Thread: 259cc @ 4bar safe for ~200whp? help

once again, props, i didnt know a 255 ran almost to 4 bar on its own, but i will run a FPR at +4 bar to security

R35, VET sounds nice, but i think that out of the scope for a safc for only being able to provide 50% more fuel over stock ecu.
i know its not the best tool, but its not one im going to continue to use.

but the 20v will work, being the max cc i can run atm is 388cc approx limited by safc

Wrong, the SAFCII can support up to around 444cc injectors easily. 370cc over 259cc is only a 30% increase. I ran my first turbo setup on a stock b13 ecu, 370cc injectors, 3 bar, safcII and ran absolutely perfect once i tuned it.

259+50%(129)=388.5 ? unless i did my math wrong

you did,lol

370cc is 111cc more than 259. So take 111/370 and that gives you 30% fuel needing to be removed at idle and off boost areas (roughly) to make the 370cc injector equal 259cc

Pretty simple

your talking about idle, and i understand what your telling me, i understand one needs to change the AFR at idle, off boost to save fuel have a good idle
but im talking about near max/max duty cycle, 259cc top mount injectors,+4bar FP

i wish i could just use 370cc's and be over with it lol

i think we are talking about 2 diffrent things unless your just moving on to another aspect? i dont mean any disrespect btw

In boost is different, Your barely if at all gonna use the postive scale of things on the SAFCII,

To get the car to run right you will need to remove 30% of fuel from the 370's to get the car to run like it would with the 259's out of boost. Basicly on your low throttle side of the tuning. On the high side throttle your still gonna be in the negative for the most part of things.

The ecu is reading maf voltage and triggering injector duty cycle as such as if it were programmed for 259cc injectors. So when the maf voltage hits a certain point your injectors are gonna be at max duty cycle, Max duty cycle on 370's is alot more fuel than 259's so you will still be taking away fuel on the SAFC even on the high throttle tune for the most part. Gotta play with it. The factory ecu is set to tune WOT a/fs for N/A applications not turbo applications so you adjust as necessary but when i used mine again talking from experience, I was still taking fuel away up to a certain point then was at 0 but only because i had s4 cams and was pretty much maxing the injectors out period so matter how much fuel id add to the safc in the high throttle, the a/f wouldnt get any richer than 12.2:1, whether it was at 0% removed or +50%, made no difference.

But for a simple setup, guranteed once you tune the a/f's in on a wideband assuming your gonna run one, to 11.8-12:1 a/f's you will still be in the negatives to do so.

also, wont i need to increase FP under boost? how do i do that? set the FPR rates according to RPM some how?

A nismo or whatever fuel pressure regulator you are gonna run, will add fuel pressure at a 1:1 ratio.

that sounds so wierd, i tuned my safc when i was na and need to add values! but remember im going to run 259's at 4 bar so will it be basicly the same deal with the 370's? ill definitly play with it, yes ill be using a LM2 wideband to view AFR according to rpm ect ect

okay cool, didnt know, thanks!