Maximum HP on stock RS fuel system with walbro fuel pump

Chav · 06-16-2002, 12:55 AM

Whats the max horsepower that can be made with the stock rs fuel system + walboro fuel pump and parallel fuel rail. Or what will the fuel pressure be with this combination at WOT?

edit: I also have a Link 2 ecu, but i dont think that makes a difference since 100% injector duty cycle is always 100% injector duty cycle.

Thanks
I'm trying to decide which size injectors I need to get. From the www.rceng.com fuel worksheet the max 440cc injectors will get me is 280 or so hp if the fuel pressure at WOT is 50psi. I'm not sure what the fuel pressure will be at WOT with a walboro fuel pump though.

-Chav

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STiTuner · 06-16-2002, 01:39 AM

are you using the stock fuel pressre regulator?

100% duty cycle is not always the same when you're changing the pressure.

Brad

Chav · 06-16-2002, 02:11 AM

ya, stock fpr. I'm leaning towards 550cc injectors instead of 440cc because the 550cc will be good to 320hp or so. I dont want to buy the 440cc be good to 7 psi and then have to change them. I should also get the svx fpr since it flows more. Man this is gonna cost sooo much.

As per the worksheet from www.rceng.com the stock fuel system + 44psi from the uprated pump will yeild 173hp. 95% injector duty cycle .6 bsf and 44 psi.

173hp??? How can I even boost 1psi then?

Anyone know where to get 550cc high impedence injectors? I called rc engineering and they said that they only have 440cc injectors and they havent made sure they fit on a 2.5rs yet.

edit: There has gotta be something wrong with what I think I know about all this. Can someone school me please? Thanks

-Chav

N/A · 06-16-2002, 02:26 AM

OK then to add another question can you post a pic of the Subaru fuel pump and bracket that goes into the tank? I want to see if the spare GTR fuel pump in my closest will work on the Subaru if so then it saves me the money for the Walboro unit.

Chav · 06-16-2002, 02:30 AM

Oh ok, thanx for hijacking my thread N/A

j/k

-Chav

N/A · 06-16-2002, 05:36 AM

Not really hijacking the thread since my next question was if you had the flow capacity info for the Walboro unit that you're going to use.

The 440's from RC are only good up to 7lbs of boost? I thought they were capable of more then that. Hell I've run the stock Silvia units to 12lbs with not a single problem so I would have thought that the 440's could take more then 7lbs.

KillerTHC · 06-16-2002, 06:03 AM

i know skywalker is maxing out his 440's at 5 psi when he shifts.

Impreza Rider · 06-16-2002, 11:33 AM

hmmm...interesting. I'm running stock injectors, with a Walbro 255 pump, and 7 pounds of boost. According to my Link, I hit 97%IDC at 6400 rpm. I would be comfortable saying that my car makes ~230 hp, since it dyno'd at ~220 at 5 pounds.

Delicious Tuning · 06-16-2002, 12:59 PM

Well I am also letting my boost spike to ~10 between shifts. He he...

Chav · 06-16-2002, 01:13 PM

Ya, the 255 walbro pump. I thought the stock injectors would hold more then 173hp and that the 440cc injectors would be past 7 psi as well, but as per rc engineering's flow rate work sheet they dont.

Impreza Rider: Is your fuel system set up like stock just with the walbro fuel pump?

Thanx,
-Chav

Impreza Rider · 06-16-2002, 04:21 PM

Quote:

Originally posted by Chav

Impreza Rider: Is your fuel system set up like stock just with the walbro fuel pump?

Yes

wcbjr · 06-17-2002, 03:42 PM

Here's the sheet that RCEngineering sent me along with my 440's. It pretty much confirms what everybody is saying about 7-9lbs of boost being the limit for them.

06-16-2002, 12:55 AM	#1
Chav Scooby Specialist Member#: 3269 Join Date: Dec 2000 Chapter/Region: SCIC Location: San Diego Vehicle: 2001 2.5RS Sedan STM RSTi	Maximum HP on stock RS fuel system with walboro fuel pump Whats the max horsepower that can be made with the stock rs fuel system + walboro fuel pump and parallel fuel rail. Or what will the fuel pressure be with this combination at WOT? edit: I also have a Link 2 ecu, but i dont think that makes a difference since 100% injector duty cycle is always 100% injector duty cycle. Thanks I'm trying to decide which size injectors I need to get. From the www.rceng.com fuel worksheet the max 440cc injectors will get me is 280 or so hp if the fuel pressure at WOT is 50psi. I'm not sure what the fuel pressure will be at WOT with a walboro fuel pump though. -Chav * Registered users of the site do not see these ads. Last edited by Chav; 06-16-2002 at 01:16 AM.

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06-16-2002, 01:39 AM	#2
STiTuner Scooby Specialist Member#: 5778 Join Date: Apr 2001 Chapter/Region: South East Vehicle: 09 135i Jet Black	are you using the stock fuel pressre regulator? 100% duty cycle is not always the same when you're changing the pressure. Brad

06-16-2002, 02:11 AM	#3
Chav Scooby Specialist Member#: 3269 Join Date: Dec 2000 Chapter/Region: SCIC Location: San Diego Vehicle: 2001 2.5RS Sedan STM RSTi	ya, stock fpr. I'm leaning towards 550cc injectors instead of 440cc because the 550cc will be good to 320hp or so. I dont want to buy the 440cc be good to 7 psi and then have to change them. I should also get the svx fpr since it flows more. Man this is gonna cost sooo much. As per the worksheet from www.rceng.com the stock fuel system + 44psi from the uprated pump will yeild 173hp. 95% injector duty cycle .6 bsf and 44 psi. 173hp??? How can I even boost 1psi then? Anyone know where to get 550cc high impedence injectors? I called rc engineering and they said that they only have 440cc injectors and they havent made sure they fit on a 2.5rs yet. edit: There has gotta be something wrong with what I think I know about all this. Can someone school me please? Thanks -Chav

06-16-2002, 02:26 AM	#4
N/A Scooby Specialist Member#: 133 Join Date: Aug 1999 Chapter/Region: NWIC Location: Burlington, WA Vehicle: TBA TBA TBA	OK then to add another question can you post a pic of the Subaru fuel pump and bracket that goes into the tank? I want to see if the spare GTR fuel pump in my closest will work on the Subaru if so then it saves me the money for the Walboro unit.

06-16-2002, 02:30 AM	#5
Chav Scooby Specialist Member#: 3269 Join Date: Dec 2000 Chapter/Region: SCIC Location: San Diego Vehicle: 2001 2.5RS Sedan STM RSTi	Oh ok, thanx for hijacking my thread N/A j/k -Chav

06-16-2002, 05:36 AM	#6
N/A Scooby Specialist Member#: 133 Join Date: Aug 1999 Chapter/Region: NWIC Location: Burlington, WA Vehicle: TBA TBA TBA	Not really hijacking the thread since my next question was if you had the flow capacity info for the Walboro unit that you're going to use. The 440's from RC are only good up to 7lbs of boost? I thought they were capable of more then that. Hell I've run the stock Silvia units to 12lbs with not a single problem so I would have thought that the 440's could take more then 7lbs.

06-16-2002, 06:03 AM	#7
KillerTHC Scooby Specialist Member#: 4942 Join Date: Mar 2001 Chapter/Region: BAIC Location: Palo Alto, CA USA Vehicle: 01 SRP 2.5 RS-T Ludespeed Stage 3 Link'd	i know skywalker is maxing out his 440's at 5 psi when he shifts.

06-16-2002, 11:33 AM	#8
Impreza Rider Scooby Specialist Member#: 756 Join Date: Jan 2000 Chapter/Region: MAIC Location: Ashburn, Va Vehicle: 2003 Legacy L wagon 2009 Kawasaki C14	hmmm...interesting. I'm running stock injectors, with a Walbro 255 pump, and 7 pounds of boost. According to my Link, I hit 97%IDC at 6400 rpm. I would be comfortable saying that my car makes ~230 hp, since it dyno'd at ~220 at 5 pounds.

06-16-2002, 12:59 PM	#9
Delicious Tuning Former Vendor Member#: 1990 Join Date: Jul 2000 Location: San Diego, CA	Well I am also letting my boost spike to ~10 between shifts. He he...

06-16-2002, 01:13 PM	#10
Chav Scooby Specialist Member#: 3269 Join Date: Dec 2000 Chapter/Region: SCIC Location: San Diego Vehicle: 2001 2.5RS Sedan STM RSTi	Ya, the 255 walbro pump. I thought the stock injectors would hold more then 173hp and that the 440cc injectors would be past 7 psi as well, but as per rc engineering's flow rate work sheet they dont. Impreza Rider: Is your fuel system set up like stock just with the walbro fuel pump? Thanx, -Chav

06-17-2002, 03:42 PM	#12
wcbjr Scooby Guru Member#: 4001 Join Date: Feb 2001 Location: I love spherical bearings! Vehicle: 2006 Legacy GT Obsidian black	Here's the sheet that RCEngineering sent me along with my 440's. It pretty much confirms what everybody is saying about 7-9lbs of boost being the limit for them.