Turbo 6.0

This has probably been covered but I didn't find anything in the search so here it is.....

What kind of AFR do you guys shoot for when in boost? I am mostly looking for people who are running 91 - 93 octane on the street.

IKnowtheFuture

iTrader: (5)

if im not mistaken its between 11.4 and 12.5

Syclone354

iTrader: (6)

I run 93 octane. At between 10-15 lbs of boost I keep it between 11.0:1 and 11.5:1. I will also be curious to see what others say, since I have never been on a dyno and tune my truck myself.

novaflash2002

iTrader: (51)

not over 11.5 if you want it to last

Bob@BruteSpeed

iTrader: (16)

11.5/1 above 5000 rpm is pretty much standard. Bob

98Z28CobraKiller

iTrader: (17)

I also target 11.5 but feel good about a log if the entire pass is 11.0-11.8. Your AFR reading also depends on how far back the sensor is in the exhaust system. Typically the further forward it is, the richer it will read. So if you see 11:9-12:0 with a sniffer in the tailpipe, that should be 11:5-11:6 up by the turbo.

Bob@BruteSpeed

iTrader: (16)

I personally would never get a tune at a place that sticks the air/fuel sniffer in the tailpipe. The sniffer in the tailpipe can be very unreliable. If an exhaust system is not 100% welded, air can suck in at the joints under wide open throttle and will throw off the readings, and you just never know how much it is being thrown off. Bob

r572cobra

not to hi jack the tread,but on a rear mount were do run the o2 sensor.

Turbo 6.0

I currently have the sensor after the turbo on my rear mount. I have run it before the turbo too. From what I understand if the sensor is before the turbo the backpressure can cause the reading to be richer than it actually is but I haven't seen any conclusive evidence supporting that theory.......

I might have to get a extra wideband, install it in one of the rear O2 ports and compare the 2 readings........

r572cobra

is it ok,to lenghten the wires,on the sensor.

JAX04

iTrader: (17)

^^^^^^^^^^^yes, you must, do NOT place the wideband in the piping before the turbo, it will skew, First hand experience, and seen it in person on other vehicles, many many times.

mike13

iTrader: (27)

Lean or rich? I've had the wideband in both locations and didn't see a difference, I also question how accurate the common widebands are when you get into the 10.0-11.5 afr range. Not disagreeing with you just questioning if what we use is that accurate. My wideband was $300 range and I here about the pro's using $3000+ setups.

JAX04

iTrader: (17)

i use an AEM, and my best Friend with similar setup uses INNOVATE LC1 , and we have an LM1 hooked up also.

When under part/normal throttle conitions when the exhaust was actually flowing somewhat like it was supposed too, i noticed ZERO differences, when WOT, i would consistantly read between 1.0 and 1.3 RICHER when the wideband was placed in piping PRE turbo. This is not good. So, when i was thinking i was in the 11.0 range i was actually closer to the 12.0+ range.

All three rearmount cars i have been around and had a hand in building or help build have done this. so i see 3 out of 3 as a sign that it should be placed in the tailpipe POST turbo.

Not to mention the numbers are very inconstant and not steady when the wideband was place pre turbo, it was very difficult to get the afr to settle into a consistant area, the reading wanted to jump around alot more when preturbo.

mike13

iTrader: (27)

It would be nice to hear an explanation on why and how different pressure ratios affect the wideband. I run mine in the midpipe (rearmount) but I also run 10.5afr's and spray 100%meth starting at 4lb's.

I tuned my WOT by richening up the car to the point it started breaking up or just ran flat and than leaned it out to get my 10.5afr.

It's a geat tool I just like to verify that when the WB says pig rich the car runs pig rich and pull fuel from there.

NicD

iTrader: (7)

The explanation is that wideband O2 sensors are affected by pressure, period. You want them in the pipe that doesn't have high pressure for the most part which is after the turbo.

mike13

iTrader: (27)

If that's the case then every wideband is affected, anytime a gas has velocity there is pressure.

hellbents10

iTrader: (10)

Yes but we are talking about .5psi in the downpipe and up-words of 45psi or better before the turbo lol.

XtremeDime

iTrader: (16)

I run around 12:1 on 90.

NicD

iTrader: (7)

Yup

pwrtrip75

iTrader: (8)

Air and fuel compressed you will have a greater density of fuel.....fuel dont compress just air does. So if your reading the amount of air and fuel in one space.. I dont think the wideband knows that the air is compressed, it just see the volume of space it is taking up....so you will see more fuel than air, even though you technically have more air there.