Target AFR's for maximum torque and economy?

[jerrah]

I've done quite a bit of reading on spark/AFR's for power and economy, just curious what AFR's people are targeting here for their peak power and cruise parts of the map?

[NitroDann]

On 91, 98, or E85?

Dann

[timk]

I used to rock this on my supercharged NA:



It gave me awesome economy.

[NitroDann]

I studied that map for a second and as I clicked reply I noticed your comment.

I was going to be a smart ass about your fuel bill haha.

Very rich at low kpa high rpm, I bet it made some flames on up shifts.

Dann

[jerrah]

14.7 at 7000rpm?

I was running 98, switched to e10 on the weekend and I'm thinking of trying e85 soon. (Suspect I'll need bigger than 550cc injectors at 10psi?)

I'm constantly fiddling with my maps but it seems to run ok how it is atm. 15.5 at cruise, idles at 14.7, around 13.5 at 100kpa scaling up to 11.6 at 160kpa.

[NitroDann]

I run a hell of a lot leaner at 7000rpm than that at 0-35kpa. Like way past 25:1.

14.7 is rich enough to get flames and backfires.

Your on the right track. You can lean out your cruise all the way to 18:1 and it will run nice, but best economy is made at almost dead on 16:1. And as I said above either use fuel cut when in vacuum (engine braking, kpa values lower than at idle) or if you cant get it to transition from fuel cut back onto accel just do as I do and run very very lean figures along that below idle row.

Also the B6 and BP both make maximum torque, and therefore power at around 11.8:1. So aim for that.

Dann

[timk]

Yeah without fuel cut on decel it made some mad overrun noises, but that issue aside, the fuel economy was awesome.