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Author Topic:   O2 Sensor
posted June 18, 2002 01:28 PM
Anyone tried an O2 sensor for jetting??? I am installing one for this weekend's race to check air fuel ratio to see how it works. Any tips or suggestions?

posted June 18, 2002 06:31 PM
Thats interesting give details, I d like to hear the results !

posted June 18, 2002 09:37 PM
Thanks for the reply C21. I bought the gauge for my street driver, but thought I would try it in the race car first. We have to burn pump gas so the sensor should survive. I have a copy of the mV vs A/F graph of the inexpensive sensors so I can see how it may be difficult to get a precise reading. On the subject, what is optimal A/F ratio under full throttle/full load conditions? Also, ever experiment with an exhaust temp gauge (pyrometer)? I notice the jet boat racers use them as well I had a set on my snowmobile. Seems to work good in these applications. The stock car may not have enough time at full throttle to get good numbers. Any comments?

posted June 19, 2002 02:04 PM
I've been looking into doing the same thing. Does anyone know whether or not methanol will damage these sensors? I've read that leaded fuels and the wrong silicon are bad for them, but haven't been able to find out anything about methanol.

posted June 19, 2002 05:06 PM
I would ask Steve Hendren what a good A/F ratio is. On my race car I always go off of plugs and exhaust gas temps .... speaking of egt's, They can be very informative on a Stock Car, but first you need to find out what temps are normal for your car (when the plugs are good) then watch your egt's for change which would normally indicate a need to change your jetting to suit conditions. I use a DIGATRON digital egt display with datalogging in the race car ...... and love it. Please check them out at (they are great people with great products!)

I use a Wide-band o2 currently (but have used a narrow band display in the past) on my supercharged street car. My set-up is fuel injected running up to 11 psi on pump gas and I look for A/F ratios around 11.5:1 and 12:1. On a non-fuel injected set-up without programable engine management (ie, a street stock)I would think you would need to run richer still (11:1 TO 10.5:1 ?) for an added margin of safety.

You can use an o2 sensor for gas,propane or alcohol, however, I think with alcohol you are looking for A/F ratios like 6:1 or 7:1.

Here is a link to a place that sells the narrow band display I used to use ...
I think they have more info on using the o2 sensor for alcohol.


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