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[matt]

Do fuel additives like upper cylinder lubricant hurt o2 sensors. This is for a nord (stock valve seats=no unleaded fuel) and i will use an o2 sensor for Air/fuel gauge on this engine but thought fuel additives like upper cylinder lubricant will fail the o2 sensor because of chemicals in additive? or is this just for leaded type fuels?
What about wide band O2 senors? same problem?
are they worth the money in a blow thru carby application? or really for finely tuned FI engines chasing that last 10hp etc

[la_strega_nera]

Hate to tell you this, but the stock Twin Cam seats are good for unleaded...

[matt]

Doh! i've been using upper cylinder lubricant for ages

Ok unleaded it is.....

But can O2 sensor be affected running AVGAS or additives? or am i confusing O2 sensor with something else like an exhaust gas analyzer?

[la_strega_nera]

Most AVGAS (if you can lay your hands on it nowdays) is low lead. As for the valve lube and seat protecting type aditives, yes, they can kill O2 sensors. I know of guys that have run 2 stroke bikes with O2 sensors, and they are accurate untill the oil cakes the sensor and kills the readings.
Tuning by EGT is always an option if you want to run funky fuels.

[matt]

I can get Avgas ok, low lead in avgas terms 100 octane (blue) the green stuff tho is 130 octane in Oz hehe but its been a while will have to check. Jules may know(Have you got PPL or CPL yet?)

Ok EGT interesting because its cheaper than Air/fuel gauge + O2 sensor. EGT used to set mixture on most piston engine aircraft by leaning mixture lever to peak egt reading then enrichen 50* F but for a car engine (carby) it would be a pain in the ass! (changing jets) (changes is RPM/Load etc) plus you would have to find your engines peak *F (for a given RPM + Load) then enrich 50*F for best power setting. It would be difficult because of so many gear/RPM/load settings and holding these settings to get acurate temp reading would be hard???

So i thought best option is 02 + Air/fuel gauge as you have a target Air/fuel ratio (no peak egt to find) an set the carbies to achieve it.

But this means no Avgas or additives.

How did they use EGT on bike or car? maybe confirm peak temp then enrich 50*F and check Air/fuel reading matches? Then remove O2 sensor for running other fuel/additives (this way EGT "calibrated" to an Air/Fuel ratio????)

interesting

[Mats]

EGT changes ALOT with timing, you tune AFR with Lambda readings and timing with EGT.

[matt]

Thanks Mats

Ok EGT for timing, do you still look for peak then reduce (enrich) reading 50*F or another increment in ?*F for best power setting in a car?
Trying to think if advancing or retarding timing will reduce EGT after setting peak, either way could do it but you would want to retard timing i guess to avoid pinging etc?

Whats the best DIY method of tuning engine with O2 and EGT. I guess using higher gears 3rd 4th and a straight bit of road, up hill if possible at constant rpm, vary load on other 'runs'? or just with car stopped, hold rpm, 2K,3K,4K,5K no load and set A/F + timing?????????????

[Mats]

Settle down Beavis...

lowering advance -> hotter exhausts
too much advance -> hole in the piston

Rolling road is the shit, no substitute.

[Zamani]

Dear Swede,

I recently went through an emission test and found that my NOx reading was very high. Could this be due to very high combustion chamber temp and can it be cured by increasing advance.

Yours truly,

XXX

[la_strega_nera]

Dear Swede,

I recently went through an emission test and found that my NOx reading was very high. Could this be due to very high combustion chamber temp and can it be cured by increasing advance.

Yours truly,

XXX

Less advance will drop the chamber pressure/temp, but will raise exhaust temps...
Or fatten the mixture up to drop the chamber temp and let the Cats do the job

[matt]

hmmmm me no comprende i need an example and limits

lowering advance -> hotter exhausts
too much advance -> hole in the piston

so forget peak egt? set timing within a range - obviosly not too advanced to avoid pinging etc and not too retarded so engine still responsive......
but do you really need a EGT then???
How would you use an EGT to set your ignition timing Mats i need an example

Less advance will drop the chamber pressure/temp, but will raise exhaust temps..

This confuses me even more why egt used to set ignition timing because egt reading would keep going up till TDC right???? So if you're adjusting timing = Advance exhaust temp goes down, = Retard exhaust temps go up.... so why bother with EGT, there must be a target exhaust temp to look for with EGT/Timing then make small adjustment if nessesary with A/R????

let the EGT ignition timing lesson begin i'm all ears

[Barry]

This pains me.....
How about setting timing and fuel up on a dyno(or the road) for max power ??Egt`s are more widely used in turbo setups..well,thats where I would use them simply to confirm the dyno setup...
Is this not getting too complicated here??

[Greg Gordon]

Just for the record, 100 Low Lead Aviation fuel (avgas) has 10 TIMES the lead content of leaded auto gas. It will wreck the O2 sensor.
Greg Gordon

[matt]

hehe your pain is me learning

Sure set timing + A/R for max power ok......BUT......

Egt`s are more widely used in turbo setups..well,thats where I would use them simply to confirm the dyno setup...

I don't see, i'm not seeing how you use EGT to confirm the dyno set up??

some aussie phrases are comming to mind now
"he's a stubby short of a six pack"
"he's got a few Roo s running loose in the top paddock mate"

What the HELL am i missing here!!!!!!!!!!!!!!

[la_strega_nera]

Basically, in a 4 stroke engine a EGT will tell you if you're running the risk of burnign an exhaust valve..
In 2 stroke bikes, with ram air and all sorts of funky stuff going on (try different ignition maps for each gear!) you use them for leaning jetting out till you get close to holing a piston (2 strokes are *extremely* sensitive to atmospheric conditions, especially at the ragged edge of tuning. but hey, you gotta give a little when you're chasing 360hp/litre)