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Installing an A/F gauge and wondering about sensor placement. I have read between 24 - 36" from exhaust port. I run leaded 110 in an R16 with typical header and 2.5" straight piped exhaust. Appreciate any thoughts.

110 octane leaded ? How ? Aircraft gas ?

My mitsu has it 15 in
Any lead you breath in stays with you for a 100 years

rahjr60 wrote: ↑Wed Aug 11, 2021 12:30 pm Installing an A/F gauge and wondering about sensor placement. I have read between 24 - 36" from exhaust port. I run leaded 110 in an R16 with typical header and 2.5" straight piped exhaust. Appreciate any thoughts.

Leaded gas will kill an O2 sensor .

Run one in the header collector in a BRE style side exhaust. Believe it has to be in the upper half of the tube and not bottom.

Believe the sensor should point down if the above was not clear. Have not been using long (months) but have run leaded race gas in it and still functions. Believe others
have done so as well for a longer term.

"Leaded gas will kill an O2 sensor ."
And it's not supposed to take long.......

Sensor should be between 12 o'clock and 9 o'clock position to help prevent moisture from forming on it inside the exhaust.

Also, for an R16, even for racing, you are unlikely to need more than a 2" exhaust pipe. For a modified street engine 1 3/4" is more than enough - unless it's a stroker - depending on the level of performance (horsepower) it's built for - 1 3/4" (mild) to 2 1/4" (VERY high performance). Anything larger than required for the horsepower level is adding unescessary weight, and possibly decreasing engine performance.

Search "engine horsepower vs exhaust size"

Will see how long it lasts. Know someone who has been using the same sensor for 3 race seasons. Aberration? Past results not indicative of future results legal disclaimer. Also replacement sensors now run well under $100 which seems cheap to identify a more sudden lean running condition for example a carburetor screen clog during a race (it happened). Time will tell. Not the worst thing I have wasted my money on.. Fairly cheap kits available now.

Would also add I am far from an expert on Datsun’s or much of anything but willing to try stuff, learn from my mistakes and generally listen to others. Appreciate this forum and it’s members. Will update if I have a sensor problem.

From what I read it looks like it would last a few seasons at least, if only for racing. The sensor itself is not that expensive if you have to change it out, and it wont hurt the controller. Agree that if you're running a motor that requires 110 a wideband is cheap insurance!
Have we seen pics of your cars?

You may not notice it going out
But the lead coating that helps the valves will coat the Platinum cup and block fumes passing thru it
The ECU has a fail safe setting and it goes to that , not even using the sensors , on most the fail safe ecu is the size of a pencil eraser , and not ment To be used long , Mine sure did though I found it hard to get out of FS on the 1st obd2 system

Thanks for the responses. I also just read another article suggesting 36" for leaded race gas and re-calibrating the sensor to fresh air after each race(now I have to find out how to do that). Yes, I am adding the gauge for insurance, unfortunately one burned piston too late. I hope to pick up the new engine this weekend and I will further discuss with the builder. New exhaust will be done in the next week or so, so I will also review size with the shop. As far as pictures, I have posted pics of my #23 race car and my street car in the past. The #00 race car(SRL 00246) was just purchased in Dec and needs a lot of work to get back on the track. It was converted to an R16 in the 90s, and as a long time race car, not much of a 67 SRL remains. The frame stamp and original logbook is about all there is to confirm the pedigree. The plan is to put in the U20/Solex engine from my very rusty 69 project car and get the body back in condition to go vintage racing. Just another time and money project!

Cool stuff Al. I know nothing other than the experience of my own car and what I can research (I'm not a racer or professional etc). I was reading on the Sunco site about the advantages to lead in gas and was not aware of the stabilizing features of leaded gas... interesting stuff. But they do make unleaded fuels and octane boosters (Boostaine comes to mind) that should meet the octane requirements of the engine and not bugger up your sensor. Mine has to be calibrated a couple times a year if on a daily driver, so I do mine every spring... it's just a matter of removing it from the pipe and running the calibration program on the controller, so relatively easy access just makes it go faster and with less hassle. What kind of compression are you running? I remember the posts about an unusual header now...

Thanks, Greg. CR is 13.8:1. I have the normal off the shelf header. Anyone ever do the over/under BRE style header for an R16?

13.8! Wholly Smokes! I see why you want leaded 110! My (Arias) pistons are at the shop being machined as we speak to drop my compression down from 11.7 to a more street friendly 10.5-11, and it seems like there's so little room left in the chamber I can't imagine what 13.8 looks like. No room for error, that's for sure. I can see why you want the wideband.

Go get em!