If i get a SAFC, can i tune it so then i can get better MPG?? (whats the max)

And how much more power can i gain from this if i tune it right???

Can it save gas and add power at the same time???

 

In either case you will be leaning out the engine, so yes.

Generally tuning it would be good for around 10HP an about 2-4 MPG.

Of course, while you are hard on the throttle to use that extra power the mileage will be just as bad as always.

 

The biggest difference I've seen with this is the fuel drain when playing around on winding roads. With the stock ECU, sustained high RPM operation sucked gas HARD. With the SAFC pulling out 30+% in some areas up high (but still running slightly rich), I don't consume the insane amounts of fuel that I used to.

In terms of highway mileage, you can lean it out nicely, but if you still have catalytic converters and such you may want to leave the O2 sensor connected. I've tried running SAFC alone, and SAFC with the O2 sensor connected, and... I really don't see a big difference between the two, though I think the SAFC without the O2 sensor is actually slightly better in terms of economy. I could still use a good injector cleaning, though.

-=Russ=-

 

Aaron, i've always wondered... I will need an A/F meter to tune SAFC properly, right? To install A/F meter i will need to install a wideband O2 sensor if i'm not mistakin'... But here's the question... Should wideband o2 sensor replace the stock one and if yes, than will closed loop system still be working with wideband o2?

Sorry if it sounds dumb... :-/

 

First, while a wideband is helpful for tuning a SAFC, at least in the NA side, it's not required. You can do a decent job with the narrowband O2 sensor. Not great, but decent, and NAs don't really have issues with detonation like a turbo motor does. If it gets too lean, it just quits.

The wideband O2 would normally replace the stock O2 sensor. However, most wideband controllers have a simulated narrowband output that can feed the stock ECU with a signal. Also, you may not even want the O2 sensor connected - if it's connected, the ECU will listen to it, not the SAFC's modified signal. If you want to run a bit lean at cruise, leaving the O2 sensor disconnected will force the ECU to listen to the modified airflow meter signal.

-=Russ=-

 

What if i take out my cats and install RB headers and Pre-Silencer?? how will the economy/MPG change?

 

Directly, you may see a slight improvement due to lowered pumping loss, as long as you don't enjoy the increased power much.

However, this eliminates the need to keep EGTs at sane values. While you're not going to be able to see the full benefit with just a SAFC (you need a full standalone to tweak the timing as well), you can run leaner, and not worry about turning catalytic converters into liquid mush.

I suspect a rotary engine tuned for peak economy (S5 NA, 16:1 or 16.5:1, 800C EGTs, according to scathcart) would destroy a catalytic converter in very short order.

-=Russ=-

 

Yes, you would use a wideband.

While tuning, you would use the wideband. When done, you would switch back to the narrow band.

 

Could you please explain why would i switch back to a narrowband and not use a narrowband simulated output from a wideband o2 if there's such an option?

Thanks

 

When you start heavily modding an N/A you will be using the SAFC to actually add fuel. I've got +8% in some parts of the rpm range when I dyno tuned mine, and I'm putting 160 to the wheels.

 

Can you list your modes? Have you ported the engine?

 

Is there like a SET good setting that can be used on any N/A for the SAFC?
Or does it vary from car to car??

 

If your wideband has simulated narrow band output, then you can run that to the ECU, and is should work just fine.

Rat

 

From my cardomain site:

Engine:

- Series 4 motor with mild street port (RacingBeat template), Turbo II housings, Rotary Aviation seals

Intake:

- K&N cone filter with cold air box, ported intake and throttlebody, pineapple port sleeves, auxilary ports wired open

Exhaust:

- RacingBeat collected header, straight unresonated mid-pipe,
2.5" RacingBeat dual exhaust

Fuel upgrades:

- 3rd gen fuel pump, Apex'i SAFC dyno tuned

Drivetrain:

- ACT Street/Strip clutch disc, ACT heavy duty pressure plate, RacingBeat lightweight steel flywheel, Mazdatrix Short Shifter, competition differential mount

Brakes:

- Stainless steel brake lines with semi-metallic pads

Suspension and handling:

- Tokico Blue shocks, Eibach Pro Kit lowering springs, front and rear camber adjusters, 17" ADR Alloy Wheels with 225/45/ZR17 tires


Tomorrow I'm actually putting in 550 secondaries because the car runs lean up top (14:1) even with the FD fuel pump and the SAFC. I've also been working on fixing my auxilary ports, I just gotta get my airpump wired up.

 

Mainly because wideband sensors have a short life compared to a narrowband, and are expensive. If you intend to put a lot of miles on the car then it could be significant.

 

Thanks Aaron, now i've got the point