How lean is too lean? How much knock retard is too much?

[bast525]

Just what the title says. I'm trying to find out what a/f is considered too lean, and, for DH users, what knock retard is too much.

I recently flashed the Cobb stage 1 map for stock intake. I have an MS CAI. The stage 1 + sf intake map sucked.. boost was no higher than stock, and a/f was way too rich.

the stage 1 stock intake map holds 17-18 psi nicely up to about 5500 rpm and leans out the a/f, but possibly too much.

If I floor it at 3000 rpm, a/f's will go to high 11's and taper down to high 10's by 6k which is where I shift.

Knock retard usually stays at 0, though sometimes see .3-.7 degrees. occasionally I have seen it go up to 1 or 2 full degrees retard briefly, always above 4500 rpm.

so are high 11's at 17 psi too lean? is 1-2 degrees knock retard a danger sign?

I hope this is still safe because the car is MUCH faster with this map on it!

 

[tru-boost]

you are super safe. 10's in the high rpm is rich. to make the best power you want to be right around 12:1 all the way through the powerband. your knock retard is very good too. i often see mine go up to 4.0 !! but i am alos running 20+psi on a stock intercooler and downpipe. (for now)

 

[bast525]

you are super safe. 10's in the high rpm is rich. to make the best power you want to be right around 12:1 all the way through the powerband. your knock retard is very good too. i often see mine go up to 4.0 !! but i am alos running 20+psi on a stock intercooler and downpipe. (for now)

See that was my thinking on it too. I know, coming from the SRT-4 world, and having a turbocharged Z before that... 11:1 or 10:1 was SUPER rich. Over on the other Mazda forum, I was talking about how the Cobb AP map I was running had me seeing high 11's down to high 10's, and they are all saying how I'm playing with fire and probably going to pop my engine.

The knock retard I had no idea though, as far as what is safe, but yeah I rarely see more than 1.0... so I figured that wasn't bad at all.

 

[ericrapp]

That dashhawk is a nice tool to have on board for sure 525 and it is good news that you are rich and on the safe side of things. Hope you will be able to dial her in a little more, in time. Good luck!

 

[Bravnik]

Looks good to me. I see 6's at times on my DH but I'm in CA with bad 91oct fuel only.

 

[desperado-c]

See that was my thinking on it too. I know, coming from the SRT-4 world, and having a turbocharged Z before that... 11:1 or 10:1 was SUPER rich. Over on the other Mazda forum, I was talking about how the Cobb AP map I was running had me seeing high 11's down to high 10's, and they are all saying how I'm playing with fire and probably going to pop my engine.

The knock retard I had no idea though, as far as what is safe, but yeah I rarely see more than 1.0... so I figured that wasn't bad at all.

I wonder if you need to factor the tiny turbo into this equation. When it's close to running outside it's efficiency maybe you need the richer AFR's. Another possible issue is the restrictive downpipe. You might need to know what the EGT's are before you can say what's too rich or too lean for this particular turbo in the long term.

 

[yup24z]

Man....I'm on stock boost with just a 3inch TBE/cobb intake and my AFR's are 12's through the meat of the powerband and fall to high 11's by 5500rpms. I don't understand it...lol. Car hauls balls though.