Welcome to the North American Subaru Impreza Owners Club Friday March 29, 2024
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Built Motor Discussion

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 01-10-2020, 09:07 AM   #26
Scuby04STi
Scooby Specialist
 
Member#: 328635
Join Date: Aug 2012
Chapter/Region: NWIC
Location: Portland*
Vehicle:
2004 STi GTX3076R
Rally Blue

Default

Yeah I think this is being over complicated, If it was the return system then I would likely be in the same boat.

I look at this very simply: Most cars running a surge tank and stock return set-up use a smaller pump feeding a large surge tank pump with zero issues.

Op has the pump sizes backwards (likely needed the large intank pump before moving to the surge tank) big red flag. Ding ding ding. Lol

Nearly all the fuel set-ups that "need" a return system modification are simply oversized for the application. The days of "fuel system limited" have changed into over building to the point of creating other issues.
* Registered users of the site do not see these ads.
Scuby04STi is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 01-11-2020, 07:13 PM   #27
2slofouru
Scooby Guru
 
Member#: 90539
Join Date: Jul 2005
Chapter/Region: South East
Location: SWLA
Vehicle:
My BOV goes
COVFEFE!

Default

Quote:
Originally Posted by Scuby04STi View Post
Yeah I think this is being over complicated, If it was the return system then I would likely be in the same boat.

I look at this very simply: Most cars running a surge tank and stock return set-up use a smaller pump feeding a large surge tank pump with zero issues.

Op has the pump sizes backwards (likely needed the large intank pump before moving to the surge tank) big red flag. Ding ding ding. Lol

Nearly all the fuel set-ups that "need" a return system modification are simply oversized for the application. The days of "fuel system limited" have changed into over building to the point of creating other issues.
He still needs to get rid of the return line restriction. He still has the oem jet pump venturi, which isn't going to work correctly with any larger than oem aftermarket pump setup, even if he used the Bosch in the tank, the oem venturi return wouldn't prevent the surge tank being pressurized. How he will plumb the larger aftermarket venturi setup is really all he needs to figure out now.
2slofouru is offline   Reply With Quote
Old 01-12-2020, 12:16 PM   #28
Scuby04STi
Scooby Specialist
 
Member#: 328635
Join Date: Aug 2012
Chapter/Region: NWIC
Location: Portland*
Vehicle:
2004 STi GTX3076R
Rally Blue

Default

Quote:
Originally Posted by 2slofouru View Post
He still needs to get rid of the return line restriction. He still has the oem jet pump venturi, which isn't going to work correctly with any larger than oem aftermarket pump setup, even if he used the Bosch in the tank, the oem venturi return wouldn't prevent the surge tank being pressurized. How he will plumb the larger aftermarket venturi setup is really all he needs to figure out now.
I have a larger than OEM pump setup and stock jet pump venturi with zero issue. Why? Because my intank pump is small like a surge tank style fuel system is baised around. Could a larger venturi help OP? Sure, but its just a work around for an oversized intank pump.
Scuby04STi is offline   Reply With Quote
Old 01-13-2020, 09:19 PM   #29
Homemade WRX
Scooby Guru
 
Member#: 33782
Join Date: Mar 2003
Chapter/Region: MAIC
Location: Milton Keynes, UK
Vehicle:
96 3MI Racing
search FIRST, then PM!!!

Default

Totally missed that he had the 450 feeding the 044. I agree with scaling down the lift pump. That thing is probably "filling" that surgetank 10 times a minute
Homemade WRX is offline   Reply With Quote
Old 01-23-2020, 01:25 PM   #30
stu
Scooby Specialist
 
Member#: 25768
Join Date: Oct 2002
Chapter/Region: RMIC
Location: CO springs
Vehicle:
2003 XONA 9569S 40++
2.3 slobaru

Default

whats up with the top hats on your coilovers?
stu is offline   Reply With Quote
Old 01-25-2020, 01:13 AM   #31
Murphdog
Scooby Specialist
 
Member#: 75414
Join Date: Nov 2004
Chapter/Region: RMIC
Location: Rock Springs,Wyoming
Vehicle:
2004 STi
Its the Blue one

Default

Quote:
Originally Posted by stu View Post
whats up with the top hats on your coilovers?


Looks like he swapped L to R for more caster.
I did the same thing with mine.

Murphdog is offline   Reply With Quote
Old 01-25-2020, 09:45 AM   #32
awdturbo04
Scooby Newbie
 
Member#: 39487
Join Date: Jul 2003
Vehicle:
2006 sti
obp

Default

I agree guys that the 450 is overkill as a lift pump that was just the natural progression from big pump in tank that couldn't keep up to adding the surge tank setup. Now that I pulled the fuel pump to investigate the jet pump i have a dilemma. Do I swap back to the OEM pump and put the radium jet pump on the return to tank with the largest orifice and risk possibly over pressuring the surge (probably not likely with the stock pump) or do I test adding the radium unit with the smallest orifice to the supply line on the 450 and leave the return to tank unobstructed? I think im going to set up a test tank in the garage this afternoon and see what I can come up with.

As for the top hats you are correct more caster FTW

Last edited by awdturbo04; 01-26-2020 at 11:03 AM.
awdturbo04 is offline   Reply With Quote
Old 01-25-2020, 05:37 PM   #33
Dave D.
NASIOC Supporter
 
Member#: 130990
Join Date: Nov 2006
Chapter/Region: NWIC
Location: Menzel Lake, WA
Vehicle:
06 Red Ltd.Wagon
Dom 1.5xtr JJ tuned

Default

I'll reiterate that my tuner put an AEM 340 in as a lift pump, with my underhood Radium surge tank using 450. I don't believe he mentioned anything about changing the orifices. Still runs perfectly.
Dave D. is offline   Reply With Quote
Old 01-26-2020, 11:23 AM   #34
awdturbo04
Scooby Newbie
 
Member#: 39487
Join Date: Jul 2003
Vehicle:
2006 sti
obp

Default

I ran a test with the venturi on the feed line directly off of the lift pump. Running the smallest orifice and adding a 5' length of hose between the supply and return of the hanger. I was very happy with the amount of suction that was created. It emptied a drinking cup in about 10 seconds. Judging by the volume coming out of the return in the test I don't think there will be any problem sacrificing the little pressure off the supply to run the venturi and still keep the surge tank well fed. this allows me to run no restriction on the return. Again as others have mentioned there is more than one way to skin this cat but this is the way im going to go.



awdturbo04 is offline   Reply With Quote
Old 01-28-2020, 09:24 PM   #35
2slofouru
Scooby Guru
 
Member#: 90539
Join Date: Jul 2005
Chapter/Region: South East
Location: SWLA
Vehicle:
My BOV goes
COVFEFE!

Default

Quote:
Originally Posted by awdturbo04 View Post
I ran a test with the venturi on the feed line directly off of the lift pump. Running the smallest orifice and adding a 5' length of hose between the supply and return of the hanger. I was very happy with the amount of suction that was created. It emptied a drinking cup in about 10 seconds. Judging by the volume coming out of the return in the test I don't think there will be any problem sacrificing the little pressure off the supply to run the venturi and still keep the surge tank well fed. this allows me to run no restriction on the return. Again as others have mentioned there is more than one way to skin this cat but this is the way im going to go.



https://youtu.be/Cykjh04W32I

Nice! That will definitely keep return restriction at a min

I still have my other two orifices and could swap to this route if needed. For now my plan is to use one of the two returns with the largest orifice and any backpressure would be relieved by the other return. This is assuming flow from one return is enough to make the venturi work.
2slofouru is offline   Reply With Quote
Old 05-30-2020, 06:18 AM   #36
Bariga
Scooby Specialist
 
Member#: 179846
Join Date: May 2008
Chapter/Region: NWIC
Location: Renton, WA
Vehicle:
07 STi Limited
EFR 8474 TS EWG

Default

Quote:
Originally Posted by awdturbo04 View Post
I ran a test with the venturi on the feed line directly off of the lift pump. Running the smallest orifice and adding a 5' length of hose between the supply and return of the hanger. I was very happy with the amount of suction that was created. It emptied a drinking cup in about 10 seconds. Judging by the volume coming out of the return in the test I don't think there will be any problem sacrificing the little pressure off the supply to run the venturi and still keep the surge tank well fed. this allows me to run no restriction on the return. Again as others have mentioned there is more than one way to skin this cat but this is the way im going to go.



https://youtu.be/Cykjh04W32I
the only issue i can see in this setup is if the driver side tank goes empty and you going to be picking up air and introducing air into surge tank
but like you said will this even work at low speed like how much back pressure does system need to operate at?

Like i am in exact same boat i got 450 acting as lift (connected to factory speed controller) that fills up radium surge tank with fuelab pump in it, the fuelab pump is going back to fuelab for like 3d time so far lol, and im running wally full time rewired to run 100% now, and my regulator cant regulate for **** now as i have my radium venturi set on return with biggest hole.

I hate all the options just makes me want to cut flat tire compartment in trunk and trow radium fuel cell in lol

Last edited by Bariga; 05-30-2020 at 02:42 PM.
Bariga is offline   Reply With Quote
Old 05-30-2020, 04:13 PM   #37
Bariga
Scooby Specialist
 
Member#: 179846
Join Date: May 2008
Chapter/Region: NWIC
Location: Renton, WA
Vehicle:
07 STi Limited
EFR 8474 TS EWG

Default

i think im just going to remove venturi completely make the return free flow into the gas tank, and trow this little guy some where on top of fuel tank for the fuel transfer

its compatible with E85 as well

https://www.holley.com/products/fuel...s/parts/12-426
Bariga is offline   Reply With Quote
Old 05-30-2020, 04:25 PM   #38
2slofouru
Scooby Guru
 
Member#: 90539
Join Date: Jul 2005
Chapter/Region: South East
Location: SWLA
Vehicle:
My BOV goes
COVFEFE!

Default

If the driver side tank goes low, it will not add air to the fuel going to the surge tank. The outlet nipple of the venturi will still be putting out some fuel, because of the lift pump. The fuel only leaves the T that leads to the venturi, doesn't go the other way.
2slofouru is offline   Reply With Quote
Old 05-30-2020, 04:45 PM   #39
Bariga
Scooby Specialist
 
Member#: 179846
Join Date: May 2008
Chapter/Region: NWIC
Location: Renton, WA
Vehicle:
07 STi Limited
EFR 8474 TS EWG

Default

Quote:
Originally Posted by 2slofouru View Post
If the driver side tank goes low, it will not add air to the fuel going to the surge tank. The outlet nipple of the venturi will still be putting out some fuel, because of the lift pump. The fuel only leaves the T that leads to the venturi, doesn't go the other way.
That's not how it works, venturi creates a pressure difference and because there is now a negative pressure there is will suck fuel or air. So my statement still hold true, if there is no fuel to suck from other chamber it will suck air and you will have air bubbles in your surge tank.
Bariga is offline   Reply With Quote
Old 05-30-2020, 04:49 PM   #40
2slofouru
Scooby Guru
 
Member#: 90539
Join Date: Jul 2005
Chapter/Region: South East
Location: SWLA
Vehicle:
My BOV goes
COVFEFE!

Default

Quote:
Originally Posted by Bariga View Post
That's not how it works, venturi creates a pressure difference and because there is now a negative pressure there is will suck fuel or air. So my statement still hold true, if there is no fuel to suck from other chamber it will suck air and you will have air bubbles in your surge tank.
I know how a venturi works, but am pretty sure the backpressure of everything past his T will be more than the air you are worried about, and fuel will still head towards the venturi. His T is not a venturi, the inside is evenly shaped and the inlet/outlets are all the same size.

If his setup worked the way you believe it does, air would get sucked in all of the time from the venturi section, and go into his surge tank. It's not going to change how it works once the driver side is depleted, fuel will still leave the venturi nipple as before. The only difference will be that some air leaves the venturi nipple with the fuel from his T.

He came up with a clever design, and while he will lose a little volume out of the venturi, the pump will still move more fuel than is needed the majority of the time.

Last edited by 2slofouru; 05-30-2020 at 04:55 PM.
2slofouru is offline   Reply With Quote
Old 05-30-2020, 04:56 PM   #41
Bariga
Scooby Specialist
 
Member#: 179846
Join Date: May 2008
Chapter/Region: NWIC
Location: Renton, WA
Vehicle:
07 STi Limited
EFR 8474 TS EWG

Default

Quote:
Originally Posted by 2slofouru View Post
I know how a venturi works, but am pretty sure the backpressure of everything past his T will be more than the air you are worried about, and fuel will still head towards the venturi. His T is not a venturi, the inside is evenly shaped and the inlet/outlets are all the same size.
what i know so far based on facts:

With radium venturi on biggest orifice hooked up on return and walbro 465 running half speed there is around 12 psi of back pressure, running it full speed creates over 30 psi pressure where regulator creates big swings in differential fuel pressure (up to 8% fuel compensation at light / medium loads "Very bad!")

IMO wile running any size pump larger than stock you need to remove all the restrictions from return and have it free slow. A lift pump speed controller is option based on back pressure but that just over complicated.
Bariga is offline   Reply With Quote
Old 05-30-2020, 05:01 PM   #42
2slofouru
Scooby Guru
 
Member#: 90539
Join Date: Jul 2005
Chapter/Region: South East
Location: SWLA
Vehicle:
My BOV goes
COVFEFE!

Default

Quote:
Originally Posted by Bariga View Post
what i know so far based on facts:

With radium venturi on biggest orifice hooked up on return and walbro 465 running half speed there is around 12 psi of back pressure, running it full speed creates over 30 psi pressure where regulator creates big swings in differential fuel pressure (up to 8% fuel compensation at light / medium loads "Very bad!")

IMO wile running any size pump larger than stock you need to remove all the restrictions from return and have it free slow. A lift pump speed controller is option based on back pressure but that just over complicated.
No Bariga, no.

The inside of the venturi on the inlet side (from his pump) has a smaller diameter orifice that leads into the chamber where it blows past the side inlet of the venturi then straight out the opposite end with the nipple open to the fuel tank. The velocity of the fuel leaving that small orifice combined with the enlarged chamber and orientation of the orifice that connects to the driver tank feed hose creates the pressure difference that draws from the driver side. Even if there is no fuel on the driver side, the fuel will just jet right past that inlet hole and out the other end. The fuel will not change direction.

He's not using typical return flow to power the venturi, where back pressure would be detrimental, he's using a pump that always provides positive pressure.
2slofouru is offline   Reply With Quote
Old 05-31-2020, 12:31 PM   #43
Bariga
Scooby Specialist
 
Member#: 179846
Join Date: May 2008
Chapter/Region: NWIC
Location: Renton, WA
Vehicle:
07 STi Limited
EFR 8474 TS EWG

Default

Quote:
Originally Posted by 2slofouru View Post
No Bariga, no.

The inside of the venturi on the inlet side (from his pump) has a smaller diameter orifice that leads into the chamber where it blows past the side inlet of the venturi then straight out the opposite end with the nipple open to the fuel tank. The velocity of the fuel leaving that small orifice combined with the enlarged chamber and orientation of the orifice that connects to the driver tank feed hose creates the pressure difference that draws from the driver side. Even if there is no fuel on the driver side, the fuel will just jet right past that inlet hole and out the other end. The fuel will not change direction.

He's not using typical return flow to power the venturi, where back pressure would be detrimental, he's using a pump that always provides positive pressure.
you are right not sure what the **** i was thinking.
any how i took my hanger out last night and found that my radium venturi not even connected any more Hose expanded and just got disconnected so it was there but aint sucking fuel from 2nd chamber.

I completely removed venturi and bought Edelbrock 30 GPH Fuel Pump, installed under driver side fuel cap (had to take the pumps case/ holder out)
Pumps good amount of fuel and uses 1 amp free flow. Going to trigger via ECU on few different conditions with 3 min run timers.
Bariga is offline   Reply With Quote
Old 06-01-2020, 09:24 AM   #44
Barge
Scooby Newbie
 
Member#: 62941
Join Date: May 2004
Chapter/Region: MWSOC
Location: @brgperformance
Vehicle:
2004 #LesboRacer
#TunedbyBarge

Default

Quote:
Originally Posted by Bariga View Post
you are right not sure what the **** i was thinking.
any how i took my hanger out last night and found that my radium venturi not even connected any more Hose expanded and just got disconnected so it was there but aint sucking fuel from 2nd chamber.

I completely removed venturi and bought Edelbrock 30 GPH Fuel Pump, installed under driver side fuel cap (had to take the pumps case/ holder out)
Pumps good amount of fuel and uses 1 amp free flow. Going to trigger via ECU on few different conditions with 3 min run timers.
I like this idea... especially since these little pumps are so affordable.

I was going to set it up with a venturi on the feed line like several posts up but this eliminates that whole hassle and worrying about how much return flow you have... too little... too much.
Barge is offline   Reply With Quote
Old 06-01-2020, 01:59 PM   #45
Bariga
Scooby Specialist
 
Member#: 179846
Join Date: May 2008
Chapter/Region: NWIC
Location: Renton, WA
Vehicle:
07 STi Limited
EFR 8474 TS EWG

Default

Already got this little pump setup and running, cant hear it when car is running. set it up to activate on Lat and Long G-force over 0.5G

Bariga is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 07:12 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2024 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.

When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission
Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.