Setup for a AFR gauge

62Cometman

Well-known member
I would like to run an air fuel ratio gauge on my comet so I wanted to ask the collective brains, since I have a dual outlet header could I get away with running the AF sensor in just one outlet or should I have one on each?
 
what is it that you want to know about, get results from, or change?
Y the A/F sensor'n guage?
 
Ease of tunibilty and I'm eventually going to run a turbo and use this header so it's preparation so to speak as well as a ease of use setup
 
I just put in a afr gauge and o2 sensor on my 170. I have a dual outlet header that I made a Y pipe to turn into a single exhaust. I put the sensor about two inches down from the intersection of the Y. Something I found out from others after struggling with getting a steady reading is that if you have any exhaust leaks you won't get a accurate reading from the sensor.

I also installed a Weber 32/36 at the same time. Something that was surprising to me while tuning was how much one change effects other stages of the carb. I still have a bunch of tuning to do, but I am so thankful that I bought a afr gauge. If I would have been tuning off of my own judgement, I would have been way off.

Good luck
 
Two sensors and gauges or two sensors switchable would be optimum but expensive or complicated. A single sensor near one collector on a dual out', would probably suffice for AFR measuring and include outer cylinder as well as inner for a distribution average.


Dual outlet headers or any tube header loses the energy of the expanding heat gas near the cylinder exhaust outlet. MacInnes in hisTurbo-bible explains it's not just the velocity of the exhaust but the thermal expansion energy captured at or near the exhaust port - recovering wasted heat energy with the turbo. I don't get the 'tailpipe' turbo setups popular with the truck enthusiasts.

With my forced induction projects, I wouldn't leave the driveway without a functioning AFR gauge.

 
powerband":yzhk2edj said:
...MacInnes in hisTurbo-bible explains...
Do U recommend his '73 or '79 book for a newbie like me?
Thank you, powerband.
 
pmueller9:
thanks, that was about the length and depth I needed.
see a few (less than a doz) turbo's in the garage. answered the very few Qs I had
AND
I avoided a whole book (locate it, choose among them all, reading all that, etc) !
:eek:
 
powerband":2xfz2m3a said:
Dual outlet headers or any tube header loses the energy of the expanding heat gas near the cylinder exhaust outlet. MacInnes in hisTurbo-bible explains it's not just the velocity of the exhaust but the thermal expansion energy captured at or near the exhaust port - recovering wasted heat energy with the turbo. I don't get the 'tailpipe' turbo setups popular with the truck enthusiasts.
Consider that once target boost is reached the wastegate throws out the extra thermal energy. In other words there is always sufficient thermal energy to drive the turbo up to target boost levels whether it is right at the exhaust port or at the rear of the vehicle.

Where turbo position makes a difference is during the time the wastegate is closed and the turbos are trying to spool up. The turbo located closer to the exhaust ports may respond faster. Does it matter?
If I'm drag racing at the track I'm transbrake bumping into the lights with the turbo already spooled up to launch boost and on the street I'm foot braking.
It does affect roll-on performance but the gap is closing up as turbo technology as well as turbo control improves including thermal barriers for exhaust pipes and turbine housings.

The turbo hanging on the end of a tube header produces more power for a given boost level than the same turbo sitting right at the exhaust ports on a log manifold. Without going into detail, the engines pumping losses are less and cylinder fill with oxygen content is greater.
 
pmuller9":p56o0uak said:
The turbo hanging on the end of a tube header produces more power for a given boost level than the same turbo sitting right at the exhaust ports on a log manifold. Without going into detail, the engines pumping losses are less and cylinder fill with oxygen content is greater.
thanks PM9', that gets me thinking , still trying to understand practical vs theoretical forces of forced induction.

My current project is the supercharged Maverick 250. The Vortech supercharger package was previously installed on a Ford 302 P/U 'Lightning' with boost controller, MSD ign/boost , FMU setup and Vortech V2sc. If they added and understood an AFR gauge, I would not have the sc and detonation would not have melted and blown their pistons . TC vs SC is yet another level of understanding...

have fun
 
62Cometman":9pry7zeu said:
I would like to run an air fuel ratio gauge on my comet so I wanted to ask the collective brains, since I have a dual outlet header could I get away with running the AF sensor in just one outlet or should I have one on each?
I would put the AF sensor on one collector and have a bung to move it to the other collector just for a reference check.
The average reading would include one outside cylinder, second one in and one center cylinder.
The other header should reflect similar results which can be verified by moving the sensor form one collector to the other once.
 
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