Fuel Pressure?

[beeza]

Hey Guys and Gals :wave:
Just wondering what is the maximum Fuel Pressure I can go to?
96 D16y4 4 Door Civic.
Mods:
Custom Intake with K&N Filter
Stock Header,2" Exhaust with Resonator and Original Cat
MSD Ignition System
Fuel Pressure Regulator
NGK Iridium Wires and Plugs

Stock is 36 psi,I currently have it set at 40 psi and it's running a charm but just wondering if I can squeeze a bit more out...

[Edgeauto]

Why do you want to increase your fuel pressure?

[beeza]

To hopefully get some more power ???

[bennjamin]

do you understand your theory at all ? Can you expand on it ?

[beeza]

I dont have a theory as such but when I put in the FPR and bumped it up from stock 36 psi to 40 psi I definately felt a power increase.So Im wondering if I can go to say 42 psi and still get a power increase or not.Should I just experiment with it? If so how will I know that I've gone too far....running rough etc.
Am I on the right track here? If not plz tell me.Thanks.

[beeza]

I know there's such a thing as a FPR calcolator where you match your mods to how much psi you can run...but I cant find it.

[bennjamin]

but you cant run beyond a certain threshold , on stock fuel pump or stock injectors etc. I think there is no point on your current setup. Get a light flywheel or smaller lighter rims , or reduce the static weight of your car to improve performance.

[ralph_ef9]

if u put too many pressure....u may kill the fule pump....30-40 when the idle will be fine....

[Mr_will]

i see where you are coming from with this theory, and it kind of relates to the advanced timing concept.

some people say: i want ot advance my timing to get more power.

but then mr correct comes along and says No. j00 advance timing to get the correct amount of power for the type of fuel you are running. if you are using higher octane fuel for maximum efficiency you ignite it earlier coz it burns more slowly - its a subtle difference but the fact is youre not actually advancing the timing to make power, your advancing it to make the CORRECT power.

same goes here - more fuel pressure simply enables you to get the CORRECT amount of fuel relative to the amount of air that is going in - without a turbo you dont have huge control over the amount of air going in, so this will only be effective up to a point.

more fuel pressure = higher load on fuel pump and injectors too.

if it were as simple as increasing fuel pressure to get more power dont you think it would come that way from the factory:p

[creativepunka]

yes but without a wide band its useless. If you keep puting the pressure up you are going to run rich. In some cases droping the pressure will make power as you lean it out a bit more, you may start to get into other problems then tho.

[dsp26]

bennjamin is correct regarding threshold.

remember that if you increase pressure you sacrifice flow rate in the whole system and vice versa... there is a certain range though different for every car. an afpr has never really been a performance mod but rather a 'band-aid fix' to fuelling ISSUES. think of a water hose thats free flowing... then you put your thumb over the hole and pressure increases because you weer sacrificing flow potential.

on my sr20, i managed an extra 4wkw by adding an external coil, 1.3mm plug gap, +4psi fuel pressure over stock... but then again even though it was the same dyno it wasn't the same day... and my circumstances at the time were also quite odd....

***EDIT***
also depends what your "MSD Ignition System" consists of... raising fuel pressure the right amount is of benefit to a multispark system as it can actually burn most of it at low revs which eventuates in torque.... but again you won't know exactly how much till your on the dyno....

[turtleEK1]

I know there's such a thing as a FPR calcolator where you match your mods to how much psi you can run...but I cant find it.

i know theres an equation that comes with the B&M fpr... its simply whatever the percentage increase in air flow is, you do the same for the fuel pressure.

eg. 10% increase in air flow... so 10% of 36psi is 3.6
3.6 + 36 = 39.6psi

or turn the percentage into a decimal and add 1 to it...
(1 + 0.1) x 36 = 39.6psi

after all that... beeza, you would have been better off spending that cash on a header... lol

[beeza]

Thanks Heaps Guys.Great Info!
Cheers Dave,that's what I am talking about.I initially got the idea from you when you put in your FPR.So that answers my query.It's simple then 10% increase in air flow in = 10% you can increase the Fuel Pressure.
Ha Ha,I know I had planned on getting a header (I will in the future),but I Love how my car runs now,stealth too,cause a Header will make it quite Grunty yeh?
The MSD System is the shit! I Love it!
MSD Box (Multiple Spark Box)
HVC (High Voltage Coil)
I Had to Modify the Stock Dizzy Cap with a MSD Power Tower since MSD don't make a Modified Dizzy Cap for the D16y4

[JasonGilholme]

how much gain from the FPR??

anything noticeable??

go pics??

[[ricer]]

how much gain from the FPR??

anything noticeable??

go pics??

im sure you've seen a fuel pressure regulator before haven't you?

[crx88rb]

walbro fuel pump + sard reg = 45 psi :)

[dsp26]

but that formula for 10% increase is in relation to vacuum... pressure rises the higher the revs.....

[beeza]

how much gain from the FPR??

anything noticeable??

go pics??

A Nice Bump in Power For sure.Obviously nothing BIG but Definately worth doing.
I installed a Walbro 255LPH Fuel Pump 3 weeks after that.I know 190LPH would have been suffice but I thought what the hell it cant hurt.If I decide to do Major Mods in the future (when I get $$$-Ha Ha) it will be better to have the bigger pump.And offcoarse there was no increase in power but I reckon my 10 yr old pump wasn't cutting the mustard anymore.
I'll take some snaps of My engine bay tomorrow,I've been meaning too :o .

[beeza]

walbro fuel pump + sard reg = 45 psi :)

Depends on what other mods ya got but


but that formula for 10% increase is in relation to vacuum... pressure rises the higher the revs.....

I'm confused :confused:

[crx88rb]

Depends on what other mods ya got but



I'm confused :confused:

i/h/e billet cams, cam gears, safc2...works nicely :)

[beeza]

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Peek a Boo I can C U
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Why Not
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[dsp26]

I'm confused :confused:

good you have a gauge on your setup... notice how when you rev the car the pressure goes up... it's rising rate... supposed to provide a little extra fuelling in higher revs....

it's controlled by that blue hose you have at the top.

[Mr_will]

fair to say that the rising rate regulator might make more of a difference if you have msd?

bit of a noob when it comes to fuel pressure stuff so willing to stand corrected

[bennjamin]

Nice thoughts , but point is with current mods and engine , increasing fuel pressure will not yield any results apart from leaving more black soot on his bumper.

[dsp26]

fair to say that the rising rate regulator might make more of a difference if you have msd?

bit of a noob when it comes to fuel pressure stuff so willing to stand corrected

as i said an afpr has never really been considered a 'performance mod'. the factory fpr is also rising rate like most other cars just not adjustable.... it will richen/lean fuel mixtures across the entire A/F curve which is why it is labelled a "temporary band-aid fix" until a car is actually tuned by a proper ecu to richen/lean mixtures at different rpm points.

you will gain power somewhere in the rpm range where you have a trouble spot at the cost of power somewhere else... kind of like putting high rpm aggressive cams in a non-vtec car.... they will lose power down low and have a lumpy idle as a price to get top end power and vice versa.

***EDIT***
as stated by this honda tuning dedicated site:


"What is an fmu?:
A Fuel Management Unit (FMU) is a special rising rate fuel pressure regulator placed in the fuel return line of the fuel injection system. This is a very common approach to handling the increased fuel demand required by turbo kits and supercharger kits. It does work. It will make the injectors flow more fuel than their rating. These are used in addition to the factory or aftermarket fuel pressure regulator and only have an affect under boost.
FMUS are rated by the ratio of fuel pressure to boost pressure. For instance, a 10:1 FMU will give you 100psi fuel pressure at 10 psi boost pressure. "

What he is talking about is a seperate rising rate unit on top of an fpr... the SARD unit is already an adjustable rising rate (or whatever the original poster has... looked like a SARD)
The only thing he is wrong about is the "Flow rate" part as it technically doesn't increase flow.. just forces out more fuel through injectors for every pulse width.

That explanation with the boost is also why i said the above 10% formula isn't exactly correct and only applicable to the rising rate/vacuum operation... and again that 10% figure is skewed by boost pressure in the intake. The rise in rate of fuel pressure is controlled by intake vacuum as well as the fuel pump... each pump provides a certain pressure already which is why the Walbro + AFPR = ???psi shouldn't be taken as gospel either.

[beeza]

Great Input Guys!
I think it's fair to say your just really guessing the psi until you get on a Dyno or hook up a wideband then.
Just out of curiousity If I bump it up a bit how will I know that I am running to rich?

'Black soot in the bumper' = Too rich? Does this mean Blowing black smoke?

[dsp26]

Great Input Guys!
I think it's fair to say your just really guessing the psi until you get on a Dyno or hook up a wideband then.
Just out of curiousity If I bump it up a bit how will I know that I am running to rich?

'Black soot in the bumper' = Too rich? Does this mean Blowing black smoke?

like you said no-one can really tell you without a dyno... HOWEVER... i'm not condoning it BUT I was gauging mine based on exhaust pop under a certain load under a certain rev. not willing to dyno now as i'm waiting for one more mod and an ecu so i can spend my $100 on a before/after of the ecu.

Heres another example though... i know my car was more responsive in the midrange at 30psi to lean out compared to stock 37psi with vac line on (vac line off is +~10psi)... however coz pressure was too low.. it's soooo hard to start sometimes so just put to like ~34psi.

***EDIT***
sorry about the emphasis on a few words... just making MY method for MYSELF clear so the nazi's don't go flaming me for dangerous methods.

[beeza]

^^ Gotcha! Cheers mate :)

[Drew]

What you need is someone with a dyno, chip, soldering iron and tuning knowhow

[beeza]

What you need is someone with a dyno, chip, soldering iron and tuning knowhow

Yes :p