Ok gents, if this is somehow a repost and I've missed it, mea culpa. In a nutshell how low of an AFR do you think one can have using 92 octane fuel? Or 91 for safetys sake/Californians. Tune down until knock and then add some fuel back in?

What about timing? Should I rather use the timing harness on the eManage to take advantage of the octane? Same as before- tune for knock and then back off a few degrees?


Thanks guys!

 

As long as you will keep an eye on the temperatures you could probably go as far as you want until everything will start melting.
I'm not a guru or anything but leaner you go, the hotter things will get in the combustion chamber. And don't forget, there is a point where too lean will reduce gains.

 

I should clarify that I'm using a WBO2 to read AFR. I'm currently around 12.7 but can I go lower or is this the premium AFR for all octanes? What if I go to the dragstrip and use 104 or higher? Is 12.7 still optimal?

 

Right but my understanding is that this "too lean" point changes based on octane. So do I now need to reinstall my EGT probe? (actually it burned off so I'd need a whole new one)

 

well, im gonna try and help here, since u help me and sooo many others. to start, i'll give u my equipment, i have a innovate wbo2 kit, and the safc2. i have been datalogging and i dynoed 3 times since i installed all this electronic crapola.

right now i am at 13.3-13.5 afr from idle all the way to redline. my mods are magnaflow catback, rrm header, no cat, semi-leaned out maf, flywheel, cai, and thats about it. here is my hi throttle fuel tables on my safc2:
rpm correction%
800 -18
1400 -27
2200 -21
2600 -14
3200 -19
3800 -28
4200 -20
4600 -21
4800 -22
5200 -24
5600 -25
6000 -21

now with those settings, i have a constant temperature pretty close to what the stock egt temp is, and i gained another 4whp and 3wtq, by going from 12.7-12.9 where i started at with tuning to 13.3-13.5 where i am now.

i also have the other map on my safc2 set for 13.9-14.1afr, at this point i still have no knock on 91 octane, but just for safety sake im using 93 when i use that map.

i tuned everything, then i went down cnfx in allentown and had them dyno it and test the egt temps, they said, and i saw in person that everything was just peachy.


on another hand, SINCE WHEN IS YOUR EMANAGE WORKING??? i thought it kept resetting itself. go tune for 13.5 and see how u like it, i guarentee you'll love it

 

I wasn't exactly quiet about it, I posted in the "Ordered my eManage now what" thread. See how large your fuel cut numbers are? That was part of what the problem was, I wasn't going large enough in those cuts. Bigger is better Boe scared me off of 13.5, but I think I'll be less conservative about it now that I see your numbers and that you've had a shop review the settings.


So- can you go leaner the higher your octane?

 

Boy you guys sure do like to get brave with the afr.

 

mmmm, a leaner afr is okay for na, but the strength of higher octane comes from advanced timing. here's a basic guide on afr from bosch. due to engine design(cooling efficiency, combustion chamber design, etc.) different afr's and ign timing will be different between cars. everyone has their tuning philosophy. kinda like how some tuners will take the 5hp fall on a turbo setup by doing 10.5AFR than 11.5AFR for safety's sake. our cars could possibly make better power going leaner na.

(i need a scanner)

 

Thanks Phil

Rhyzin, "the strength of octane comes from timing" is kinda what I thought. Back to tuning with timing Thanks

 

Just saw this...

For NA i never got past 13:1... i try to keep it around 12.7:1 for all street driving and 13:1 at the track with race gas. The AFR tuning for NA won't usually get you pinging with the higher octane.

Thus you adjust timing. Timing should not effect your AFR... advance timing to audible pinging is found. Then retard 5 degrees for street... 2-3 for race gas.

Remember leaning the car out may not get you to ping as your base timing may be pulled enough on stock ecu. However your exhaust gas temps may be so high that you get pre-ignition... the silent killer. You won't hear it... the car will run real fast then boom... hole in the pistons or melted cylinder wall or both.

Pre-ignition and detonation are not the same... Use an egt for your tuning with the AFR is best. Keep the motor around 850C for safety... and 875-880 for race.

 

good thing I ordered the EGT probe for the zeitronix earlier this week I'll back off the timing advances for now and richen up a touch (just add 2% in the 12.9 areas and 3% in the 13.1 areas) and call it good for now. Of course now I know what I'm lookin fer thanks Boe.

 

no prob...

 

great information thanks to all