rb25 and safc 2 question

[adasportped]

i have a s1 rb25det w/FMIC 3" no cat to N1, nismo fpr and greddy intake manifold .. i just bought a gt3271 my power goals are about 350ish so i was looking at the safc 2 and a z32 maf and i want to run about 15psi would that set up be good for me or is there anything else i should look into, because ive heard that the safc is fine then ive heard that it sucks.. im confused i need some advice on what i should do... thanks ppl

[midnightsliding]

well i have stock 370s injectors SafcII, some crap t3t4,38mm waste gate, stock intake manifold and turbo manifold,and Q45MAFs,and Sard FPR . i made 361and 340ft. with my 9lbs. spring but it was spiking and holding around 12psi after 6000rpms.

[jon1971]

At least 500cc but no bigger then 680cc or so injectors. You don't want to go to big. The SAFCII can only add or pull 50% out. If you go to big you will have to pull fuel and the ecu will start adding timing. This can be a bad thing if you have no way of adjusting your timing curve. I like to see only about 10-20% fuel added or taken away on a safcII. It makes for a more predictable power curve and a better running car!

Here is a little way to calculate your needed injector size for your HP goal.

HP X .65 (In our case 350*.65=227.5) divided by number of cylinders x .08. (6 x .08=.48)

So, 227.5 divided by .48=473.958 roughly 500cc injectors.

Now this is for Crank HP! Not wheel! Not sure what the drive train loss is on an RB but I would guess around 20-25% or so.

Now if you wanted to figure what size injectors you needed for 350whp.

350*.25=87.5 + 350=437.5HP. This is the HP you would have to make at the crank in order to make 350whp if the drive train loss is 25%.

So:

437.5 x .65= 284.37 divided by .48=592.45cc injectors or 600cc injectors.

[blurrbosi]

woah. If you only want 350... that setup is more than enough.

[GTR Shop]

At least 500cc but no bigger then 680cc or so injectors. You don't want to go to big. The SAFCII can only add or pull 50% out. If you go to big you will have to pull fuel and the ecu will start adding timing. This can be a bad thing if you have no way of adjusting your timing curve. I like to see only about 10-20% fuel added or taken away on a safcII. It makes for a more predictable power curve and a better running car!

Here is a little way to calculate your needed injector size for your HP goal.

HP X .65 (In our case 350*.65=227.5) divided by number of cylinders x .08. (6 x .08=.48)

So, 227.5 divided by .48=473.958 roughly 500cc injectors.

Now this is for Crank HP! Not wheel! Not sure what the drive train loss is on an RB but I would guess around 20-25% or so.

Now if you wanted to figure what size injectors you needed for 350whp.

350*.25=87.5 + 350=437.5HP. This is the HP you would have to make at the crank in order to make 350whp if the drive train loss is 25%.

So:

437.5 x .65= 284.37 divided by .48=592.45cc injectors or 600cc injectors.

A few things.. if you have 87.5 hp loss in your trans, what happens if you put a VW engine infront of it which doesn't make that much power? does the car move? Sure does.If you lost that much power, do you think you could turn the input shaft by hand with the box in gear?

Also your injector calcs are WAY off.If you're after 600hp at the wheels (on a REAL dyno not a Dynoguess, or Must'beclose'tang) then you require ~600cc/min per cylinder at full load.Stock RB26 injectors will make over 400hp at wheels... 440ccAlbiet that is getting close to upper limits of duty cycle, but if you run 600cc injs on 370hp engine, you're going to be at around 60% duty.. 1/2 the control possible.

[BEST1TUNING.COM]

You could go through the ECU...just a thought.

[Carl H]

i would go with a modified stock ecu over a safc ANY day.

[Joe]

i would go with a modified stock ecu over a safc ANY day.

+iouy62096q50962q56001256

i hate SAFC's

[BlAcK95sE]

i would go with a modified stock ecu over a safc ANY day.

so what should the people with seriesII motors that dont have the 700 for the power fc right now use?

[BEST1TUNING.COM]

^ Im workin on it but right now options are pricey.