Injectors and Fuel Pump question(s)

[AC]

Is injector size the only (real) determining factor when considering increased fuelling?

or

Can a high pressure fuel pump also have an effect irrespective of injector size (e.g. if at 100% duty cycle)?


The reason I ask; I have 2zz 310cc's at the mo, when Noble mapped they reported/described the characteristic of "almost seems like it needs more pressure in the rail" as they had max'd the fuel adjust through the EMB to reach result.  So, one 'to do' on my list was change to a HP fuel pump (something like an MWR 255lph item) as its a fairly easy mod, rather than pulling out the 310's for even bigger, but I can't seem to find a consensus on the question partly as anecdotal evidence supports all the answers, such as;

1. The PE kit only prescribes a rising rate pressure regulator and I understand for example Davy (VVT-I) has reached 234hp keeping std injectors and pump.
2. However, nearly all people agree larger injectors = better fuelling capability.
3. My Apexi kit on previous car ran std injectors with a HP fuel pump and made good enough results.

The reason I didn't go to 440's or bigger was because I'd heard the EMB can have issues with this size and greater and that idling starts to deteriorate when big.  I'm in no rush, just asking the question, then I can either scrub from my list or keep it on.

[markiii]

raise the pressure and you will flow more fuel during the same injector cycle, so almost the same effect as larger nozzles

I'm not sure if one solution is better than another but might be worth a chat with Tem, I beleive he is running the mwr pump

[Ilogik]

do you not need a fuel regulator if running a bigger pump? I know fuel regulators are both a pita to fit and pretty pricey.

[aaronjb]

Injectors are rated at a nominal (searches memory) 43psi fuel rail pressure, if memory serves.  So at 43psi, they flow 310cc in your case.

Now remember that 43psi is regulated in our car by a fixed regulator - the regulator uses atmospheric pressure as a reference in the tank.

Now consider that a standard car sees, at most, atmospheric pressure in the intake manifold (actually always slightly less, but lets ignore that for now).

Now consider that you're pressuring your intake manifold to, say, 10psi (I'm sticking to round numbers now!)

So you've actually got the equivalent of 33psi in the fuel rail, because you're fighting against a pressurised intake tract.

Your 310cc fuel injectors now only flow 270cc in real world terms.


A high pressure fuel pump - assuming it changes out the regulator assembly as well - will maintain a greater pressure in the fuel rail (say, 53psi), meaning your injectors will flow more in the real world when on boost.


The rising rate fuel pressure regulator (which most factory turbo cars have) works around this by referencing the fuel rail pressure to the inlet manifold pressure, maintaining a constant 43psi pressure differential between the fuel rail and the inlet manifold - ergo your injectors fuel a constant amount of fuel per minute regardless of how far you turn the boost up.  Assuming a 1:1 RR, of course (you can get FPRs that rise at a multiple of that, for specific applications).

This actually makes tuning a car withou a RR FPR more challenging, since any change in boost will not only change the airflow characteristics (therefore where on the map you are) but actually the amount of fuel that the injectors are flowing in real terms (reducing it!).



Now, if your HP fuel pump does not change out the regulator assembly it will not actually raise the pressure in the rail.  It will give you greater headroom as injector size increases, but will not help you unless you step up injector size.

The reason you'd do this if the pump cannot flow enough to maintain the set pressure when the injectors open (since opening them is asking the pump to momentarily pressurise the universe, so to speak).



In an ideal world I'd like a RR FPR, but since I've quit modding...

That would be my preferred solution - switch to a return type fuel rail (rather than a dead-end rail) and have a rising rate pressure regulator fitted.  You'll gain headroom in your existing injectors, and if you use an adjustable RR FPR you can maintain any pressure differential you choose (though don't go too high - injector latency increases as pressure does, unless you use pintle-less injectors).


I hope that helps a little, even if it doesn't directly answer your question!



Having said all that - people have hit ~270hp with 440 injectors and the standard fuel pump, and that's going to be a much cheaper - if less elegant - solution!

[MattPerformance]

Injectors are rated at a nominal (searches memory) 43psi fuel rail pressure, if memory serves.  So at 43psi, they flow 310cc in your case.

Now remember that 43psi is regulated in our car by a fixed regulator - the regulator uses atmospheric pressure as a reference in the tank.

Now consider that a standard car sees, at most, atmospheric pressure in the intake manifold (actually always slightly less, but lets ignore that for now).

Now consider that you're pressuring your intake manifold to, say, 10psi (I'm sticking to round numbers now!)

So you've actually got the equivalent of 33psi in the fuel rail, because you're fighting against a pressurised intake tract.

Your 310cc fuel injectors now only flow 270cc in real world terms.


A high pressure fuel pump - assuming it changes out the regulator assembly as well - will maintain a greater pressure in the fuel rail (say, 53psi), meaning your injectors will flow more in the real world when on boost.


The rising rate fuel pressure regulator (which most factory turbo cars have) works around this by referencing the fuel rail pressure to the inlet manifold pressure, maintaining a constant 43psi pressure differential between the fuel rail and the inlet manifold - ergo your injectors fuel a constant amount of fuel per minute regardless of how far you turn the boost up.  Assuming a 1:1 RR, of course (you can get FPRs that rise at a multiple of that, for specific applications).

This actually makes tuning a car withou a RR FPR more challenging, since any change in boost will not only change the airflow characteristics (therefore where on the map you are) but actually the amount of fuel that the injectors are flowing in real terms (reducing it!).



Now, if your HP fuel pump does not change out the regulator assembly it will not actually raise the pressure in the rail.  It will give you greater headroom as injector size increases, but will not help you unless you step up injector size.

The reason you'd do this if the pump cannot flow enough to maintain the set pressure when the injectors open (since opening them is asking the pump to momentarily pressurise the universe, so to speak).

In an ideal world I'd like a RR FPR, but since I've quit modding...

That would be my preferred solution - switch to a return type fuel rail (rather than a dead-end rail) and have a rising rate pressure regulator fitted.  You'll gain headroom in your existing injectors, and if you use an adjustable RR FPR you can maintain any pressure differential you choose (though don't go too high - injector latency increases as pressure does, unless you use pintle-less injectors).


I hope that helps a little, even if it doesn't directly answer your question!



Having said all that - people have hit ~270hp with 440 injectors and the standard fuel pump, and that's going to be a much cheaper - if less elegant - solution!

Wot he said!

[AC]

A high pressure fuel pump - assuming it changes out the regulator assembly as well - will maintain a greater pressure in the fuel rail (say, 53psi), meaning your injectors will flow more in the real world when on boost.

This is the MWR pump, I'm guessing it doesn't include an FPR as MWR list one seperately (at $415  s:crazyeyes: :crazyeyes: s:crazyeyes:  ).

http://store.monkeywrenchracing.com/index.php?cPath=43_72_207

There must be other FPR alternatives?  I've read that its located in the tank but also a pain to change?  Does it and is it?

Otherwise, most roads lead back to injectors which having already changed makes me a little "  s:evil: :evil: s:evil:  ".

[muffdan]

What Aaron said  s:) s:)

The MWR uprated pumps are high flow pumps, not higher pressure pumps. This is why they rate them in terms of flow rather than pressure. They are just the pump and direct replacements for the stock one. I believe there's some wiring to splice but mechanically they're a direct swap. The high flow means exactly what Aaron pointed out. When the injectors are open, the pressure on the fuel rail drops. The pump needs to work harder to maintain the pressure the FPR (rising rate or not) is trying to set. The higher flow pumps are more able to do this especially with larger injectors.

Again as Aaron said, you want to get yourself a Rising Rate 1:1 fuel pressure regulator (with return). This alone will probably get you where you need to be.

For reference I use the MWR 255l/h pump with a SARD 1:1 Rising Rate FPR.

[aaronjb]

Oh - I forgot to mention..

There is a 'hack' you can do with the stock pressure regulator, if memory serves.  Essentially you dismantle it and 'shim' the spring up with washers, then reassemble it.  Shimming the spring raises the pressure at which it will open (it effectively shortens the spring and increases the spring rate).  It's an inexact science though, and you'll need to plumb in a fuel pressure gauge so you know how far you've gone. I know at least one person on SC did that..

However if you're splicing pressure gauges into the moulded fuel pipework, you're half way to fitting a return system with 1:1 FPR and pressure gauge so.. you may as well go the whole hog at that point!

[Tem]

This is the MWR pump, I'm guessing it doesn't include an FPR as MWR list one seperately (at $415  s:crazyeyes: :crazyeyes: s:crazyeyes:  ).

Pump is a pump and a regulator is a separate item.

It you replace the stock pump with a high performance pump, nothing changes, cause the pressure will still be the same and it can't flow more.

There must be other FPR alternatives?  I've read that its located in the tank but also a pain to change?  Does it and is it?

Yeah, the regulator is in the tank. It's bloody easy to change, if you do while you do the pump. It practically falls off when you change the pump.

But don't confuse changing the in-tank regulator with external return-flow regulator, that's completely another thing and Aaron already said why.

[Tem]

The MWR uprated pumps are high flow pumps, not higher pressure pumps. This is why they rate them in terms of flow rather than pressure.

They can also handle higher pressures than stock pump.  s8) s8)  

They are just the pump and direct replacements for the stock one. I believe there's some wiring to splice but mechanically they're a direct swap.

The MWR pump is actually physically bigger than stock and you have to modify the plastic pump assembly to make it fit. Not a big deal, but not a direct swap either.[/quote]

[AC]

Again as Aaron said, you want to get yourself a Rising Rate 1:1 fuel pressure regulator (with return). This alone will probably get you where you need to be.

For reference I use the MWR 255l/h pump with a SARD 1:1 Rising Rate FPR.

How about this one;

http://cgi.ebay.co.uk/SARD-Fuel-Pressure-Regulator-Kit-for-NISSAN-TOYOTA-S14_W0QQitemZ180452732450QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item2a03d22e22

What's the fitting process?  Situate it near the rail?  Does the fuel tank need touching?  Is there a stock regulator to remove?

[Tem]

There is a 'hack' you can do with the stock pressure regulator, if memory serves.  Essentially you dismantle it and 'shim' the spring up with washers, then reassemble it.  Shimming the spring raises the pressure at which it will open (it effectively shortens the spring and increases the spring rate).  It's an inexact science though, and you'll need to plumb in a fuel pressure gauge so you know how far you've gone. I know at least one person on SC did that..

I'm not sure if you can dismantle it...but you you can just squeeze it with a vice bench doing what you just described. Quite common among budget tuners. Just be careful, cause you can't go backwards..

[Tem]

How about this one;

http://cgi.ebay.co.uk/SARD-Fuel-Pressure-Regulator-Kit-for-NISSAN-TOYOTA-S14_W0QQitemZ180452732450QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item2a03d22e22

What's the fitting process?  Situate it near the rail?  Does the fuel tank need touching?  Is there a stock regulator to remove?

Fitting process roughly:
1) Change the fuel rail to one where you can install a connector or hack the stock rail to have an output
2) Run a fuel line from fuel rail to regulator
3) Run a fuel line from regulator back to fuel tank
4) Run a vacuum/pressure from intake manifold to regulator
5) Remove and block the stock in-tank regulator

Same process for every generic external regulator.

[AC]

How about this one;

http://cgi.ebay.co.uk/SARD-Fuel-Pressure-Regulator-Kit-for-NISSAN-TOYOTA-S14_W0QQitemZ180452732450QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item2a03d22e22

What's the fitting process?  Situate it near the rail?  Does the fuel tank need touching?  Is there a stock regulator to remove?

Fitting process roughly:
1) Change the fuel rail to one where you can install a connector or hack the stock rail to have an output
2) Run a fuel line from fuel rail to regulator
3) Run a fuel line from regulator back to fuel tank
4) Run a vacuum/pressure from intake manifold to regulator
5) Remove and block the stock in-tank regulator

Same process for every generic external regulator.

Are there higher pressure internal regulators that the stock regulator can be swapped out for, without then changing the pump?  I'm presuming that, or something similar is what the PE kit came with?

*edit* replaced rising rate with higher pressure now I've plugged my brain in.

Oh b*ll*cks to it, if needed, bigger injectors it will have to be.

[Tem]

Are there higher pressure internal regulators that the stock regulator can be swapped out for, without then changing the pump?  I'm presuming that, or something similar is what the PE kit came with?

Yeah, the PE it comes with in-tank regulator:
 m http://www.powerenterpriseusa.net/carmo ... s/mrs.html m

Might wanna ask PE (or their distributors) if they sell that without the kit.

Oh b*ll*cks to it, if needed, bigger injectors it will have to be.

That is the easiest and most common way.  s8) s8)

[Tem]

The reason I ask; I have 2zz 310cc's at the mo, when Noble mapped they reported/described the characteristic of "almost seems like it needs more pressure in the rail" as they had max'd the fuel adjust through the EMB to reach result.

3. My Apexi kit on previous car ran std injectors with a HP fuel pump and made good enough results.

I just re-read the first post and now I'm wondering if the issue is the EMB...

If you made enough power with stock injectors and PFC(?), but fail to get similar power with bigger injectors and EMB, then the EMB has to be the issue right? Or are you going for lots more power now?

It has been forever since I touched EMB, but I recall it had issues that limited injector choices and usage. I forgot what they were though, but I have a faint memory about some 50% being some limit. Could it be you're hitting the EMB limits instead of the injector limits?

[AC]

The reason I ask; I have 2zz 310cc's at the mo, when Noble mapped they reported/described the characteristic of "almost seems like it needs more pressure in the rail" as they had max'd the fuel adjust through the EMB to reach result.

3. My Apexi kit on previous car ran std injectors with a HP fuel pump and made good enough results.

I just re-read the first post and now I'm wondering if the issue is the EMB...

If you made enough power with stock injectors and PFC(?), but fail to get similar power with bigger injectors and EMB, then the EMB has to be the issue right? Or are you going for lots more power now?

It has been forever since I touched EMB, but I recall it had issues that limited injector choices and usage. I forgot what they were though, but I have a faint memory about some 50% being some limit. Could it be you're hitting the EMB limits instead of the injector limits?

Sorry Tem, when I said "Apexi kit" I was refering to the actual turbo kit which is the Apexi AX53B60 kit, not a PFC.  The previous car ran the same Emanage Blue with std injectors but an MWR fuel pump, don't know about the regulator.  It also had intake cooling (WI (I have none at present)) and the power figure quoted then was 200hp which if was measured at road wheels will be roughly same as my 230hp at flywheel following Noble mapping.

As for the fuel adjust on the EMB; I think you could be right that 50% is the max adjust, as soon as I can get my map downloaded I plan to post up the timing, fuel and airflow matrices.  I'm not sure though whether the EMB is the bottleneck but I have asked Noble once again.  On another front, I'm sure I read that the EMB has problems with injector size over a certain factor, maybe over 400cc???

This post is in preperation for whatever form of intake cooling I go for (soon to happen) as when I get to second map I'd hate to find out then that the extra benefit of the intake cooling can't be realised due to fuelling limits of present set up.

[Ilogik]

The reason I ask; I have 2zz 310cc's at the mo, when Noble mapped they reported/described the characteristic of "almost seems like it needs more pressure in the rail" as they had max'd the fuel adjust through the EMB to reach result.

3. My Apexi kit on previous car ran std injectors with a HP fuel pump and made good enough results.

I just re-read the first post and now I'm wondering if the issue is the EMB...

If you made enough power with stock injectors and PFC(?), but fail to get similar power with bigger injectors and EMB, then the EMB has to be the issue right? Or are you going for lots more power now?

It has been forever since I touched EMB, but I recall it had issues that limited injector choices and usage. I forgot what they were though, but I have a faint memory about some 50% being some limit. Could it be you're hitting the EMB limits instead of the injector limits?

Sorry Tem, when I said "Apexi kit" I was refering to the actual turbo kit which is the Apexi AX53B60 kit, not a PFC.  The previous car ran the same Emanage Blue with std injectors but an MWR fuel pump, don't know about the regulator.  It also had intake cooling (WI (I have none at present)) and the power figure quoted then was 200hp which if was measured at road wheels will be roughly same as my 230hp at flywheel following Noble mapping.

As for the fuel adjust on the EMB; I think you could be right that 50% is the max adjust, as soon as I can get my map downloaded I plan to post up the timing, fuel and airflow matrices.  I'm not sure though whether the EMB is the bottleneck but I have asked Noble once again.  On another front, I'm sure I read that the EMB has problems with injector size over a certain factor, maybe over 400cc???

This post is in preperation for whatever form of intake cooling I go for (soon to happen) as when I get to second map I'd hate to find out then that the extra benefit of the intake cooling can't be realised due to fuelling limits of present set up.

Rather than go for the bigger fuel pump you thought about going stand alone with some bigger injectors. That way if you want to take it further in the future you can. What are your power aims? I ran 230-240 fwhp, fueling seemed fine, I was running 440 injectors with stock fuel pump, think my limiting factor was the TTE turbo kit.

What is the Apexi turbo rated for?

[Tem]

Sorry Tem, when I said "Apexi kit" I was refering to the actual turbo kit which is the Apexi AX53B60 kit, not a PFC.

Yeah, I got that, I just assumed it came with PFC.  s:? :? s:?  

The stock fuel pump was good for some 300hp, of course with bigger injectors. Here's another thought, could the fuel pump filter be clogged, if it seems like the pump doesn't flow enough for 230hp? I guess it's also possible that the pump is worn and just doesn't flow enough anymore.

[AC]

Rather than go for the bigger fuel pump you thought about going stand alone with some bigger injectors. That way if you want to take it further in the future you can. What are your power aims? I ran 230-240 fwhp, fueling seemed fine, I was running 440 injectors with stock fuel pump, think my limiting factor was the TTE turbo kit.

What is the Apexi turbo rated for?

TBH don't know, possibly 250hp.  Bigger injectors are the simple answer, just trying not to make too many (costly) mistakes along the way in buying twice to reach final set up.

The stock fuel pump was good for some 300hp, of course with bigger injectors. Here's another thought, could the fuel pump filter be clogged, if it seems like the pump doesn't flow enough for 230hp? I guess it's also possible that the pump is worn and just doesn't flow enough anymore.

I guess its possible.  I understand the fuel filter isn't the typical in line type, is it in the tank (with everything else)?  When is its change interval?  My car is a late 2003, 34k, low use/mileage so wear shouldn't be that much of a factor yet, hopefully  s:? :? s:?  .

[Tem]

The stock fuel pump was good for some 300hp, of course with bigger injectors. Here's another thought, could the fuel pump filter be clogged, if it seems like the pump doesn't flow enough for 230hp? I guess it's also possible that the pump is worn and just doesn't flow enough anymore.

I guess its possible.  I understand the fuel filter isn't the typical in line type, is it in the tank (with everything else)?  When is its change interval?  My car is a late 2003, 34k, low use/mileage so wear shouldn't be that much of a factor yet, hopefully  s:? :? s:?  .

Yeah, it's in the tank, within the same plastic holder as the pump and regulator. I don't remember if it had a change interval at all.

Should be fine at 34k, but then again, I guess one tank of bad fuel could clog it. But it really was just a guess anyway.

[Ilogik]

Rather than go for the bigger fuel pump you thought about going stand alone with some bigger injectors. That way if you want to take it further in the future you can. What are your power aims? I ran 230-240 fwhp, fueling seemed fine, I was running 440 injectors with stock fuel pump, think my limiting factor was the TTE turbo kit.

What is the Apexi turbo rated for?

TBH don't know, possibly 250hp.  Bigger injectors are the simple answer, just trying not to make too many (costly) mistakes along the way in buying twice to reach final set up.

The stock fuel pump was good for some 300hp, of course with bigger injectors. Here's another thought, could the fuel pump filter be clogged, if it seems like the pump doesn't flow enough for 230hp? I guess it's also possible that the pump is worn and just doesn't flow enough anymore.

I guess its possible.  I understand the fuel filter isn't the typical in line type, is it in the tank (with everything else)?  When is its change interval?  My car is a late 2003, 34k, low use/mileage so wear shouldn't be that much of a factor yet, hopefully  s:? :? s:?  .

Haha been there done it got the tshirt, when i first got it, got it mapped on stock injectors which caused fault, then got it mapped on the 440's it cured lack of fuel but mapping was still crap. 8 mapping sessions later I went elsewhere, then I decided I couldn't be bothered with turbo cars especially mapping.   s:lol: :lol: s:lol:

[AC]

Are there higher pressure internal regulators that the stock regulator can be swapped out for, without then changing the pump?  I'm presuming that, or something similar is what the PE kit came with?

Yeah, the PE it comes with in-tank regulator:
 m http://www.powerenterpriseusa.net/carmo ... s/mrs.html m

Might wanna ask PE (or their distributors) if they sell that without the kit.

I have been investigating the above, on the Jap PE website found this, does it look like the uprated regulator from the PE1215S turbo kit?



If so I just need to learn Japanese now and I'm there  s:lol: :lol: s:lol: .

[Tem]

I have been investigating the above, on the Jap PE website found this, does it look like the uprated regulator from the PE1215S turbo kit?

I have never seen the PE regulator, I wish someone with the PE kit would comment on that. That does kinda look like a regulator, but the stock one isn't connected to the pump like that.

For comparison, here's few pics of the stock assembly.

Here's the whole assembly, the pump is in there where the wires go to. The regulator is the metal piece, not directly connected to the pump. The regulator is basically on the fuel line through a T-branch, just within the assembly. So the pump always runs at full speed, feeding the fuel line and injectors, but the regulator just opens when the set pressure is reached and lets the excess pressure back to the tank. And the filter is within the white plastic too.
 m http://www.aijaa.com/v.php?i=5604950.jpg m

Closeup of the regulator. It does have a similar looking O-ring as in your pic.
 m http://www.aijaa.com/v.php?i=5604967.jpg m


Can't really help more with just that pic.  s:? :? s:?

[Ilogik]

I sent an email to my english speaking contact at Trial Japan asking if they could source one if you need it.