007
Chapter/Region: Tri-State
Location: PA
2000 Outback Limited


1. I'm on my phone an can't see the Amazon pic/link.

2. Try without injectors first. You may not need them. Running bigger injectors is not recommended. I would go with a piggyback ecu over flashing. Good luck tuning with the adjustable intake timing on these engines.

3. Regular fuel pump is fine if you use the stock injectors. Otherwise you should look into walbro 255 or similar.

4. If there aren't any codes, don't bother. You'd be wasting $ on something not needed. Is do the rear of the diff gear oil. Use redline oil (redlineoil.com). Look into a new fuel filter. Parallel fuel rails are a good idea, as well as a fuel pressure regulator, other bolt-on performance mods to get the most put of the SC. You will get a CEL with this but if you tune you may be able to work that out. Not 100% sure but doubtful. Try a rear o2 sensor spacer.
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Old 04-15-2017, 06:58 AM   #3
Scooby Newbie
Member#: 437670
Join Date: Jan 2016
2005 2.5 SC OB


Thanks for the reply.

The link is for WRX 420cc injectors. I'm not sure the stock ones are big enough but they may be. They are 245cc. Interestingly, the H6 3.0 injectors are only 270cc. That is a 245hp motor. I don't know if one can be linear with injector flow but that is 1.10cc per HP in which case my little 245cc injectors would be OK for 220hp. I'm sure it's not that simple. I don't know how annoying injectors are to install (looks pretty easy) but I am all for doing as little unnecessary work as possible.

Again the stock fuel pump is the same as the H6 pump (I think), so I'm hoping I'm good to about 245hp. I doubt I will make 245hp. For reference the stock 2004 WRX only made ~226hp stock but had 420cc injectors... I figure I will make about as much HP as a stock 2004 WRX motor, so 420cc injectors could work. Again, I don't want to over do it. Not looking for extra work!!!

This car doesn't have ACVS.

Professional tuners seem to think they can tune with the stock ECU but want to see the MAF before the supercharger which may be an issue just finding physical room to be able to stick the MAF there and pipe a BPV back in after the MAF but before the SC.

With any annoying codes they can just be turned off in the computer as long as they are just advisory codes like P2096 whatever.

I'll check on the rear diff fluid. It was done about 30k ago so probably a good time to do it again. I'm curious why the front diff/transmission fluid rarely gets changed but the rear diff gets changed more often. I did check the front fluid and it looked quite clean but I'm quite sure it's been 100+k since it's been done. Just want to get any maintenance items out of the way.

Fuel filter, if I'm going to dig into that fuel tank I might as well put in an upgraded fuel pump too...It looks annoying but not difficult.

Last edited by pcampbell; 04-15-2017 at 08:35 AM.
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