Part Throttle Tuning (Boost and AFR)

[knochgoon24]

Everyone talks about WOT and closed loop AFR's but there really isn't much discussion on the transition between the two.

So what AFR do you run at 0psi, 5psi, 10psi, full boost (whatever that may be) and just as importantly, mention your fuel?

To get the discussion going, I'll start with where my car is at right now.

Pump Gas 93
0: 14.5
5: 13.2
10: 12.2
15: 11.3
20: 11.1

If my AFR's look alright, my next step will be to start advancing the timing to see where that gets me.

 

[williillii]

Nice thread. But imo kinda silly to list by boost level only especially when talking about part throttle tuning. I would just post the part throttle section of my fuel map but apparently my ECUFlash install broke .

At 3000rpm and 15psi I run 12:1 but at 6000rpm and 15psi I run 11.2 or so. So Ill list like you did...

Sam's Club pump 93 (its cheap )

0: 14.0
5: 12.8
10: 12.3
15: 11.3
20: 11.0

My car likes it rich...stupid 4g64

 

[gofer]

Yea, its a strange thread but hey if it helps someone I'm all about it. Of course there are a lot of variables but I pulled the results off of a log from my dyno pull in 3rd gear.

Ethanol (E85) and my closed loop operation AFR's are 15.2 ~ 14.6:1.

• 5 psi @ 3k - 13.2:1 and 19.4*
• 10 psi @ 3.5k - 12.4:1 and 19.1*
• 15 psi @ 3.8k - 12.1:1 and 18*
• 20 psi @ 4k - 11.8:1 and 17*
• 25 psi @ 4.1k - 11.5:1 and 11*
• 29 psi @ 4.3k - 11.1:1 and 9.9*

Advance timing to spool the turbo faster but as you hit full boost (29psi for me) you've got to retard the timing quite a bit to keep it from knocking, then start bringing it back.

 

[knochgoon24]

True, there are other variables that affect how much air flow you're actually getting, but I was just curious about the general trend.

And since my car is more a DD than race car, I'm not usually part throttle at 6000rpm. It happens during autox the few times a year I go, but no too often otherwise.
My map is a bit richer up there too, though. It seems to be pretty close to your 93 oct numbers.

I guess to be more specific, I'm looking for AFR numbers during that spool up phase. I run an Evo 8 ecu in my car, and it has this option activated from the factory called lean spool. It takes the values in the fuel map and pulls some fuel out during spool up. Most guys deactivate it for more consistent AFRs but no one seems to talk about what they actually tune too after that.

 

[turboglenn]

good point and one i work a lot on...currently i run 13.5:1 from 1 - 7-8psi, then 13 - 12.8:1 from 10 - 15psi, then i ramp into the 12.5:1 range on e85 but the 1-10psi settings i use on pump gas as well as ethanol with great results

Cruising i run abour 15 - 15:1 on avverage

edit: for timing in the same areas i have about 25 - 29* (tune dependant on fuel) at 0 vac /0boostthen by 10psi i'm rampoed down to the low 18 - 20* on ethanol and around 16* on pump, then work in a degre or 2 every 500 RPM till redline with both e85 and 92 octane tunes