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Has someone with more money than I have right now put in a set of O2 sensors in their headers to monitor and therefore allow one to tune each SU ? If so how did you do it, how much $$, what parts and what would you do different now that you've done it once? Thanks in advance...I'm thinking possible winter project here.
 

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Flattops and O2 sensors

I'm working on that setup as we speak. Need to identify and procure two sensors and weld-on threaded ports. To be installed with stock exhaust manifold and downpipe, locate on in each port of the two-into-one section of the downpipe.

There are 1-, 3-, and 4-wire options. Pegasus racing has the 4-wire unit. Many turbo-heads use the 1-wire. Shane (Turbo) had some great posts on that a while back. Pegasus has a single unit 2.25" gauge. Too, bad they don't have a dual unit, single gauge. Think I'll follow Shane's advice and just use a multimeter for spotcheck reads. Many of the air/fuel displays running off the O2 sensor are hokey and cheap-looking.

I wish I could get engineering data on Bosch O2 sensors. Wife's fi Jetta has these. Supposed to change every 80k miles or so.

I'm looking for more data and sources on this, too. Any tips or tricks from you guys will be most appreciated!

Later,
Al
 

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Re: Flattops and O2 sensors

do a search under air fuel ratio and some stuff should pop up.. i think the autometer air fuel guage they sell in summit and all over is not cheap and hokey looking.. i have a vw and the sensor is connected to a box halfway in between the speedo cable.. every 80k miles the 02 sensor lights up to change it and you jsut press a button and it goes away.. i am going to put one 02 sensor from a zx in the 02 sensor port in my header.. use a zx header on a 240.. and run power to it and run the other wire to the air fuel ratio mounted in place of the non working clock.. i think its cool..
 

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I had this system in a SCCA 240Z ITS racecar-

O2 sensors in each collector of a 6-3-2 header, with a switch to select which one feeds a Halmeter AFR meter.

Since cylliders 1-2-3 feed one collector and 4-5-6 feed the other, you can watch the mixture on your SUs individually.

Heated O2 sensors (about 45.00 each at parts stores) work best.

Worked great.

Since then I have used the Autometer AFR meter and can recommend it. (Halmeter is 130.00, Autometer is 50.00).
 

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Simple switch.

You can use a toggle switch to feed two O2 sensors into one gauge. Thereby showing front or rear mixture instantaneously. Just use a quality switch, as we're dealing with lessthan a volt here in most cases, and cheapo tiawan switches don't have the best continuity record.
Heated sensors work great as you can set the mixture at idle. Otherwise,with single-wire sensors, after idling for a bit, they will cool off and the reading you get will drift---they respond a bit slower than the four-wire units also.
You can read them with a voltmeter if you have to, no need for a fancy meter. I use my fancy Fluke 87 on "min-max-record" mode during a run, and can go back and look at highest (max) lowest (min) and average voltages over a run. Pretty handy if you think you are intermittently running lean--say at 120---speeds where you don't really want to have to watch for a flickering led to light or drop out...
 
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