Tastic

3 Questions:

Is there a relationship between timing and AFR? Does setting timing a certain way allow for higher AFRs?
I pushed canzoomer to the max for the 7000-7800 rpm range but it stays in the low 12s.

I was surprised how good my stock map was already. Never went below 12 and maintained mid 13s in the 5000s RPM range. Stock average AFR for 5.6K-Redline was 12.7.

Hours of tuning got me an average of 13, getting my 8000+ and 6600-6800 range from mid-high 12s to low 13s.

Does messing with timing affect power in and of it self? Are there any other options for increasing AFR in the 7000s?

MazdaManiac

iTrader: (3)

Eventually, lean A/F will lower EGT as well. Ignition advance lowers EGT and retard raises it.
EGT is only useful after you have determined peak lean torque. Then, the EGT at that point can be used as a reference for timing at correct A/F.

r0tor

iTrader: (1)

i showed some gains in testing adding 4-6 degrees of advance over 7000 rpms

yiksing

I read somewhere AFR is pretty rich up top in the rpm range, does that mean if we tune it to more advance timing without detonation we are getting more hp?

MazdaManiac

iTrader: (3)

No. As noted above, proper ignition timing is an absolute. It is just a matter of how close to the proper number you can get without the flame front moving too fast.

yiksing

How about leaning the mixture above or am I just asking the same question? Sorry very bad in the tuning field although I read a lot about it.

yiksing

CRH, mind sharing why exhaust gas temperature is involved in tuning as well, does it have anything to do with air flow velocity or I'm totally out of point?

MadDog

Regarding boost and detonation:

I recorded AFR over 15 in the 4300RPM range under boost (~5psi) with no detonation. I pushed the boost up to 10psi (falling to 5 at redline), letting the PCM do all the timing, with no detonation. Only when I pushed the boost over 8psi AND over 6kRPM did I get some mild pinging - even with AFR around 11.5. That's when I started retarding the timing. Now, no detonation.

r0tor

iTrader: (1)

If you buy into the flame front speed theory, then Captain obvious would point out timing should always be increasing with higher rpms since the rotor is moving faster and not just reach 30 degrees and stay there for the last 3000 rpms in the rev band...

(... hence my 4-6 degrees comment from above)

MazdaManiac

iTrader: (3)

That would be true if all else remaind equal in the combustion chamber. Obviously, it does not.
Charge density, VE and temperature wreak havoc on the whole process.
Not to mention instability in the formulation of gasoline itself...

bedrock83

What is the ideal AFR, and what would you recommend in regards to ignition timing? It has been said that the stock ecu will pretty much prevent you from pinging on an na setup, with either a CEL, or automatically adjust your map, is this accurate?