Fuel Return Line Mod??

Matthew Reese · Post by **Matthew Reese** » Tue Jun 18, 2002 10:16 pm

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Matthew Reese · Post by **Matthew Reese** » Tue Jun 18, 2002 10:16 pm

Would I be a ble to restrict fuel flow on the return line and create an increased back pressure which might inject more fuel? Getting ready for 1/8 mile drags - the sube is sweet in the 1/8!

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Josh Colombo · Post by **Josh Colombo** » Tue Jun 18, 2002 11:16 pm

No not really. If you want....pull the vacuum line off the fuel pressure regulator. You'll have full fuel pressure at low rpms, which may....or may not help.....I really don't know.....and I really don't know of the long term effects.......so if you break something.....not my fault

Josh

************************************
Josh Colombo
<mailto:Josh@surrealmirage.com> Josh@surrealmirage.com

"Life, an ever-changing melody
of beats and rhythm" - ME
************************************

-----Original Message-----
From: Matthew Reese [mailto:carmat76@hotmail.com]
Sent: Tuesday, June 18, 2002 9:10 PM
To: BC-BFLegacyWorks@yahoogroups.com
Subject: [BC-BFLegacyWorks] Fuel Return Line Mod??

Would I be a ble to restrict fuel flow on the return line and create an increased back pressure which might inject more fuel? Getting ready for 1/8 mile drags - the sube is sweet in the 1/8!

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Z1Auto@aol.com · Post by **Z1Auto@aol.com** » Wed Jun 19, 2002 12:16 am

Are you finding yourself out of injector? If not, upping fuel pressure can
often cause more harm than good......

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Matthew Reese · Post by **Matthew Reese** » Wed Jun 19, 2002 8:06 am

I'm not sure how badly I need the fuel...I am running ~16 + pounds of boost now (figured out that intercooler plumbing problem I was having)and the air/fuel is reading a little lean (actually I use a volt meter and I'm seeing .75 - .8 volts). I would like to see .9 to 1.0 and I did with stock boost. I am sure I read of doing this mod on other turbo sites. I am not wanting to block off the return but just put a valve in to control flow. I would be able to fine tune fuel flow with the valve. I have a larger pump I could install to take the extra load. I understand the larger pump alone is not going to push more fuel to the injectors - that is regulated by the fuel pressure regulator, right? Any more thoughts on this?

>From: Z1Auto@aol.com
>Reply-To: BC-BFLegacyWorks@yahoogroups.com
>To: BC-BFLegacyWorks@yahoogroups.com
>Subject: Re: [BC-BFLegacyWorks] Fuel Return Line Mod??
>Date: Wed, 19 Jun 2002 005:52 EDT
>
>Are you finding yourself out of injector? If not, upping fuel pressure can
>often cause more harm than good......

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Josh Colombo · Post by **Josh Colombo** » Wed Jun 19, 2002 8:36 am

Give use the low down on all the mods, and sorta what you are trying to accomplish with this.

I still don't quite understand the fuel return line thing you're talking about.

Yes, the FPR controls the fuel pressure. It does so with vacuum. At idle vacuum is the highest, and it pulls on the diaphragm in the regulator to restrict fuel pressure. When your engine starts to rev.....vacuum drops, diaphragm no longer has as much if any vacuum on it, so you get full fuel pressure.

There are rising rate fuel pressure regulators, that can boost your fuel pressure.....I'm not exactly sure how it is done.....but I would think a bigger pump would be more advantageous.

Josh

-----Original Message-----
From: Matthew Reese [mailto:carmat76@hotmail.com]
Sent: Wed 6/19/2002 6:58 AM
To: BC-BFLegacyWorks@yahoogroups.com
Cc:
Subject: Re: [BC-BFLegacyWorks] Fuel Return Line Mod??

I'm not sure how badly I need the fuel...I am running ~16 + pounds of boost now (figured out that intercooler plumbing problem I was having)and the air/fuel is reading a little lean (actually I use a volt meter and I'm seeing .75 - .8 volts). I would like to see .9 to 1.0 and I did with stock boost. I am sure I read of doing this mod on other turbo sites. I am not wanting to block off the return but just put a valve in to control flow. I would be able to fine tune fuel flow with the valve. I have a larger pump I could install to take the extra load. I understand the larger pump alone is not going to push more fuel to the injectors - that is regulated by the fuel pressure regulator, right? Any more thoughts on this?

>From: Z1Auto@aol.com
>Reply-To: BC-BFLegacyWorks@yahoogroups.com
>To: BC-BFLegacyWorks@yahoogroups.com
>Subject: Re: [BC-BFLegacyWorks] Fuel Return Line Mod??
>Date: Wed, 19 Jun 2002 005:52 EDT
>
>Are you finding yourself out of injector? If not, upping fuel pressure can
>often cause more harm than good......

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Matthew Reese · Post by **Matthew Reese** » Wed Jun 19, 2002 8:36 am

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Z1Auto@aol.com · Post by **Z1Auto@aol.com** » Wed Jun 19, 2002 8:36 am

First, I wouldn't go by O2 voltage as a standalone item for reading
A/F...coltages fluctuate a LOT with weather and humidity,. it is best to use
O2 voltage in conjuntion with EGT, actual A/F (like from the GReddy A/F
gauge), and a datalogger (to measure IPW and knock). As an example, on race
gas, I can tune my Galant and was able to tune my Subaru (GC8 with STi swap)
down to about .78-80 O2 voltage, but still ahev no knock correction at
all...this was due top the higher ocatne of the race gas we used at the
track. Granted, you are not running race gas, but you get my point...it is
not a very accurate tuning tool, unless it is used in conjunction with other
data , so you can begin to spot trends.

In any event, a bigger pump might give you a bit more base pressure at idle,
that is if the stock regulator cannot bypass enough fuel. You might just try
fitting an aftermarket fuel pressure regulator....one that is still 1:1 (you
don't want higher on a factory turbo car), but one that will let you raise
pressure a few points...you can probably get a bit more out of the injector
that way,

The otehr way is to use an Apex'i SAFC or HKS SAFR fuel controller to
increase IPW (lengthen it), thus giving you a bit more fuel as well...but
again, best used with a t least a datalogger.

adam
Z-1 Performance
www.z1auto.com

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Matthew Reese · Post by **Matthew Reese** » Wed Jun 19, 2002 8:46 am

My purpose: I am trying to inject more fuel. I was under the impression that a larger pump would push more fuel (maybe or maybe just handle an equivalent volume doing less work) but the regulator will only allow a certain max pressure to see the injectors. I understand how the regulator works.. I've taken different ones apart and the diaphram is controlled by vaccum as you say etc... I am confident from my experimenting with injectors and pumps (working on water injection system) that if the return line was completely blocked the injectors would flow far more than 360 or 390 mls (whatever it is). That flow rate is measured as max using a certain pressure. Anyway I guess the idea I'm considering is not very clear - no problem I'll start tinkering!

Thanks!

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Josh Colombo · Post by **Josh Colombo** » Wed Jun 19, 2002 9:26 am

Adam sorta hit the nail on the head when he mentioned IPW. Those numbers 360 & 390 are in units of cc/min. That is a flow rate......meaning you can flow soo much stuff through this injector in a give amount of time. This is rgardless of the pressure...(assuming your tuning is stock...more on that in a minute)

Think of it this way. Let's say I have one of those small coffee straws, I give it to Johny....a 12 year old kid, he blows through the straw....and get's say 5 cc of air per min through the straw with 10 psi (yes I know I shouldn't mix metric & standard units...) (numbers are completely random and arbitrary) Then I give that same straw to the Hanz.....a big body builder type guy. He blows through the straw.....maybe get's like 6 or 6 cc per min through the straw, but at 17 psi.......He's upped the pressure....however the return in flow due to the higher pressure is not really seen.

Granted the example is not a very scientific one.....but it helps the point.

Now back to IPW.....like Adam said.....if you make this longer, you will have more time for fuel to be squirted into the combustion chamber.....hence more volume of fuel being put in. But you do need some sort of aftermarket controller.

Not sure if this post helps....or confuses more....hopefully it helps.

Josh

-----Original Message-----
From: Matthew Reese [mailto:carmat76@hotmail.com]
Sent: Wed 6/19/2002 7:41 AM
To: BC-BFLegacyWorks@yahoogroups.com
Cc:
Subject: RE: [BC-BFLegacyWorks] Fuel Return Line Mod??

My purpose: I am trying to inject more fuel. I was under the impression that a larger pump would push more fuel (maybe or maybe just handle an equivalent volume doing less work) but the regulator will only allow a certain max pressure to see the injectors. I understand how the regulator works.. I've taken different ones apart and the diaphram is controlled by vaccum as you say etc... I am confident from my experimenting with injectors and pumps (working on water injection system) that if the return line was completely blocked the injectors would flow far more than 360 or 390 mls (whatever it is). That flow rate is measured as max using a certain pressure. Anyway I guess the idea I'm considering is not very clear - no problem I'll start tinkering!

Thanks!

_____

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Matthew Reese · Post by **Matthew Reese** » Wed Jun 19, 2002 10:56 am

1 ml = 1 cc of water ~=1 cc fuel: close enough for us in this discussion! I have to disagree with the flow and time explanation. Ex - My saab injector for my water injection is rated at 210 cc/min. I have a Bosch fuel pump from the Saab and when feeding the injector it put out about 450 ml/min (I have measured the volume because I wanted the volume around 175 ml/min). This injector, like the sube, is rated at a certain pressure. On the Saab the standard regulator is 2.5 bar. The pump is kicking out 5 bar but the extra is routed around the injector and returned. With my installing the pump directly to the injector I doubled it's flow. Are these principles different for the sube? Please point out my misunderstanding.

Thanks for discussing this!

>From: "Josh Colombo"
>Reply-To: BC-BFLegacyWorks@yahoogroups.com
>To:
>Subject: RE: [BC-BFLegacyWorks] Fuel Return Line Mod??
>Date: Wed, 19 Jun 2002 08:25:11 -0500
>
>Adam sorta hit the nail on the head when he mentioned IPW. Those numbers 360 & 390 are in units of cc/min. That is a flow rate......meaning you can flow soo much stuff through this injector in a give amount of time. This is rgardless of the pressure...(assuming your tuning is stock...more on that in a minute)
>
>Think of it this way. Let's say I have one of those small coffee straws, I give it to Johny....a 12 year old kid, he blows through the straw....and get's say 5 cc of air per min through the straw with 10 psi (yes I know I shouldn't mix metric & standard units...) (numbers are completely random and arbitrary) Then I give that same straw to the Hanz.....a big body builder type guy. He blows through the straw.....maybe get's like 6 or 6 cc per min through the straw, but at 17 psi.......He's upped the pressure....however the return in flow due to the higher pressure is not really seen.
>
>Granted the example is not a very scientific one.....but it helps the point.
>
>Now back to IPW.....like Adam said.....if you make this longer, you will have more time for fuel to be squirted into the combustion chamber.....hence more volume of fuel being put in. But you do need some sort of aftermarket controller.
>
>Not sure if this post helps....or confuses more....hopefully it helps.
>
>Josh
>
> -----Original Message-----
> From: Matthew Reese [mailto:carmat76@hotmail.com]
> Sent: Wed 6/19/2002 7:41 AM
> To: BC-BFLegacyWorks@yahoogroups.com
> Cc:
> Subject: RE: [BC-BFLegacyWorks] Fuel Return Line Mod??
>
>
>
> My purpose: I am trying to inject more fuel. I was under the impression that a larger pump would push more fuel (maybe or maybe just handle an equivalent volume doing less work) but the regulator will only allow a certain max pressure to see the injectors. I understand how the regulator works.. I've taken different ones apart and the diaphram is controlled by vaccum as you say etc... I am confident from my experimenting with injectors and pumps (working on water injection system) that if the return line was completely blocked the injectors would flow far more than 360 or 390 mls (whatever it is). That flow rate is measured as max using a certain pressure. Anyway I guess the idea I'm considering is not very clear - no problem I'll start tinkering!
>
> Thanks!
>
>
>
>
> _____
>
> Send and receive Hotmail on your mobile device: Click Here
>
> To unsubscribe from this group, please send an email to:
> BC-BFLegacyWorks-unsubscribe@egroups.com
>
>
>
> zZz .
>
>
><< winmail.dat >>

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Josh Colombo · Post by **Josh Colombo** » Wed Jun 19, 2002 11:36 am

Yeah, what you have done does make sense.

You hit on a point I sorta didn't touch on, but sorta took for granted in my little examble.

At some point there is a physical limitation to how much stuff you can fit through a certain sized hole, regardless of pressure. In my example I used one of those little coffee straws because they're rather small and can be "saturated" more easily in comparison to a normal straw.

Pretty much same goes for the injectors. I'll use the word saturation.....there's probably a more correct term....but it works.

Let's look at your Saab injector. It's rated at 210 cc/min at 2.5 bar. When doubling pressure you bumped it's flow rate up too....more then double 450 cc/min at 5 bar.

The above results would indicate to me that the Saab injector's physical flow characteristics are pretty damn good. At stock they may be at 40% saturation....when doublin pressure they may be at 80-85% saturation to how much they can physically flow. At some point......with you increasing pressure......you shouldn't continue to see an increase in flow rate.....consider that 100% saturation of the injector's physical flow characteristics.

Things to keep in mind......does fuel not flow as well as water? I'm not sure?
What sort of long term affects is the higher pressure going to do to your fuel system. It may not be worth the safety hazard....or the headache of replacing all your fuel lines with higher pressure lines.....really not sure.

As for the subie injectors.....Who's to say what saturation point or level they are currently running at right now. It could be 40%, could be 50%, could be 80%. I really don't know, and without doing some testing, it would be almost impossible to tell.

Hope this helps clarify things.

Josh

-----Original Message-----
From: Matthew Reese [mailto:carmat76@hotmail.com]
Sent: Wed 6/19/2002 9:50 AM
To: BC-BFLegacyWorks@yahoogroups.com
Cc:
Subject: RE: [BC-BFLegacyWorks] Fuel Return Line Mod??

1 ml = 1 cc of water ~=1 cc fuel: close enough for us in this discussion! I have to disagree with the flow and time explanation. Ex - My saab injector for my water injection is rated at 210 cc/min. I have a Bosch fuel pump from the Saab and when feeding the injector it put out about 450 ml/min (I have measured the volume because I wanted the volume around 175 ml/min). This injector, like the sube, is rated at a certain pressure. On the Saab the standard regulator is 2.5 bar. The pump is kicking out 5 bar but the extra is routed around the injector and returned. With my installing the pump directly to the injector I doubled it's flow. Are these principles different for the sube? Please point out my misunderstanding.

Thanks for discussing this!

>From: "Josh Colombo"
>Reply-To: BC-BFLegacyWorks@yahoogroups.com
>To:
>Subject: RE: [BC-BFLegacyWorks] Fuel Return Line Mod??
>Date: Wed, 19 Jun 2002 08:25:11 -0500
>
>Adam sorta hit the nail on the head when he mentioned IPW. Those numbers 360 & 390 are in units of cc/min. That is a flow rate......meaning you can flow soo much stuff through this injector in a give amount of time. This is rgardless of the pressure...(assuming your tuning is stock...more on that in a minute)
>
>Think of it this way. Let's say I have one of those small coffee straws, I give it to Johny....a 12 year old kid, he blows through the straw....and get's say 5 cc of air per min through the straw with 10 psi (yes I know I shouldn't mix metric & standard units...) (numbers are completely random and arbitrary) Then I give that same straw to the Hanz.....a big body builder type guy. He blows through the straw.....maybe get's like 6 or 6 cc per min through the straw, but at 17 psi.......He's upped the pressure....however the return in flow due to the higher pressure is not really seen.
>
>Granted the example is not a very scientific one.....but it helps the point.
>
>Now back to IPW.....like Adam said.....if you make this longer, you will have more time for fuel to be squirted into the combustion chamber.....hence more volume of fuel being put in. But you do need some sort of aftermarket controller.
>
>Not sure if this post helps....or confuses more....hopefully it helps.
>
>Josh
>
> -----Original Message-----
> From: Matthew Reese [mailto:carmat76@hotmail.com]
> Sent: Wed 6/19/2002 7:41 AM
> To: BC-BFLegacyWorks@yahoogroups.com
> Cc:
> Subject: RE: [BC-BFLegacyWorks] Fuel Return Line Mod??
>
>
>
> My purpose: I am trying to inject more fuel. I was under the impression that a larger pump would push more fuel (maybe or maybe just handle an equivalent volume doing less work) but the regulator will only allow a certain max pressure to see the injectors. I understand how the regulator works.. I've taken different ones apart and the diaphram is controlled by vaccum as you say etc... I am confident from my experimenting with injectors and pumps (working on water injection system) that if the return line was completely blocked the injectors would flow far more than 360 or 390 mls (whatever it is). That flow rate is measured as max using a certain pressure. Anyway I guess the idea I'm considering is not very clear - no problem I'll start tinkering!
>
> Thanks!
>
>
>
>
> _____
>
> Send and receive Hotmail on your mobile device: Click Here
>
> To unsubscribe from this group, please send an email to:
> BC-BFLegacyWorks-unsubscribe@egroups.com
>
>
>
> zZz .
>
>
><< winmail.dat >>

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Matthew Reese · Post by **Matthew Reese** » Wed Jun 19, 2002 12:26 pm

Thanks for the reply Josh - I think we've beat this one to death but hey, that's what it's all about! As I have the time, I think I'll insert a valve and start slow with the restriction. A few more pounds of pressure might work well.

I'll let the group know when and if I do this.

>From: "Josh Colombo"
>Reply-To: BC-BFLegacyWorks@yahoogroups.com
>To:
>Subject: RE: [BC-BFLegacyWorks] Fuel Return Line Mod??
>Date: Wed, 19 Jun 2002 10:30:42 -0500
>
>Yeah, what you have done does make sense.
>
>You hit on a point I sorta didn't touch on, but sorta took for granted in my little examble.
>
>At some point there is a physical limitation to how much stuff you can fit through a certain sized hole, regardless of pressure. In my example I used one of those little coffee straws because they're rather small and can be "saturated" more easily in comparison to a normal straw.
>
>Pretty much same goes for the injectors. I'll use the word saturation.....there's probably a more correct term....but it works.
>
>Let's look at your Saab injector. It's rated at 210 cc/min at 2.5 bar. When doubling pressure you bumped it's flow rate up too....more then double 450 cc/min at 5 bar.
>
>The above results would indicate to me that the Saab injector's physical flow characteristics are pretty damn good. At stock they may be at 40% saturation....when doublin pressure they may be at 80-85% saturation to how much they can physically flow. At some point......with you increasing pressure......you shouldn't continue to see an increase in flow rate.....consider that 100% saturation of the injector's physical flow characteristics.
>
>Things to keep in mind......does fuel not flow as well as water? I'm not sure?
>What sort of long term affects is the higher pressure going to do to your fuel system. It may not be worth the safety hazard....or the headache of replacing all your fuel lines with higher pressure lines.....really not sure.
>
>As for the subie injectors.....Who's to say what saturation point or level they are currently running at right now. It could be 40%, could be 50%, could be 80%. I really don't know, and without doing some testing, it would be almost impossible to tell.
>
>Hope this helps clarify things.
>
>Josh
>
> -----Original Message-----
> From: Matthew Reese [mailto:carmat76@hotmail.com]
> Sent: Wed 6/19/2002 9:50 AM
> To: BC-BFLegacyWorks@yahoogroups.com
> Cc:
> Subject: RE: [BC-BFLegacyWorks] Fuel Return Line Mod??
>
>
>
>
> 1 ml = 1 cc of water ~=1 cc fuel: close enough for us in this discussion! I have to disagree with the flow and time explanation. Ex - My saab injector for my water injection is rated at 210 cc/min. I have a Bosch fuel pump from the Saab and when feeding the injector it put out about 450 ml/min (I have measured the volume because I wanted the volume around 175 ml/min). This injector, like the sube, is rated at a certain pressure. On the Saab the standard regulator is 2.5 bar. The pump is kicking out 5 bar but the extra is routed around the injector and returned. With my installing the pump directly to the injector I doubled it's flow. Are these principles different for the sube? Please point out my misunderstanding.
>
> Thanks for discussing this!
>
>
> >From: "Josh Colombo"
> >Reply-To: BC-BFLegacyWorks@yahoogroups.com
> >To:
> >Subject: RE: [BC-BFLegacyWorks] Fuel Return Line Mod??
> >Date: Wed, 19 Jun 2002 08:25:11 -0500
> >
> >Adam sorta hit the nail on the head when he mentioned IPW. Those numbers 360 & 390 are in units of cc/min. That is a flow rate......meaning you can flow soo much stuff through this injector in a give amount of time. This is rgardless of the pressure...(assuming your tuning is stock...more on that in a minute)
> >
> >Think of it this way. Let's say I have one of those small coffee straws, I give it to Johny....a 12 year old kid, he blows through the straw....and get's say 5 cc of air per min through the straw with 10 psi (yes I know I shouldn't mix metric & standard units...) (numbers are completely random and arbitrary) Then I give that same straw to the Hanz.....a big body builder type guy. He blows through the straw.....maybe get's like 6 or 6 cc per min through the straw, but at 17 psi.......He's upped the pressure....however the return in flow due to the higher pressure is not really seen.
> >
> >Granted the example is not a very scientific one.....but it helps the point.
> >
> >Now back to IPW.....like Adam said.....if you make this longer, you will have more time for fuel to be squirted into the combustion chamber.....hence more volume of fuel being put in. But you do need some sort of aftermarket controller.
> >
> >Not sure if this post helps....or confuses more....hopefully it helps.
> >
> >Josh
> >
> > -----Original Message-----
> > From: Matthew Reese [mailto:carmat76@hotmail.com]
> > Sent: Wed 6/19/2002 7:41 AM
> > To: BC-BFLegacyWorks@yahoogroups.com
> > Cc:
> > Subject: RE: [BC-BFLegacyWorks] Fuel Return Line Mod??
> >
> >
> >
> > My purpose: I am trying to inject more fuel. I was under the impression that a larger pump would push more fuel (maybe or maybe just handle an equivalent volume doing less work) but the regulator will only allow a certain max pressure to see the injectors. I understand how the regulator works.. I've taken different ones apart and the diaphram is controlled by vaccum as you say etc... I am confident from my experimenting with injectors and pumps (working on water injection system) that if the return line was completely blocked the injectors would flow far more than 360 or 390 mls (whatever it is). That flow rate is measured as max using a certain pressure. Anyway I guess the idea I'm considering is not very clear - no problem I'll start tinkering!
> >
> > Thanks!
> >
> >
> >
> >
> > _____
> >
> > Send and receive Hotmail on your mobile device: Click Here
> >
> > To unsubscribe from this group, please send an email to:
> > BC-BFLegacyWorks-unsubscribe@egroups.com
> >
> >
> >
> > zZz .
> >
> >
> ><< winmail.dat >>
>
> _____
>
> Get your FREE download of MSN Explorer at http://explorer.msn.com .
>
> To unsubscribe from this group, please send an email to:
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>
>
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>
>
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Z1Auto@aol.com · Post by **Z1Auto@aol.com** » Wed Jun 19, 2002 1:06 pm

Although Josh - increasing pressure does increase the effective flow rate f the injector...you can probably get a 360 cc inejctor to behave like a 390 cc or even 400cc by increasing pressure to a point..thogh the ecu might not like it

Adam
Z-1 Performance
www.z1auto.com
(631)254-8277
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milehial2000 · Post by **milehial2000** » Wed Jun 19, 2002 7:06 pm

Why would voltages fluctuate with weather and humidity?? The O2
sensors are sealed units and if the voltages fluctuated so would the
mixture, something a lot of money has been spent on to hold very
close.

--- In BC-BFLegacyWorks@y..., Z1Auto@a... wrote:
> First, I wouldn't go by O2 voltage as a standalone item for reading
> A/F...coltages fluctuate a LOT with weather and humidity,. it is
best to use
> O2 voltage in conjuntion with EGT, actual A/F (like from the GReddy
A/F
> gauge), and a datalogger (to measure IPW and knock). As an example,
on race
> gas, I can tune my Galant and was able to tune my Subaru (GC8 with
STi swap)
> down to about .78-80 O2 voltage, but still ahev no knock correction
at
> all...this was due top the higher ocatne of the race gas we used at
the
> track. Granted, you are not running race gas, but you get my
point...it is
> not a very accurate tuning tool, unless it is used in conjunction
with other
> data , so you can begin to spot trends.
>
> In any event, a bigger pump might give you a bit more base pressure
at idle,
> that is if the stock regulator cannot bypass enough fuel. You might
just try
> fitting an aftermarket fuel pressure regulator....one that is still
1:1 (you
> don't want higher on a factory turbo car), but one that will let you
raise
> pressure a few points...you can probably get a bit more out of the
injector
> that way,
>
> The otehr way is to use an Apex'i SAFC or HKS SAFR fuel controller
to
> increase IPW (lengthen it), thus giving you a bit more fuel as
well...but
> again, best used with a t least a datalogger.
>
> adam
> Z-1 Performance
> www.z1auto.com

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milehial2000 · Post by **milehial2000** » Wed Jun 19, 2002 7:16 pm

Subaru only gives a fuel pump that is large enough for the engine
without mods of any sort and this will show on a fuel pressure gauge
as a drop in pressure at wide open throttle because the volume can not
be delivered by the stock pump. By raising the pressure you might get
a very small amount of fuel but the closed loop system will cut back
injector time if the fuel is sensed by the O2 sensor. The gain in
raising the pressure is a better pattern and to offset the pressure
delivered by the turbo.
Al(CO)

--- In BC-BFLegacyWorks@y..., "Matthew Reese" <carmat76@h...> wrote:
>

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milehial2000 · Post by **milehial2000** » Wed Jun 19, 2002 7:26 pm

Ok say that you could possibly double the flow of a injector by
doubling the pressure unless you have a controller of some sort the O2
sensor will tell the ECU to cut the injector time in half so all you
have really gained is a high fuel pressure and a very rich mixture out
of loop that will probably cut power.

--- In BC-BFLegacyWorks@y..., Z1Auto@a... wrote:
> Although Josh - increasing pressure does increase the effective flow
rate f
> the injector...you can probably get a 360 cc inejctor to behave like
a 390 cc
> or even 400cc by increasing pressure to a point..thogh the ecu might
not like
> it
>
> Adam
> Z-1 Performance
> www.z1auto.com
> (631)254-8277

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