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Kingtal0n · 01-16-2021, 08:15 PM

300zx maf goes with Apexi Power FC and 740CC Injectors to take care of that turbo

If you wanted to use SAFC with that turbo it needs to be on the OEM MAF sensor, with 550cc injectors, and the max boost will be approx 14psi (340rwhp~ max?)

Anything smaller than 550cc is for stock size turbocharger. Even S15 stock turbo uses 4xxcc so just imagine going from T-25 to T3 size 4xx isn't going to cut it.

SAFC cannot adjust engine timing so the motor will probably eat rod bearings even with the A/F dialed in properly. That is why he says "Trash it" because even though it can tune the A/F properly the engine's advanced, stock ignition timing can still ruin your engine.

In other words, when you use SAFC to remove fuel (-xx%) the OEM computer is going to ADD TIMING in response. So the larger the injector is, the more fuel you remove, the more timing gets added. Additional timing is unwanted and the OEM computer has no idea you are using a SAFC to remove fuel so it thinks you are reducing boost pressure (-xx%) when in reality you are increasing boost pressure.

Tuning wise. It is necessary to use heat range 7 NGK plugs and an aftermarket, low lift(lowest lift), long duration (260-270*)camshaft or you are wasting time.

0. Before tuning, Remove some base engine timing at the crankshaft by retarding at the CAS. Remove approx 2-3* minimum. You may even wish to remove a bit more. This will help protect the engine from the excess timing an SAFC will add, at the expense of fuel economy cruising (you may lose a couple MPG)

1. You must unplug the factory O2 sensor before trying to tune an SAFC.
2. Aim for 14.7 to 15.2:1 (slightly lean) for all cruise and near idle.
3. Aim for 11.2 to 11.5 for all boost over 10-12psi
Never go above 12.2:1 in boost
Never go below 14.4:1 in cruise/idle (anything below say 14.2:1 air fuel ratio will foul plugs, carbon coat piston/valve/chamber, it allows a brittle hard diamond-like carbon coating to persist in every recess and may over time lead to engine damage, cylinder wall scarring, hot spots, even chunks can break off and damage the turbine)

01-16-2021, 08:15 PM	#3
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 38 Posts: 4,646 Trader Rating: (17)	300zx maf goes with Apexi Power FC and 740CC Injectors to take care of that turbo If you wanted to use SAFC with that turbo it needs to be on the OEM MAF sensor, with 550cc injectors, and the max boost will be approx 14psi (340rwhp~ max?) Anything smaller than 550cc is for stock size turbocharger. Even S15 stock turbo uses 4xxcc so just imagine going from T-25 to T3 size 4xx isn't going to cut it. SAFC cannot adjust engine timing so the motor will probably eat rod bearings even with the A/F dialed in properly. That is why he says "Trash it" because even though it can tune the A/F properly the engine's advanced, stock ignition timing can still ruin your engine. In other words, when you use SAFC to remove fuel (-xx%) the OEM computer is going to ADD TIMING in response. So the larger the injector is, the more fuel you remove, the more timing gets added. Additional timing is unwanted and the OEM computer has no idea you are using a SAFC to remove fuel so it thinks you are reducing boost pressure (-xx%) when in reality you are increasing boost pressure. Tuning wise. It is necessary to use heat range 7 NGK plugs and an aftermarket, low lift(lowest lift), long duration (260-270)camshaft or you are wasting time. 0. Before tuning, Remove some base engine timing at the crankshaft by retarding at the CAS. Remove approx 2-3 minimum. You may even wish to remove a bit more. This will help protect the engine from the excess timing an SAFC will add, at the expense of fuel economy cruising (you may lose a couple MPG) 1. You must unplug the factory O2 sensor before trying to tune an SAFC. 2. Aim for 14.7 to 15.2:1 (slightly lean) for all cruise and near idle. 3. Aim for 11.2 to 11.5 for all boost over 10-12psi Never go above 12.2:1 in boost Never go below 14.4:1 in cruise/idle (anything below say 14.2:1 air fuel ratio will foul plugs, carbon coat piston/valve/chamber, it allows a brittle hard diamond-like carbon coating to persist in every recess and may over time lead to engine damage, cylinder wall scarring, hot spots, even chunks can break off and damage the turbine)