legacycentral bbs

first off. i have some access to a wrx fuel system as in rails and blues. will i be able to bolt this up into my car or are they so totaly different that it wont work? second along wiht this question is, is it possible for the piggyback being discussed in the hijacked thread bo able to control modded 740cc blues if and when they could be installed in my car.

next. rrfpr's.. will one of these along wiht a 255 pump be able to squeze more fuel thorugh the stock 370's to make 15 psi on a 16g a little more reliable and rich?

lastly. wet fuel injection. similar to a wet nitrous system without the nitrous. bascily injecting more fuel into the manifold at wot and high boost. i currently have a 2 stage boost controler that i will be setting up for 12 psi on low and 15-16 on high (currently running 15 on low). with the boost at 12 the car should be fine but when i flip the swich to 15 ill need more fuel at wot so would injecing help it not lean out or will it cause the car to run like crap?

I don't think WRX rails will bolt to our manifolds.

That piggyback is still at the earliest stages of development so there's no knowing what it will and won't be able to do. That said, its functionality in terms of fuel control will be kind of like that of the UTEC which is known to operate 740cc injectors okay.

An RRFPR and a Walbro high-pressure fuel pump should be a decent stopgap measure until you get proper engine management.

Adding extra injectors used to be a common way of enriching mixtures on boost. It's extremely crude, but in principle it'll work. You might have to do a lot of experimenting to get it right (and by "right" I mean effective at enriching but not causing ridiculous bogging).

At the very least, you'd need the injector and a pressure switch of some type. If you're going to the junkyard to look for stuff, some Jaguar fuel injectors have hose barb inlets, as do many early EFI cars' cold-start injectors. Cold-start injectors also often are designed to be held open for significant lengths of time, as opposed to most injectors which are meant to be run at duty cycles less than 100%. For a cheap pressure switch you might be able to use a relay with normally-closed contacts and an OEM oil pressure switch from some random car. Most oil pressure switches open at pressures above a couple of psi. It's probably more trouble than it's worth though.

Of these options, I suggest the RRFPR and the high-pressure pump. You should have the pump already, right?

the pump is on its way. i realise how dangerous my stiuation is. i havent hit fuel cut with my advanced morgie style fcd at hight boost though i havent stayed on high boost long enough to tell. ive been driving around like a grandma because of it.

i was thinkin of using a wet nitrous fuel solenoid and dry nossle jet to get suplemented fuel. i was also thinking that if i was able to add enough fuel with a rrfpr and a pump along with the wet injection to run up to 20 psi safely. thought i wont be able to tell wihtout a wideband which i will have acces to in a few days. using an cold start injector may be a little more trouble just because of size and id be putting it in a place where it wasnt meant to go whereas using nos parts would be easier becasue it was built for it.

edit*. fuel pump just arived. found it on my porch. gss341. this thing is smaller than i thought it would be. fits in the palm of my hand.

will something like these for fpr's work well?

http://cgi.ebay.com/ebaymotors/ws/eBayI ... gory=33553
http://www.x3racing.com/product.asp?pid=FPR-RA

No. You're not looking for an adjustable fixed-rate regulator. You need one with a rising rate; otherwise you'll be flowing too much fuel at low loads.

By way of advice, I'd also say to avoid FPRs like that eBay one that are sold with no brand name, with the acronym "JDM" instead, and by companies obviously targeting the ricer market. A poorly built or bad RRFPR could not only grenade your motor if it malfunctions but also kill you if somehow it develops a high-pressure fuel leak under the hood.

they should both be rising rate. there are vac line taps on both of them but if name is can make a problem the one form ralliart would do fine. im just looking for alternatives to AEM fpr;s that cost tiwce as much as thoes

Why do you say they should both be rising rate? Nothing in the descriptions suggests that.

I think Kelley said he had one for $110 or something.

We use the Aeromotive FPR. It's a rising rate adjustable regulator and it works EXTREMELY well. They're as durable as they come and we've never had one fail.

They make them with -6 dual inlet/outlet and -10 dual inlet/-6 oulet. For comparison they're $132.50-140 depending on the inlet size.

-Mike

nothing on aem's website says that their fpr is rising rate either, but it is. the phiscal features on both the aem unit and the ralli art ones are the same so im making an asumption

How do you know AEM's FPR has a rising rate? What is its rise ratio?

In any case, I think we can agree that you'd want to know what someone's selling you before you give them your money.

that point i do agree with you.

the aem is a 1 to 1 ratio. i know this because my friend is using one on his wrx with pe 800's and a t61 turbo.

1 to 1? Sounds like a fixed rate to me.

vrg3 wrote:1 to 1? Sounds like a fixed rate to me.

You can have a 1:1 rising rate regulator. It adds fuel in a fixed ratio with increased boost pressure. This is how the Aeromotive works. The AEM FPR is a 1:1 RRFPR as well and it isn't a bad unit, but after seeing a few fail, we choose to stick with the Aeromotives.

-Mike

What is that fixed ratio?

Can you explain using example numbers what a 1:1 RRFPR does?

I've never known a circumstance where a rising rate is better then a fixed rate adjusted accordingly.

Jason (Grahn) - What about situations where not everything else is tuned right? Like, say, a 2000 Impreza 2.5RS with a WRX turbo slapped on? How could a fixed-rate FPR provide better performance than a rising rate FPR that doesn't kick in until manifold pressure goes above atmospheric?

Jason (Grahn) - What about situations where not everything else is tuned right?

See, that's the kicker; why do it halfassed?

How could a fixed-rate FPR provide better performance than a rising rate FPR that doesn't kick in until manifold pressure goes above atmospheric?

With either rising or fixed rate, the fuel pressure won't increase until manifold pressure goes above atmospheric - that's what that handy vacuum hose to the regulator is for. Yes, a RRFPR can be used as a bandaid. Do I agree that one SHOULD be used? No. It doesn't allow for the accuracy inherent in an adjustable regulator. Does not adjusting your base pressure up give the effect of larger injectors anyway?

Lets look at our application specifically. With the FMIC, bigger turbo, yadda yadda that (the other) Jason has put on his car, i think it's about time for him to quick pussyfootin around and go big or go home.

Or maybe i'm just making an ass out of myself. You're more technical then I, what do you perceive to be the pro's and con's of both?

JasonGrahn wrote:See, that's the kicker; why do it halfassed?

That's a valid question, but this whole discussion began with the presumption that a halfassed approach was needed as a stopgap measure until a wholeassed solution is ready.

With either rising or fixed rate, the fuel pressure won't increase until manifold pressure goes above atmospheric - that's what that handy vacuum hose to the regulator is for.

That is not true. A fixed-rate FPR maintains a static pressure differential between the fuel rail and the intake manifold. Always. Always always.

Yes, a RRFPR can be used as a bandaid. Do I agree that one SHOULD be used? No. It doesn't allow for the accuracy inherent in an adjustable regulator.

I don't understand why the precision in pressure adjustability is such a concern. If you're doing things right, you have that adjustability in your fueling tables anyway.

Does not adjusting your base pressure up give the effect of larger injectors anyway?

It does, kinda. But that's exactly what you don't want. Remember, we're missing half of the ass -- the half that knows how to meter fuel with big injectors.

What we want is something that'll increase fueling at precisely the times where stock fueling is insufficient. A rising rate fuel pressure regulator does that.

Lets look at our application specifically. With the FMIC, bigger turbo, yadda yadda that (the other) Jason has put on his car, i think it's about time for him to quick pussyfootin around and go big or go home.

Again, that's not what this discussion is about.

Or maybe i'm just making an ass out of myself. You're more technical then I, what do you perceive to be the pro's and con's of both?

I think an adjustable fixed-rate FPR and a rising-rate FPR are an apple and an orange. The former allows you to tune your fuel pressure if you have some reason to, and the latter allows you to enrich your mixtures with boost if you have some reason to.

Then I agree whole-halfassed-heartedly.

How can a 1:1 ratio be a rising rate fuel pressure regulator? A 1:1 ratio means for every 1 psi of boost pressure there's goingt o be 1 pressure of fuel added, and for every 5 psi of boost there will be 5 psi of fuel. A rising rate such as 3:1 or 6:1 means for every 1 psi of boost there will be 3 and 6 psi of fuel added respectively, or for 5 psi of boost 15 and 30 psi respectively.

k guys that was really intertaining but as has been mentioned, until a reasonable whole assed solution presents itself this is what im looking at.

according to a discussion on nasioc stacic fuel pressure is 43 psi. the rrfpr alows you to increase static. with the gauge thats included you are allowed to moniter you static fuel pressure and the subsequent fuel pressure is increased with manifold pressure. the stock rail alread has a rrfpr that is set at stock static or 43psi. if you increace the boost to 15 psi and your static to 53 or 10 psi above stock static, your subsequent fuel pressure is 68 psi instead of 58psi and with a little math you can figure out what your injector equlivent is after the turn up.

kingpin did a thread in which you dimple the stock fpr to increase its static rate. you have to get a gauge so you can see exactly how high it goes but the adjustabilty of a another fpr sounds much better than permanently adjusting the stock unit.

the 1 to 1 is just the rate in psi of fuel pressure increased to the rate of psi manifold pressure increased while on boost.


inovative, does the fpr your talking about come with barbed ends and a gauge for that price?

I was under the impression that our fuel pressure was 36.3 psi. But it sounds to me like you just want to increase the static pressure and not the rate that the pressure raises. You should be able to do this with a nissan fpr. I believe the 89-94 maxima regulator is the same shape as ours. There are others though. Most any of them should bolt in and that should raise you to 43.5psi.

That's not correct, Jason.

Static fuel pressure is 36.3 psi.

The stock fuel pressure regulator has a fixed rate, not a rising rate. Any change in manifold pressure is met by the exact same change in fuel pressure.

This fixed 1:1 rate is required in order to maintain fuel flow across the injector, since the injector is a valve between the fuel rail and the intake manifold.

Crushing the stock regulator, or using an adjustable fixed-rate regulator, changes the static pressure differential. Raising static fuel pressure this way effectively makes the injectors flow more fuel at all times. With otherwise stock engine management, this will cause your engine to run badly rich most of the time.

A rising rate fuel pressure regulator does not always increase fuel pressure by the same amount that manifold pressure increases. The amount of the fuel pressure increase is some multiple of the manifold pressure increase; thus the rate at which fuel pressure increases with respect to boost rises. This means the injectors flow more and more as boost increases. Since most RRFPRs only start to act once manifold pressure exceeds a certain threshold (often simply 0 psig but sometimes adjustable), this will cause your engine to run normally at low loads and then richer than usual at high loads.

The latter is what you want.

Please try to understand this. Don't think that giving money to a vendor will solve your problems.

Wow, okay, there's a lot going on here

THAWA wrote:A 1:1 ratio means for every 1 psi of boost pressure there's goingt o be 1 pressure of fuel added, and for every 5 psi of boost there will be 5 psi of fuel. A rising rate such as 3:1 or 6:1 means for every 1 psi of boost there will be 3 and 6 psi of fuel added respectively, or for 5 psi of boost 15 and 30 psi respectively.

Absolutely correct. Who said a 1:1 was a rising rate?

azn2nr wrote:until a reasonable whole assed solution presents itself ...

The whole assed solution apparently isn't reasonable.

according to a discussion on nasioc stacic fuel pressure is 43 psi. the rrfpr alows you to increase static.

By static, do you mean BASE fuel pressure? If so, then no, your rrpfr does not allow you to increase base pressure.

If you only want to increase base pressure (as you call it, "static") then a rising rate is not the correct way.