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#1 |
Assault Mechanic
Join Date: Apr 2004
Location: Reno
Posts: 996
Car: 13 Sti Hatch Satin white
Class: TBSP/TT-2
Aim for the EYES!
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I have been hearing that the stock cycle duty is too high on our fuel pumps and then I watched a show where they moded a Sti one mod was to change the fuel pump has anyone besides matt and I hear of this.
It is a cheap mod and is walburo pump plug and play! I have read it changes the cycle duty from 105% to 90% so when you drive hard the #3 piston doesnt run too lean! does anyone have any more info on this ![]() |
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#2 |
The Doink
Real Name: Scott Join Date: Nov 2002
Location: Portland, OR
Posts: 20,335
Car: '09 OBXT, '02 WRX, '96 Miata
Class: PDX/TT-6
The way out is through
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I didn't think injector duty cycle on a stock STi was that high!
However, I'm not sure that having more pressure behind the injectors will change their duty cycle any. It would just add some reassurance that if an injector is maxing out there's at least no shortage of fuel. In order to lower duty cycles, I think you have to simply get higher flowing injectors (and of course a pump that can supply them). Also, how do you get an injector to run at 105% duty? Doesn't 100% mean the injector is basically locked open? Anyway, I believe the Walbro pump is a plug-n-play replacement for stock Subaru pumps, but the install still involves the gas tank, so you have to prep carefully. You don't want a fire!
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#3 |
EJ22
Join Date: Jun 2004
Location: RENO
Posts: 484
Car: 03 evo, 06 R6
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by replacing the pump to a walburo 255 you will increas your amount of fuel and it will help a bit you will get more flow to your injectors but they will still only deliver so much fuel, you will get a little more per duty cycle % and it should drop in if anything you might need to do a trim on the ring the pump mounts on. but thats easy enough. I've done a few subie fuel pumps let me know if you need a hand
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#4 |
Assault Mechanic
Join Date: Apr 2004
Location: Reno
Posts: 996
Car: 13 Sti Hatch Satin white
Class: TBSP/TT-2
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I think thats what they are saying the #3 is stuck open under hard driving . So you think that higher cfm injector is the answer and the fuel pump?
this of course all after I can get the cobb accesport and high flow cat with down pipe what do think of this downpipe from helix? |
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#5 |
EJ22
Join Date: Jun 2004
Location: RENO
Posts: 484
Car: 03 evo, 06 R6
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using a higher CC injector will lower your duty cycle, but you need a way to control the fuel amount now since a cars stock ecu will not be able to compensat for the diffrent size. an Apex safc II will do the trick very well.
Question ..what is the stock cc rating for and sti 410? 510? |
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#6 |
Captain Turbo
Join Date: Feb 2004
Location: Reno
Posts: 3,318
Car: 05 STi
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I am not sure about the STi, but I was under the impression that for the WRX you only have to upgrade the pump if you upgrade the injectors.
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#7 |
EJ22
Join Date: Jun 2004
Location: RENO
Posts: 484
Car: 03 evo, 06 R6
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you could try it..but stock ecu's can't compensate for higher flow injectors and you will run richer than you wish to. or you cold just try the pump and see how it goes. The pump will help a little. its also in what goals you have. you could also do the fuel delivery mod. that they use on the 2.5 rs when they go turbo so the #3 cyl. gets enough fuel.
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#8 | |
JDM Cowboy
Real Name: Nick Join Date: Oct 2003
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#9 | |
The Doink
Real Name: Scott Join Date: Nov 2002
Location: Portland, OR
Posts: 20,335
Car: '09 OBXT, '02 WRX, '96 Miata
Class: PDX/TT-6
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Perhaps that's only something that's done with a remap of the ECU. All I know is, I wouldn't bother with a piggy-back AFC when you can reprogram the ECU to do it. The ECUs in Subarus are powerful computers! Use them to your advantage!
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#10 | ||
EJ22T
Join Date: Sep 2003
Location: Reno
Posts: 9,445
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#11 |
EJ22
Join Date: Jun 2004
Location: RENO
Posts: 484
Car: 03 evo, 06 R6
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yes the ecu in the subies are very good but I've never seen any cars ecu that will compensate for highr flow injectors because higher flow injectors will supply more fuel at every rpm range your cars stock ecu is programed to run a certain size injector. The SAFC 2 will control the fuel amount easly with no problems with running rich. remember scott all stand alone ecus require you to tell it what size injectors you will be using so it knows what the flow will be and calculate for it once you have you base map done same with a stock ecu at the factory. here is a link for where I read about the fuel delivery mod for turbo rs cars. http://www.ravensblade-impreza.com/
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#12 | |
The Doink
Real Name: Scott Join Date: Nov 2002
Location: Portland, OR
Posts: 20,335
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#13 | |
EJ22T
Join Date: Sep 2003
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#14 | ||
EJ22T
Join Date: Sep 2003
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#15 | |||
The Doink
Real Name: Scott Join Date: Nov 2002
Location: Portland, OR
Posts: 20,335
Car: '09 OBXT, '02 WRX, '96 Miata
Class: PDX/TT-6
The way out is through
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#16 | ||||
EJ22T
Join Date: Sep 2003
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Posts: 9,445
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#17 |
EJ22
Join Date: Jun 2004
Location: RENO
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thanks I couldn't remember its been a long time since I read it. I was going to do it but well no more turbo. well still if he just wants a little safty I'd suggest using that mod it should eliminate the #3 cyl running lean.
Man this thread became all about Scott, myself and BAN...I hope he got the answer he was looking for. |
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#18 |
Assault Mechanic
Join Date: Apr 2004
Location: Reno
Posts: 996
Car: 13 Sti Hatch Satin white
Class: TBSP/TT-2
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The COBB acessport will do the the trick and does the helix down pipe with highflocat make a differnce from stock
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#19 | |
The Doink
Real Name: Scott Join Date: Nov 2002
Location: Portland, OR
Posts: 20,335
Car: '09 OBXT, '02 WRX, '96 Miata
Class: PDX/TT-6
The way out is through
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#20 | |
EJ22T
Join Date: Sep 2003
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Posts: 9,445
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Yes, you'll love the downpipe. The stock downpipe is the single worst part on the whole car, both WRX and STi. Go with the highflow cat, you won't really miss the slight gains from being catless, you'll stay in Street Touring/Street Mod autocross, and the cat will probably prevent boost creep up here.
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#21 |
Assault Mechanic
Join Date: Apr 2004
Location: Reno
Posts: 996
Car: 13 Sti Hatch Satin white
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What size injectors are not over kill for what I want to do
![]() New down pipe high flow cat and cobb acessport and feul pump ![]() Perrin does do a core trade for a larger injector $219.0 |
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#22 |
Assault Mechanic
Join Date: Apr 2004
Location: Reno
Posts: 996
Car: 13 Sti Hatch Satin white
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What type of engine managment is the answer
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#23 | |
The Doink
Real Name: Scott Join Date: Nov 2002
Location: Portland, OR
Posts: 20,335
Car: '09 OBXT, '02 WRX, '96 Miata
Class: PDX/TT-6
The way out is through
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#24 | |
EJ22T
Join Date: Sep 2003
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#25 | ||
EJ22T
Join Date: Sep 2003
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