Bags

iTrader: (3)

here is PLENTY of good info.....

http://forums.maxima.org/search.php?searchid=76632


However, there are more questions.

I am starting this to get some good info to be made a sticky.

So those that can help please do.

Those that have questions ask.

My first questions..

1. How do I know what injector I will need for my application?

Answer... http://www.rceng.com/technical.htm.. there is a chart that will help you understand more, but you may have more questions.


2. When using either Stand alone or JWT ECU, what is the base fuel pressure? What is the WOT fuel pressure?

Answer.. I do not have one, this is my question..lol


3. When using an FMU, what should my base fuel pressure be? What should my WOT fuel pressure be?

Answer... I don't know enough to have a good answer.


4. Do I need to change my wires for new injectors.

Answer... for the 1996 TT 300z injectors NO. For the NISMO 1996 555 cc injectors NO. For other injectors YES. ( IF I AM WRONG CORRECT ME AND I WILL EDIT THIS THANKS )


5. Which is better, an FMU or stand alone/ecu upgrade to control biiger injectors.

Answer.. IMHO.. I think Standalone or ECU upgrade.


So there is a start If I can find answers, I'll post them.

Let's get all of our **** together

Stephen Max

iTrader: (59)

Some additional answers.

2. JWT assumes stock fuel pressure, which for the 4th gen Maxima would be 34 psi at idle and 43 psi at WOT. However, you can have JWT program the ecu based on other WOT fuel pressures. Perhaps they can also program based on a different base fuel pressure.

3. Base fuel pressure should be close to stock so that the afr at idle isn't affected. However, if you use larger injectors you will need to lower base fuel pressure in order to get proper idling. WOT fuel pressure depends on how much boost you are running. I have seen two rules of thumb regarding fuel pressure requirement vs boost. One is where you multiply the stock WOT fuel pressure and multiply that by the pressure ratio at full boost. For instance, if you are running 9 psi, that is a PR of 1.61, so you need 1.61 x 43 psi = 70 psi of fuel pressure. The other rule of thumb I've seen is to square the PR and multiply that times stock WOT fuel pressure, so (1.61)^2 x 43 psi = 111 psi. Most of us running 9 psi and using FMUs seem to be running WOT fuel pressures somewhere in between. I was at about 85-90 psi at redline with no problems.

4. The new style 95-96 Z32 injectors will plug right in to the 4th gen Maxima harness connectors.

5. JWT ecu. You might not be squeezing out every last ounce of power, but you will be running a safe system based on many, many dyno runs and a thorough knowledge of the VG and VQ engines. Plus you get the increased midrange torque from increased timing angles in the mid-rpm, mid-power level regime.

Bags

iTrader: (3)

AWESOME

Another question about your post... The PR stands for what? Pressure Ratio is what I am guessing.

How did you come up with that 1.61 number?

And when running 8 LBS of boost and using an 8:1 fmu I had 95 PSI of Fuel Presure. That is rich enough for 11:1 on a dyno. JUST MORE INFO.

And I'll look for the Pressure ratios for the walbro, mardi posted them, I'll either find those or go to there website.

Bags

iTrader: (3)

**********CREDIT MARDIGRASMAX********


Most pumps will fall off their ability to flow as the pressure gets
higher. For instance, the Walbro GSS342 will support...
@ 40psi-60gph~720bhp
@ 50psi-56gph~650bhp
@ 60psi-52gph~620bhp
@ 70psi-49gph~588bhp
@ 80psi-44gph~528bhp
@ 90psi-37gph~444bhp
@100psi-27gph~325bhp
@110psi-13gph~156bhp

As you can see after 90psi is falls off real hard. Remebmer this is BHP not WHP so subtract drive line loss and it get even worse. This may not be your problem, but it could be, this is also a best case 14.4 volt situation, err on the side of caution.

Even at a higer pressure with a 10-1 FMU disc you may not be able to flow enough fuel to support you needs.

Stephen Max

iTrader: (59)

Yes, PR is my shorthand for pressure ratio.

PR = (boost pressure + pressure at blower inlet)/(pressure at blower inlet)

so for 9 psi boost and assuming 14.7 psi at the blower inlet,

PR = (9 + 14.7)/14.7 = 23.7/14.7 = 1.61

slimer

iTrader: (13)

what about those 440 injectors that hnda eatr is offering. they are skyline i think. would they plug in and would jwt be able to adapt a fuel map for that?

JeffesonM

iTrader: (5)

Okay, I've got a general question here...

It sounds like you can increase fuel delivery by increasing the fuel pressure, or by upgrading to bigger injectors. What are the tradeoffs between these two methods?

Stephen Max

iTrader: (59)

Larger injectors are used to provide sufficient fuel without having to increase fuel pressure. The main advantage here is avoiding injector lockup at high fuel pressure. The conventional wisdom is if you're jacking up fuel pressure to 100 psi or over, you are in the danger zone. This translates to a limit of about 10 psi of boost pressure if you use an 8:1 fmu.

The downside of larger injectors is the additional cost of the injectors. Also, idling smoothness can suffer due to poor fuel atomization with the really large injectors.

JeffesonM

iTrader: (5)

thanks! 6789

ejj

iTrader: (5)

Have you noticed either? I haven't with the method I'm using (MardiGraxMax's).

Stephen Max

iTrader: (59)

No, my car idles same as before. I don't think the 370's are big enough to make much difference in idling smoothness. Probably the 555's would, I'm thinking.

Stephen Max

iTrader: (59)

Those look like top feed injectors. Won't work in a 4th gen without major replumbing. I'm wondering if they are peak and hold, too, being out of a Skyline. Maximas need saturated type injectors.

Bags

iTrader: (3)

ok, now I don't care how dumb this sounds.. I am gonna ask...


How do you know pressure at blower inlet?

sorry if this seems like I have no idea what your talking about, WELL I don't, but I do want to learn.

If there is to much to type, can you point me to a website and I'll read as much as long as the mouse stays on the wheel

pblaze

It may be poor atomization, but I think the reason is better called minimum fuel angle controllability. At very small injection angles the injector opening and closing delays consume a significant portion of the commanded injection duration. When this happens injected fuel quantity becomes less predictable. Depending on how the fuel maps are shaped this may also present a worsening problem at higher speeds and very light loads.

If big injectors are required, faster ones will perform better over a wide dynamic range. Nonsaturated injectors would be the way to go especially if one has the ability to play around with the injector drive circuits.

Stephen Max

iTrader: (59)

The only way to know it is to put a vacuum gauge test port in between the air filter and the blower inlet and collect data. It is common to assume that the pressure at the blower inlet is atmospheric (i.e. 14.7 psi) but a filter usually creates a pressure drop of a couple of tenths of a psi. A dirty filter will have a higher pressure drop. So with a dirty air filter you may actually have a pressure at the blower inlet of 14-14.2 psi, which is what you should base the pressure ratio on. The pressure drop across the filter will increase the calculated pressure ratio. This does not mean you are making more boost, rather it means that the blower is working harder to create a certain level of boost, resulting in decreased efficiency (higher air charge temperature).

Stephen Max

iTrader: (59)

Good information.

slimer

iTrader: (13)

yeah, pblaze has been bustin out info right and left all over this board, but he still hasn't gone to the faqs

Bags

iTrader: (3)

ahh.. thank you...


grashopper is learning and will soon be able to take grain of rice from masters hand

pblaze

Thirty eight posts in two years, yeah I'm really tearing this place up.

I read the FAQ's when I registered. Everything I never wanted to know about clear corners, colored light bulbs, basoon intakes, and fart can exhausts, along with a few gems of real info, is in there.

Feel free to discount anything I post because of a website tag.

nismology

iTrader: (8)

He meant the info you've posted hasn't been entered into the FAQ's

tampamax

Could you please elaborate on the theory of faster not bigger choices of injectors for induction systems. Or at least direct me to a site to collect this info at.

And when you speak of injection angles are you speaking of the angles at the pintle in regards to fuel atomization out of the injector, or are you speaking of the actual position or angle the injector takes in relation to fuel delivery to the chamber: OR did i just miss it all-it is kind of late here.

:Young grasshoppar mus rest wiery eye's foar big day of knowledge with new sun:

tampamax

Could you please elaborate on the theory of faster not bigger choices of injectors for induction systems. Or at least direct me to a site to collect this info at.

And when you speak of injection angles are you speaking of the angles at the pintle in regards to fuel atomization out of the injector, or are you speaking of the actual position or angle the injector takes in relation to fuel delivery to the chamber: OR did i just miss it all-it is kind of late here.

:Young grasshoppar mus rest wiery eye's foar big day of knowledge with new sun:

Prodeje79

Very good info.

That courtesty link was helpfull too: http://www.courtesyparts.com/z32/oe_fuel.html

So what else is recommended to be replaced upon replacing injectors?
2 insulators and 2 o-rings per injector? I am confused over exactly what to order from said web page, old style, new style etc? It would be nice to have an exact list of what part numbers to order and how many, etc for the 4th gen.

[maxi-overdose]

iTrader: (3)

so are you saying that even you see 100psi + on your fuel pressure gauge, it doesnt mean there's enough fuel flow thru to support your application?

Bags

iTrader: (3)

From what I read in another thread the 96 TT will plug directly into the 4th gen wiring harness

Bags

iTrader: (3)

yes... MY APPLICATION.

Sorry, I missed that. I tried to delete everythign pertianing to my situation. He answered a question I aksed about fuel pressure. I was asking about which fmu would be best for 8 PSI.

And using the chart, you can se the walbro flows less LPH the higher psi.

hopefully that made sense and aswered your question

[maxi-overdose]

iTrader: (3)

I am asking how does this apply in real world. I assume the data from mardi is from a test done on a machine where they generate the pressure and measure the fuel flow.

I thought when the fuel delivery decreases due to increase of fuel pressure, the pump will pump less fuel and it cannot build up the fuel pressure. We would see fuel pressure drop too, right?

say with a regular walbro 255lph pump (not the high pressure one) I want to know if we see 100psi of rail pressure generated by FMU and the pump, does this mean the fuel delivery is very low. Or we just wouldnt be able to see 100psi rail pressure with this pump. I know if we run an SC on a stock pump, we wont see the fuel pressure goes above 50 psi because the stock pump just cannot generate that much pressure and fuel flow.


thx

Prodeje79

I understand that the 96 TT appear to work fine in our cars.

My request is for someone to provide the exact part numbers for the main situations, this would be an excellent sticky, also I am sure that people that have done this already have the information:

What all do you recommend to replace along with the 370 upgrade?
(o-rings, insulators,etc with part numbers. Might as well include the correct part number for the injector too. It is confusing for me to look at the courtesy page to determine which I need from old style, new style etc.)

What all do you recommend to replace along with the stock injectors?
(o-rings, insulators,etc with part numbers. Might as well include the correct part number for the injector too. )

What all do you recommend to replace along with the 555 upgrade?
(o-rings, insulators,etc with part numbers. Might as well include the correct part number for the injector too. )

etc.....


Thanks!

Bags

iTrader: (3)

Well for the real world application..

I dyno tuned with an 10:1 FMU and swapped in the 8:1.... with the 10:1 I was around 11.3:1 AFR.

With the 8:1 I was around 10.2:1 AFR.

I posted the question and mardi came back with the chart on how the walbro flows better under less PSI.

On the fuel pressure drop... I have no answer sorry.

On the last question I have no good answer... so I won't say anything.

Sorry I can't help much.

[maxi-overdose]

iTrader: (3)

thanks~ you've already helped me a lot by sharing your experience.

I guess mardi's test works for your case. I want to know if the pump can sustain high rail pressure. I always thought more pressure means more fuel....I guess it is not ture.

what kinda pump do you have when you dynoed your car @ 10:1?

Bags

iTrader: (3)

I think matt found the info on another website.

I tihnk I have the think 255 hi flow walbro. It's the gss342. ( although the 341 is the hi flow from what I read)

And For those of you that wanna break it down barney style...

I found this while researching something else..GREAT INFO..

http://www.supras.nl/view.php?page=modsFuelPump.htm

Bags

iTrader: (3)

more walbro fuel related info


http://www.stealth316.com/2-fuelpumpguide.htm

pblaze

When I use the term “injection angle” you can just substitute “injection duration”. What I mean by angle is the time duration expressed as an angle of crankshaft rotation at a given engine speed. The types of fuel injection pumps I work with are called “positive displacement” which means that they have a defined output per pump revolution. Converting injection timing and duration into units of angle makes the math simpler for me when working with engine maps. This works because in order to inject a constant quantity of fuel per injection as RPM increases, I would use a relatively constant “injection angle” (angular duration) regardless of the time duration of the injection event. This is the way the “direct injection” systems work. An MPFI fuel injection system (as in the Max) does not work this way. In MPFI you have a defined rail pressure. The time duration of the injection will be constant at a given rail pressure regardless of engine speed. This is why FMU’s work, because if you can increase rail pressure in response to some variable (like boost) you can increase fuel delivery per injection.

The comment about “fast” injectors has to do with metering very small quantities of fuel, and time delays in opening and closing the injector. The opening delay is the time period between the start of the inject pulse and when the injector is fully open. The closing delay occurs between the end of the inject pulse and when the injector is actually closed. The minimum practical injection pulse width is the sum of these two delays. When an injector is operating in this region it’s shot to shot fuel scatter is going to be high. The larger the fuel injector, the larger the scatter. Minimizing the opening and closing delays will improve and injector’s ability to operate at short injection durations. In reality though, it would be easier to try to make a smaller injector flow more than it would be to make a bigger injector flow more consistently.

[maxi-overdose]

iTrader: (3)

thx bags for the reading material.

tampamax

Hugh, it must be cause its so late, but i didn't quite grasp what you were trying to relay to me. I'll try a reread in the morning. Thanks though---any links that you could provide that i could read up on for what you are speaking of. It seems that there are some benifits of DI that i need to read up on.

Aaron92SE

iTrader: (128)

I have confirmed that the injectors for the VE30DE and the 4th gen VQ are the same part number.

Now with that said, what is the stock flow rate of the VE30DE or 4th gen VQ injectors? I have heard 240 and 259cc.

I have also confirmed that 259cc is the flow rate of the z32 VG30DE injectors. But I'm not sure which year since I know there is a new design for the injectors in 1994+. I hope somebody can answer my question with 100% assurity. Thanks.

Bags

iTrader: (3)

GLAD I COULD HELP

Stephen Max

iTrader: (59)

I have always heard that the 4th gen injectors are 240 cc/min. The 5th gen injectors may be 259 cc/min to handle the increase in power. But that is pure speculation on my part.

Aaron92SE

iTrader: (128)

Thanks for replying. But do you have any ideas on how I can find out for sure? The dealership doesn't know b/c I talked to a very reputable Maxima guy that has worked at the dealership for years now. He was only able to dig up that the VG30DE z32 injectors are 259cc.

So far i have heard, 180, 240, 260, 259cc. The 259cc came from most reliable source. But I'm still unsure. I need to be sure about my stock flow rate before I start tinkering with my ECU. Cause if I enter 259cc when it's really 240cc, then it won't get enough fuel and run lean.

tampamax

Heard a wise man once say "tis easier to err on the side of caution" Just go with the smaller one and work your way up by safely tuning on a dyno with proper tools.
Honestly there is such little difference between the two you could correct for this by uping the fuel pressure a point or 2. That is only if you are not already pushing the envelope and running the ragged edge.

DISCLAIMER--the previous comments are only an opinion and not know to be factual.

PLEASE!!!!!!!!!!!!!If anyone see's an error in my thought process speak up and explain why.!!!!!!!!!!