SAFC question
I read the whole thing about setting up a SAFC/VAFC Im confused about something he said hopefully you all can help me out
He said The scale for common injector sizes used is 5% for 440-450cc, 4%, 390cc, 3% for 310cc.. then subtract 1 percent per 500 RPM increase. This will give us are starting point. For a boosted application, running stoichiometric is dangerous because of the high volume of air. To "play it safe", you want to run a bit on the stoich/rich side, so we increase fuel flow by 1% per 1000 rpms, My question is. When you subtract 1 percent per 500 rpms what do you do when you get to 0 percent? do you just then start increasing a percent per 1000 rpms? Just making sure i have it right correct me if im wrong |
Re:SAFC question
Yes, but as you're decrease by one, you're adding by 1% per 1000 RPMs, so like this..
46% + 5% = 41% @ 1000 40% @ 1500 40% @ 2000 40% @ 2500 39% @ 3000 39% @ 3500 38% @ 4000 ..and so on.. |
Re:SAFC question
I've also heard that the SAFC changes your timing. Is it that as you go lower in your percentage settings that your timing will advance? Or is it the other way around?
Can someone clear this up? |
Re:SAFC question
Please read the Engine Management FAQ, section 2, question 3.
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Re:SAFC question
Originally Posted by john duh
I've also heard that the SAFC changes your timing. Is it that as you go lower in your percentage settings that your timing will advance? Or is it the other way around?
Can someone clear this up? |
Re:SAFC question
...that's backwards...
When used with as the "AFC Hack", it actually makes your ECU think there is LESS air going into your manifold. This makes it read from leaner parts of the fuel map ("pumping less fuel"). In doing this it indirectly advances your ignition timing by shifting over to move advanced region of the ignition map. "But if it's leaning your car out, how does it let you give more fuel for boost?" You compensate with larger injectors. Larger injectors will flow more fuel at the same pulse widths of smaller injectors, simply because they're larger. This is how the "AFC Hack" works. |
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