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Discussion Starter · #1 ·
I did do some research in regards to the o2 sensor discussion that evolved from the cam post. I see Jim that you did edit your post indicating that the ports on the head pipes were probably for EGT (exhaust gas temp) sensors. I had come to that conclusion myself, and when I went back to suggest that, I saw you had come to that conclusion yourself. I am now convinced that is the intended use of these ports, the big question now is how do we find the specs that the factory uses to set them by. My research indicates that readings are very accurate using this method but, you need the baseline calculations determined by the distance from the head you set the probes as to what temp to expect at correct air/fuel ratio. Does anyone have access to these specs? The Triumph service manual does not cover these setups.

[ This message was edited by: ecrabbit96 on 2006-12-30 12:08 ]
 

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I don't want to put a red herring in this but you also need to know the type of sensor used, specifically how far in it sits beyond the thread as you stated.
Also need a matched thermocouple sensor and readout.
Probably type K but I am guessing.

Nige. :???:

[ This message was edited by: Ballacraine on 2006-12-30 11:55 ]
 

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Discussion Starter · #3 ·
There is several setups available now and the cost is reasonable. These kits are used by Snowmobile racers, drag racers, cart racers, and alot in aviation due to air pressure changes from atlitude. It allows the pilot to compensate for lean/rich conditions in flight. You are probably already aware of this. The ports are already established in the head pipes at the factory at a predetermined location for a specific result, the probe need only be placed in the approximate center of the pipe, easy enough. With the expected temps the factory uses, one should be able to come close. Without them the system is useless without a bunch of other equipment (primarily o2 snifers) to know the expected temp at correct a/f ratio. Triumph would have to have the charts that would give the correct temps for idle, mid, and WOT in order to meet EPA regs. Correct?
 

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Yes, I follow your reasoning.

Wilcox did a lot of development work on the T3 series IIRC.
They would have had the information, I don't know if they would be able or willing to give the information.

I'll see if I can find their website...

Nige. :cool:
 

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I haven't messed with EGT, but I'd guess that if Triumph is using EGT for production setup it's only for adjusting the idle mixture screws before installing the EPA plugs.

It would make more sense to use a dyno for an end of production test to verify that the engine is operating properly since the carbs are pre-set by the makers. That would also verify the cam settings, ignition and the drive train condition.

I know EGT is used for setting up 2-strokes but that might be partly due to the large HC emissions that would foul an oxy sensor. That also works in racing situations since they're operating pretty much flat out.

As close as I've come to checking EGT is to look up the temperature at which chrome blues (about 900F) and figure I was running too lean! :-D

Jeez... Now you've got me thinking again.

There I was happily searching the internet for sights and grips for my Christmas present, contemplating the preparation of a batch of sushi for a party tomorrow... and you guys had to make me think. Talk about a buzz-kill! :wink:

Lemmie think about it a bit.

Jim
 

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Discussion Starter · #7 ·
There, that's a start. Awsome!! I'm going to look into this even if it's just an educational Adventure..(r). Besides, it's not like its a secret recipe. I just dont want to do all that math, and or test runs on a dyno to get these numbers. I think on average all motors produce about the same heat at idle and so on. The air to fuel ratio is determining the actual burn temp which is why the sensor cant touch any side of the pipe, at the same distance from the valve. From what I've found so far it's somewhere around 400 deg f. at idle and 12-13k deg f. WOT. These are the magic, mystical numbers I'm looking for. :ppcn:
 

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Discussion Starter · #8 ·
I must have been posting my last while you were Jim. I was going to mention that it was funny how the blue stops just at or below the EGT ports. This would be consistent because at high RPM's you would be making probably 1250 at the valve cooling as it makes the bend into the head pipe. It's kind of like an oxy-acedyline (spelling) torch. When you get the mix rich it burns cooler and yellow, lots of smoke. Dial in the ratio and you get perfect burn for a very powerful tool. The key it to get all three torches making the same heat. Combine this with a well maintained motor and it will run like butter and love you back for a long time. I guess this confirms it...I'm OCD about my bike. OK I said it. Besides it's food that kills the buzz, everyone knows that. :cool:
 

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Well, it's been about 20 years since I worked with thermocouples so let me 'think out loud' a bit:

The smaller the diameter of the thermocouple wires, the faster it will respond to changes in temperature.

The thermal inertia of the thermocouple will tend to 'round off' the measurement in a dynamic situation like engine exhaust -- the peak temp shown will never be the actual peak exhaust gas temperature.

The exhaust is vented for half of one crankshaft revolution on every second revolution, so the maximum duty cycle of the thermocouple would be 1/4 of the period of the crankshaft revolution.

So... the thermocouple output would represent the average heating on a 25% duty cycle.

As the rpm increases, the duty cycle would remain the same but the period would decrease. Thermal inertia would remain constant but since the heat pulses would be closer together, the average temperature read by the thermocouple would increase with rpm.


The major cooling of the exhaust gasses is the result of decompression -- compressed gasses cool as the pressure decreases, and that's why only part of the exhaust pipes turn blue. The pressure of the exhaust pulse decreases as it overcomes the inertia of the air column in the exhaust pipes.

That makes placement of the thermocouple a bit sensitive.


There's also the issue of cylinder filling prior to compression. More fill means more absolute compression (cylinder pressure vs. atmospheric pressure) and so a better fill would produce a higher temperature and a larger exhaust mass.

At an idle the fill is the minimum amount requred to keep the engine running but at full acceleration load the air-fuel mass is much larger, so that's going to introduce another variable in heating the thermocouple.


All in all, I'd say that thermocouple experiments might prove valuable but only as a 'relative' and non-absolute measurement.

It would be an interesting bunch of experiments! Exactly the kind of warped and twisted stuff (that nobody wants to hear about) but I enjoy! :-D


Good mental exercise, but now I need to get some physical exercise and practice my Weaver stance with a 3 pound hammer. Works well, but our stupid 'rescue' dog freaks out any time I pick anything that looks like it might be used to hit him. I think his previous owner needs a flaming turpentine enema, but then I'm not very PC. :wink:


Jim
 

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Discussion Starter · #11 ·
WOW :wow:

Now my buzz is gone. Odly enough it's the same twisted
***** I love to find out. My body may wear out, but my mind wont. All these things you describe have already been done by someone. It's probably written on the torn corner of someone's lunch bag, sitting in the bottom back corner of a drower. To be honest, trying to get absolute perfect a/f ratio is not the goal so much as tuning all three cyl's to be making the same power. After all, that's why they mount this stuff on race machines. The driver can see at a glance if he is running to lean or rich on any given cyl. I'm not saying that I plan on mounting one of these babies up, I would however us it as a shop setup tool. Anytime I tune, re-jet, sync, bla bla bla... A complete setup would run about 3 bills. Not cheap but not hugh either. Hang it on the bike for the afternoon and make some runs. Tweek as needed, take it off the bike until next I screw with my setup. :)

[ This message was edited by: ecrabbit96 on 2006-12-31 15:49 ]
 

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Right Jim,

Your brain has been working overtime on that...

Time to chill....Kick back and have a Beer or whatever.

Oh, and try not to freak the dog out!

Happy New Year to all!

Nige. :-D

[ This message was edited by: Ballacraine on 2006-12-31 16:10 ]
 

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All these things you describe have already been done by someone. It's probably written on the torn corner of someone's lunch bag, sitting in the bottom back corner of a drower.
Mostly it's in engineering lab books marked "Company Confidential: Dissemination Will Be Prosecuted" :-D

Try looking up BMEP. You might find some good info, but be sure to have your slide rule handy...

Jim
 

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Discussion Starter · #14 ·
Member Mikey put a link in the cam post that turns out to be a good start as well. Good call Mikey. If you check out the site it does not give any pricing but does reference a heat chart for placing the probes 5-6" from the exhaust port. Look at the installation guide. This is exactly what I need, but it has to be the expected temps at the locations chosen by Triumph. I'm sure the reading woud be fairly close, the actual temps would be my quest.Pro-flo.com
 
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