Thread: Why I tune to 12.0:1 A/F ratio (0.82 lambda) and why you should too. (all welcome)

Lambda makes more sense, as that is what gives the power and what the sensor actually measures.

Mike

kind of an old thread but, does this apply to sr20ve's with turbos? i mean a stock stock ve.

i was told to shoot for 11.5 but that seems super duper rich after reading this thread. but i figure since theres more guys now with these setups someone could shed some light on the subject.

i'd also like to see some timing maps, but thats for another thread.

Personally I would apply the same methods for a turbo VE, yes.

i tune to 11.5 for a peace of mind, but i agree with you on the timing maps, i usually play it safe timing wise, but im hearing its best to tune for mbt and lower the boost, ive always done the opposite

I tune to 12:1 as well, I was just talking to Ben about this today to out of the blue get his thoughts, and my O2 feedback map was very much in line with what he had, just needed to smooth it out. I have worked with a few different tuners and have just always ended up there. Now, on my much larger turbo setups that I go to 28psi on, I have usually tuned to 11.7 or so.

Brent

good info, thanks guys!

Yeah i think with smaller turbos its good to try to get the most power you can out of it while keeping the boost low. A 12:1 a/f ratio is a good way to accomplish this. 12:1 is still fairly safe but you need to have things right on. I wouldnt go any higher than that.

For large turbos running huge boost and again this is on a gasoline engine, I tune my car and customers cars to around 11.5-11.7:1 and it seems to do really well and is much safer and gives you that safety margin. Any richer than 11.5:1 and your just wasting fuel and losing some power because of it.

Lots of good info in this thread.

For me, 12.0:1 is the ratio to use when you're in the good parts of the compressor map. This is regardless of turbo size, power output, or boost level. If you're in the efficient islands of the map, you belong at 12.0:1. Once you start pushing off of the normal efficient range of the turbo and/or losing efficiency for other reasons (poor flow in intake or exhaust) then it can make sense to go richer (although really I'd rather see a more efficient setup instead). I think 11.5:1 is tolerable in those situations. If you're going past 11.0:1 then for me you're off the reservation.

Thread-defib!

@BenFenner: So is 13* timing with 12.0 A/F or 15* timing with 11.0 A/F 'better' and why? As long as both are not detonating...

Excuse me if this has already been answered as this thread is pretty long.

-G

12.0:1 burns faster than 11.0:1
12.0:1 will require later timing than 11.0:1 to have the flame/pressure front meet the piston top at the ideal time (20 degrees ATDC) because of the difference in burn speed
Faster burns create more power if they reach the piston at the correct time


That should cover it. And it truly is as simple as that.