Fuel managment....500-600hp?

[DETurbine]

I am going to rebuild my block over the winter, since it leaned out and my rings or ring lands went out. I am going forged pistons, rings, ARP head studs, and metal head gasket. The setup should be good to a little over 600hp with ease. My question is that I don't have that much money and am affraid that I am spending it all on the motor getting rebuilt and a bigger turbo with a few other goodies (FMIC, 720-850cc injectors, etc....).

My question to you guys is that I know the Q45 MAF can handle right around 600hp, but will an Apex'i SAFC or ROM tunned ecu handle those numbers?

What is the SAFC good to?

Also does anyone have another method or idea?

I just don't have the money to get an expensive stand alone (PowerFC, Link, Haltech, etc......)

Help would be greatly appreachated....thanks

[KamikazeR33]

a safc will be able to take u to a certain point where aftermarket management is needed

just dont go running 2 bar boost or something crazy

safc will do for the time but u really need to be doing a/f, timing etc to really achieve the best reliable results

[DETurbine]

so the SAFC is capable of 500-550hp?

I have not really seen that many use it after they get around 450+, but then agian those that have the money to achieve 500-600hp normally have the money to go stand alone. I do not though. I do plan on getting a Power FC sooner or later, but will not have the money right away.

I will have an SAFC and a adjustable FPR....and am hoping to acheive 500-500hp, if possible. Would like to hear everyones opinion first and see if it is possible.

[KamikazeR33]

nah id say around 350-400 at most

to keep ur engine save the money n buy a computer, worth its weight in gold

[KamikazeR33]

run ur engine at lower power until u have enough for one... otherwise its almost asking for trouble

[magic1]

tuning tuning tuning its all about the tune, buy the computer first do the motor later, or build the motor now and have an average tune on a highly strung motor and save for a second rebuild

[Sydneykid]

I am going to rebuild my block over the winter, since it leaned out and my rings or ring lands went out. I am going forged pistons, rings, ARP head studs, and metal head gasket. The setup should be good to a little over 600hp with ease. My question is that I don't have that much money and am affraid that I am spending it all on the motor getting rebuilt and a bigger turbo with a few other goodies (FMIC, 720-850cc injectors, etc....).  

My question to you guys is that I know the Q45 MAF can handle right around 600hp, but will an Apex'i SAFC or ROM tunned ecu handle those numbers?

What is the SAFC good to?

Also does anyone have another method or idea?

I just don't have the money to get an expensive stand alone (PowerFC, Link, Haltech, etc......)

Help would be greatly appreachated....thanks

SAFC only adjust A/F ratios in pretty broard steps at that when used on a 600 bhp engine. It does NOTHING for igntion timing, in fact in many cases an SAFC makes the ignition timing problem worse. Following is a previous post of mine explaining why......

a quick, simplistic explanation of how an SAFC works might help...

As the airflow into the engine increase, the AFM records this as increased voltage that the ECU sees. What an SAFC does is sit in between the AFM and the ECU and take the voltages from the AFM and either increase or decrease them depending on what you have programmed the SAFC to do. By increasing the voltage, this tricks the ecu into pumping in more fuel, you do this when the engine is running lean. By decreasing the voltage, this tricks the ecu into pumping in less fuel, you do this when the engine is running rich.

The next bit is hard to understand unless you remember that the standard ecu does not supply fuel in direct proportion to the afm voltage ie; 4 volts is not twice as much fuel as 2 volts. Engine rpm, boost and throttle position also help the ecu determine how much fuel to add.

It has been my experience that RB25's run a little lean down low in the rpm range (Nissan do this for fuel economy and emissions) and a lot rich up high (Nissan do this to protect the engine). So I have to increase the voltage (using the SAFC) up to around 3,000 rpm (part throttle especially) and decrease the voltage over 5,000 rpm (full throttle).

The real problem is in the 3,000 to 5,000 rpm range as the engine comes on boost. They really need lots of fuel very quickly in this area. This can mean that you need to increase the voltage (that the ecu sees) over 5.1 volts to get the right A/F ratios. The ecu then goes into engine protection mode, rich and retarded (sounds like a girl I knew once) . Past that rpm you can start leaning it out as it runs too rich, so the voltage needs to be turned down under 5.1 volts. The ecu sees this as the engine not needing protection mode any more, no more rich and retarded.

It is not unusual to get good performance up to 3,000 rpm, then sluggish from 3,000 rpm to 5,000 rpm and then good performance from 5,000 rpm and over. The SAFC may not help this, in fact as explained above, it can in fact make it worse if the tuner is not switched on to this stuff.

With bent afm voltages, the ecu (tricked by the SAFC) also fires the ignition to suite the airflow it THINKS the engine is getting. This is not a good thing as you generally end up with ignition that is too far advanced in some rpm ranges.

The poor tuner has to juggle the SAFC settings, so that the A/F ratios are OK, the ecu doesn't get into rich and retard (engine protection) mode and the ignition timing is not too far advanced so as to cause detonation. My experience (I am not a good tuner) has been that this is full of compromises, sometimes you just can't win and have to reduce the boost level a bit to get even a reasonable compromise.

Keep in mind that this explanation is very simplified to make it fit in a reasonable space, the rpm's used are rough guides only and every car is different.

Hope it helps (and makes some sense).

[600hp]

mate whats this don't have the money for the computer, you don't have the money not to get a computer, you can grap a power fc soo cheap now days you have no reason not to.

[DETurbine]

Thanks for the info sidneykid, I know what the SAFC does and how it works, just wasn't sure where people have taken it (max hp). I know a few shops here in the states have taken it a little past 450hp....just checking if anyone has taken it past the 500hp mark.

Do you guys think it will be safe to use the SAFC and Q45 maf to 450hp and then in the near future get a power fc and tune it to my 600hp goal?

Has anyone used the ROM tune on their ecu?

[N I B]

If you use an Safc to lean out your car it also advances the timing and if you richen it it will retard the timing as it is tricking the ECU to think it is under more or less load so be careful.

Laptop tunable ECUs are only 1395 now and compared to a 600+hp motor thats cheap.