what AFR's should I aim for
 

Hi Guys,

This weekend I will be installing my LC-1 :) and after that I will be tweaking my Hi Octane Fuel Map - what AFR's should I be aiming for?

I read that some people like 12.5 on spool, but others like low 11's

Any advice would be much appreciated.

Cheers
Dave

all depeds wut u use the car for...

what do you mean?

Generally folks recommend an AFR ~11.5 and a bit leaner (high 11's / low 12's) under 3000 rpm...That said, it really depends on several factors including gas, timing, and boost...

I like 12's before boost and low 11's the rest of the pull. {thumbup}

I aim for 12:1 at spool to peak torque then have it fatten up to 11:1 till about 6k where I richen it up just a little more till the next shift.

Whatever gear I tune in I normally end up with mid to high 11's till 5k because of lean spool. Even with the lean condition I still rarely ever get knock so I'm keeping it the way it is.

I do things a bit different than posted here. I like to have my AFR as rich as it's gonna get by peak torque and hold that AFR to redline. I don't like leaning it out at peak torque, which is the area that is most likely to knock.

For example, if I am aiming for 11.2:1, then I will get it 11.2:1 right before peak torque and hold it from there. Then, I use the timing to make adjustments. To each his own, though.


Eric

Use what ever AFR that you think is best, whatever you do make sure you have a real-time knock_sum display visible after changes

hrmm ok - so how does AFR affect torque?

11.5 seems pretty rich...

interesting stuff thou - thanks

11.0 to 11.5 is ideal for pump gas, let your boost and timing make the power.

ya I agree more adjustment in the timing is better. Gots to do both though to peak out your torque. Pretty lean on spoil up, I richen the hell out of it on top RPM and load though.

11.5:1 would be rich for an NA car, but for a turbo car, the extra gasoline helps control combustion chamber temperatures and provides a bit of detonation resistance. You wouldn't want to go leaner than 12:1 at high load/boost, and even that is pretty lean.

that have resulted from timing advance.

but isn't it wrong to richen when you have advanced the timing too far? wouldn't it be better to retard the timing a bit??

i tune for high 11's for spool up but by redline i like to aim for low 11's since that will allow me to run more timing, which creates the power...and the richer you are, the more you can advance the timing....