S-AFC. 1st gen or 2nd gen? Limitations?

[Morphius]

Alright, a coworker and I are on the road to putting together a car with a big turbo and intercooler. Not sure where we are going to end up HP wise, but just looking to have a little fun with a DSM at a DCX event that Roush will be setting up at a Jet dyno. The turbo will remain nameless now, but it has a compressor map similiar to a Garret T04E-50. However, this turbo has a better surge lines, and higher boost and maximium flow capability.

Injectors will be on the order of 700-800cc and fuel pump is upgraded to 300+lph. FPR is also upgraded. The next toy needed is something to control the fuel. It would look like I have 2 roads to go. One is to get a standalone. This would be nice, but at the moment we are on a tight budget. We'll save that for the stage 2 mod. The other route is a S-AFC. Looks like we can pick up a used one for a decent price. But, I see there is a 1st gen (knobs) and 2nd gen (buttons and graphics) versions. Is one substantially better? Which is easier to tune with?

What are the limitations of the S-AFC? Can you exceed the capability of the AFC once you get a turbo/injectors that's above a certain size? Thus, would I be wasting my time trying to tune using a AFC?

 

[Coup D E'Tat]

The newer S-AFC's will only let you lean out to -50, and 700cc injectors or bigger are 60% larger than stock, and because of this, you won't be able to lean it out enough.

You could run a 2nd gen MAS, and take lower honeycombs out to make the engine normally run leaner. I'm not sure as to how much (in percent) this would help, because I have not done it, but this is the only way I could see you running 700cc or bigger with an AFC.

 

[Morphius]

Thanks for the info. I haven't purchased the injectors or fuel controller yet, so if I stay with 650cc injectors then I'm within the limits of the S-AFC. That's easy. I'm not out to push the limits on the set-up, just to liven up the car a little. I'll just keep the boost levels within check of the 650cc injectors and see where I land.

 

[kpt4321]

Using a SAFC to do a ton of correction is going to result in timing that is out of control, and a car that does not run so awesome.

 

[Morphius]

Then, I pose the question, what is a reasonable limit on compensation? Who's gone to a standalone because of the capability of the S-AFC? Meaning, you've tested the limits and know where that lies.

I'm looking for suggested limits on the compensation, which then would affect injector size before I end up having stability issues.

I see there is a thread on personal AFC settings that's stickied. I'll do some reading.

 

[kpt4321]

If you use modified ECU code to compensate for larger injectors, the sky is the limint for how much a SAFC can be used for.

I would say 30% is a reasonable maximum, but that's really not something you can just put a number on. More is worse, but there's no distinct line of suck.