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RB20DET injector probs? see my dyno print-out

bbenny

By bbenny,
in Engines & Forced Induction

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bbenny Mentor

bbenny

Posted
Posted

Hey guys,

as some of you know i am ironing out all the minor probs with my R32 and getting it ready for the drags.

I have been talking to Toshi over email ragarding a tuned chip for my standard ECU.

when i emailed him my last dyno-sheet (as below) he explained that the injectors are already at 100% duty.

as you can see the engine does cut out at 5500rpm (I have always thought this was the AFM signal maxing out) is it the injectors? what is the max power std RB20 injectors make?

This dyno print was using just over 1bar (anything under 1bar i have no cut-out problems)

Cheers

Ben.

Dynosheet.jpg

whatsisname Grand Master

whatsisname

Posted
Posted

12.8 A/FR up top is getting a tad too lean for my liking! Are you sure it's 'just' your injectors? What fuel pump are you using? What's your fuel pressure doing across the rev range?

meggala Grand Master

meggala

Posted
Posted

well I would be lowering your boost immedatly as you engine is at risk from running too lean the max power of the rb 20 injectors is around 250 hp@ the wheels or 195 rwkw you will need bigger injectors and a z32 afm

btw this is one of the reasons I went sr rather than rb 20

cheers

meggala

whatsisname Grand Master

whatsisname

Posted
Posted

Yep, I agree with Meg's, wind the boost down till you get it sorted.

I know Clint (Clint32 from SA section of SAU) got 230rwkw (308rwhp) out of his RB20DET injectors. I'm not sure what fuel pump, reg, or pressure that was with though? He ran 12.8 @ 113mph with that power level.

Nice dyno and 1/4 numbers too Meg's!

bbenny Mentor

bbenny

Posted
  • Author
Posted

Yeah dont worry about me running that boost, because it is running at 12psi only.

but as a few of you said, i thought the injectors would have a little more in them.

I am running a 650hp intank bosch pump and sard adj reg, so the rest of the fuel system should be able to cope.

Would my cutting-out problem be AFM related. i wound the boost uip the otherday, it went to 1.2bar but as soon as it reached around 5500rpm it would cut again...

considering that many have gone 230rwkw on std injectors should i really bother as i only expect i will make around 220rwkw once tuned and boost raised?

Roy Grand Master

Roy

Posted
Posted

Do R32 RB20s have fuel or boost cuts, i never paid too much attention as my old ECU had them removed...id suggest giving Doctor a buzz as he is using my old ECU, but i think he is OS on holidays.

I suspect its the std ECU measuring too much airflow and ending the party, so more the ECUs fault then the AFM.

I didnt want to have to bother with a Z32 meter, and i still dont believe that they are 100%necessary, but the person tuning my car made it pretty clear that he thinks its needed and wanted me to install one.... so to make sure the tune is what i want, im getting a Z32 AFM, but at 200-220rwkws i dont think they are a MUST have, though its not a bad idea to have one if you can afford it.

rbs13 Community Regular

rbs13

Posted
Posted

check the filter thing on the fuel pump too.. i know its a bitch but this car block fuel to the motor obviously - if there is shit on it.. also check the wires to the fuel pump. mine unconnected it self once and made the car a bitch to drive.. taking corners at low speed and made it jerk like i hit a brick wall..

bbenny Mentor

bbenny

Posted
  • Author
Posted

I know there are no problems with my fuel system, everything is brand new and works perfectly well.

I suspect Roy is correct assuming the ECU just craps itself and doesnt know what to do.

well I might buy a chip off Toshi with all the cut outs and limiters removed and see what happens on the dyno. might run a little more fuel pressure and then fine tune the SAFCII (and before anyone asks, i had the boost cut issues before installing the SAFCII)

Seeing as there are a few other making good power with std injectors i will leave them alone. Troy i also agree with you that its not neccessary to go Z32afm at this power level.

MM2death Grand Master

MM2death

Posted
Posted

Here is my print out. Std injectors and no adj fuel reg. It is 2530 (i think) running 1 bar...and clutch isn't holding up, mind you it's standard...lol

My injectors have got alot of life still left in them by the look of the std ecu AF curve.

BTW this is a comparision between Toshi's chip and my std ECU. He made this chip without seeing my car.

Regards,

Scott

jnr32r Proficient

jnr32r

Posted
Posted

BBenny i can confirm that the cut out you are getting is your AFM. When i had the Std AFM i could see at about 1bar it was hitting a max of 5.1V.

Im sure your fuel system should cope but its the AFM that will give you that cut off.

Ive heard of people with 230kw with std inj and AFM. but realistically that cant be too healthy as your tunability is right up the top of your hardware with inj. and AFM close to their max.

If i were you and was on a tight budget or dont want too much higher in power i would get a Z32 AFM and increase the fuel press. a tad. 220kw is just around the corner...

bbenny Mentor

bbenny

Posted
  • Author
Posted

yeah i have mixed feelings about going Z32AFM.

having done a fair bit of reading on the topic i have found there are two primary arguments for and against, and to me they both make alot of sense!

the first is what you are describing jnr32r - that it is impossible to tune correct airflow readings at high boost/rpm because the std meter runs out of resolution. and installing the z32 (which uses a lower voltage reading) allows you to obtain accurate readings at high rpm.

the other argument against the z32 is that if you have a decent tuner they should be able to tune your computer or ecu regardless, and ensure a safe A/F ratio. and the only time to replace is if the factory AFM size is restricting flow.

So i dont know which to go, obviously if i can get someone to safely tune without the z32 i can save good $$ for other mods, however if it means piece of mind and insurance on my engine...

what does everyone think!

Sydneykid Grand Master

Sydneykid

Posted
Posted
yeah i have mixed feelings about going Z32AFM.

having done a fair bit of reading on the topic i have found there are two primary arguments for and against, and to me they both make alot of sense!

the first is what you are describing jnr32r - that it is impossible to tune correct airflow readings at high boost/rpm because the std meter runs out of resolution. and installing the z32 (which uses a lower voltage reading) allows you to obtain accurate readings at high rpm.

the other argument against the z32 is that if you have a decent tuner they should be able to tune your computer or ecu regardless, and ensure a safe A/F ratio. and the only time to replace is if the factory AFM size is restricting flow.

So i dont know which to go, obviously if i can get someone to safely tune without the z32 i can save good $$ for other mods, however if it means piece of mind and insurance on my engine...

what does everyone think!

Hi bbenny, I don't know any tuner "decent" enough to tune past 5.1 volts on the RB20/25DET AFM with a standard ECU and an SAFC. The SAFC bends the input signals to the ecu but I don't care how clever they are, the tuner can't get past the basic logic of the ecu. This is of course not the case with aftermarket ecus' where we can program the throttle position and rpm to cover for the afm voltage being at 5.1 volts for long periods.

Keep in mind that tuning an RB20 to run a Z32AFM with an SAFC is not a simple task. You will need a "decent" tuner for that.

bbenny Mentor

bbenny

Posted
  • Author
Posted

im not going to attempt to tune the SAFC to run a z32 AFM as i have heard to many horror stories of ppl attempting it.

I am having the std ecu rechipped shortly so if i decide to upgrade the afm i will do it then.

but i would prefer to not buy a new afm and upgrade to GTR cams and/or adj cam gears...

but if it comes down to not being able to correctly tune the ecu without the afm upgrade, i guess i wont have any choice...

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