What is the normal O2 range with the sensor in the header collector for alcohol?

Are you asking what people see from the lowest to highest on a pass or are you asking what people consider normal for a good tuned engine?

I see a range from 4.7 at launch up to 6.0 at the shift. Averaging 5.70

Your good tune/results will probably vary slightly from everyone else's depending on sensor calibration, position and induction.



Curtis

Tune your car to best ET and then use your O2 readings for the tune up.
I use the gas scale and it does not matter what scale you use but mine works best at 12.9 to 13.1. Due to calibration differences and location of sensor yours may be a little different. O2 readings are very important but do not forget it is the ET and consistency we are trying to get to not some magic number on the O2 sensor.

Like my timing my motor likes 28* on the dyno and on the track plus my timing light may be a few degrees different than yours. If you used same timing as I do you may be giving up a lot and leaving a bunch on the table. So do not worry too much about the numbers until you get best ET and then you have a good reference from there.

There might not be a normal in the collector.

I tune for consistency since I am bracket racing. I use the O2 to see "something out of the ordinary" only. SBC with an alcohol carb, 1/8 mile racing.

Driver side is 4.9 to 5.2

Passenger side is 5.4 to 5.7

They are both in the same spots in the collectors.

quote:

Originally posted by Tom Reyer:
I tune for consistency since I am bracket racing. I use the O2 to see "something out of the ordinary" only. SBC with an alcohol carb, 1/8 mile racing.

Driver side is 4.9 to 5.2

Passenger side is 5.4 to 5.7

They are both in the same spots in the collectors.

I assume you're running a standard firing order cam?

Yes, standard firing order.

I want to swap them (plug n play) and see if the numbers follow the sensor or boxes they plug in to. Using 2 MSD 7765's.

Where are people locating the sensors in their collectors?
I know you're not supposed to put them near the outlet end because of outside air contamination, but if you put them too close to the tubes you wouldn't get a good read on all the cylinders.
So would the best placement be the exact middle between the end and the tubes?

I have 8 O2's and they are not all exactly same, most are approx 8 inches from the heads. Due to the bends of the tubes and where wires were attached it simply was not possible to get them all the same.
Does not matter much on O2 as the ratio is the same all the way down the tube. Now if you had EGT's it is important to get them all the same as the temperature cools as it leaves.

quote:

Originally posted by imakehp:
Where are people locating the sensors in their collectors?
I know you're not supposed to put them near the outlet end because of outside air contamination, but if you put them too close to the tubes you wouldn't get a good read on all the cylinders.
So would the best placement be the exact middle between the end and the tubes?

Thermocouples 1" or so from the head. o2's downstream further based on packaging.

quote:

Originally posted by imakehp:
Where are people locating the sensors in their collectors?
I know you're not supposed to put them near the outlet end because of outside air contamination, but if you put them too close to the tubes you wouldn't get a good read on all the cylinders.
So would the best placement be the exact middle between the end and the tubes?

In a primary tube gives you the best reading. Back-pulses of clear air can easily give you false lean readings. I have lots of NHRA Stock eliminator customers who can't get a good reading if the sensor is in the collector until after the 60' mark. 632" bracket dragster not usually a problem.

Weld a bung in the collector and and one in every primary tube - that's what I did

When I raced an LT-1 Stocker and used an Innovate LM-1 data recorder for O2 recording,

I had the sensor in the collector and it lean spiked pretty bad at low rpm.

Footbrake launched at 3000rpm and at that rpm with the sensor in the collector it was lean spike city....

Once the car left the starting line it cleaned right up...

I did add a long collector extension and that helped...

I have an O2 recorder on my dragster....A Daytona sensor unit......sensor is in #1 primary....I turn it on occasionally but have really never used it for down track readings...

quote:

Weld a bung in the collector and and one in every primary tube - that's what I did Smile

What a good idea..
Easy to back-to-back test to see if there's a difference..
Thanks Greg...