Ideal Afr?

[gt-ahhh!]

hello.

recent dyno run of my r33 gtst displayed rather inconsistent air fuel ratio readings. not surprising given the lack of a/m management despite the state of mods. (about 240rwkw)

ranges from 12.1 to about 13.0. my understanding is that this is rich, what i found on my searches was that something like 14.7 is ideal.

opinions?

i do hope its not in fact running lean. because i just havent quite got the cash for ecu goodness.

[The Mafia]

depends where?

Full load is 12:1 or below to be safe, cruise or light load, 14.7:1.

Post up the dyno graph.

[gt-ahhh!]

bear in mind that the peak power is only at about 5300rpm 13psi, because the coilpacks fried themselves and the test was aborted. the AFR at this point is about 12.2. i will take it back soon and wind it right out to 18 or 20psi.

[VB-]

i'd be more worried about the shape of the boost plot( looks like that of a centrifugal supercharger), although it seems like your running out of fuel in the top end. your running standard injectors i would assume? seems like a big hump in the middle where it leans out, what sort of management are you using?

PS, how much power are you making? the graph says ~170 but you sy 240? your overall power curve seems a bit peaky also... more specs on your setup overall?

Edited July 5, 2008 by VB-

[gt-ahhh!]

theyre 440cc injectors i believe. i want to upgrade the fuel pump soon.

not sure what you mean in regards to the boost curve. i thought it looked ok except for at the end where the massive misfire wrecked the run. stock ecu. ive heard they generally run rich, so if its leaning out its because the injectors/pump arent big enough yeh?

it made 170rwkw at 150kmh, or 5250rpm. judging by the shape of the curve youd expect it to keep going up and make 230+ at around 6500 or so. remember the run was aborted due to misfiring.

kkr430 @ 16psi

injectors

greddy style ff plenum

3/3.5in turbo back

fmic

hks pod

atmo bov

'custom high-flowed' cat

i'd be more worried about the shape of the boost plot( looks like that of a centrifugal supercharger), although it seems like your running out of fuel in the top end. your running standard injectors i would assume? seems like a big hump in the middle where it leans out, what sort of management are you using?

PS, how much power are you making? the graph says ~170 but you sy 240? your overall power curve seems a bit peaky also... more specs on your setup overall?

[R31Nismoid]

430hp turbo doesnt make 170rwkw till 5000rpm?

You have some major issues to attend to mate, should be around a good 1000rpm sooner

Id start with boost control, then timing/tune etc

[VB-]

yeah you should be all in by about 4000rpm with that turbo. take a look at the plot for boost, it just keeps climbing and climbing till redline, it should shoot straight up as early as possible, then hold flat at 16psi till redline (ideally, you wont get it perfect but should be able to get it damn close)

has your stock ECU been chipped or is it just a standard computer? i would expect with all those other mods that its at least remapped, if not, then you've really gone off track buying all those other mods and this should be addressed immeadiately, without management all you've done is thrown away your money till this point. what size are your injectors?

1. invest in a fuel pump

2. sort out the boost issue, do you have an electronic controller?

3. get the A:F ratio flat at 12:1 till redline

4. get it tuned properly. i dont know the specifics of your mods and what you told your tuner you wanted done, but it really does seem like a rush job (dare i say it, a poor effort?)

did you ask for a tune or just a power run? if tune, who did it? (this assumes you got remap at least)

[PM-R33]

How are you running larger injectors on stock engine management?

[gt-ahhh!]

yeah you should be all in by about 4000rpm with that turbo. take a look at the plot for boost, it just keeps climbing and climbing till redline, it should shoot straight up as early as possible, then hold flat at 16psi till redline (ideally, you wont get it perfect but should be able to get it damn close)

has your stock ECU been chipped or is it just a standard computer? i would expect with all those other mods that its at least remapped, if not, then you've really gone off track buying all those other mods and this should be addressed immeadiately, without management all you've done is thrown away your money till this point. what size are your injectors?

1. invest in a fuel pump

2. sort out the boost issue, do you have an electronic controller?

3. get the A:F ratio flat at 12:1 till redline

4. get it tuned properly. i dont know the specifics of your mods and what you told your tuner you wanted done, but it really does seem like a rush job (dare i say it, a poor effort?)

did you ask for a tune or just a power run? if tune, who did it? (this assumes you got remap at least)

what does that boost curve mean then? is it leaking? i agree its silly how late it reaches boost.

as far as i know the ecu is completely stock. i blew the stock turbo which took the engine with it, and replaced it with all that kit because i bought it all off a bloke as a package.

admittedly it is stupid, but i needed to get the car back on the road asap and so its not exactly an ideal situation.

as i said above, i believe the injectors are 440cc.

no i havent got an ebc, this along with fuel pump and maybe safc are on top of the shopping list. will an ebc improve the boost curve?

it was going to be tuned, but the coilpacks shat themselves. timed to perfection.

also, someone mentioned how can i run bigger injectors on the stock ecu. i dont know... why wouldnt you be able to?

[bumble_bee]

u wouldnt be able to run bigger injectors becoz u wouldnt be able to tune wit the stock ecu...

or the fuel pump module/reg would adjust but i dont c how???

and would the spray from the injector be all ova the place???

well i dont get it..lol

can some1 else try explain this?

[Toshi]

You need bigger fuel pump,Z32 AFM and PFC or remap ECU.

Std AFM is up to 300hp(220kw) max.

S-AFC can not handle Z32 AFM.

I am able to remap.

[gt-ahhh!]

You need bigger fuel pump,Z32 AFM and PFC or remap ECU.

Std AFM is up to 300hp(220kw) max.

S-AFC can not handle Z32 AFM.

I am able to remap.

cheers. i will look into this stuff.

i checked out your topics about the remapping. sounds good. a lot cheaper than a pfc.

no one answered my question about the ebc though. will it improve the boost curve?

[PM-R33]

The boost problem is in the stock engine management, i had a similar problem. Replace the ECU and the tune should fix it.

You can't run bigger injectors on a stock ECU because you have no way to rescale them. Its the same if you put bigger injectors on an aftermarket ECU, it still wont run them unless you rescale them which you can't do on a stock ECU.

[Toshi]

Std injector is up to 360-380hp , So do not need change injectors.

Just need change bigger fuel pump.

[WARLORD]

Std injector is up to 360-380hp , So do not need change injectors.

Just need change bigger fuel pump.

r u sure !!!

[Toshi]

RB20DET up to 260-270hp and RB25DET up to 360-380hp.

This is not Kw.

[gt-ahhh!]

thanks for your help guys.

toshi, will a remap fix the boost problem? do i need ebc and fuel pump first? or just remap + fuel pump?

i have a manual bc at the moment.

[Toshi]

What type of boost controller are you fitting now?

Do you have boost gauge?

Normaly about 4000rpm max boost then come down.

If you come to me I will check for you.

[gt-ahhh!]

What type of boost controller are you fitting now?

Do you have boost gauge?

Normaly about 4000rpm max boost then come down.

If you come to me I will check for you.

id get one of the greddy ones. no i dont have a gauge, do i need one of those also?

while ive got you here, which fuel pump would you recommend? bosch 040/044, or the walbro in-tank or external? theyre cheaper than the bosch.

should i get a z32 afm before i come to you for remap?

thanks for your help, hopefully i can accumulate these parts over the next couple of weeks and come see you. do you install the pump/ebc/afm/gauge too? do me a nice deal lol.

...whod modify cars huh?

[Toshi]

How much power would you like?

If under 300hp(220kw) you need fuel pump and evc or boost guage for check boost.

If you want to power over 300hp you need Z32 AFM befor remap.

Walbro is good.

I am able to install all.